AIRC Radiology Dictionary — Library
Comprehensive A–Z radiology terminology and imaging signs. Concise, student-friendly definitions. Green-blue theme, card layout.
General Radiology Terminology (A–Z)
Ablation (Image-guided)
Minimally invasive treatment using heat (RFA/MWA) or cold (Cryoablation) to destroy tissue, guided by CT, US, or MRI.
Abscess
A localized collection of pus or infected material, often appearing hypodense with a rim of enhancement on CT/MRI, requiring drainage.
ADC Map (Apparent Diffusion Coefficient)
A quantitative MRI map derived from DWI, where low values indicate restricted water motion (e.g., acute stroke, high cellularity tumors).
Adenopathy
Enlargement of lymph nodes, often a sign of infection, inflammation, or malignancy; size and morphology are key imaging features.
Angiography
Radiologic technique for visualizing blood vessels after injecting contrast media, historically X-ray based, now often CTA or MRA.
Anisotropy
Directional dependence of diffusion (DTI) or signal (MSK MRI) in structured tissues like white matter or tendons; an artifact if misinterpreted.
Aortography
Angiographic study specifically focused on the aorta to evaluate for aneurysm, dissection, or stenosis.
Artifact (Motion)
Blurring or ghosting on an image caused by patient movement during acquisition, especially critical in MRI and long CT scans.
Asbestosis
Lung disease caused by asbestos inhalation, characterized by pleural plaques, parenchymal fibrosis, and honeycomb lung on HRCT.
Asymmetry
Difference in size, shape, or density/signal between paired organs or corresponding parts of the body, often an important sign of pathology.
Backscatter
Radiation or acoustic energy reflected backward toward the source, a component of image formation, especially in ultrasound.
Base of Skull
Complex bony region separating the brain from the neck and face; critical area for tumor extension and fracture assessment.
Benign
Non-cancerous; imaging features suggesting a low risk of malignancy (e.g., smooth borders, lack of growth, characteristic internal features).
Biliary Atresia
Congenital blockage of the bile ducts; diagnosed by US/MRCP and critical to detect early in neonates.
Blunt Trauma
Injury caused by impact without penetration; requires rapid imaging (CT/FAST US) to detect internal hemorrhage or organ damage.
Bowel Obstruction
Blockage of the small or large intestine, visualized by dilated loops of bowel and air-fluid levels on radiographs or CT.
Branching Opacities
Tubular opacities in the lung, typically seen in centrilobular distribution, often indicative of chronic bronchitis or infection.
Bronchiectasis
Irreversible widening of the bronchi, often associated with recurrent infection, seen as “tram tracks” or “signet rings” on CT.
Bursitis
Inflammation of a bursa (fluid-filled sac near a joint), appearing as a fluid collection on US or MRI.
Capsule (Fibrous)
A thin rind or border often surrounding benign lesions (e.g., simple cysts, certain adenomas), visible with contrast agents.
Carcinoid Tumor
A neuroendocrine tumor, often located in the small bowel or lung, with a characteristic intense enhancement pattern on contrast imaging.
Cavitation
Formation of a gas or fluid-filled space within a consolidation or mass, common in necrotizing infections or certain lung cancers.
Cerebral Edema
Swelling of the brain tissue, appearing as effacement of sulci and decreased gray-white differentiation on CT, or increased T2 signal on MRI.
Chondrocalcinosis
Calcification of cartilage, especially menisci or joint capsules, a sign of crystal deposition disease (Pseudogout).
Collateral Vessels
Accessory blood vessels that develop to bypass an obstruction, a key feature in chronic arterial or venous disease.
Congenital
A condition or anomaly present at birth (e.g., congenital heart disease, congenital lung airway malformation).
Consolidation (Lung)
Airspaces filled with fluid, pus, or cells, appearing as a dense, homogeneous opacity on CXR/CT that *does* obscure underlying vessels (unlike GGO).
Coronal Plane
A vertical imaging plane dividing the body into anterior (front) and posterior (back) portions.
Cyst
A fluid-filled sac with a thin, smooth wall; simple cysts are typically anechoic (US) or low-density (CT) with no enhancement.
Deconvolution
A mathematical technique used in perfusion imaging (CTP/MRP) to derive flow, volume, and mean transit time.
Diaphyseal
Pertaining to the shaft or central part of a long bone.
Diaphragm (Phrenic)
Musculotendinous partition separating the thoracic and abdominal cavities; assessed for elevation or rupture after trauma.
Diarthrodial Joint
A synovial joint, freely movable, commonly affected by arthritis; assessed for effusion, cartilage loss, and erosions.
Dichorionic
Referring to a twin pregnancy with two separate placentas (and two amniotic sacs), visible on prenatal ultrasound.
Digital Subtraction Angiography (DSA)
X-ray technique that subtracts a “mask” image without contrast from images with contrast, to clearly visualize vessels by removing bone/soft tissue.
Doppler Effect
The change in frequency of ultrasound waves reflected off moving blood cells, used to assess blood flow direction and velocity.
DR (Digital Radiography)
Modern X-ray technique using flat-panel detectors for immediate digital image acquisition without a cassette.
Duct Ectasia
Dilatation of a duct (e.g., bile duct, pancreatic duct, breast duct), a common finding that may indicate obstruction or inflammation.
Dysplasia (Skeletal)
Abnormal development or growth of bone, often involving multiple bones, as seen in skeletal dysplasias.
Effacement
Obliteration of a normal tissue boundary or contour (e.g., loss of fat planes surrounding an inflamed appendix).
Embolism
Obstruction of a blood vessel by a traveling mass (embolus), such as a clot (PE) or fat/air, requiring rapid diagnosis via CTA/V/Q scan.
Embolization (Therapeutic)
Minimally invasive procedure to intentionally block a blood vessel to treat bleeding, aneurysms, or to starve a tumor.
Emphysema
Permanent enlargement of airspaces distal to the terminal bronchiole, seen as low-attenuation (dark) lung parenchyma on CT.
Endovascular
Pertaining to procedures performed within a blood vessel, a major part of interventional radiology (e.g., stenting, coiling).
Epidural Hematoma
Collection of blood between the dura mater and the inner surface of the skull, typically lens-shaped on CT, a neurosurgical emergency.
Epiphysis
The end part of a long bone, which is initially separated from the main bone by cartilage (the growth plate).
Erosion (Bone)
Focal loss of bone or cartilage, commonly seen at joint margins in inflammatory arthritis.
Exophytic
Growing outward from an organ surface (e.g., an exophytic renal mass).
Extra-axial
Lesion located outside the brain parenchyma (e.g., subdural hematoma, meningioma).
FAST Exam (Focused Assessment with Sonography for Trauma)
A quick, bedside ultrasound scan used in trauma to check for free fluid (blood) in the abdomen/pericardium.
Fat Saturation (Fat-Suppression)
MRI technique that nulls the signal from fat, making fluid/edema/lesions more conspicuous on T2 or post-contrast T1 images.
Fibrin Sheath
A layer of fibrin surrounding a vascular access catheter, which can cause catheter malfunction or occlusion.
Fibrosis
Replacement of normal tissue with scar tissue, often seen in the lung (pulmonary fibrosis) or liver (cirrhosis) on CT/MRI.
Field of View (FOV)
The physical area covered and displayed in the final image; affects resolution and patient coverage.
Fistula
An abnormal tract connecting two epithelialized surfaces (e.g., bowel to bladder), demonstrated by contrast on fluoroscopy or CT.
Focal Lesion
A localized, circumscribed abnormality, as opposed to a diffuse process.
Fractionation
In radiation therapy, the delivery of the total radiation dose in multiple smaller doses over time.
Free Air (Pneumoperitoneum)
Gas within the peritoneal cavity, usually indicating perforation of a hollow viscus (e.g., bowel), a surgical emergency.
Fusion Imaging
Combining images from different modalities (e.g., PET/CT, SPECT/CT, or US/MRI) to leverage the strengths of each.
Gamma Camera
Detector used in Nuclear Medicine (SPECT) to capture radiation from injected radiotracers, forming a functional image.
Gating (Cardiac/Respiratory)
Technique used in CT/MRI to acquire images at a specific phase of the cardiac or respiratory cycle to minimize motion artifact.
GERD (Gastroesophageal Reflux Disease)
Backward flow of stomach contents into the esophagus, sometimes demonstrated by fluoroscopic barium swallow study.
Glomerular Filtration Rate (GFR)
A measure of kidney function; important for assessing risk before administering iodinated contrast or Gadolinium.
Glioblastoma (GBM)
The most common and aggressive primary malignant brain tumor in adults, typically showing ring enhancement and central necrosis.
Ground-Glass Hepatocytes
Term sometimes used on MRI to describe the signal pattern of hepatocellular carcinoma (HCC) or adenoma.
Helical (Spiral) CT
A CT scanning technique where the patient moves continuously through the gantry while the X-ray tube rotates, allowing faster, volumetric acquisition.
Hemangioma
A common benign vascular tumor, often in the liver, with characteristic imaging features (e.g., peripheral nodular enhancement, “lightbulb” T2 signal).
Hematoma
A localized collection of clotted blood outside of blood vessels; its appearance changes over time on CT/MRI.
Hepatocellular Carcinoma (HCC)
Primary liver cancer; typically demonstrates arterial hyperenhancement followed by “washout” in the portal venous phase.
Heterogeneous
Non-uniform or varied in composition, density, or signal intensity (e.g., a complex, heterogeneous mass).
Hilum
The area where structures (vessels, nerves, ducts) enter or exit an organ (e.g., pulmonary hilum, renal hilum).
HRCT (High-Resolution CT)
A CT technique using thin slices and high-spatial-frequency reconstruction, primarily for detailed assessment of lung parenchyma.
Hydrosalpinx
Fluid accumulation in a fallopian tube, appearing as a tubular, anechoic/hypoechoic structure in the pelvis on US/MRI.
Hyperdense
Area of high attenuation (bright) on CT relative to adjacent tissue (e.g., acute hemorrhage, dense bone).
Hypoechoic
Ultrasound appearance: darker than surrounding tissues (low echo amplitude), suggesting less density or more fluid.
Infarcation (Infarct)
Tissue death (necrosis) caused by lack of blood supply (ischemia); appears as a wedge-shaped or focal area of hypoperfusion.
Infiltrate (Pulmonary)
A general term for an opacity in the lung that can represent pneumonia, edema, or hemorrhage.
Internal Derangement
Damage to the non-bony structures within a joint (e.g., meniscal tear, ligament rupture).
Intra-axial
Lesion originating from or located within the brain parenchyma (e.g., glioma, intraparenchymal hemorrhage).
Intraperitoneal
Located within the peritoneal cavity (the space containing most abdominal organs).
Intussusception
Telescoping of one segment of bowel into an adjacent segment; classic “target sign” on US/CT, common in pediatrics.
Inversion Recovery
A type of MRI pulse sequence (e.g., STIR, FLAIR) that uses an initial 180° pulse to null the signal from a specific tissue (fat or fluid).
Ionizing Radiation
Radiation with enough energy to remove electrons from atoms (X-rays, gamma rays); used in X-ray, CT, and Nuclear Medicine.
Irradiation
Exposure to ionizing radiation, either in a controlled therapeutic setting (radiotherapy) or accidental exposure.
Jejunostomy Tube (J-tube)
A feeding tube inserted directly into the jejunum (small intestine), placement confirmed via fluoroscopy or X-ray.
Junction (Gray-White)
The boundary between the cerebral cortex (gray matter) and the subcortical white matter; important area for subtle pathology like hemorrhage or early stroke.
Juvenile Idiopathic Arthritis (JIA)
A group of arthritides in children; imaging shows joint effusion, synovial thickening, and early erosions.
KUB (Kidneys, Ureters, Bladder)
A plain abdominal X-ray, typically used as a scout film or to look for large calcifications/foreign bodies.
K-edge
The energy level where X-ray absorption abruptly increases for a given element (e.g., iodine, bone); exploited in dual-energy CT.
Kinematics
Study of motion, often applied to dynamic joint imaging (e.g., fluoroscopy of the wrist) to assess ligament stability.
Laminar Necrosis
A pattern of gray matter injury, often seen after hypoxic-ischemic insult, visible as linear hyperintensities on T1 MRI.
Ligament
A band of fibrous tissue connecting bones or supporting organs; assessed on MRI for tears or sprains.
Lipoma
A common, benign tumor composed entirely of mature fat cells, appearing uniformly fat-dense (CT) or T1 bright with fat saturation (MRI).
Liver Cirrhosis
Advanced scarring of the liver, resulting in a nodular contour, signs of portal hypertension, and increased risk of HCC.
Lobe (Anatomic)
A major subdivision of an organ (e.g., lung lobes, liver lobes), separated by fissures or planes.
Longitudinal Plane
An imaging plane parallel to the long axis of a structure (e.g., an artery or tendon), often used in ultrasound.
Lymphadenopathy (LAD)
See Adenopathy. A general term for disease or enlargement of the lymph nodes.
Malignancy
A cancerous tumor with features of aggressive growth and potential for metastasis (e.g., irregular borders, rapid growth, invasion).
Mammography
Low-dose X-ray imaging of the breast, used for cancer screening and diagnosis; primary modality for microcalcification detection.
Mass Effect
Displacement or compression of adjacent structures caused by an underlying lesion (e.g., a tumor or hematoma).
Matrix (Bone)
The uncalcified or calcified background material of bone; characteristic patterns (e.g., osteoid, chondroid) can help characterize bone tumors.
Mediastinum
The central compartment of the chest between the two pulmonary cavities, containing the heart, great vessels, trachea, and esophagus.
Meniscus
C-shaped cartilage in the knee joint; frequently torn, with tears best visualized on MRI.
Metaphysis
The widening part of the long bone near the growth plate (physis); common site for benign bone tumors and osteomyelitis.
Microcalcification
Tiny flecks of calcium, especially in the breast, that are highly important signs of potential malignancy on mammography.
MIP (Maximum Intensity Projection)
A volume rendering technique that displays the maximum voxel value along a ray, useful for visualizing bright structures (e.g., contrast-filled vessels, bone).
MRCP (Magnetic Resonance Cholangiopancreatography)
Heavily T2-weighted MRI sequence that visualizes the bile and pancreatic ducts without contrast, useful for stones/strictures.
Nephrogram
The phase of renal enhancement (CT/IVU) where contrast is uniformly distributed throughout the renal parenchyma before excretion.
Neurofibroma
A benign tumor of peripheral nerves, appearing as a fusiform, enhancing mass along the course of a nerve on MRI.
Necrosis
Cell death, often appearing as a non-enhancing, low-density/signal center within a solid mass after contrast administration.
Neoplasm
An abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of normal tissue; can be benign or malignant.
Noise (Image)
Graininess or random fluctuations in image signal, inversely related to dose/exposure and image quality; high noise obscures subtle findings.
Oblique Plane
An imaging plane cut at an angle that is neither axial, coronal, nor sagittal, often used to align with a specific anatomic structure.
Osseous
Pertaining to bone (e.g., an osseous lesion).
Osteomyelitis
Infection of the bone and bone marrow, often detected by signs of soft tissue inflammation, periosteal reaction, and abnormal marrow signal on MRI.
Ovarian Torsion
Twisting of the ovary on its vascular pedicle, a surgical emergency; Doppler US shows absent/reduced flow to the ovary.
Paramagnetic
Substances (like Gadolinium) that are weakly attracted to a magnetic field and are used as MRI contrast agents.
Parenchyma
The functional tissue of an organ (e.g., liver parenchyma, lung parenchyma) as opposed to its supporting connective tissue.
Partial Volume Artifact
Artifact caused by a structure occupying only part of the volume of a thick imaging slice, leading to averaging of signals and misrepresentation.
Pathognomonic
A sign or symptom that is specifically characteristic of a particular disease (e.g., the “target sign” of intussusception).
Pelvimetry
Radiographic measurement of the female pelvis to assess its capacity for childbirth, rarely performed today.
Perfusion Imaging
Techniques (CTP/MRP/Nuclear) used to measure blood flow (perfusion) through tissues, often used in brain or tumor assessment.
Periosteal Reaction
New bone formation by the periosteum (outer layer of bone) in response to injury, infection, or tumor.
Phlegmon
A diffuse, inflammatory soft-tissue process that has not yet formed a localized pus collection (abscess).
Pneumothorax
Air in the pleural space, collapsing the lung; seen as an absence of lung markings past the visceral pleural line on CXR/CT.
Pulse Sequence
A specific timing and ordering of radiofrequency and gradient magnetic field pulses in MRI that determines image contrast (T1, T2, PD, etc.).
Quality Factor (Q)
A factor used in radiation protection to relate the absorbed dose to the biological effect (e.g., X-rays have a Q of 1).
Radiosensitivity
The susceptibility of a tissue or tumor to damage by ionizing radiation, important for radiation oncology planning.
Reflux (Vesicoureteral)
Backward flow of urine from the bladder into the ureter/kidney, diagnosed by VCUG (voiding cystourethrogram).
Renal Cell Carcinoma (RCC)
The most common kidney cancer; often appears as an enhancing, heterogeneous mass, typically hypervascular.
Requisition
The paper or electronic order from a referring clinician detailing the study requested and the clinical question.
Retropneumoperitoneum
Gas within the retroperitoneal space, often from perforation of a retroperitoneal viscus (e.g., duodenum, colon).
Rupture
A complete tear of a tissue or organ (e.g., splenic rupture, Achilles tendon rupture), often resulting in surrounding hemorrhage.
Sagittal Plane
An imaging plane dividing the body into left and right portions; useful for spinal cord and joint assessment.
Scout View (Topogram)
The initial low-dose X-ray image taken by a CT scanner to plan the start and end points of the full scan.
Sclerosis (Bone)
Focal increase in bone density (brightness on X-ray/CT) due to increased calcification, typically in response to stress or benign process.
Septation
Thin internal walls or dividers within a fluid collection or cyst, suggesting complexity or infection.
Shunt (Ventriculoperitoneal)
A tube placed to drain excess cerebrospinal fluid from the brain ventricles to the peritoneal cavity; position confirmed by X-ray/CT.
Sinus Tract
A narrow channel leading from an abscess or infection to an epithelial surface, often demonstrated by contrast injection.
STIR (Short Tau Inversion Recovery)
An MRI sequence that uses an inversion pulse to suppress fat signal, very sensitive to pathology (edema, tumor) in fatty backgrounds.
Stenosis
Abnormal narrowing of a blood vessel or duct (e.g., spinal canal stenosis, renal artery stenosis), often measured by Doppler US or MRA/CTA.
SUV (Standardized Uptake Value)
A quantitative measure in PET imaging representing the concentration of radiotracer in a lesion relative to the injected dose and patient weight.
T2* Weighted Image
An MRI sequence (often GRE-based) highly sensitive to magnetic susceptibility effects, excellent for detecting hemorrhage, calcification, and iron deposition.
Teleradiology
The practice of interpreting medical images remotely from a location outside of where the images were acquired.
Tendon Sheath
A layer of synovial membrane that wraps around a tendon; inflammation (tenosynovitis) is seen as fluid around the tendon on US/MRI.
Teratoma
A tumor composed of various tissue types (e.g., fat, hair, teeth, bone); often identified by its heterogeneous nature on imaging.
Time of Flight (TOF) MRA
A non-contrast-enhanced MRI technique that visualizes blood flow based on the difference in signal between inflowing blood and stationary tissue.
Transducer (Probe)
The handheld device in ultrasound that generates and receives sound waves; categorized by shape (linear, curvilinear) and frequency.
Transesophageal Echocardiography (TEE)
An ultrasound study of the heart performed by placing a probe down the patient’s esophagus for closer visualization.
Unilateral
Pertaining to one side of the body only (e.g., unilateral pleural effusion).
Ureteropelvic Junction (UPJ)
The area where the renal pelvis (collecting system) connects to the ureter; a common site of obstruction (UPJ obstruction).
Vasospasm
Sudden narrowing of a blood vessel, often seen after subarachnoid hemorrhage, which can be monitored by transcranial Doppler US.
Ventilation Scan (V-scan)
The part of a V/Q scan where a radioactive gas or aerosol is inhaled to assess airflow in the lungs.
Vertebral Body
The weight-bearing, cylindrical front portion of a vertebra; common site for compression fractures and metastases.
VIP (Volume Imaging Protocol)
A term for advanced CT or MRI protocols that acquire very thin, contiguous slices, allowing for high-quality multiplanar and 3D reconstructions.
Wall Thickening
Abnormal thickening of the wall of a hollow viscus (e.g., bowel, gallbladder, bladder), indicating inflammation, infection, or tumor.
Washout (Contrast)
Rapid decrease in enhancement of a lesion on delayed post-contrast images; a key feature in characterizing some malignant tumors (e.g., HCC).
Wedge Biopsy
Surgical removal of a small, wedge-shaped piece of tissue; less common than image-guided needle biopsy.
Xenon-enhanced CT
An older technique using inhaled non-radioactive Xenon gas as an agent to measure cerebral blood flow via CT.
Xeroradiography
An outdated technique of plain film radiography using an electrostatic plate instead of film, primarily used in early mammography.
Yellow Marrow
Bone marrow composed primarily of fat; it is the normal marrow component in adult long bones, appearing T1 bright on MRI.
Z-score
A statistical measure indicating how many standard deviations a value is from the mean; used in bone density (DEXA) reporting.
Aberrant
Deviating from the normal course, size, or anatomical position (e.g., aberrant right subclavian artery).
Acoustic Shadowing
Ultrasound artifact: a dark area deep to a highly reflective, dense structure (e.g., gallstone, calcification) due to sound wave absorption.
Acute
Referring to a disease or condition that is of recent onset, typically hours to a few days.
Adnexal Mass
A mass or lesion located in the adnexa (ovary, fallopian tube, and surrounding connective tissues) of the uterus.
Agenesis
Complete failure of an organ or structure to develop (e.g., renal agenesis).
Air-Fluid Level
A horizontal interface between air (or gas) and fluid, typically seen in obstructed bowel or a complicated abscess on upright radiographs/CT.
ALARA (As Low As Reasonably Achievable)
The principle guiding radiation safety and dose minimization in all X-ray and CT procedures.
Amputation Neuroma
A painful, nodular proliferation of nerve tissue at the site of a nerve transaction; seen as a mass on US or MRI.
Anastomosis
A surgical or pathological connection created between two hollow structures (e.g., bowel loops, vessels).
Aneurysm
A localized, abnormal dilatation of a blood vessel (artery), usually due to weakness in the vessel wall.
Antegrade
Moving forward or in the normal direction of flow (e.g., antegrade pyelography).
Arterial Phase
The post-contrast CT/MRI timing (≈20-30s) when contrast is predominantly in the arteries and hypervascular tumors are best seen.
Arteriovenous Malformation (AVM)
A congenital tangle of arteries and veins without a capillary bed; highly vascular and prone to hemorrhage.
Arthrogram
An injection of contrast media into a joint (often followed by MRI or CT) to visualize joint capsule, ligaments, or cartilage.
Ascites
Abnormal accumulation of serous fluid in the peritoneal cavity, appearing anechoic (US) or low density (CT).
Atelectasis
Partial or complete collapse of a lung or lung lobe, seen as volume loss and increased density on CXR/CT.
Autofluorescence
Fluorescence emitted naturally by tissue when excited by light, sometimes used in optical imaging.
Background Parenchymal Enhancement (BPE)
Diffuse enhancement of normal breast tissue on contrast-enhanced MRI; its degree can influence breast cancer screening.
Barium Swallow
A fluoroscopic examination using barium contrast to evaluate the pharynx and esophagus for masses, strictures, or motility disorders.
Basal Ganglia
Deep nuclei of the brain (e.g., caudate, putamen, globus pallidus); common sites for stroke and degenerative diseases.
Bone Marrow Edema
Increased fluid within the bone marrow space, appearing bright on T2/STIR MRI, indicative of fracture, contusion, or inflammation.
BRTO (Balloon-Occluded Retrograde Transvenous Obliteration)
An interventional procedure to treat gastric varices by occluding and injecting a sclerosant into the shunting vein.
Bronchogram (Air)
The visualization of air-filled bronchi outlined by surrounding consolidated lung (fluid/pus/cells) on CXR/CT, a sign of consolidation.
C-arm
A fluoroscopic X-ray machine with a C-shaped arm, allowing for imaging from various angles, commonly used in IR and OR.
Cervical Spine
The upper seven vertebrae of the spine (C1-C7); imaged frequently for trauma, degenerative disease, and cord compression.
Chronic
Referring to a disease or condition that is long-standing or permanent, often with signs of scarring or remodeling.
Cirrhosis
See Liver Cirrhosis. Diffuse process characterized by fibrosis and the formation of structurally abnormal nodules in the liver.
Coiling (Endovascular)
Placing detachable platinum coils into an aneurysm or vessel to promote thrombosis and prevent rupture or hemorrhage.
Collimation
The process of restricting the X-ray beam to a defined area to reduce scatter and limit the radiation dose to the patient.
Complicated Cyst
A cyst with internal features like septations, thick walls, or solid nodules, suggesting infection, hemorrhage, or potential malignancy.
Coned Down View
A radiograph taken with the collimator tightened to focus on a small area of interest for greater detail.
Corpus Callosum
The large band of nerve fibers connecting the two hemispheres of the brain; assessed for lesions, atrophy, or agenesis.
Coup-Contrecoup
Pattern of brain injury with a lesion at the site of impact (coup) and another lesion on the opposite side of the brain (contrecoup).
CR (Conventional Radiography)
General term for basic X-ray imaging, including film and digital techniques.
Cryoablation
Image-guided procedure using extremely cold temperatures to freeze and destroy diseased tissue, often for kidney or lung tumors.
Dacryocystography
Fluoroscopic study of the tear ducts after contrast injection to evaluate for obstruction or leakage.
Delayed Enhancement
Enhancement of a tissue or lesion occurring minutes to hours after contrast injection, often seen in fibrotic tissue (e.g., cardiac scar, hemangioma).
Diastasis
Separation of two normally joined bones or muscles (e.g., pubic symphysis diastasis).
DICOM (Digital Imaging and Communications in Medicine)
The standard protocol for handling, storing, printing, and transmitting information in medical imaging.
Dissection (Vascular)
A tear in the inner lining of an artery (intima), allowing blood to flow into the wall and create a false lumen; diagnosed by CTA/MRA.
Dural Tail Sign
Thickening and enhancement of the dura mater adjacent to a mass, classic (though not exclusive) for meningioma on MRI.
Dysphagia
Difficulty swallowing, often investigated with a barium swallow/esophagram to look for strictures or motility disorders.
Ectopic
Abnormally located (e.g., ectopic pregnancy outside the uterus, ectopic kidney).
Edema
Swelling caused by excess fluid in the tissues, appearing as increased T2 signal on MRI or low density on CT.
Empyema
A collection of pus in a cavity, especially the pleural space, often showing a thickened, enhancing, split pleura on CT.
Endometrial Stripe
The thickness of the endometrium (lining of the uterus) measured on transvaginal ultrasound; critical for postmenopausal bleeding assessment.
Enhancement
Increase in tissue density (CT) or signal (MRI) after contrast administration, indicating increased blood flow or breakdown of the blood-brain barrier.
Enteritis
Inflammation of the small intestine, seen as bowel wall thickening and hyperenhancement on CT/MRI.
Epiphyseal Plate (Physis)
The growth plate in pediatric long bones; damage to this is critical in pediatric trauma imaging.
Exostosis (Osteochondroma)
A benign, bone-forming tumor that grows outward from the bone surface, with a continuous cortex and marrow space.
Extravasation
The leakage of injected contrast media from a blood vessel into the surrounding soft tissues, which can be an emergency.
Fascia
Layers of connective tissue that separate muscles and organs; thickening or blurring of fascia can indicate inflammation (fasciitis).
Fissure (Pulmonary)
The normal invaginations of the visceral pleura that divide the lungs into lobes; visible on CXR/CT.
FNAC (Fine-Needle Aspiration Cytology)
Image-guided procedure to obtain a sample of cells using a small needle for rapid diagnosis.
Frame Rate
The number of images acquired per second in real-time imaging (e.g., fluoroscopy, ultrasound), affecting the perception of motion.
Frostbite
Tissue damage due to freezing; imaging (angiography, MRI) is used to determine the extent of viable tissue.
Fusion (Spinal)
Surgical procedure to permanently join two or more vertebrae; assessed by CT/X-ray for complete bony bridge formation.
Gantry
The doughnut-shaped part of the CT or MRI scanner that houses the X-ray tube/detectors or the magnet/gradient coils.
Glioma
A tumor arising from the glial cells of the brain or spinal cord; varies widely in aggressiveness (e.g., GBM, astrocytoma).
Gonadal Shielding
Lead shielding placed over the gonads during X-ray procedures to minimize reproductive organ dose, especially in pediatrics.
Half-life (Physical)
The time it takes for half of the radioactive atoms in a radiotracer to decay; important for dose calculation in nuclear medicine.
Hemothorax
Collection of blood in the pleural space, often a result of trauma; seen as a dense fluid collection on CT.
Hydatid Cyst (Echinococcosis)
A parasitic cyst, often in the liver or lung, with characteristic internal features like daughter cysts or a detached membrane.
Hyperemia
Increased blood flow to a region, often due to inflammation, appearing as increased enhancement on contrast imaging or increased Doppler flow.
Hypodense
Area of low attenuation (dark) on CT relative to adjacent tissue (e.g., simple cyst, fat, chronic stroke).
Hypointense
Area of low signal intensity (dark) on MRI relative to adjacent tissue.
Hypoxic-Ischemic Encephalopathy (HIE)
Brain injury due to lack of oxygen and blood flow, with specific imaging patterns that vary with age (especially in neonates).
Iatrogenic
Resulting from the activity of a physician or treatment (e.g., iatrogenic vascular injury from a procedure).
Idiopathic
Of unknown cause (e.g., idiopathic pulmonary fibrosis).
Innominate Artery
The brachiocephalic artery, the first major branch off the aortic arch; assessed for stenosis or compression.
Insufficiency Fracture
A stress fracture in abnormally weakened bone (e.g., osteoporosis) caused by normal physiologic stress.
Invasion (Tumor)
The local extension of a malignant tumor into adjacent tissue or structures, a key sign of unresectability.
Ischemia
Insufficient blood supply to an organ or tissue, which can lead to infarction (e.g., acute stroke, bowel ischemia).
Juxtaposition
Placed side by side; often used to describe two structures lying unusually close to each other.
Kidney Stone (Nephrolithiasis)
A common cause of acute pain; appears hyperdense on non-contrast CT, the modality of choice for detection.
Kilohertz (kHz)
Unit of frequency; relates to the rate of sound wave cycles in ultrasound and radiofrequency pulses in MRI.
Klatskin Tumor
A cholangiocarcinoma (bile duct cancer) located at the confluence of the right and left hepatic ducts.
Laceration
A tear in solid organ tissue (e.g., liver or splenic laceration), often seen with a surrounding hematoma after trauma.
Lead Apron
Protective clothing worn by personnel in the room during fluoroscopy or angiography to shield against scatter radiation.
Linear Accelerator (LINAC)
A device used in radiation therapy to generate high-energy X-rays or electrons to treat tumors.
Limbus (Corneal)
The border between the cornea and the sclera of the eye; a landmark in ophthalmology and orbital imaging.
LIP (Lymphocytic Interstitial Pneumonia)
A form of interstitial lung disease characterized by peribronchovascular cystic spaces on HRCT.
Luminosity
Brightness of a structure; in Doppler, can refer to the intensity of the color/power signal.
MR Spectroscopy (MRS)
MRI technique that measures the concentration of different metabolites in a tissue, useful for characterizing brain tumors and differentiating causes of stroke.
Maximum Permissible Dose (MPD)
The largest dose of radiation that is considered acceptable for an individual in a given period.
Medulla
The inner portion of an organ (e.g., adrenal medulla, renal medulla) as opposed to the cortex (outer portion).
Meningioma
The most common benign tumor of the meninges (brain coverings); typically dural-based, avidly enhancing, and often shows a “dural tail.”
Mesentery
The fold of peritoneum that attaches the intestine to the posterior abdominal wall; assessed for edema, masses, or hemorrhage.
Metastasis
The spread of cancer cells from the primary site to a new, distant site (e.g., liver or bone metastases).
MRA (Magnetic Resonance Angiography)
A specialized MRI technique used to visualize blood vessels; can be performed with or without Gadolinium contrast.
Mucinous Cystic Neoplasm (MCN)
A potentially malignant tumor of the pancreas or other organs that contains mucin (thick, gel-like fluid).
Multicentric
Referring to a disease or tumor that arises in two or more distinct locations within the same organ.
Nephrogenic Systemic Fibrosis (NSF)
A rare, severe reaction in patients with severe renal failure to certain types of Gadolinium contrast agents, causing fibrosis of the skin and internal organs.
Neuroblastoma
A highly malignant tumor of the sympathetic nervous system, most common in children, often arising in the adrenal gland.
Nidus
The core or focus of a pathological process, often used to describe the small, central core of a benign bone tumor (Osteoid Osteoma).
Null Point
In Inversion Recovery MRI, the time (tau) at which a specific tissue’s net magnetization passes through zero, allowing its signal to be nulled.
Occlusion
Complete blockage of a vessel (e.g., artery, vein, duct) due to thrombus or mass.
Oncocytoma
A benign kidney tumor; can sometimes be differentiated from cancer by characteristic central scar and imaging features.
Optic Nerve Sheath Complex
The optic nerve surrounded by its dural sheath; assessed for swelling, masses, or inflammation.
Organizing Pneumonia
A pattern of lung inflammation and repair (formerly BOOP) that presents as patchy or peribronchial consolidation on CT.
Osteonecrosis (Avascular Necrosis, AVN)
Bone death due to impaired blood supply, most commonly affecting the femoral head; characteristic crescent sign on X-ray/MRI.
Palliative
Treatment aimed at relieving symptoms and improving quality of life, rather than curing the disease (e.g., palliative stenting).
Pancreatitis
Inflammation of the pancreas, seen as diffuse edema, peripancreatic fluid, and enhancement changes on contrast CT/MRI.
Pathology
The medical specialty concerned with the causes and effects of diseases; the final diagnostic step after imaging-guided biopsy.
Pericardial Effusion
Fluid accumulation in the sac surrounding the heart (pericardium); assessed by US (Echocardiography), CT, or MRI.
Phlebitis
Inflammation of a vein, often leading to thrombosis (thrombophlebitis).
PI-RADS (Prostate Imaging Reporting and Data System)
A standardized scoring system used to report and assess the likelihood of clinically significant prostate cancer on MRI.
Pneumobilia
Gas (air) within the bile ducts, usually due to communication between the biliary system and the GI tract.
Posterior Reversible Encephalopathy Syndrome (PRES)
A clinical-radiological syndrome of posterior brain edema, classically T2 hyperintense and reversible, often related to hypertension.
Prosthesis
An artificial replacement for a missing body part, such as a joint replacement or a vascular graft; assessed for complication.
Pulmonary Edema
Fluid in the air sacs and interstitial tissues of the lungs, often cardiac-related, presenting as diffuse lung opacities with Kerley B lines on CXR.
Quadrilateral Space
An anatomic space in the shoulder/armpit region, assessed for nerve or vessel compression (Quadrilateral space syndrome).
Radiofrequency Ablation (RFA)
Image-guided procedure using heat generated by high-frequency radio waves to destroy small tumors.
Radiology Information System (RIS)
A networked software system used for managing image orders, scheduling, reporting, and patient tracking in a radiology department.
Reflectivity
The ability of a surface or tissue to reflect sound waves (echogenicity) or radio waves (signal intensity).
Resection
Surgical removal of an organ or part of an organ (e.g., tumor resection); follow-up imaging is critical.
Resolution (Spatial)
The ability to distinguish between two close-together objects on an image; measured in line pairs per millimeter.
Retrograde
Moving backward or against the normal direction of flow (e.g., retrograde pyelography, retrograde venography).
Rib Notching
Erosion of the inferior margins of the ribs, typically caused by dilated intercostal arteries collateralizing around an aortic coarctation.
Ring Enhancement
A pattern of enhancement where the center of a lesion is non-enhancing (necrotic/cystic) and the border enhances; seen in abscesses, gliomas, and metastases.
Salter-Harris Fracture
A classification system used for fractures involving the growth plate (physis) in pediatric long bones.
Scatter Radiation
X-rays that deviate from their straight path after interacting with the patient, contributing to image noise and personnel dose.
Scintigraphy
General term for nuclear medicine imaging that uses a gamma camera to create 2D images of radiotracer distribution.
Sella Turcica
The depression in the sphenoid bone that houses the pituitary gland; assessed for tumors (pituitary adenoma).
Semi-recumbent
Position where the patient is lying down but with the head and chest slightly elevated; used for certain CXR/abdomen views.
Sequelae
Pathological conditions resulting from a prior disease or injury (e.g., scarring is a sequelae of a burn).
Shading (Ultrasound)
A subtle, low-level echo pattern within a cystic structure on US, often seen in endometriomas due to protein/blood products.
SNR (Signal-to-Noise Ratio)
The ratio of meaningful signal to random background noise; higher SNR means better image quality, often at the expense of acquisition time or dose.
Soft Tissue Window
A specific range of Hounsfield Units (CT window setting) used to optimally visualize soft tissues and organs.
Splenomegaly
Abnormal enlargement of the spleen, often a sign of underlying systemic disease, portal hypertension, or infection.
Stent
A small tube placed into a vessel or duct to keep it open (e.g., coronary stent, biliary stent), a key IR procedure.
Target Sign (Bowel)
The classic concentric ring pattern seen on cross-sectional imaging (US/CT) in cases of intussusception or severe bowel wall thickening/edema.
Tension Pneumothorax
A life-threatening condition where air in the pleural space cannot escape, causing lung collapse and mediastinal shift; a clinical diagnosis but seen on CXR/CT.
Terahertz Imaging
An experimental imaging modality using non-ionizing terahertz waves, with potential applications in dermatology and breast imaging.
Tethered Cord
A congenital condition where the spinal cord is abnormally attached to surrounding structures (e.g., a fatty filum terminale), leading to stretch injury.
Thoracentesis
Image-guided procedure to aspirate (remove) fluid from the pleural space for diagnostic or therapeutic purposes.
Tracheostomy Tube
A tube placed into the trachea through the neck; position and potential complications (e.g., pneumothorax) are assessed by CXR/CT.
Transarterial Chemoembolization (TACE)
IR procedure to inject chemotherapy agents and embolic particles directly into the artery supplying a tumor (typically liver cancer).
Transjugular Intrahepatic Portosystemic Shunt (TIPS)
IR procedure to create a shunt within the liver to relieve portal hypertension; patency assessed by Doppler US.
Unilocular
Consisting of a single cavity or space (e.g., a simple unilocular cyst).
Ureteric Stent
A tube placed in the ureter (the tube connecting the kidney to the bladder) to maintain patency and allow urine flow.
Urticaria
Hives; a common, mild allergic reaction to contrast media that may precede a more severe anaphylactic reaction.
Vallecula (Epiglottic)
The space between the base of the tongue and the epiglottis; assessed for retained secretions or masses.
Varices
Abnormally dilated veins, typically due to portal hypertension, seen around the esophagus (esophageal varices) or stomach (gastric varices).
Ventriculomegaly
Abnormal enlargement of the fluid-filled spaces (ventricles) within the brain, indicating hydrocephalus or atrophy.
Vascular Ring
A congenital anomaly of the aortic arch/great vessels that forms a ring around the trachea/esophagus, potentially causing compression.
Water Density
CT density equal to zero Hounsfield Units (HU), typical of simple fluid (e.g., urine, CSF, simple cyst).
White Matter Disease
General term for pathology (e.g., microvascular ischemia, demyelination) affecting the white matter tracts of the brain, seen as T2 hyperintensities.
Xenograft
Tissue or organ graft from a different species; imaging is used to assess its integrity and function.
Yttrium-90 (Y-90)
A radioactive isotope used in radioembolization (SIRT) for the treatment of liver tumors.
Z-plane
The longitudinal axis (head-to-toe) in cross-sectional imaging (CT/MRI), perpendicular to the axial plane.
Zonal Anatomy
The division of an organ (especially the prostate and breast) into different functional or embryological regions, used for standardized reporting.
Acoustic Enhancement
Ultrasound artifact: a bright area deep to a structure that transmits sound well (e.g., simple cyst) due to less attenuation.
Adrenal Gland
Endocrine gland located superior to the kidney; commonly imaged for adenomas (lipid-rich) and pheochromocytomas.
Air Gap Technique
Method used in radiography (historically in chest) where a gap between the patient and detector reduces scatter radiation.
Angioplasty
Interventional procedure to open a narrowed or blocked blood vessel, typically using a balloon catheter, often followed by stenting.
Annulus Fibrosus
The tough, outer fibrous ring of the intervertebral disc, assessed for tears that can cause disc herniation.
Aortic Dissection
A tear in the inner layer of the aorta, leading to a true and false lumen; an emergency diagnosis by CTA.
Appendicitis
Inflammation of the appendix, diagnosed by a dilated, non-compressible, enhancing appendix with surrounding fat stranding on US/CT.
Archiving
The long-term storage of digital medical images (DICOM files) in the PACS system.
Arteritis
Inflammation of an artery (e.g., Takayasu arteritis); diagnosed by wall thickening and enhancement on CTA/MRA.
Arthrography
A specialized X-ray or CT procedure where contrast is injected directly into a joint space to highlight soft tissue structures.
Asymptomatic
Presenting with no subjective signs or symptoms of disease, often requiring screening or incidental finding characterization.
Atherosclerosis
Hardening and narrowing of the arteries due to plaque buildup; assessed by degree of stenosis on CTA/MRA.
Baseline Study
The initial imaging exam used as a reference point for future follow-up studies to track changes in size or appearance.
Bi-RADS (Breast Imaging Reporting and Data System)
A standardized system for reporting mammography, ultrasound, and MRI findings, with categories from 0 (incomplete) to 6 (proven malignancy).
Blood Pool Agent
An MRI or Nuclear Medicine contrast agent that remains within the vascular space for a prolonged period, useful for vascular tumors and MRA.
Blunt Abdominal Trauma
Injury to the abdomen without open wound; evaluated primarily by FAST US and multiphasic abdominal CT.
Bone Scan (Nuclear)
A nuclear medicine study using a Tc-99m labeled phosphate tracer to evaluate the entire skeleton for metastases, infection, or occult fracture.
Brachytherapy
A type of radiation therapy where a radioactive source (seed) is temporarily or permanently placed directly inside or next to the area requiring treatment.
Breslow Thickness
The depth of invasion of a melanoma, measured pathologically, but imaging can determine clinical stage.
Bronchopneumonia
Pneumonia originating in the bronchi and bronchioles, spreading patchily through the adjacent lung parenchyma.
Calvarium
The dome or superior part of the skull, assessed for fractures or metastases.
Capillary Leak
Increased permeability of capillary walls, allowing fluid/protein/contrast to leak into the interstitial space (e.g., cerebral edema, enhancing lesions).
Cardiac MRI
Specialized MRI to evaluate the structure and function of the heart, including viability, function, and scar detection (LGE).
Cauda Equina
The bundle of nerve roots at the inferior end of the spinal cord; assessed for compression by disc herniation or mass.
Celiac Plexus Block
Image-guided injection of anesthetic/alcohol to block nerves near the celiac axis to treat chronic pain (e.g., from pancreatic cancer).
Cerebellar Tonsils
The most inferior part of the cerebellum; assessed for herniation (Chiari malformation).
Cholangiocarcinoma
Cancer of the bile ducts; typically appears as a mass with peripheral enhancement and delayed central filling.
Coarctation of the Aorta
Congenital narrowing of the aorta, usually near the ductus arteriosus insertion; diagnosed by CTA/MRA and associated with rib notching.
Cochlear Implant
An electronic medical device that provides a sense of sound to a person who is profoundly deaf; device artifact must be managed during imaging.
Contrast Nephropathy
Acute kidney injury following the administration of iodinated contrast media; risk is mitigated by proper screening and hydration.
Corpus Luteum Cyst
A normal, transient ovarian cyst formed after ovulation; often appears thick-walled and vascular on Doppler US.
Craniosynostosis
Premature fusion of the sutures of the skull; diagnosed by plain X-ray or dedicated cranial CT.
Cribriform Plate
Part of the ethmoid bone that separates the nasal cavity from the brain; fractures can lead to CSF leak.
Decompression (Surgical)
Relief of pressure on a structure (e.g., spinal cord, nerve root) by surgical removal of bone or mass.
Demyelination
Loss of the myelin sheath that insulates nerve fibers (e.g., Multiple Sclerosis); appears as focal T2 hyperintense lesions in the brain/cord.
DEXA (Dual-Energy X-ray Absorptiometry)
A non-invasive technique using two X-ray energies to measure bone mineral density (BMD) for diagnosing osteoporosis.
Diaphyseal Aclasis (Multiple Hereditary Exostoses)
A genetic disorder characterized by the presence of multiple osteochondromas.
Diverticulitis
Inflammation of a colonic diverticulum (outpouching), seen as focal wall thickening and surrounding fat stranding on CT.
Dopamine Transporter Scan (DAT Scan)
Nuclear medicine study (SPECT) used to evaluate the density of dopamine transporters in the brain, aiding in Parkinson’s disease diagnosis.
Ductography (Galactography)
A mammographic procedure where contrast is injected into a milk duct to identify the cause of nipple discharge.
Ectasia
Dilatation or distention of a tubular structure, often a vessel (e.g., aortic ectasia) or a duct.
Endoluminal
Located within the lumen of a tubular structure (e.g., an endoluminal stent).
Endophthalmitis
Inflammation of the internal structures of the eye; assessed by ultrasound/MRI for vitreous debris and retinal thickening.
Epididymitis
Inflammation of the epididymis; diagnosed by an enlarged, hyperemic (increased Doppler flow) epididymis on scrotal ultrasound.
Erlangen Scale
A scoring system used in MRCP to grade the degree of biliary dilatation.
Esophagram
See Barium Swallow. Fluoroscopic study of the esophagus.
Exclusion Criteria
Patient conditions or circumstances (e.g., severe renal failure) that prohibit or significantly increase the risk of an imaging procedure.
Exposure Time
The duration the X-ray tube is producing radiation; a key factor in calculating mAs and reducing motion artifact.
Fat Pad Sign (Elbow)
Displacement of the anterior or posterior fat pads of the elbow on a lateral radiograph, highly suggestive of an occult fracture.
Fibroadenoma
The most common benign breast tumor; typically seen as a smooth, oval, mobile mass on mammography/ultrasound.
Focal Nodular Hyperplasia (FNH)
A benign liver lesion; classically shows intense arterial enhancement with a non-enhancing central scar that enhances on delayed phases.
Foreign Body
Any material originating outside the body found in tissues or organs (e.g., aspirated food, surgical clip, bullet).
Four-dimensional (4D) CT/MRI
3D imaging acquired over time (the 4th dimension) to track motion (e.g., tumor breathing motion) or contrast kinetics.
Fungus Ball (Aspergilloma)
A mass of fungal hyphae within a lung cavity, often mobile and surrounded by air (air-crescent sign).
Gallbladder Hydrops
Extreme, tense overdistention of the gallbladder, often due to obstruction of the cystic duct.
Gastrointestinal Bleeding (GIB)
Hemorrhage in the GI tract; located/treated by Nuclear Medicine bleeding scan or interventional angiography/embolization.
Ghosting Artifact
Repetitive artifacts in the phase-encoding direction on MRI, caused by motion (breathing, swallowing, blood flow).
Grid (Radiography)
A device placed between the patient and the X-ray detector to absorb scatter radiation and improve image contrast.
Groove Pancreatitis
A rare form of chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum, and the common bile duct.
Gyri
The rounded, elevated ridges on the surface of the cerebral cortex; atrophy leads to widening of sulci and ventricles.
Hardware (Orthopedic)
Metallic plates, screws, rods, or wires used to fix a fracture or stabilize a joint; causes significant artifact on CT/MRI.
Hepatic Steatosis (Fatty Liver)
Abnormal accumulation of fat in the liver, appearing low density (CT) or with signal drop on opposed-phase MRI.
Hernia
Protrusion of an organ or tissue through an abnormal opening in the body wall (e.g., inguinal, umbilical hernia).
Hydrocele
A collection of fluid in the scrotum surrounding the testis; appears anechoic on ultrasound.
Hysterosalpingogram (HSG)
A fluoroscopic procedure where contrast is injected into the uterus to visualize the uterine cavity and fallopian tubes for fertility assessment.
Ileus
A functional, non-mechanical obstruction of the bowel due to paralysis of intestinal motility, often post-surgical.
Inclusion Cyst (Epidermoid)
A benign cyst lined with squamous epithelium, containing keratin debris; often bright on DWI MRI.
Infiltrative
Spreading into or through surrounding tissue in a diffuse, ill-defined manner (e.g., an infiltrative tumor).
Intercostal
Located between the ribs (e.g., intercostal nerve, intercostal space).
Intracranial Hypotension
Low cerebrospinal fluid (CSF) pressure, often causing symptoms; MRI findings include diffuse pachymeningeal enhancement and sagging brain.
Intra-luminal
Located inside a lumen (e.g., an intraluminal thrombus).
IVC Filter (Inferior Vena Cava Filter)
A device placed in the IVC to prevent pulmonary embolism from lower extremity DVT; placement checked by X-ray/fluoroscopy.
J-wire (Guide Wire)
A flexible wire with a curved tip, used in interventional procedures to safely navigate blood vessels and ducts.
Kerley B Lines
Short, horizontal lines seen at the lung periphery on CXR, representing thickened, edematous interlobular septa; a sign of pulmonary edema.
Kocher’s Point
A common entry point for ventricular catheters in the skull for hydrocephalus or intracranial pressure monitoring.
Large Vessel Occlusion (LVO)
A clot blocking a major cerebral artery (e.g., MCA, ICA), causing a large stroke; requires rapid diagnosis and often endovascular treatment.
Late Gadolinium Enhancement (LGE)
MRI technique where fibrotic (scarred) or inflamed myocardium retains Gadolinium contrast, making it appear bright on delayed images; gold standard for myocardial scar.
Left-to-Right Shunt
Abnormal blood flow from the left side of the heart to the right side (e.g., ASD, VSD); causes chamber enlargement and pulmonary hypertension.
Liquefaction
Conversion of solid tissue (e.g., a hematoma, abscess) into a liquid state, typically seen as a low-density/signal center.
Lung Nodule
A small, focal, round opacity in the lung parenchyma (typically <3 cm); requires follow-up based on size, morphology, and risk factors (Fleischner criteria).
Lymphocele
A collection of lymphatic fluid, typically caused by disruption of lymphatic channels after surgery or trauma; appears as a simple fluid collection.
Macrocyst
A breast cyst larger than 1.5 cm; easily palpable and assessed by ultrasound.
Magnetic Field Strength
Measured in Tesla (T), the power of the main magnet in an MRI scanner; higher field strength generally means better image resolution and SNR.
Mammotone Biopsy
A vacuum-assisted breast biopsy system that uses a large needle and a vacuum to obtain multiple tissue samples through a single skin incision.
Mantle Field
In radiation oncology, a large treatment field used for radiation therapy of supradiaphragmatic lymph nodes (e.g., in Hodgkin’s lymphoma).
Mediastinal Widening
Abnormal broadening of the central chest silhouette on CXR, often suggesting hemorrhage (aortic injury) or a large mass/adenopathy.
Meningitis
Inflammation of the meninges; classic finding on post-contrast MRI is leptomeningeal (sulcal) enhancement.
Microlobulated Margin
A margin with small, irregular undulations; a suspicious feature of a breast mass on ultrasound/mammography.
Minimally Invasive
Pertaining to procedures (e.g., IR procedures) that involve small incisions, resulting in less patient trauma and faster recovery.
Multifocal
Referring to multiple separate lesions of the same disease, confined to one organ or quadrant.
Myelopathy
Any functional disturbance or pathological change in the spinal cord; seen as cord signal change (T2 hyperintensity) on MRI.
Nephrostomy Tube
A tube placed percutaneously into the renal collecting system to drain urine, bypass an obstruction, or access the ureter.
Neurofibromatosis (NF)
Genetic disorders causing tumors to grow on nerve tissue; imaging features include optic pathway gliomas and numerous neurofibromas.
Non-Hodgkin Lymphoma (NHL)
A heterogeneous group of lymphoproliferative malignancies; imaging features vary widely but often involve bulky adenopathy and extranodal disease.
Nuchal Translucency (NT)
Measurement of the fluid space at the back of a fetal neck on first-trimester ultrasound; used as a screening tool for chromosomal anomalies.
Open Magnet
An MRI scanner design that does not completely surround the patient, used for claustrophobic patients or interventional procedures; typically lower field strength.
Opposed-Phase Imaging
A specialized GRE MRI sequence that is sensitive to the presence of microscopic fat within a lesion (e.g., adrenal adenoma, hepatic steatosis), which causes a loss of signal.
Osteochondritis Dissecans (OCD)
A condition where a fragment of bone and cartilage separates from a joint surface; assessed by X-ray/MRI.
Over-couch Tube
An X-ray tube mounted above the patient table (couch), used for most general radiography and fluoroscopy.
Pachymeningeal Enhancement
Enhancement of the dura mater (the thick, outermost layer of the meninges), often seen in spontaneous intracranial hypotension or post-dural puncture.
Pancreatic Divisum
A common congenital anomaly where the pancreatic ducts fail to fuse completely; can predispose to pancreatitis.
Pedicle (Spinal)
The bony bridge connecting the posterior arch to the vertebral body; assessed for bone destruction (mass) or fracture.
Perforator Vein
A vein that connects the superficial venous system to the deep venous system; assessed by ultrasound for incompetence (reflux).
Pericarditis
Inflammation of the pericardium; best evaluated by cardiac MRI for pericardial thickening and enhancement.
Phthisis Bulbi
A shrunken, non-functional eye, often due to severe trauma or disease, appearing small and disorganized on imaging.
Pilot Study
A preliminary study or scan used to test and optimize imaging parameters before the full-scale acquisition.
Pneumocystis Pneumonia (PCP)
An opportunistic infection in immunocompromised patients; classically causes perilobular, often upper-lobe predominant ground-glass opacity on HRCT.
Probe (MRI)
A non-imaging device (e.g., endorectal probe) used to improve signal homogeneity or receive signal from a specific area during an MRI.
Protocol (Imaging)
The specific, standardized set of imaging sequences, parameters, and post-processing steps used for a particular clinical question (e.g., Stroke Protocol, Liver Mass Protocol).
Pseudoaneurysm
A collection of clotted blood (hematoma) that communicates with an artery; often treated by US-guided thrombin injection or coil embolization.
Pulmonary Embolism (PE)
Blockage of one or more pulmonary arteries by a thrombus; diagnosed by the filling defect in the vessels on CT Pulmonary Angiography (CTPA).
Pyelonephritis
Infection of the kidney; seen as wedge-shaped areas of decreased enhancement and delayed nephrogram on contrast CT.
Quality Improvement (QI)
A systemic approach to continually reducing errors, waste, and variation in healthcare (e.g., reducing contrast reactions, improving turnaround time).
Radionuclide
A radioactive atom used as a tracer in nuclear medicine imaging (e.g., Tc-99m, F-18).
Rectal Contrast
Contrast agent (usually water-soluble or dilute barium) administered via the rectum to opacify the distal colon, often for CT appendicitis workup.
Refractory
Resistant to ordinary treatment; often leads to the use of more aggressive or interventional procedures.
Renal Angiomyolipoma (AML)
A benign kidney tumor containing fat, muscle, and blood vessels; diagnosed by its macroscopic fat content on CT/US/MRI.
Retinal Detachment
Separation of the retina from the underlying choroid; assessed by orbital ultrasound or MRI.
Retroperitoneal
Located in the space behind the peritoneum (e.g., kidneys, aorta, pancreas, most of the colon).
Rhabdomyosarcoma
A malignant tumor of skeletal muscle origin, common in pediatrics, assessed by MRI for extent and invasion.
Right-to-Left Shunt
Abnormal blood flow from the right side of the heart to the left side, often causing cyanosis; diagnosed by echocardiography/CTA.
Sarcoidosis
A multisystem inflammatory disease; characteristic imaging features include hilar and mediastinal lymphadenopathy and perilymphatic nodules in the lungs.
Septic Emboli
Small thrombi infected with bacteria that travel through the bloodstream, lodging in the lungs; appear as peripheral, often cavitating nodules on CT.
Shrapnel
Fragments of metal from an explosive device or projectile; causes severe artifact on imaging but MRI is generally safe if the fragments are small and non-ferromagnetic.
Signal Void
An area of extremely low signal intensity (black) on MRI, typically caused by rapidly flowing blood, metal, or air.
Simple Cyst
A benign, fluid-filled sac with no internal features (septations, solid components) and a thin, smooth wall; requires no follow-up.
Spiculation (Mass)
Sharp, linear lines radiating outward from the border of a mass, highly suggestive of malignancy (especially breast and lung cancer).
Spondylolisthesis
Anterior (forward) slippage of one vertebral body relative to the one below it, often due to degenerative change or fracture.
Subarachnoid Hemorrhage (SAH)
Bleeding into the subarachnoid space (where CSF flows), usually from an aneurysm rupture; diagnosed by hyperdensity in the cisterns/sulci on non-contrast CT.
Subdural Hematoma (SDH)
Collection of blood between the dura mater and arachnoid mater; typically crescent-shaped and conforms to the brain surface.
Sulci (Cerebral)
The grooves or depressions that mark the separation of the gyri on the surface of the brain; widened in atrophy.
Teleradiology
The practice of interpreting medical images remotely from a distant location.
Tenaculum
A surgical clamp used in hysterosalpingography to grasp the cervix and prevent contrast backflow.
Teratogen
An agent (e.g., radiation) that can cause a birth defect in a developing fetus; a concern for pregnant patients.
Tissue Harmonic Imaging (THI)
An ultrasound technique that uses the returning harmonic frequencies to create a cleaner image with reduced artifact and noise.
Total Body Irradiation (TBI)
A radiation oncology technique used before bone marrow transplantation to eliminate the patient’s existing marrow.
Transarterial Radioembolization (TARE)
See Y90 Radioembolization. Delivery of Y-90 microspheres via the hepatic artery to treat liver tumors.
Transluminal
Passing through the wall of a tubular structure, often used to describe a catheter access technique (e.g., transluminal biliary drainage).
TRUS (Transrectal Ultrasound)
Ultrasound performed with a probe in the rectum, primarily used for prostate imaging and biopsy guidance.
Tumor Bed
The area where a tumor was surgically removed; often assessed for recurrence by post-operative imaging.
Unenhanced
Refers to imaging performed without the use of intravenous contrast media (e.g., unenhanced CT).
Ureterocele
A ballooning-out of the lower end of the ureter into the bladder; appears as a focal cystic structure in the bladder on US/CT.
Vascular Access
Establishing a route to the bloodstream for long-term administration (e.g., PICC line, port-a-cath), often placed by interventional radiology.
Venography
X-ray or CT/MR imaging of veins after contrast injection, used to diagnose thrombosis or assess venous anatomy.
Vertebroplasty/Kyphoplasty
IR procedure to inject bone cement into a painful, collapsed vertebral body (compression fracture) for stabilization and pain relief.
Virchow’s Node
An enlarged, suspicious lymph node in the left supraclavicular fossa, sometimes the first sign of abdominal malignancy.
Volvulus
Twisting of a loop of bowel around its mesentery, causing obstruction and potential ischemia; signs include the “whirl sign” on CT.
Wartime Imaging
The distinct and challenging protocols and pathology encountered in military and austere medical settings.
Wipeout Artifact
Severe signal loss on MRI due to large metallic objects, completely obscuring the adjacent anatomy.
Xerostomia
Dry mouth, a common side effect of head and neck radiation therapy.
Young’s Syndrome
A syndrome associated with sinopulmonary infections and male infertility; lung findings include bronchiectasis.
Zonal Anatomy (Breast)
The division of the breast into three main layers (premammary, mammary, retromammary) for description of mass location.
Absorbed Dose
The amount of energy deposited by ionizing radiation per unit mass of an object (measured in Gray, Gy).
Acute Tubular Necrosis (ATN)
Intrinsic kidney injury that can be caused by severe contrast nephropathy; kidneys often appear normal on imaging.
Adhesion (Abdominal)
Bands of scar tissue that form between abdominal organs after surgery or infection; a common cause of small bowel obstruction.
Air Kerma
Kinetic Energy Released in MAss; a measure of radiation exposure at a specific point in the air, often used to track patient dose.
Alveolar Proteinosis
A rare lung disease where protein and lipids accumulate in the air sacs; classic CT finding is the “crazy-paving” pattern.
Amniocentesis
Ultrasound-guided procedure to withdraw a small amount of amniotic fluid for fetal testing.
Angiosarcoma
A rare, aggressive malignant tumor of vascular endothelial cells; highly variable appearance on imaging.
Anticoagulation
Medication (e.g., warfarin, heparin) used to prevent blood clot formation; a contraindication for many biopsy procedures.
Aorto-Iliac Occlusive Disease
Severe atherosclerosis blocking the distal aorta and iliac arteries; imaged by CTA/MRA for surgical planning.
Arachnoid Cyst
A benign, congenital, CSF-filled cyst located between the brain and the dura mater; follows CSF signal on all MRI sequences.
Atrophy
Decrease in size of an organ or tissue due to cell wasting (e.g., cerebral atrophy, renal atrophy).
Ball-Valve Lesion
A lesion (e.g., a thrombus or tumor) that intermittently obstructs the flow of fluid (e.g., in a ventricular foramen or bile duct).
Bilateral
Affecting both sides of the body (e.g., bilateral pleural effusions).
Boilerplate
Standardized, pre-written text used in radiology reports for common findings or technical descriptions.
Bone Mineral Density (BMD)
The mass of mineral per unit volume or area of bone, measured by DEXA scan.
Brain Death Protocol
A set of imaging studies (often CTA/MRA) performed to confirm the absence of cerebral blood flow in the setting of suspected brain death.
Breast Density
The amount of fibrous and glandular tissue relative to fat in the breast, categorized on mammography (A-D); higher density can mask cancer.
Bridging Veins
Veins that drain the surface of the brain and cross the subdural space to enter the dural sinuses; prone to rupture in trauma, causing SDH.
B-value (DWI)
A parameter in Diffusion-Weighted Imaging that determines the strength and timing of the diffusion gradients, affecting sensitivity to water motion.
Calcific Tendinitis
Calcium deposition within a tendon (most commonly the rotator cuff); appears as dense, amorphous calcification on X-ray/US.
Carcinomatosis (Peritoneal)
Widespread dissemination of cancer (often ovarian or GI) throughout the peritoneal surfaces, seen as nodular peritoneal enhancement.
Cavernous Malformation
A non-neoplastic, low-flow vascular lesion in the brain or spinal cord, typically appearing as a “popcorn” lesion with T2* blooming.
Choroid Plexus
Tissue within the ventricles of the brain that produces CSF; often calcified and can be a site of benign tumors (papilloma).
Colonoscopy (Virtual)
A non-invasive screening technique using low-dose CT to create 3D views of the colon to detect polyps or masses.
Conspicuity (Lesion)
The visibility or distinctness of a lesion against the background tissue; enhanced by contrast or specific pulse sequences.
Contour Abnormality
An irregular or non-smooth surface of an organ or mass (e.g., nodular liver contour in cirrhosis).
Cortex (Renal/Cerebral)
The outer layer of an organ (e.g., renal cortex, cerebral cortex) that contains the functional units (nephrons, neurons).
Cuff Tear (Rotator)
A tear in the tendons of the rotator cuff (shoulder); diagnosed by US or MRI, often with fluid extending into the bursa.
Curvilinear Probe
A low-frequency ultrasound probe with a curved head, used for deep abdominal structures and general imaging.
Decay (Radioactive)
The spontaneous transformation of an unstable atomic nucleus, resulting in the emission of radiation; used to generate signal in nuclear medicine.
Dehiscence (Surgical)
A partial or complete separation of wound edges; assessed by imaging for underlying collection or hernia.
Density (Bone)
The concentration of mineral content in bone, measured quantitatively by DEXA (BMD) or qualitatively by X-ray/CT.
Double Density Sign (CXR)
A sign on a frontal chest X-ray indicating left atrial enlargement, where the left atrium is seen through the right atrium.
Duplex Ultrasound
A combination of B-mode (2D) ultrasound and Doppler (color/spectral) to assess both the anatomy and blood flow in vessels.
Echo Planar Imaging (EPI)
A very fast MRI acquisition technique used as the basis for DWI, fMRI, and perfusion studies; prone to susceptibility artifact.
Effective Dose
A calculated radiation dose that estimates the overall stochastic (cancer) risk to the whole body from a localized exposure (measured in Sieverts, Sv).
Ejection Fraction (EF)
The percentage of blood in the ventricle that is ejected with each beat; a critical measure of heart function, accurately assessed by cardiac MRI.
Embolic Protection Device
A filter or balloon placed in a vessel during angioplasty/stenting to prevent debris from traveling downstream and causing a stroke or infarct.
En-face View
An imaging projection or reconstruction where the observer is looking directly at the surface of a structure (e.g., a vessel ostium).
Enthesitis
Inflammation where a tendon or ligament attaches to bone (the enthesis); a key feature in seronegative spondyloarthropathies.
Extra-capsular
Located outside the joint capsule (e.g., an extra-capsular hip fracture).
Extramedullary Hematopoiesis (EMH)
Production of blood cells outside of the bone marrow, often appearing as paraspinous masses on CT/MRI in chronic anemias.
False Lumen
The abnormal channel created within an artery wall in a vascular dissection, carrying blood flow in parallel with the true lumen.
Femoral Head Slipped Epiphysis (SCFE)
Displacement of the proximal femoral growth plate; a pediatric hip condition diagnosed by X-ray.
Filtration (Beam)
The use of metal (usually aluminum) plates to remove low-energy X-ray photons from the beam, improving beam quality and reducing patient dose.
Focal Liver Lesion (FLL)
A general term for any localized abnormality in the liver (e.g., cyst, hemangioma, metastasis, HCC) requiring characterization.
Foramen Magnum
The large opening at the base of the skull through which the spinal cord passes; assessed for mass or herniation.
Fungemia
Fungal infection in the bloodstream, often leading to multiple tiny, enhancing lesions in the solid organs (e.g., candidiasis).
Gain (Ultrasound)
The electronic amplification of the received ultrasound echoes; adjusting it changes the overall brightness of the image.
Ghost Tumor
A mass visible on a prior study (e.g., PET) but not clearly seen on the current anatomical study (e.g., CT), often due to subtle infiltration.
Glottis
The part of the larynx consisting of the vocal cords and the opening between them; assessed by CT/MRI for tumor invasion.
Gradient Coils
Components in an MRI scanner that create temporary, variable magnetic fields, allowing for spatial localization of the MRI signal.
Hazy Border
An indistinct or blurry edge of a lesion, often a sign of infiltration or edema, particularly suspicious in breast masses.
HEART Score (CT)
A scoring system used to assess the severity of coronary artery disease from CTA, based on the number and extent of stenoses.
Heterotopic Ossification
Abnormal bone formation in soft tissues (e.g., muscle) after trauma or surgery; appears as dense, mature bone on X-ray/CT.
Histiocytosis (Langerhans Cell, LCH)
A rare group of disorders involving the proliferation of immune cells; classic findings include “punched-out” lytic bone lesions and cystic lung disease.
Honeycomb Lung
Cystic airspaces (traction bronchiectasis) representing end-stage lung fibrosis, typically seen subpleurally on HRCT.
Hyperacute
The earliest phase of a stroke (first few hours); DWI is positive, but T1/T2/CT may be normal or subtly abnormal.
Hypocellular
Low number of cells in a tissue; can lead to low signal on DWI (e.g., normal CSF, benign cyst).
Implant (Metallic)
A permanent metal object placed surgically (e.g., joint replacement, clips); its presence must be documented and managed in MRI.
Incidentaloma
A mass or lesion discovered unexpectedly during an imaging study performed for an unrelated reason (e.g., an adrenal incidentaloma).
Interdigitate
To interlock or overlap like fingers, used to describe the appearance of muscle fibers or serrated margins.
Intralobular Septal Thickening
Thickening of the delicate connective tissue within the lung lobule, seen in conditions like pulmonary edema or infection.
Inversion Time (TI)
The time delay between the 180-degree inversion pulse and the 90-degree excitation pulse in an Inversion Recovery MRI sequence.
Joint Effusion
Abnormal accumulation of fluid within a joint space (e.g., knee, shoulder), seen as distension of the joint capsule on US/MRI.
Kaposi Sarcoma
A vascular tumor associated with AIDS; may involve the skin, lymph nodes, or viscera (e.g., peri-bronchovascular nodules in the lung).
Koilocyte
A pathognomonic cell type for HPV infection, found in cervical cytology and pathology; not an imaging term but relevant for follow-up.
K-Space
In MRI, the data matrix where spatial frequency information is stored before Fourier transform converts it into the final image.
Laminotomy
Surgical removal of a small portion of the lamina (the posterior part of a vertebra) to relieve spinal cord or nerve root compression.
Lipid-Rich Adenoma
A benign adrenal tumor (adenoma) containing a high concentration of fat; diagnosed by signal drop on opposed-phase MRI or low HU on non-contrast CT.
Low-Attenuation
Having low density on CT (dark), typical of fat, air, or simple fluid.
Lung Abscess
A localized, necrotic infection in the lung, often appearing as a thick-walled cavity with an air-fluid level.
Lymphoma (Extranodal)
Lymphoma arising outside of the lymph nodes (e.g., gastric, thyroid, cerebral lymphoma); typically appears dense/isodense and restricts diffusion.
Mammary Gland
The functional glandular tissue of the breast; density of this tissue is a key factor in mammography screening.
Margin (Lesion)
The boundary or edge of a mass; descriptors like circumscribed, spiculated, or ill-defined are critical for characterization.
Meckel Diverticulum
A congenital outpouching of the small intestine; may contain ectopic gastric mucosa and cause GI bleeding, diagnosed by Meckel scan (Nuclear Med).
Mesothelioma (Pleural)
An aggressive cancer of the pleura, strongly associated with asbestos exposure; typically presents as diffuse pleural thickening and effusion.
Microadenoma (Pituitary)
A pituitary gland tumor less than 10mm; best seen on dynamic contrast-enhanced MRI as an area of relatively delayed enhancement.
Minimum Intensity Projection (MinIP)
A volume rendering technique that displays the minimum voxel value along a ray, useful for visualizing dark structures (e.g., air trapping in the lung).
MRA Time-Resolved
A dynamic MRA technique that acquires multiple, rapid vascular images over time to show the real-time flow and filling of vessels.
Multiple Sclerosis (MS)
An autoimmune demyelinating disease; characterized by multiple, ovoid, T2 bright white matter lesions in the brain and spinal cord, often periventricular.
Myelogram (CT/X-ray)
Imaging of the spinal cord and nerve roots after injecting contrast media into the subarachnoid space (CSF) via a spinal tap.
Nephroblastomatosis
Diffuse, multifocal remnants of embryonal renal tissue, often seen in the kidney prior to the development of a Wilms tumor.
Nipple-Sparing Mastectomy (NSM)
Surgical removal of breast tissue while preserving the nipple and areola; follow-up imaging is necessary for recurrence.
Non-Union (Fracture)
Failure of a fractured bone to heal completely after a prolonged period; assessed by CT or X-ray for lack of bony bridge.
Ortho-Voltaic X-rays
Low-energy X-rays used primarily in older radiation therapy techniques; contrast with high-energy megavoltage beams.
Osteochondroma
See Exostosis. A common, benign bone tumor arising from the external surface of a bone.
Osteogenesis Imperfecta (OI)
A genetic disorder characterized by brittle bones, leading to multiple fractures; diagnosed by X-ray.
Over-couch Technique
General X-ray imaging setup where the X-ray tube is positioned over the patient, and the detector is under the table.
Paracentesis
Image-guided procedure to aspirate (remove) fluid (ascites) from the peritoneal cavity for diagnostic or therapeutic purposes.
Pneumocephalus
Air within the cranial cavity, often due to trauma or surgery; appears as a very dark collection on CT.
Portal Hypertension
Abnormally high blood pressure in the portal venous system, often due to cirrhosis; leads to splenomegaly and varices.
Proton Density (PD) Weighted Image
An MRI sequence where the signal is primarily determined by the concentration of protons (water/fat); useful for joint and MSK imaging.
Pulmonary Hypertension
High blood pressure in the pulmonary arteries; signs on CT include a dilated main pulmonary artery and right heart chambers.
Punctate Calcification
Very small, dot-like calcifications, often a concerning finding in breast cancer if clustered or linear.
Rad
Radiation Absorbed Dose; an older unit for measuring absorbed dose, replaced by the Gray (Gy).
Radioactive Seed Localization (RSL)
A pre-operative procedure where a tiny radioactive seed is placed under image guidance to mark a non-palpable breast lesion for surgical removal.
Re-bleeding
Recurrent hemorrhage from the same site (e.g., aneurysm, GI tract); a serious complication assessed by angiography/CT.
Regeneration Nodule
A nodule of hyperplastic liver cells that forms in a cirrhotic liver; differentiation from HCC can be challenging.
Relative Biological Effectiveness (RBE)
A factor used in radiation biology to compare the biological effects of different types of radiation.
Renal Colic
Severe flank pain caused by the passage of a kidney stone (urolithiasis); diagnosed by non-contrast CT.
Retrospective Gating
Cardiac imaging technique where data is continuously acquired and then retrospectively sorted according to the ECG signal.
Rhinorrhea (CSF)
Leakage of cerebrospinal fluid through the nose, often due to a fracture of the cribriform plate; confirmed by CT/MR cisternography.
Sampling Error
The possibility that a needle biopsy missed the true pathology, especially in heterogeneous or small lesions.
Scrub (IR)
The sterile preparation and dress worn by interventional radiology personnel during a procedure.
Sentinel Lymph Node
The first lymph node to receive drainage from a tumor site; identified by nuclear medicine or dye injection prior to biopsy/surgery.
Sheath (Vascular)
A short, plastic tube with a valve placed into a blood vessel to allow multiple catheter exchanges during an IR procedure.
Sinus Tarsi
A small canal in the ankle/foot; assessed for fluid, inflammation, or tear (Sinus Tarsi Syndrome).
Spinal Cord Injury Without Radiographic Abnormality (SCIWORA)
Clinical findings of spinal cord injury despite normal initial plain X-rays and CT; often diagnosed by MRI.
Spine Segments
The division of the spine into cervical (C), thoracic (T), lumbar (L), sacral (S), and coccygeal regions.
Splenic Artery Aneurysm (SAA)
An abnormal dilatation of the splenic artery; the most common visceral artery aneurysm, often requiring embolization.
Stripping (Vein)
Surgical removal of a superficial varicose vein; increasingly replaced by endovenous ablation techniques (laser, RFA).
Stroke (Hemorrhagic)
Bleeding into the brain parenchyma; appears hyperdense on non-contrast CT in the acute phase.
Teleradiology
The practice of interpreting medical images remotely from a distant location.
Tenography
Contrast injection into a tendon sheath to evaluate for rupture or tenosynovitis.
Thallium Scan
Nuclear medicine study (SPECT) using Thallium-201 to assess myocardial perfusion and viability.
Time-Averaged Velocity (TAV)
The average velocity of blood flow over the cardiac cycle, measured by Doppler ultrasound.
Tomo-synthesis (Digital Breast)
A type of 3D mammography where multiple low-dose X-ray images are acquired at different angles and reconstructed into thin slices.
Tractography (DTI)
A 3D modeling technique based on Diffusion Tensor Imaging (DTI) that traces the white matter fiber pathways of the brain.
Transarterial Oily Chemoembolization (TOCE)
A variant of TACE where lipiodol (an oily contrast agent) is mixed with chemotherapy and delivered to the tumor.
True Lumen
The original, normal channel of a blood vessel in a dissection, in contrast to the false lumen.
Tuberculosis (Pulmonary)
Infection by *Mycobacterium tuberculosis*; imaging features vary (primary/post-primary) and include cavitation, tree-in-bud opacities, and adenopathy.
Under-couch Tube
An X-ray tube mounted beneath the patient table, typically used for fluoroscopy so the detector can be placed above the patient.
Urography (IVU)
Intravenous Urography (or Pyelography); a historical X-ray technique using IV contrast to visualize the renal collecting system and ureters.
Vascular Interventional Radiology (VIR)
The subspecialty of IR focused on the diagnosis and treatment of vascular diseases (e.g., angiography, stenting, embolization).
Vasculitis
Inflammation of the blood vessel walls; seen as vessel wall thickening and enhancement on CTA/MRA.
Vena Cava
The large veins (superior and inferior) that return deoxygenated blood from the body to the right atrium of the heart.
Ventriculostomy
Surgical or IR procedure to place a catheter into the brain ventricles to measure pressure or drain CSF (e.g., External Ventricular Drain, EVD).
Water-Soluble Contrast
Contrast agents (e.g., Gastrografin, Omnipaque) that dissolve in water, used for GI tract imaging when perforation is suspected.
Whipple’s Disease
A rare systemic bacterial infection; abdominal CT findings may include small bowel wall thickening and mesenteric adenopathy.
Xenon
A non-radioactive gas used experimentally in CT (Xenon-enhanced CT) or historically in lung ventilation studies.
Yolk Sac Tumor (Endodermal Sinus Tumor)
A malignant germ cell tumor, often in the testes or ovaries; imaging is used for staging and follow-up.
Zone of Transition (Bone Tumor)
The interface between a bone lesion and the adjacent normal bone; a narrow zone suggests a benign lesion, a wide zone suggests an aggressive/malignant one.
Common Imaging Signs (A–Z)
Air Bronchogram
Air-filled bronchi visible within consolidated lung tissue; classic for alveolar consolidation such as pneumonia.
Apple-Core Sign
Constriction of colon with shouldered edges on contrast study — suggests annular colorectal carcinoma.
Aunt Minnie
A pattern or image that is so characteristic and unmistakable that it is immediately recognized without need for differential diagnosis.
Acorn Cyst
Ovoid/round configuration of a simple renal cyst with a smooth, sharp margin.
Absent Scintigraphy Signal
Lack of tracer uptake in an area of a nuclear medicine study (e.g., cold nodule in thyroid scan).
Air Crescent Sign
A crescentic air collection surrounding an intracavitary mass (e.g., fungus ball, hematoma) in the lung.
Aortopulmonary Window Opacity
Filling of the space between the aorta and pulmonary artery, usually due to enlarged lymph nodes or mass.
Angiosome Mapping
Visualization of arterial territories and their collateral supply using CTA or MRA; critical for amputation planning.
Antler Sign
Appearance of prominent, branching pulmonary arteries due to pulmonary hypertension.
Ascending Venous Enhancement
Contrast reflux into the inferior vena cava from the renal veins due to increased pressure (e.g., right heart failure).
Bat-Wing Pattern
Perihilar alveolar opacities typically seen in cardiogenic pulmonary oedema.
Beaded Appearance
Alternating strictures and dilatations of a tubular structure (e.g., primary sclerosing cholangitis).
Bear Paw Sign
Multiple enlarged lymph nodes fused together with intervening low density/signal—seen in abdominal or thoracic lymphoma on CT/PET.
Blade-of-Grass Sign
Flame-shaped, V-shaped periosteal reaction extending toward the metaphysis—characteristic of Paget’s disease.
Blush (Capillary)
Faint, transient parenchymal enhancement seen on angiography or CT perfusion that outlines a vascular territory (e.g., renal cell carcinoma).
Bone-Within-Bone Sign
Dense lines of growth arrest or sclerotic contour seen within a vertebral body or long bone—seen in sickle cell, osteopetrosis, or treated leukemia.
Brim Sign (Pelvic)
Sclerotic thickening of the pelvic brim on radiograph/CT—also suggestive of Paget’s disease.
Bristle Brush Sign
MRI appearance of the corticospinal tracts in the pons/medulla due to atrophy and gliosis in Multiple System Atrophy (MSA).
Bubbly Appearance
Multiple small, internal lucencies within a mass on X-ray/CT—suggests mucinous or cystic nature (e.g., chondroblastoma, myxoid tumor).
Claw Sign
Organ parenchyma wrapping around a lesion, indicating origin from that organ (helps differentiate metastasis vs primary).
Calcified Rim
Peripheral calcification around a lesion suggesting chronicity (e.g., old granuloma, healed hematoma).
Crazy Paving
Ground-glass opacity combined with superimposed thickened interlobular septa on HRCT—seen in alveolar proteinosis, infection, or edema.
Comet Tail Sign (Lung)
Curved opacity extending from the pleura toward a mass or consolidation—suggests benign/fibrotic nature (e.g., rounded atelectasis).
Crescent Sign (AVN)
A subchondral radiolucent line on X-ray or MRI, indicating subchondral collapse in avascular necrosis (osteonecrosis), typically in the femoral head.
Crow’s Feet Sign
Branching radiolucent lines radiating from the hilum, seen on bronchography (obsolete) or HRCT, representing dilated bronchioles.
Cord Sign
Hyperdense appearance of the thrombus within a venous sinus on non-contrast CT—suggests acute cerebral venous sinus thrombosis.
Corkscrew Esophagus
Segmented, irregularly contracted esophagus seen on barium swallow—classic for diffuse esophageal spasm.
Coiled Spring Sign
Appearance of folded mucosa within the intussuscepted bowel on contrast studies or CT.
Coin Lesion
A solitary, well-circumscribed lung nodule seen on chest X-ray—requires CT for definitive characterization.
Collar Sign
Thickening or bulging of the colon wall around a lipoma, seen on CT colonography.
Cookie Cutter Lesion
A sharply demarcated lytic lesion in bone; suggests a benign process or specific infection (e.g., histiocytosis).
Double Bubble
Two adjacent gas-filled structures in neonatal abdomen—classic for duodenal atresia or proximal obstruction.
Double Density Sign
Two overlapping cardiac silhouettes suggesting left atrial enlargement on chest radiograph.
Doughnut Sign (Brain)
Appearance of a necrotic lesion with a surrounding ring of enhancement; non-specific but seen in abscesses, glioblastoma, or metastases.
Drooping Lily Sign
Inferior and lateral displacement of a ureter due to an obstructed upper pole moiety—seen in complete duplicated collecting system with ureterocele.
Dural Tail Sign
Thickening and enhancement of the dura mater adjacent to an extra-axial mass, suggestive of a meningioma.
Dirty Chest
Non-specific chest radiograph findings of increased linear opacities and subtle consolidation, often seen in chronic bronchitis.
Dagger Sign
A single, central, dense line of ossification within the interspinous ligaments of the spine, seen in ankylosing spondylitis.
Double Marginal Contour
Dual lines seen on CT/MRI of an aortic dissection, representing the intima and media (true and false lumen interface).
Double PCL Sign
Visualization of a folded or bucket-handle meniscal tear mimicking a second posterior cruciate ligament (PCL) on sagittal MRI.
Dry Tap
Failure to aspirate fluid during a biopsy or drainage procedure, suggesting the lesion is solid or highly viscous.
Empty Delta Sign
Central filling defect with peripheral enhancement in superior sagittal sinus on contrast imaging—suggests venous sinus thrombosis.
Eggshell Calcification
Thin, peripheral calcification in lymph nodes—classic but non-specific for silicosis or sarcoidosis.
Eiffel Tower Sign
Loss of the normal lumbar lordosis and visualization of the sacral spinous process on a pelvic radiograph—suggests osteopenia/osteoporosis.
Enlarged Cardiac Silhouette
Heart occupying more than 50% of the maximum thoracic width on a PA chest radiograph (Cardiomegaly).
Eye-of-the-Tiger Sign
Bilateral symmetric high signal in the globus pallidus on T2 MRI—seen in neurodegeneration with brain iron accumulation (NBIA) disorders.
Football Sign
Large pneumoperitoneum outlining the abdomen in neonates, resembling an American football.
Figure-of-3 Sign
A localized indentation of the aorta (pre- and post-stenotic dilatation) seen on X-ray/angiography—suggests aortic coarctation.
Filling Defect
An area within a contrast-filled structure (vessel, duct, hollow viscus) that lacks contrast—suggests thrombus, mass, or foreign body.
Flame Sign
A linear, flame-shaped pattern of bone destruction—suggests aggressive spread of a lesion (e.g., myeloma, metastasis).
Flip-Flop Sign
Appearance of air or fluid in a lesion that shifts position with patient rotation (e.g., fungal ball in a cavity).
Ground-Glass Opacity (Sign)
Hazy lung opacity on CT that partially obscures underlying vessels; seen in infection, inflammation, edema.
Gingko Leaf Sign
Segmental atrophy pattern in the liver after portal vein occlusion; less commonly used term.
Giant Cell Arteritis (Imaging Sign)
Long segment thickening and enhancement of a large artery wall (e.g., temporal or subclavian artery) on MRA/CTA.
Globus Pallidus Enhancement
Abnormal symmetrical enhancement of the basal ganglia—seen in carbon monoxide poisoning or metabolic disorders.
Goiter (Plunging)
An enlarged thyroid gland extending downward into the superior mediastinum.
Grey-Turner’s Sign (Imaging Correlate)
Hemorrhage in the flanks; CT/US shows fluid or blood in the retroperitoneum/flank soft tissues (e.g., severe pancreatitis, AAA rupture).
Gyral Enhancement
Serpentine enhancement following the folds (gyri) of the cerebral cortex—suggests subacute infarction, meningitis, or encephalitis.
Halo Sign
Ground-glass halo surrounding a pulmonary nodule on CT—seen in hemorrhage, angioinvasive infection, or neoplasm.
Horseshoe Kidney
Congenital fusion of lower poles of kidneys across midline; characteristic U-shaped appearance on axial imaging.
Hampton’s Hump
A peripheral, wedge-shaped opacity in the lung on CXR/CT—suggests pulmonary infarction due to pulmonary embolism.
Hanging Drop Sign
Contrast agent remaining suspended in a collection after drainage—suggests persistent communication (e.g., fistula).
Headlight Sign
Focal hyperostosis (bone thickening) on the inner table of the skull—non-specific, sometimes seen in meningioma.
High-Attenuation Lesion
A lesion that appears bright on non-contrast CT—suggests calcification, acute blood, or metal (e.g., renal stone).
Hilum Overlay Sign
Visualization of the hilar vessels through a central mass on CXR—indicates the mass is in the anterior or posterior mediastinum, not the hilum.
Hot Nodule
Area of increased radiotracer uptake in a nuclear medicine study—e.g., hyperfunctioning thyroid nodule on iodine scan.
Hyperdense MCA Sign
Increased attenuation (brightness) of the middle cerebral artery on non-contrast CT—suggests acute thrombus within the artery.
Island Sign
Small focus of enhancement within necrotic tumor on contrast studies—may indicate residual viable tumor.
Interrupted Aortic Arch
Complete discontinuity between the ascending and descending aorta; complex CHD diagnosed by CTA/MRA.
Irregular Margin
A border that is not smooth or sharply defined—a highly suspicious feature for malignancy (e.g., breast mass).
Ivory Vertebra
Uniformly dense, sclerotic vertebral body without collapse—seen in Paget’s disease or osteoblastic metastasis.
Jet Effect
High-velocity jet of contrast or blood creating focal artifact or flow-related appearance (seen on angiography/Doppler).
J-Sign (Patella)
The “J” shape formed by the patella as it tracks laterally during early knee flexion—indicates lateral patellar subluxation/maltracking.
Knuckle Sign
Angulated, obstructed bowel loop with abrupt change in lumen caliber — suggests closed-loop obstruction.
Kerley B Lines
Short, horizontal lines seen at the lung periphery on CXR/HRCT, representing thickened, edematous interlobular septa—classic for pulmonary edema.
Knot Sign
Twisted appearance of the sigmoid colon due to volvulus on plain film or CT.
Learning Curve (appearance)
Gradual change in radiologic appearance over serial imaging reflecting learning or evolution of treatment response—rarely used as a ‘sign’.
Lenk’s Triad (imaging correlate)
Clinical triad for splenic rupture with variable imaging signs: left upper quadrant pain, tenderness and hypotension—CT shows splenic injury.
Ligamentous Calcaneal Bridge
Bony bridging between the talus and calcaneus in the subtalar joint—a form of tarsal coalition.
Luftsichel Sign
A paramediastinal crescent of air surrounding the aortic arch—seen in left upper lobe collapse on CXR.
Linear Calcification
Thin, straight calcification, often seen in the walls of vessels (atherosclerosis) or ducts.
Loss of Silhouette Sign
A feature where an opacity obscures the border of an adjacent structure (e.g., right heart border obscured by right middle lobe consolidation).
Meniscus Sign
Concave superior margin of pleural effusion on upright chest radiograph forming a meniscus.
Milk-of-Calcium
Layering sediment of microcrystalline material in cystic lesion visible on decubitus radiographs/CT.
Mass Effect
Displacement or compression of adjacent structures by an underlying lesion (e.g., midline shift in brain, hydronephrosis in kidney).
Mosaic Attenuation
Patchwork of varying lung parenchymal density on CT—seen in mosaic perfusion (pulmonary hypertension) or air trapping.
Mushroom Cap Sign
Appearance of a stalked bone lesion where the cap is cartilage—characteristic of osteochondroma (exostosis).
Molar Tooth Sign
Midbrain anomaly (enlarged superior cerebellar peduncles) on axial MRI—classic for Joubert syndrome.
Nutmeg Liver
Mottled hepatic parenchymal enhancement pattern due to chronic passive congestion (cardiac failure).
Negative Predictive Value (Imaging)
High likelihood that a disease is absent when the imaging test is negative (e.g., negative D-dimer in PE).
Neonatal Bowel Gas Pattern
Distribution and amount of air in the GI tract of a neonate; highly variable and sensitive to pathology.
Nonspecific Enhancement
Diffuse, usually mild, enhancement pattern that doesn’t point to a specific pathology, often due to inflammation or early infection.
Onion-Skinning
Layered periosteal reaction producing concentric rings on bone imaging—seen in Ewing sarcoma and other conditions.
Open Ring Sign
Incomplete ring of enhancement on axial MRI in the brain—suggests demyelinating disease (e.g., Multiple Sclerosis).
Orbital Wall Fracture
Break in the thin bones surrounding the orbit (eye socket); may show “tear-drop” sign (herniated soft tissue) or air in the orbit.
Osseous Lesion (Blastic)
A bone lesion characterized by increased density (sclerosis) due to new bone formation.
Osteolytic Lesion (Lytic)
A bone lesion characterized by decreased density (radiolucency) due to bone destruction.
PTC Sign (Periportal Tracking)
Linear periportal low attenuation lines on CT—may indicate edema or inflammation in hepatitis/CHF.
Popcorn Calcification
Coarse, lobulated calcification pattern typical of degenerating pulmonary hamartoma or chondroid lesions.
Pancreatic Duck Sign
Appearance of the pancreas resembling a duck with a swollen head—seen in severe acute pancreatitis.
Pericardial Fat Pad
Fat collection adjacent to the heart; should not be mistaken for mass or effusion on CXR.
Phrygian Cap
A fold in the fundus of the gallbladder creating a cap-like appearance; a common congenital variant.
Pneumatosis Intestinalis
Gas within the wall of the small or large bowel; concerning for bowel ischemia/necrosis but can be benign.
Polypoid Defect
A round or lobulated filling defect protruding into the lumen of a contrast-filled viscus (e.g., gallbladder polyp, colon polyp).
Pseudokidney Sign
Appearance of thickened bowel wall resembling a kidney on ultrasound; seen in bowel wall inflammation or mass.
Pulmonary Artery Cutoff
Abrupt termination of a pulmonary artery branch—seen in pulmonary embolism or vasculitis.
Quadruple Wall Sign
Multiple concentric bowel wall layers on CT suggesting intussusception (rare descriptive term).
Quadrilateral Space Syndrome (Imaging)
Compression of the axillary nerve/posterior circumflex humeral artery; CTA/MRA may show vessel narrowing and post-stenotic dilatation.
Ring Enhancement
Peripheral enhancement around central non-enhancing area on contrast images — can indicate abscess, necrotic tumor or demyelination.
Radiating Spicules
Spiculated margins with radiating lines from a lesion — suspicious for malignancy in soft tissue or breast imaging.
Reversal of Flow
Blood flow direction opposite to the norm, seen on Doppler US/MRA—suggests severe stenosis or a vascular steal phenomenon.
Rib Notching
Erosion of the inferior margins of the ribs on CXR—classic for collateral vessels due to aortic coarctation.
Rim Sign (Renal)
Enhancement of the renal rim (capsule) in the setting of acute renal vein thrombosis or cortical necrosis.
Rodent Ulcer Sign
Small, irregular surface depression seen in basal cell carcinoma on soft-tissue imaging.
Rotator Cuff Tear (Imaging)
Non-visualization of the tendon, fluid signal within the tendon, or fluid tracking from the joint to the bursa on US/MRI.
Round Ligament of the Liver
The fibrous remnant of the umbilical vein; abnormal dilatation or enhancement may indicate portal hypertension.
Sunburst Appearance
Radiating periosteal reaction from bone lesion creating a sunburst pattern—associated with aggressive bone tumors like osteosarcoma.
String Sign
Thin contrast column in a narrowed bowel lumen—classically seen in Crohn’s disease strictures.
Starry Sky
Ultrasound pattern in liver with bright portal radicals against hypoechoic parenchyma—seen in acute hepatitis or lymphoma.
Steeple Sign
Subglottic narrowing on frontal neck radiograph—classic for croup in children.
String of Pearls
Multiple small gas-filled loops in small-bowel obstruction on upright radiograph—also describes polycystic ovarian sonographic appearance in other contexts.
Silhouette Sign (Positive)
Loss of the normal border between two structures of the same radiodensity (e.g., heart border loss with lung consolidation).
Single Bubble
One distended, gas-filled stomach bubble in a neonate—suggests pyloric or gastric outlet obstruction.
Snowstorm Appearance
Diffuse, tiny, miliary nodular opacities throughout the lungs—seen in miliary TB, fungal infection, or pulmonary metastatic disease.
Spine Sign (Thoracic)
Visualization of the normally obscured thoracic vertebral bodies on a lateral chest radiograph—suggests a lower lobe process (pneumonia, effusion).
Split Pleura Sign
Separation of the thickened visceral and parietal pleural layers by a fluid collection on CT—highly suggestive of an empyema.
Stacked Coin Appearance
Transverse mucosal folds of the small bowel resembling a stack of coins—seen in bowel wall thickening due to ischemia or edema.
Subpulmonic Effusion
A pleural effusion localized below the lung base, mimicking a raised diaphragm on CXR.
Swirl Sign
Whirlpool-like appearance of flowing blood or mesentery on Doppler US or CT—highly specific for a torsed pedicle (e.g., ovarian torsion).
Target Sign
Concentric rings on cross-sectional imaging indicating intussusception or rim-and-core hepatic lesions like metastasis with central necrosis.
Tree-in-Bud
Small centrilobular nodules with branching linear opacities on CT—represents endobronchial spread of infection or bronchiolitis.
Tram-Track Sign
Parallel linear opacities representing thickened, dilated bronchial walls on CXR/CT—classic for cylindrical bronchiectasis.
Thumbprint Sign
Focal, rounded thickening of the large bowel wall on plain film or contrast study—suggests ischemic colitis or acute epiglottitis (neck X-ray).
Too-Many-Tubes Sign
Presence of excessive or redundant central venous catheters/tubes on a single CXR—non-pathologic but indicative of critically ill status.
Traumatic Diaphragmatic Hernia (Imaging)
Visualization of abdominal contents (e.g., stomach, colon) herniating into the chest, often seen on CXR or CT.
Tunnel Vision
Narrowing of the imaging field of view (FOV) in a large area of pathology, potentially missing adjacent findings.
Uhl’s Anomaly (radiologic correlate)
Rare congenital absence of right ventricular myocardium; imaging shows thin-walled RV with dilatation—very uncommon.
Uncovering of the Talus
Increased separation between the talus and calcaneus on X-ray—suggests subtalar coalition.
Uptake on PET
Increased accumulation of radiotracer (usually FDG) in a lesion—suggests high metabolic activity (e.g., malignancy, inflammation).
Vessel Cutoff Sign
Sudden termination of an artery on angiography suggesting occlusion or embolus.
Vacuum Phenomenon
Gas within the intervertebral disc space or joint space, typically indicative of disc degeneration or severe osteoarthritis.
Venous Lakes
Multiple, small, slow-flowing venous collections seen on Doppler US, often in the liver in portal hypertension.
Ventriculomegaly
Dilatation of the cerebral ventricles, indicating hydrocephalus or atrophy.
Whirl Sign
Twisting of mesenteric vessels and bowel on CT suggesting volvulus or closed-loop obstruction.
Westermark Sign
Localized oligemia (decreased vascular markings) in a segment of lung on CXR—suggests pulmonary embolism.
Wet Read
Preliminary interpretation of a study performed immediately after acquisition (especially in emergency/trauma setting).
Worn-Down Joint
Irregularity, sclerosis, and loss of joint space on X-ray—a general term for advanced osteoarthritis.
Xanthoma Sign
Fatty deposits producing characteristic appearances in soft tissues or tendon sheaths on imaging—context dependent.
X-ray Beam Attenuation
The pattern of signal reduction as the X-ray beam passes through tissues; the basis of contrast on all X-ray-based modalities.
Y Sign
Y-shaped configuration seen in certain vascular or biliary branching patterns—used as descriptive shorthand.
Yin-Yang Sign
Biphasic color flow seen within a pseudoaneurysm or partially thrombosed vessel on Doppler ultrasound.
Zenker’s Diverticulum (Imaging Sign)
Posterior pharyngoesophageal outpouching seen with barium swallow presenting as contrast-filled pouch above the upper esophageal sphincter.
Zebra Stripes
Alternating bands of hypodensity and hyperdensity in a bone lesion—sometimes seen in growth disturbances or drug effects.
Air Fluid Level
A straight horizontal line between gas and fluid in a hollow viscus or cavity—suggests obstruction, abscess, or consolidation.
Accordion Sign
Marked thickening and folding of the colonic wall due to edema, resembling the bellows of an accordion—seen in pseudomembranous colitis.
Angled X-ray View
A non-standard radiograph taken with the tube angled to highlight a specific area, such as a fracture or joint space.
Apical Cap
Unilateral or bilateral thickening/fibrosis at the apex of the lung—non-specific, often post-inflammatory or due to old TB.
Arterial Flow Velocity
The speed of blood in an artery, measured by Doppler ultrasound; abnormal values indicate stenosis or increased flow (e.g., fistula).
Aortitis
Inflammation and wall thickening of the aorta, often seen on CTA/MRA in conditions like Takayasu arteritis.
Avascularity
Absence of blood flow or contrast enhancement in a region, often indicating infarction or avascular necrosis.
Band (Fibrous)
A thin, linear opacity representing scar tissue or an adhesion on cross-sectional imaging.
Basket Sign (Angiography)
Web-like appearance of vessels within a tumor on angiography, indicating hypervascularity (e.g., renal cell carcinoma).
Bilateral Hilar Adenopathy
Symmetrical enlargement of lymph nodes in both hila of the lungs—classic for sarcoidosis or berylliosis.
Black Bronchus Sign
An air-filled bronchus distal to a bronchial obstruction that is seen against surrounding lung collapse/consolidation.
Blow-out Fracture
A fracture of the orbit wall, typically the floor or medial wall, often causing periorbital emphysema.
Bone Bridge
Solid fusion of two adjacent bony structures, either naturally occurring or post-surgically planned.
Butterfly Vertebra
A midline coronal cleft in a vertebral body, giving it a butterfly appearance—a congenital anomaly.
Capillary Hemangioma (Imaging)
A highly vascular, often small lesion that shows intense, early, homogeneous enhancement on contrast studies.
Caudal Regression Syndrome
Underdevelopment of the lower spine, often resulting in a conical spinal cord termination (tethered cord).
Central Scar
A non-enhancing or delayed-enhancing fibrotic core within a mass (e.g., FNH, oncocytoma).
Chordoma
A malignant bone tumor arising from notochord remnants, classically at the clivus or sacrum; often shows characteristic T2 high signal and calcification.
Cingulate Herniation
Displacement of the cingulate gyrus under the falx cerebri due to mass effect.
Comet Tail Sign (US)
A form of reverberation artifact on ultrasound appearing as a hyperechoic V-shaped tail deep to a calcification (e.g., adenomyomatosis of the gallbladder).
Contusion (Pulmonary)
Hemorrhage within the lung parenchyma after trauma, appearing as poorly defined consolidation/GGO on CT.
Coronary Artery Calcification (CAC)
Calcified plaque within the coronary arteries, measured on non-contrast CT (Agatston Score) as a predictor of cardiovascular risk.
Cortical Blister
A small, subperiosteal fluid collection on bone surface, often seen in early osteomyelitis.
Dirty Fat Sign
Increased density or stranding within the fat surrounding an organ on CT—suggests inflammation (e.g., diverticulitis, appendicitis).
Displaced Fat Pad Sign
Elevation of fat pads around a joint (e.g., elbow, knee) due to joint effusion or hemarthrosis, indicating an occult fracture.
Diverticulum
A small, pouch-like herniation of the wall of a tubular organ (e.g., colon, bladder, esophagus).
Double Duct Sign
Simultaneous dilatation of the common bile duct and the pancreatic duct—highly suspicious for pancreatic head mass (cancer).
Double Track Sign
Two linear lucencies representing air in the submucosa of the bowel wall—seen in pneumatosis intestinalis.
Effacement of Cisterns
Loss of definition or obliteration of the normal CSF spaces (cisterns) around the brain stem—suggests diffuse cerebral edema or mass effect.
En-Plaque Enhancement
Diffuse, sheet-like enhancement along a serosal or pleural surface—seen in peritoneal carcinomatosis or mesothelioma.
Enterolith
A calcified concretion (stone) within the bowel lumen; may cause small bowel obstruction (gallstone ileus).
Erosion (Imaging)
Focal, discrete bone destruction at a joint margin, typically seen in inflammatory arthritis (e.g., Rheumatoid Arthritis).
Facet Joint Arthropathy
Degenerative changes (hypertrophy, effusion, vacuum phenomenon) in the small joints of the spine, often causing spinal stenosis.
Filling Defect (Cardiac)
Lack of contrast within a heart chamber or valve on CTA/MRI, suggesting thrombus (clot) or vegetation.
Fish-Mouth Sign (Spine)
Biconcave shape of the vertebral bodies due to disc space expansion—seen in osteoporosis or hyperparathyroidism.
Fluoroscopy (Imaging)
The use of continuous X-ray to generate a real-time, live video stream of a patient’s internal structures.
Focal Enhancement
Localized, distinct area of increased density/signal after contrast injection, often indicative of a mass or active inflammation.
Frattura (Fracture)
A discontinuity in the surface or structure of bone, appearing as a radiolucent line or area of displacement.
Gas Bubbles
Small, irregular collections of gas within a soft tissue mass or fluid collection—suggests infection (abscess) or a fistula.
Giant Cell Tumor (Bone)
An aggressive, typically benign bone tumor that classically extends to the articular surface of long bones.
Globe (Ocular)
The eyeball; its shape and contents are assessed by orbital ultrasound or MRI for mass or rupture.
Glove Finger Sign
Opacification of finger-like, branching bronchi with mucus—seen in allergic bronchopulmonary aspergillosis (ABPA).
Grid Shadow
Artifactual lines on an X-ray caused by misalignment or improper use of the scatter-reducing grid.
Hair-on-End Appearance
Fine, perpendicular periosteal reaction extending outward from the bone shaft—seen in chronic hemolytic anemia (e.g., Thalassemia).
Hilar Dance
Exaggerated pulsation of the hilar pulmonary arteries on fluoroscopy—suggests increased flow (e.g., left-to-right shunt).
Hyperaemia (Doppler)
Increased blood flow in an area, represented by increased color or spectral Doppler signal—suggests active inflammation/infection.
Hypoechoic Mass
A mass that appears darker than the surrounding tissue on ultrasound, often suggesting high cellularity or fluid content.
Indented Capsule
Deformation of the outer contour of a lesion due to scar tissue or a fibrous capsule (e.g., post-traumatic splenic scar).
Inverted Visceral Situs
Reversal of the normal position of internal organs (Situs Inversus), confirmed by CT/X-ray.
Isodense (Imaging)
A lesion or structure having the same attenuation (density) as adjacent normal tissue on CT—can make detection difficult (e.g., subacute SDH).
Ivory Epiphyseal Line
A dense line of calcification at the growth plate—seen in hypervitaminosis D or lead poisoning.
Joint Space Narrowing
Decrease in the expected distance between two bones at a joint—a hallmark of degenerative or inflammatory arthritis.
Koplik’s Spots (Imaging Correlate)
Though a clinical sign, the imaging equivalent in other diseases may be focal enhancement or edema (e.g., oral mucosa inflammation).
Kissing Spines
Close proximity and physical contact between adjacent spinous processes of the lumbar spine (Baastrup’s disease).
Lead Pipe Appearance
Thickened, short, and tubular colon lacking normal haustral markings—classic for chronic ulcerative colitis.
Loculated Effusion
A fluid collection (e.g., pleural effusion) that is confined by septations or adhesions, preventing free movement and drainage.
Lumpy Bumpy Contours
Irregular, nodular surface of an organ (e.g., liver) suggesting cirrhosis or metastatic disease.
Luschka’s Crypts (Imaging)
Small mucosal outpouchings in the gallbladder wall (Rokitansky-Aschoff sinuses); visible in adenomyomatosis.
Microcalcifications (Breast)
Tiny calcium deposits in the breast; their morphology (pleomorphic, linear) and distribution are critical features of malignancy.
Midline Shift
Deviation of the midline structures (e.g., septum pellucidum, falx) in the brain due to severe mass effect.
Multicystic Appearance
A mass or organ (e.g., kidney) composed of multiple non-communicating fluid-filled sacs (cysts).
Nested Calcification
Clustered, small calcifications within a lesion, often seen in thyroid cancer (psammoma bodies) or neuroendocrine tumors.
Normal Variant
An anatomical feature that is a variation of the norm but is not pathologic (e.g., accessory spleen, Phrygian cap).
Osseous Deformity
Abnormal shape or configuration of a bone due to prior trauma, congenital anomaly, or chronic disease.
Ovarian Torsion (Imaging)
Whirlpool sign (twisted pedicle), enlarged, edematous ovary, and lack of venous/arterial flow on Doppler ultrasound.
Overlying Density
An opacity projected over an area of interest on a projection radiograph, requiring a cross-sectional view for clarification.
Pneumomediastinum (Sign)
Air outlining structures in the mediastinum (e.g., “continuous diaphragm sign,” “ring-around-the-artery sign”).
Pseudolesion
An apparent abnormality caused by normal anatomical variation or imaging artifact, not true pathology (e.g., partial volume artifact).
Pulsatility (Vascular)
Rhythmic change in vessel diameter or Doppler signal corresponding to the cardiac cycle—indicates arterial flow.
Quiescent Sclerosis
A dense, healed area of bone that is no longer growing or active, typically requiring no further follow-up.
Rebound Enhancement
Delayed, persistent enhancement of a lesion after initial washout, often seen in hemangiomas and some fibrotic tumors.
Regional Pain Syndrome (RPS)
Bone scan findings (e.g., increased juxta-articular uptake) suggesting complex regional pain syndrome (CRPS).
Reversed Target Sign
Central high attenuation with a peripheral low attenuation rim—seen in subacute brain abscesses or treated tumors.
Rotator Interval
An anatomical space in the shoulder between the supraspinatus and subscapularis tendons; assessed for fibrosis or capsular tear.
Sail Sign (Thymus)
Triangular, upward-pointing opacity in the superior mediastinum of a child’s CXR, representing the normal thymus gland.
Scalloped Margin
Smooth, undulating, or wavy border of a mass, typically associated with benign or slow-growing lesions (e.g., simple cyst, schwannoma).
Sclerotic Border
A dense, sharp rim of bone surrounding a lytic bone lesion—suggests a slow-growing, benign process.
Smooth Contour
A mass border that is perfectly round or oval with sharp margins—a favorable, though not definitive, sign of benignity.
Spinal Subluxation
Partial or incomplete dislocation of a vertebral body relative to the one below it, often a sign of ligamentous injury.
Split Cord Malformation (SCM)
Longitudinal division of the spinal cord (diastematomyelia); diagnosed by MRI for surgical planning.
Stenosis (Vascular)
Narrowing of a vessel lumen, quantified by Doppler US or CTA/MRA, typically due to atherosclerotic plaque.
Susceptibility Artifact
Signal loss (black area) on MRI caused by local magnetic field distortion (e.g., metal, blood products, air).
Telltale Sign
A classic, non-obvious finding that directs the diagnosis (e.g., crescentic fat in a hernia sac).
Thick Wall (Vascular)
Abnormal mural thickening of an artery (e.g., temporal arteritis) or vein (e.g., phlebitis) on CTA/MRA.
Thymic Rebound Hyperplasia
Rapid enlargement of the thymus gland after chemotherapy cessation, mimicking a mediastinal mass.
Tram-Line Calcification
Parallel linear calcification, typically seen in the cerebral cortex in Sturge-Weber syndrome.
Triple Density Sign
A complex pattern of varying densities on CT, often used in liver characterization (e.g., fat, cyst, solid component).
Trisomy 18 (Imaging)
Fetal anomalies (e.g., choroid plexus cysts, rocker-bottom feet, cardiac defects) seen on prenatal ultrasound.
Ulceration (Contrast)
A focal outpouching or niche of contrast from the wall of a viscus, suggesting deep mucosal defect.
Unilateral Hilar Enlargement
Enlargement of lymph nodes on only one side of the chest; more suspicious for malignancy than bilateral.
Ureteric Jet
A burst of urine entering the bladder from the ureter, visible as a jet of color on Doppler ultrasound.
Vascular Steal
Blood flow diverted from one vascular bed to another via a low-resistance pathway (e.g., AV fistula or dialysis graft).
Vein of Galen Malformation (VOGM)
A rare, high-flow intracranial vascular malformation in children; large flow void or enhancing mass on MRI.
Vertebral Hemangioma (Imaging)
Benign vascular lesion in the spine; classic appearance is vertical striations (corduroy sign) on X-ray/CT and T1 high signal on MRI.
Watershed Infarct
Infarction (stroke) occurring at the border zones between two major arterial territories, often seen in hypotension.
Wedge-Shaped Defect
A lesion or area of abnormal enhancement/attenuation that is triangular in shape, pointing toward the hilum or center of an organ—suggests infarction.
X-ray Density
The overall brightness or darkness of a structure on a projection radiograph, determined by its atomic number and thickness.
Yawn Maneuver (TMJ)
A dynamic view or sequence used to assess the motion and alignment of the temporomandibular joint (TMJ) during jaw opening.
Zonulysis (Imaging)
Disruption of the zonular fibers in the eye, assessed on orbital imaging.
Absence of Gallbladder Contraction
Failure of the gallbladder to contract after a fatty meal on HIDA scan, classic for chronic cholecystitis.
Accessory Spleen
Small, round focus of splenic tissue separate from the main spleen, appearing identical to the spleen on all imaging.
Acute Myeloid Leukemia (AML) Imaging
Imaging features include leukemic infiltrates (hypodense/hypoechoic masses) in liver, spleen, or kidneys, and diffuse bone marrow infiltration.
Adynamic Ileus
Diffuse dilatation of bowel loops with air-fluid levels but no clear point of mechanical obstruction, due to paralysis of gut motility.
Adrenal Adenoma (CT)
A small, smooth, low-density (under 10 HU) adrenal mass on non-contrast CT, suggesting a benign, lipid-rich adenoma.
Anatomical Variant
A normal variation in human anatomy that can sometimes mimic pathology (e.g., accessory fissure, prominent Pacchionian bodies).
Anterior Junction Line
A thin, vertical line on the lateral chest X-ray formed by the juxtaposition of the anterior pleura; assessed for deviation by mass.
Apex of the Lung
The uppermost portion of the lung; common site for fibrosis, old TB, and Pancoast tumors.
Arterial Enhancement Pattern
The way a mass enhances in the arterial phase, typically rapid and intense, seen in hypervascular tumors (e.g., HCC, renal cell carcinoma).
Aspiration Pneumonia (Imaging)
Consolidation typically involving the dependent lung segments (posterior upper lobes, superior/basal lower lobes).
Atherosclerotic Calcification
Linear or curvilinear calcification seen in the walls of arteries on X-ray or CT.
Atrial Enlargement
Dilatation of the heart atria, diagnosed by specific cardiothoracic ratio and contour changes on CXR or MRI/CT.
Avulsion Fracture
A fracture where a tendon or ligament pulls a small fragment of bone away from the main mass (e.g., fibular avulsion).
Axial Skeletal Sclerosis
Increased bone density predominantly involving the spine and pelvis, seen in disorders like Paget’s disease or fluoride toxicity.
Bamboo Spine
Fusion and syndesmophyte formation of the vertebral bodies, resembling bamboo—classic for advanced ankylosing spondylitis.
Barber’s Pole Sign
The twisting of vessels around the neck of a hernia sac on Doppler ultrasound.
Bird’s Beak Sign
Tapering of the distal esophagus into a narrow point—classic for achalasia on barium swallow.
Black Pleura Sign
Dark, non-enhancing T1 signal of the pleura, sometimes seen in benign pleural plaques or old fibrosis.
Blending Contour
A poorly defined margin where a mass seems to merge imperceptibly with the surrounding tissue—a malignant feature.
Bowel Wall Thickening
Abnormal increase in the thickness of the bowel wall on CT/US/MRI—suggests inflammation, ischemia, or tumor.
Breast Mass with Microlobulation
A breast mass with slightly irregular, small lobules along its margin, a suspicious feature on ultrasound.
Buckled Bronchus Sign
Wavy or folded appearance of a bronchus due to surrounding volume loss (e.g., post-obstructive collapse).
Calcified Aorta
Extensive linear calcification in the wall of the aorta, a sign of advanced atherosclerosis.
Calyceal Clubbing
Flattening of the renal papillae and blunting of the calyces—seen in chronic pyelonephritis or reflux nephropathy.
Cartilage Loss
Decrease in the smooth, high-signal hyaline cartilage layer in joints on MRI—a sign of degenerative or inflammatory arthritis.
Cavitary Lesion
A mass or nodule containing an internal gas/air space (cavity)—seen in infections (TB, fungal) or certain cancers.
Cerebral Edema (CT)
Loss of gray-white matter differentiation and effacement of sulci and cisterns on non-contrast head CT.
Chest Wall Mass
A soft tissue mass arising from the rib cage or surrounding musculature; assessed for bone invasion.
Cobblestone Appearance (Bowel)
Irregular, raised mucosal nodules separated by deep fissures on contrast studies or colonoscopy—classic for Crohn’s disease.
Codman’s Triangle
A triangular elevation of the periosteum away from the bone shaft—suggests an aggressive or rapidly growing bone lesion (e.g., osteosarcoma).
Colon Cut-off Sign
Abrupt collapse or narrowing of the transverse or left colon, often seen in acute pancreatitis.
Congenital Cystic Adenomatoid Malformation (CCAM)
Fetal/pediatric lung mass composed of multiple cysts; classification (Type I, II, III) determined by size of cysts on US/MRI.
Continuous Diaphragm Sign
Visualization of the entire diaphragm as a continuous line across the midline on CXR—suggests pneumomediastinum or pneumopericardium.
Coronary Artery Aneurysm (CAA)
Abnormal dilatation of a coronary artery, often seen in Kawasaki disease or severe atherosclerosis.
Cribriform Calcification
Diffuse, sieve-like pattern of calcification within a mass, often seen in certain meningiomas.
Curved Arrows (Spine)
Appearance of curved radiodense lines within the neural foramen on oblique spinal views—can suggest spondylolisthesis.
Dead Organ (Imaging)
Lack of perfusion or enhancement in an organ on contrast study (e.g., testicular torsion, splenic infarction).
Deep Sulcal Enhancement
Enhancement along the sulci of the brain—suggests leptomeningeal disease (e.g., infectious meningitis, leptomeningeal carcinomatosis).
Diffuse Calcification
Widespread, non-focal calcification throughout an organ (e.g., kidney, breast), usually benign.
Dilated Bowel Loops
Abnormal enlargement of the small or large bowel, a sign of obstruction or ileus.
Disc Desiccation
Loss of T2 high signal in the intervertebral discs on MRI, indicating dehydration and degeneration.
Double Lumen
Two distinct channels seen in a vessel (aorta or artery) on CTA/MRA—suggests dissection.
Dromedary Hump
A focal bulge on the lateral border of the left kidney, a normal anatomical variant sometimes mistaken for a mass.
Ectopic Ureterocele
A ureterocele located at the bladder neck or urethra, associated with a duplicated collecting system.
Endobronchial Lesion
A mass or lesion located within the lumen of a bronchus, often leading to post-obstructive atelectasis/pneumonia.
Epiphyseal Dysplasia
Abnormal development of the ends of the long bones (epiphyses), leading to joint deformity and early arthritis.
Eversion of the Bladder Mucosa
Bulging of the bladder lining into the prostatic urethra, seen in BPH (Benign Prostatic Hyperplasia).
Extra-Articular Extension
Spread of a joint disease process (e.g., synovial hypertrophy, tumor) beyond the confines of the joint capsule.
Fat-Fluid Level
A horizontal interface between fat and fluid within a lesion (e.g., dermoid cyst) or a trauma setting (lipohaemarthrosis).
Fibrin Sheath (Imaging)
Linear enhancement along the course of an indwelling catheter (e.g., central line), indicating a thin layer of clot/protein.
Flame-Shaped Enhancement
Enhancement pattern seen in acute MS plaques, often incomplete and asymmetric, resembling a flame.
Flower-Like Appearance
A mass with internal septations radiating outward, often seen in liver adenomas or certain cystic renal masses.
Fluid-Fluid Level (Imaging)
Layering of fluids of different densities/signals within a cyst or mass (e.g., blood products, pus), suggesting complexity/hemorrhage.
Fusiform Aneurysm
Symmetrical, spindle-shaped dilatation of a vessel involving the entire circumference of the wall.
Gallstone Ileus
Mechanical small bowel obstruction caused by a gallstone that has eroded into the small bowel (Bouveret’s Syndrome if proximal).
Gas Gangrene (Imaging)
Feathery or bubble-like gas collections dissecting along fascial planes in soft tissues, indicating clostridial myonecrosis.
Giant Cell Tumor (Tendon Sheath)
A common, typically benign soft tissue mass often appearing heterogeneous and low-signal on T1/T2 MRI.
Glabella Sign
Midline lucency in the frontal bone on a skull radiograph, sometimes mistaken for a fracture.
Grown-up Spleen
An unusually large spleen (splenomegaly), often secondary to portal hypertension or hematologic disease.
Hanging Liver (Sign)
Liver hanging freely in the upper abdomen; seen in patients with diaphragmatic rupture and absence of supporting ligaments.
Hepatocellular Carcinoma (HCC) Imaging
Classic pattern of arterial hyperenhancement and subsequent “washout” in the portal venous phase.
Herringbone Pattern (Bowel)
Folds of small bowel mucosa resembling the weave of tweed fabric; suggests small bowel obstruction.
High-Level Obstruction
Bowel obstruction located in the jejunum or proximal ileum, showing multiple distended loops.
Hot Spot (Nuclear Med)
Area of increased radiotracer concentration (uptake), usually indicating inflammation, infection, or high metabolic rate.
Hydronephrosis (Imaging)
Dilatation of the renal pelvis and calyces due to obstruction; graded by severity on US/CT.
Hyperostosis Frontalis Interna
Thickening of the inner table of the frontal bone, a common, benign finding, predominantly in elderly women.
Inverted Diaphragm
Flattening or downward bowing of the diaphragm on CXR/CT—seen in severe emphysema/air trapping.
Inverted U Sign
Appearance of a gas-filled small bowel loop draped over the superior margin of a large pneumoperitoneum.
Ischemic Infarct (Imaging)
Wedge-shaped or territorial area of low density (CT) or restricted diffusion (MRI) in the brain/organ.
Junctional Parenchymal Defect
A normal invagination of the renal capsule toward the hilum at the junction of two lobes, mimicking a scar.
Kinked Tube (Imaging)
Abrupt angulation of an indwelling catheter or drain (e.g., chest tube, biliary drain), causing malfunction.
Laminated Periosteal Reaction
Multiple parallel layers of new bone formation beneath the periosteum (Onion-Skinning), suggesting intermittent aggressive growth.
Lateral Displacement of Trachea
Shift of the trachea away from the midline—suggests mass, volume loss on the contralateral side, or pneumothorax on the ipsilateral side.
Leaky Aneurysm
An aneurysm with a small, contained rupture, often seen as a crescent of high density in the wall (e.g., AAA).
Low-Level Echoes
Fine, diffuse echoes within a fluid collection on ultrasound—suggests internal debris, protein, or blood products.
Lung Abscess (Imaging)
Thick-walled, irregular cavity in the lung, often with an air-fluid level and surrounding consolidation.
Melanoma Metastasis (Imaging)
Metastases that may appear hyperdense on non-contrast CT and T1 bright on MRI due to melanin or hemorrhage.
Meniscal Extrusion
Displacement of the meniscal cartilage body outside the confines of the joint space, a sign of severe tear or instability.
Metastatic Lung Nodules (Imaging)
Multiple, usually round, nodules of varying size, often with a peripheral and basal predominance (cannonball metastases).
Mucus Plugging
Opaque, tubular filling of a bronchus with thick mucus, often causing distal atelectasis.
Myeloma (Imaging)
Multiple, well-defined, “punched-out” lytic lesions in the axial skeleton without a sclerotic border.
Nephrographic Phase
The time interval (approx. 80-120 seconds post-contrast) when contrast is uniformly distributed throughout the renal parenchyma.
Nonspecific Interstitial Pneumonia (NSIP)
Lung pattern with fine reticulation and GGO, often subpleural and basal, but lacking the honeycombing of UIP.
Oligemia (Lung)
Reduced vascularity and brightness of a lung segment on CXR/CT (e.g., Westermark sign in PE).
Open Fontanelle
Unfused fibrous space between the skull bones in an infant (anterior/posterior fontanelles); used for neonatal brain ultrasound.
Opacification (Sinus)
Filling of the paranasal sinuses with fluid or soft tissue, seen as white density on X-ray/CT—indicates sinusitis or mass.
Pachymeningeal Thickening
Thickening of the dura mater (outer meningeal layer)—often seen in intracranial hypotension or chronic inflammation.
Paradoxical Diaphragmatic Motion
Movement of the diaphragm upward during inspiration, instead of downward—a sign of diaphragmatic paralysis.
Paralytic Ileus
See Adynamic Ileus. Bowel dilatation due to impaired peristalsis.
Pericardial Tamponade (Imaging)
Diastolic collapse of the right atrium/ventricle due to a large pericardial effusion, seen on echocardiography.
Perilymphatic Nodule Distribution
Small lung nodules clustered along the pleura, fissures, and bronchovascular bundles—classic for sarcoidosis/silicosis.
Perinephric Stranding
Increased density and thickening of the fat around the kidney on CT—suggests inflammation (e.g., pyelonephritis) or hemorrhage.
Pneumobilia (Imaging)
Air seen within the central bile ducts, usually due to communication with the GI tract.
Portal Venous Thrombus (PVT)
A filling defect in the portal vein on contrast study (US/CT/MRI)—can be bland (clot) or tumor (HCC).
Posterior Tracheal Stripe
The thin soft-tissue stripe posterior to the trachea; abnormal thickening suggests esophageal mass or mediastinal disease.
Positive Predictive Value (Imaging)
The likelihood that a lesion is truly malignant when the imaging test suggests malignancy (e.g., BI-RADS 5).
Psoas Sign
Loss of the sharp border of the psoas muscle on an abdominal X-ray, suggesting retroperitoneal fluid or mass.
Quadrant of Injury
The specific quadrant of the abdomen or lung where the majority of trauma or pathology is located.
Rat-Bite Erosion
Small, sharply defined erosions at the margins of joints, often with overhanging edges—seen in gout.
Rebound Tenderness (Imaging Correlate)
Clinical sign of peritonitis; imaging shows signs of inflammation and/or free fluid.
Rectus Sheath Hematoma
Blood collection within the rectus abdominis muscle sheath, appearing as an oval/spindle-shaped, dense mass on CT.
Renal Cyst (Simple)
A non-enhancing, water-density/anechoic, smooth-walled lesion in the kidney (Bosniak I).
Respiration Artifact
Blurring or ghosting on an image caused by patient breathing during image acquisition.
Retrograde Filling
Contrast agent flowing backward against the normal direction in a vessel, suggesting severe downstream stenosis or occlusion.
Reversed Target Sign (Lung)
Central ground-glass opacity surrounded by a ring of consolidation—seen in some fungal infections (e.g., mucormycosis).
Saber-Sheath Trachea
Coronal narrowing and sagittal widening of the intrathoracic trachea—seen in Chronic Obstructive Pulmonary Disease (COPD).
Sacroiliitis (Imaging)
Erosions, subchondral sclerosis, and eventual fusion (ankylosis) of the sacroiliac joints—classic in ankylosing spondylitis.
Salt and Pepper Sign
Multiple tiny T1 signal voids in the vertebral body or skull on MRI—suggests hypervascular lesions like paraganglioma or hemangioma.
Sandstorm Appearance (Breast)
Diffuse, finely scattered microcalcifications in the breast, typically benign in distribution.
Scimitar Syndrome (Imaging)
Partial anomalous pulmonary venous return from the right lung to the IVC, with a characteristic scimitar-shaped vein on CXR/CT.
Secondary Signs of PE
CXR/CT findings that suggest pulmonary embolism but are not diagnostic (e.g., pleural effusion, Westermark sign, Hampton’s Hump).
Septal Thickening (Lung)
Thickening of the interlobular septa (Kerley B lines if prominent) due to edema, lymphangitic carcinomatosis, or fibrosis.
Shouldering (Mass)
Abrupt shelf-like projection of a bone lesion from the cortex (e.g., osteosarcoma)—an aggressive feature.
Signet Ring Sign (Bronchiectasis)
A dilated bronchus next to a smaller accompanying pulmonary artery, resembling a signet ring on cross-sectional CT.
Snout Sign (Pituitary)
A mass (e.g., pituitary macroadenoma) that extends superiorly and molds the optic chiasm into an hourglass shape.
Spiculated Mass
A lesion with irregular, sharp lines radiating from its core, highly suggestive of an invasive malignancy.
Star-Shaped Scar
A central, non-enhancing, star-like area within a hepatic mass—classic for Focal Nodular Hyperplasia (FNH).
Steal Phenomenon
Blood is diverted (stolen) from one organ to another due to a lower resistance circuit (e.g., dialysis fistula stealing flow from the hand).
Stress Fracture (Imaging)
A small crack in the bone from repetitive stress; often occult on X-ray but seen as a linear focus of bone marrow edema on MRI.
Subdural Fluid Collection
A crescent-shaped collection between the dura and arachnoid, typically isodense in the subacute phase.
Suspicious Calcification
Calcification with morphology (e.g., fine linear, pleomorphic) or distribution (e.g., clustered) that suggests malignancy.
T-Sign (Joint)
Specific tear pattern of the triangular fibrocartilage complex in the wrist, often seen on MR arthrogram.
Telltale Scar
A subtle line or area of fibrosis on imaging indicating a previous injury or procedure site.
Tibia Vara (Blount’s Disease)
Growth disturbance of the proximal medial tibia, causing bowing of the legs (bow-legged deformity).
Trident Hand
Shortening of the proximal and middle phalanges of the hand, a classic sign of achondroplasia.
Unilateral Emphysema
Hyperlucency and hyperinflation of one lung due to air trapping (e.g., Swyer-James Syndrome).
Vallecular Pseudotumor
Retained secretions in the vallecula (space at base of tongue) that can mimic a mass on cross-sectional imaging.
Ventriculitis (Imaging)
Inflammation of the ventricular lining; classic finding is enhancement of the ependyma (ventricular lining) on contrast MRI.
Visceral Perfusion Defect
An area in a solid organ that lacks enhancement on contrast studies, indicating ischemia or infarction.
Wall Enhancement (Bowel)
Increased density or signal in the bowel wall after contrast, indicating active inflammation (e.g., enteritis, colitis).
Washout (Adrenal)
Rapid loss of contrast from an adrenal mass on delayed CT images—highly suggestive of a benign adrenal adenoma.
Xenon Ventilation Scan
A specific phase of a V/Q scan where inhaled Xenon gas is imaged to show air distribution in the lungs.
Yellow Marrow Conversion
Replacement of red hematopoietic marrow with fatty (yellow) marrow, seen as bright signal on T1 MRI; a normal aging process in the appendicular skeleton.
Zoon’s Balanitis (Imaging)
A localized, inflammatory process of the glans penis; imaging may show focal skin thickening/enhancement.