Radiology terms, in plain words

An ACL tear is a partial or complete tear of the anterior cruciate ligament, a key ligament that keeps the knee stable when you twist or turn.

MRI

Acoustic shadowing is a dark band on ultrasound behind something that blocks sound, such as a stone, calcium or bone.

Ultrasound

Adenomyosis means tissue like the lining of the uterus is growing into its muscle wall. It is common and can cause heavy, painful periods.

Ultrasound, MRI

An adrenal adenoma is a benign (non-cancerous) lump in an adrenal gland. It is very common and usually found by chance on a scan.

CT, MRI

Anechoic means an area looks completely black on ultrasound because it sends back no echoes. This is typical of clear fluid.

Ultrasound

An aneurysm is a bulge in a weakened artery wall, most often in the aorta or a brain artery. Its size and growth guide what happens next.

CT, MRI, Ultrasound

An angiomyolipoma is a benign kidney tumor made of blood vessels, muscle and fat. Small ones usually need no treatment.

Ultrasound, CT, MRI

An annular fissure is a small crack in the tough outer ring of a spinal disc. It is very common with age and often causes no pain.

MRI

An aortic dissection is a tear in the inner lining of the aorta that lets blood split the layers of its wall apart. A new one is an emergency.

CT

An arachnoid cyst is a pocket of clear brain fluid within the brain's thin covering. Most are present from birth, harmless and found by chance.

MRI, CT

Architectural distortion means breast tissue looks pulled in or puckered toward a point on a mammogram, without a clear lump.

Mammogram

An artifact is something on a scan that is not really in the body, caused by movement, metal or the equipment. It can hide or mimic a finding.

Any scan

Ascites is a buildup of fluid inside the belly, in the space around the bowel, liver and other organs.

Ultrasound, CT

Atelectasis means part of the lung is not fully inflated, so it holds less air. Small areas are very common and usually minor.

CT, X-ray

Atherosclerosis is a build-up of fatty, often calcified plaque in artery walls. It is very common with age and is linked to heart and stroke risk.

CT, Ultrasound

Atrophy means an organ, muscle or part of the brain has become smaller than expected because some of its tissue has been lost.

Any scan

Avascular necrosis means part of a bone has died because its blood supply was cut off. It most often affects the ball of the hip joint.

MRI, X-ray

A Baker's cyst is a pocket of joint fluid that bulges out behind the knee. It usually goes with another knee problem, such as arthritis or a meniscal tear.

MRI, Ultrasound

Benign means not cancer: it does not invade nearby tissue or spread to other parts of the body. On a scan, it is a reassuring word.

Any scan

BI-RADS is the 0 to 6 scale used to sum up a mammogram, breast ultrasound or breast MRI. Each category comes with a recommended next step.

Mammogram, Ultrasound, MRI

Biliary dilatation means the bile ducts, the tubes that carry bile from the liver to the gut, are wider than usual.

Ultrasound, CT, MRI

A bone island is a small, benign spot of dense, compact bone inside normal bone. It shows as a white dot on X-ray or CT.

X-ray, CT

Bone marrow edema means extra fluid inside a bone, seen as a bright patch on MRI. It often follows an injury or strain and usually settles with time.

MRI

The Bosniak classification sorts kidney cysts into categories I, II, IIF, III and IV by how complex they look, to estimate the chance of cancer.

CT, MRI, Ultrasound

A breast cyst is a round sac filled with fluid inside the breast. Simple cysts are benign and very common, especially in the years before menopause.

Ultrasound, Mammogram

Breast density describes how much of the breast is dense glandular tissue rather than fat on a mammogram, in four categories from A to D.

Mammogram

Bronchiectasis means some of the lung's airways (bronchi) are permanently wider than normal. Mild forms are common on CT.

CT

Bursitis means a bursa, a small fluid-filled cushion near a joint, is irritated and swollen, often holding extra fluid.

MRI, Ultrasound

CAD-RADS is a 0 to 5 scale on coronary CT angiography that sums up the worst narrowing in the heart's arteries, from none to a full blockage.

CT

A calcification is a small deposit of calcium in soft tissue. It looks bright white on X-ray and CT, and most are harmless.

Any scan

Cannot be excluded means the scan cannot fully rule out a possibility. It is cautious wording, not a diagnosis, and often refers to a less likely cause.

Any scan

Cardiomegaly means the heart looks larger than normal, usually on a chest X-ray. It is a sign that needs explaining, not a diagnosis by itself.

X-ray, CT

Cerebral atrophy means the brain has lost some volume, so its grooves and fluid spaces look wider. A mild degree is normal with age.

MRI, CT

A Chiari malformation means the lowest part of the cerebellum, at the back of the brain, extends down through the opening at the base of the skull.

MRI

Chondromalacia means the smooth cartilage lining a joint has softened, frayed or thinned. It is most often reported behind the kneecap.

MRI

Cirrhosis is advanced, long-term scarring of the liver. On scans the liver often has a bumpy (nodular) surface and an altered shape.

Ultrasound, CT, MRI

Clinical correlation recommended means the radiologist asks your doctor to compare a finding with your symptoms, examination and test results.

Any scan

A compression fracture means a vertebra has partly collapsed and lost height, most often because the bone is weakened by osteoporosis.

X-ray, CT, MRI

Consolidation means part of the lung has filled with fluid, pus or cells instead of air, so it looks solid and white on X-ray or CT.

CT, X-ray

A contrast agent is a substance given before or during a scan, usually into a vein, that makes blood vessels and some tissues easier to see.

CT, MRI, X-ray

A coronary calcium score measures calcified plaque in the heart's arteries on a quick CT scan, to help estimate the risk of a heart attack.

CT

The corpus luteum is a normal, short-lived structure that forms on the ovary after an egg is released. It often looks like a small cyst.

Ultrasound

A cyst is a sac filled with fluid. Simple cysts are very common and almost always harmless; cysts with thick walls or solid parts get a closer look.

Any scan

DaTscan is a SPECT brain scan of the dopamine nerve endings that help control movement. It helps doctors assess tremor and possible Parkinson's disease.

PET and nuclear medicine

The Deauville score is a 1 to 5 scale that rates lymphoma activity on a PET scan by comparing it with the blood in the chest and the liver.

PET and nuclear medicine

Degenerative changes are signs of wear and tear in the joints, discs and bones. They build up slowly with age and are very common in adults.

Any scan

Degenerative disc disease is the gradual wear of spinal discs with age: drying out, thinning and bulging. Despite the name, it is not really a disease.

MRI, X-ray, CT

Demyelination is damage to myelin, the protective coating around nerve fibers. On MRI it can show up as bright spots called lesions or plaques.

MRI

A dermoid cyst is a common benign growth of the ovary that can contain fat, hair, skin and sometimes teeth.

Ultrasound, MRI, CT

A developmental venous anomaly is a harmless variation in how a group of brain veins drains. It is present from birth and usually found by chance.

MRI

A differential diagnosis is the list of possible causes a radiologist thinks could explain a finding, often with the most likely one first.

Any scan

Diffuse means spread throughout an organ or area rather than limited to one spot. It describes the pattern of a finding, not how serious it is.

Any scan

Diffusion restriction means water molecules cannot move as freely as usual in part of the tissue, a pattern seen on diffusion MRI images.

MRI

Dilated means wider than normal. It describes tubes and spaces in the body, such as ducts, blood vessels, the bowel or the kidney's drainage system.

Any scan

A disc bulge means a spinal disc extends slightly past the edges of the vertebrae around a wide part of its rim. It is very common and often painless.

MRI, CT

Disc desiccation means a spinal disc has lost some of its water, so it looks darker on T2 MRI images. It is an early, very common sign of aging.

MRI

A disc extrusion is a disc herniation in which the pushed-out part is wider than its base or reaches above or below the disc. Many shrink over time.

MRI

Disc herniation means material from a spinal disc has moved past the disc's normal edge in one area. Protrusions and extrusions are types of herniation.

MRI

A disc protrusion is a common type of disc herniation: disc material pushes out in one area, but its base stays wider than the part sticking out.

MRI

Diverticulitis is inflammation or infection of one or more small pouches (diverticula) in the wall of the colon.

CT

Diverticulosis means small pouches have formed in the wall of the colon. It is very common with age and usually harmless.

CT

A dural tail is a thin, tapering strip of the brain's covering that brightens after contrast next to a mass. It is typical of meningioma but not proof.

MRI

Edema means extra fluid has built up in a tissue and made it swollen. On scans it often appears around an injury, inflammation or a growth.

Any scan

Ejection fraction is the percentage of blood the heart's main pumping chamber pushes out with each beat. It is also used for gallbladder emptying.

MRI, PET and nuclear medicine, Ultrasound

Emphysema means some of the lung's tiny air sacs are damaged and merged into larger spaces. It is most often caused by smoking.

CT, X-ray

Empty sella means the bony pocket that holds the pituitary gland looks mostly filled with fluid, with the gland flattened against its floor.

MRI

Encephalomalacia means an area of brain tissue was lost after an earlier injury, such as a stroke, head injury or surgery. It is an old scar.

MRI, CT

An enchondroma is a benign growth of cartilage inside a bone. It is often found by chance, especially in the hand or near the knee or shoulder.

X-ray, MRI

An endometrioma is a cyst on the ovary filled with old blood, caused by endometriosis. It is often called a chocolate cyst.

Ultrasound, MRI

Enhancement means an area turns brighter on CT or MRI after a contrast agent is injected, because the agent reaches it through the blood.

CT, MRI

An enlarged prostate is a prostate gland that is bigger than usual. It is very common with age and is usually benign (not cancer).

Ultrasound, MRI

Facet arthropathy means arthritis in the facet joints, the small paired joints at the back of the spine. It is very common with age.

MRI, CT, X-ray

Fat stranding means hazy, streaky lines in the fat around an organ on CT. It usually signals inflammation nearby.

CT

The Fazekas scale grades white matter bright spots on brain MRI from 0 to 3, from none to large merged areas.

MRI

FDG-avid means a spot takes up FDG, the sugar-like tracer used in most PET scans, so it lights up on the images.

PET and nuclear medicine

A fibroadenoma is a common benign breast lump made of gland and connective tissue. It is usually smooth and oval, and most common in younger women.

Ultrasound, Mammogram

Fibrosis means scar tissue. It forms where tissue has healed after an injury, an infection or long-lasting inflammation.

CT, MRI

FLAIR is a type of MRI image, used mostly for the brain. It turns normal fluid dark, so swelling and small spots in brain tissue stand out as bright.

MRI

The Fleischner criteria are guidelines for following up lung nodules found by chance on CT in adults 35 and over, based on size, type and risk.

CT

A flow void is the black look of fast-flowing blood inside a blood vessel on MRI. Normal flow voids suggest the main vessels are open.

MRI

Focal means limited to one spot or a small area. It describes where something is, not how serious it is. The opposite is diffuse.

Any scan

A focal asymmetry is a small area of denser tissue in one breast on a mammogram, with no matching area in the other breast and no clear lump.

Mammogram

Focal nodular hyperplasia (FNH) is a benign liver lump made of normal liver cells arranged in an unusual way. It usually needs no treatment.

MRI, CT

Follow-up imaging is a repeat or extra scan after a set time, to check whether a finding changes. It is usually a precaution.

Any scan

Foraminal stenosis means one of the side openings where nerve roots leave the spine is narrowed. Reports grade it as mild, moderate or severe.

MRI, CT

Free fluid is fluid lying loose in the belly or pelvis, outside the organs and bowel. A small amount in the pelvis is often normal.

CT, Ultrasound, MRI

A gallbladder polyp is a small growth that sticks out from the gallbladder wall. Most are harmless clumps of cholesterol, not true tumors.

Ultrasound

Gallstones are hard, pebble-like pieces that form inside the gallbladder. They are very common and often cause no symptoms.

Ultrasound, CT

A ganglion cyst is a benign, jelly-filled sac that grows from a joint or tendon sheath, most often at the wrist.

MRI, Ultrasound

Gliosis is scar-like tissue the brain forms where it was injured before, for example by a stroke, head injury, infection or surgery.

MRI

A goiter is an enlarged thyroid gland. It can be smooth all over or contain several lumps, which is called a multinodular goiter.

Ultrasound, CT, PET and nuclear medicine

A granuloma is a tiny cluster of immune cells that walled off an old infection or irritant. In the lungs it is usually a harmless leftover.

CT, X-ray

Ground-glass opacity is a hazy gray area on a lung CT. The lung looks cloudy there, but the blood vessels inside it can still be seen.

CT

A hematoma is a pool of blood that has collected outside the blood vessels, like a deep bruise, usually after an injury or surgery.

CT, MRI, Ultrasound

Hemorrhage means bleeding. On a scan it describes blood that has escaped from blood vessels into tissue or a body space.

CT, MRI

A hepatic hemangioma is a noncancerous lump in the liver made of tangled blood vessels. It is the most common benign liver lesion and rarely needs treatment.

Ultrasound, CT, MRI

Hepatic steatosis means extra fat has built up in the liver, often called fatty liver. It is very common and often reversible.

Ultrasound, CT, MRI

Hepatomegaly means the liver is larger than expected. It has many possible causes, such as fat, congestion from the heart or infection.

Ultrasound, CT

A hernia is tissue, often fat or a loop of bowel, pushing through a weak spot in the muscle wall that normally holds it in place.

CT, Ultrasound, MRI

Heterogeneous means uneven or mixed in appearance, with different shades within one organ or lesion. On its own it is neither good nor bad.

Any scan

A hiatal hernia means part of the stomach has pushed up through the opening in the diaphragm into the chest. Small ones are very common.

CT, X-ray

Hot and cold nodules are thyroid scan terms: a hot nodule takes up more tracer than the rest of the gland, and a cold nodule takes up less.

PET and nuclear medicine

Hounsfield units (HU) measure density on a CT scan. Water is 0, fat is below 0, and dense bone reads in the hundreds or more.

CT

Hydrocephalus means a build-up of brain fluid (CSF) inside the brain's fluid chambers, so they enlarge and can press on the brain.

MRI, CT

Hydronephrosis is swelling of the part of the kidney that collects urine, usually because urine cannot drain freely to the bladder.

Ultrasound, CT

Hyperdense means an area looks brighter than the tissue around it on a CT scan, because it is denser.

CT

Hyperechoic means an area looks brighter than the tissue around it on ultrasound, because it sends back more echoes.

Ultrasound

Hyperintense means an area looks brighter than the tissue around it on an MRI image. What that means depends on the type of image.

MRI

Hypermetabolic means an area takes up more of the sugar-like tracer FDG than the tissue around it on a PET scan, so it looks brighter.

PET and nuclear medicine

Hypodense means an area looks darker than the tissue around it on a CT scan, because it is less dense.

CT

Hypoechoic means an area looks darker than the tissue around it on ultrasound, because it sends back fewer echoes.

Ultrasound

Hypointense means an area looks darker than the tissue around it on an MRI image. What causes the darkness depends on the type of image.

MRI

Ill-defined means a finding has blurry or indistinct edges, so it is hard to see where it ends. It is seen with inflammation as well as some tumors.

Any scan

The impression is the summary section of a radiology report, usually at the end. It gives the main conclusions and any advice on next steps.

Any scan

An incidental finding is something spotted by chance on a scan done for another reason. Most are harmless, and some need a later check.

Any scan

Increased uptake means an area takes up more tracer than the tissue around it on a nuclear medicine or PET scan. It is often called a hot spot.

PET and nuclear medicine

Indeterminate means the scan cannot tell whether a finding is clearly harmless or a concern. It often leads to another test or a later check.

Any scan

An infarct is an area of tissue damaged because its blood supply was cut off. In the brain this is a type of stroke, and in the heart a heart attack.

CT, MRI

Infiltrate is an older, loose word for an area of lung filled with something other than air, often from infection or inflammation.

X-ray, CT

Inflammatory changes are signs on a scan that an area is inflamed, such as swelling, extra fluid, increased blood flow or hazy fat.

Any scan

Interstitial lung disease (ILD) is a group of conditions that inflame or scar the thin tissue around the lung's air sacs.

CT

Interval change means a difference since your previous scan. No interval change means a finding looks the same as it did last time.

Any scan

Isodense means an area has about the same density as the tissue around it on a CT scan, so it looks the same shade of gray.

CT

Isoechoic means an area sends back about as many echoes as the tissue around it on ultrasound, so it looks the same shade of gray.

Ultrasound

Isointense means an area looks about as bright as the tissue it is compared with on an MRI image, so the two blend together.

MRI

A joint effusion is extra fluid inside a joint. A small amount is often normal; more can follow an injury, arthritis or inflammation.

MRI, Ultrasound, X-ray

Joint space narrowing means the gap between two bones in a joint looks smaller than normal, usually because the cartilage has worn thin.

X-ray, MRI

The Kellgren-Lawrence grade rates osteoarthritis on X-ray from 0 (none) to 4 (severe), based on bone spurs and joint space narrowing.

X-ray

A kidney stone is a hard deposit of minerals that forms in the kidney and may move into the tube that drains urine to the bladder.

CT, Ultrasound, X-ray

The Krenning score grades how strongly a neuroendocrine tumor takes up a somatostatin receptor tracer, compared with normal liver and spleen.

PET and nuclear medicine

A labral tear is a tear in the labrum, the rim of cartilage around the shoulder or hip socket that deepens it and helps keep the joint stable.

MRI

A lacunar infarct is a small stroke deep in the brain, caused by a blocked tiny artery. Many are old and found by chance on a scan.

MRI, CT

A lesion is any area that looks different from the normal tissue around it. It is a general word and does not mean cancer by itself.

Any scan

LI-RADS is a scoring system for liver spots in people at high risk of liver cancer, from LR-1 (definitely benign) to LR-5 (definitely cancer).

CT, MRI, Ultrasound

Ligamentum flavum hypertrophy means a ligament lining the back of the spinal canal has thickened. It is common with age and can narrow the canal.

MRI

A liver cyst is a small sac of clear fluid in the liver. Simple liver cysts are very common, harmless and usually need no follow-up.

Ultrasound, CT, MRI

Loss of lordosis means the normal inward curve of the neck or lower back looks straighter than usual. It is common and often means little on its own.

X-ray, MRI

A lucency is an area that looks darker than expected on an X-ray or CT because it lets more X-rays through, such as air or thinner bone.

X-ray, CT

A lung nodule is a small, round spot in the lung, up to 3 cm across. Most are harmless, such as scars from old infections.

CT, X-ray

Lung-RADS sorts lung cancer screening CT scans into categories, from 0 (incomplete) and 1 (negative) to 4 (suspicious), each with a next step.

CT

Lymphadenopathy means lymph nodes that are enlarged or abnormal in shape. It is often a reaction to infection or inflammation.

CT, MRI, Ultrasound, PET and nuclear medicine

A lytic lesion is an area where bone has been lost or replaced by other tissue, so it looks darker than the bone around it on X-ray or CT.

X-ray, CT

Malignant means cancerous. A scan can raise the concern, but a biopsy, a small tissue sample, is usually needed to confirm it.

Any scan

A mass is a lump of tissue that takes up space. In the lung it means a spot larger than 3 cm. It is a description, not a diagnosis.

Any scan

Mass effect means something is pressing on or pushing aside nearby structures, most often in the brain. "No mass effect" is a reassuring phrase.

CT, MRI

A meningioma is a usually benign, slow-growing tumor of the membranes that cover the brain. Many are found by chance and simply watched.

MRI, CT

A meniscal tear is a tear in one of the two C-shaped cartilage cushions inside the knee. Tears from wear are very common with age.

MRI

A metastasis is a deposit of cancer that has spread from where it started to another part of the body. The plural is metastases.

Any scan

Microbleeds are tiny spots of old bleeding in the brain, usually a few millimeters across, seen as dark dots on special MRI sequences.

MRI

Microcalcifications are tiny specks of calcium seen on a mammogram. Most are benign; their shape and pattern tell the radiologist whether to look closer.

Mammogram

Modic changes are MRI signs of altered bone marrow in the vertebrae next to a worn disc, grouped into types 1, 2 and 3.

MRI

A nabothian cyst is a small, harmless bubble of mucus in the cervix, the lower end of the uterus. These cysts are very common.

Ultrasound, MRI

Nerve root compression means a disc, bone spur or thickened tissue is pressing on a spinal nerve root, one of the nerves branching off the spinal cord.

MRI

No acute findings means the scan shows no sign of a new or urgent problem. It is not always the same as completely normal; older changes may be listed.

Any scan

A nodule is a small, rounded spot that stands out from the tissue around it. In the lung it means 3 cm or smaller. Most nodules are harmless.

Any scan

A nondisplaced fracture is a break in a bone where the pieces have stayed in their normal position, still lined up.

X-ray, CT, MRI

Nonspecific means a finding could have several different causes, and the image alone cannot tell which one. Many nonspecific findings are harmless.

Any scan

O-RADS is a 0 to 5 risk score for findings in the ovaries and nearby structures on ultrasound or MRI, from a normal ovary to high risk of cancer.

Ultrasound, MRI

An opacity is an area that looks whiter than expected on an X-ray or CT, most often in the lungs. It is a description, not a diagnosis.

X-ray, CT

Osteopenia means bones are less dense than expected. On a DEXA scan it means a T-score between -1 and -2.5, not low enough to be osteoporosis.

X-ray, CT

An osteophyte is a bone spur: a small bony outgrowth at the edge of a joint or vertebra. It forms with wear and is very common with age.

X-ray, CT, MRI

An ovarian cyst is a fluid-filled sac on or in an ovary. Most are a normal part of the monthly cycle and go away on their own.

Ultrasound, MRI

A pancreatic cyst is a pocket of fluid in the pancreas. Most are small and found by chance, and many stay unchanged for years.

CT, MRI

A perfusion defect is an area of tissue getting less blood than expected, most often heart muscle on a heart perfusion scan.

PET and nuclear medicine, MRI

A pericardial effusion is extra fluid in the sac around the heart. Small amounts are common and often harmless.

CT, Ultrasound, MRI

Perivascular spaces are small fluid-filled channels around blood vessels in the brain. They are normal and often become more visible with age.

MRI

The Pfirrmann grade rates disc wear on spine MRI from I (healthy, bright disc) to V (dark, collapsed disc).

MRI

Photopenic means an area shows less tracer than expected on a nuclear medicine or PET scan, so it looks blank. It is often called a cold spot.

PET and nuclear medicine

Physiologic uptake is tracer seen where it normally collects on a PET or nuclear medicine scan. It is expected and not a sign of disease.

PET and nuclear medicine

PI-RADS is a 1 to 5 score on prostate MRI for how likely an area is to be clinically significant prostate cancer, from very low to very high.

MRI

A pineal cyst is a small fluid-filled sac in the pineal gland, deep in the brain. It is common and almost always harmless.

MRI

A pituitary microadenoma is a small benign growth in the pituitary gland, under 10 mm across. It is common and often found by chance.

MRI

A pleural effusion is a build-up of fluid between the lung and the chest wall. Small ones are common, and finding the cause is what matters most.

X-ray, CT, Ultrasound

A pneumothorax is air that has leaked into the space between the lung and the chest wall, letting part of the lung collapse.

X-ray, CT

Postoperative changes are the expected marks that surgery leaves on a scan, such as scar tissue, metal clips, stitches or removed tissue.

Any scan

Prominent means a structure looks a little larger or more noticeable than usual, though it is often still within the normal range.

Any scan

Prominent CSF spaces means the brain's fluid spaces look a little larger than average, most often from mild age-related volume loss.

MRI, CT

PSMA is a protein found in large amounts on most prostate cancer cells. A PSMA PET scan uses it to find prostate cancer in the body.

PET and nuclear medicine

A pulmonary embolism is a blood clot blocking an artery in the lungs, usually one that traveled from a leg vein. It needs prompt treatment.

CT, PET and nuclear medicine

A radiotracer is a small amount of a radioactive substance given before a nuclear medicine or PET scan, so a camera can see where it collects.

PET and nuclear medicine

RECIST is a set of rules for measuring whether solid tumors shrink, stay stable or grow on CT or MRI during cancer treatment.

CT, MRI

A renal cyst is a fluid-filled sac in the kidney. Simple cysts are very common, especially with age, and are harmless.

Ultrasound, CT, MRI

A rotator cuff tear is a tear in the tendons that keep the shoulder steady and help lift the arm. It can go partway or all the way through.

MRI, Ultrasound

A Schmorl's node is a small pocket where disc material has pushed into the bone of the vertebra above or below. It is common and usually harmless.

MRI, CT, X-ray

Scintigraphy is a nuclear medicine scan: a small amount of radioactive tracer is given, and a gamma camera shows where it collects in the body.

PET and nuclear medicine

Sclerotic means an area of bone looks denser and whiter than normal on X-ray or CT, because it contains more bone mineral.

X-ray, CT, MRI

Scoliosis is a sideways curve of the spine, measured as the Cobb angle on X-ray. A curve of 10 degrees or more counts as scoliosis.

X-ray

Sinus mucosal thickening means the lining of the air-filled sinuses around the nose looks swollen. It is very common on head scans and often harmless.

CT, MRI

Small vessel disease is wear and narrowing of the brain's tiniest blood vessels. On scans it shows as patchy changes deep in the brain.

MRI, CT

SPECT is a nuclear medicine technique that turns gamma camera pictures into 3D slices, so tracer uptake can be located in depth.

PET and nuclear medicine

Spiculated means a lump has thin lines or spikes reaching out from its edge. In the lung and breast, radiologists take this feature seriously.

CT, MRI, Mammogram

Spinal canal stenosis means the central tunnel of the spine, which holds the spinal cord and nerve roots, has become narrower. It is common with age.

MRI, CT

Splenomegaly means the spleen is enlarged. Causes include infections, liver disease and blood conditions, and mild cases often have no clear cause.

Ultrasound, CT

Split renal function is the share of your total kidney function that each kidney provides, measured on a nuclear medicine kidney scan.

PET and nuclear medicine

Spondylolisthesis means one vertebra has slipped forward or backward on the one below it. Mild slips are common, especially in older adults.

X-ray, MRI, CT

Spondylolysis is a crack or gap in the pars, a thin bridge of bone at the back of a vertebra. It usually starts as a stress fracture, often in young athletes.

X-ray, CT, MRI

Spondylosis is a general term for age-related wear of the spine, including worn discs, bone spurs and arthritic joints. It is very common.

X-ray, MRI, CT

Stable means a finding looks the same as on an earlier scan. Staying unchanged over time is often a reassuring sign.

Any scan

Stenosis means narrowing. It is used for blood vessels, the spinal canal, the openings where nerves leave the spine, and ducts such as the bile duct.

CT, MRI, Ultrasound

A stress fracture is a small crack in a bone caused by repeated strain rather than a single injury. It is common in runners.

MRI, X-ray

Subcentimeter means smaller than one centimeter (10 millimeters) across, which is less than half an inch.

Any scan

SUV (standardized uptake value) is a number on a PET scan that shows how strongly a spot takes up the tracer compared with the body overall.

PET and nuclear medicine

T1 and T2 are the two basic types of MRI image. Fluid looks dark on T1 and bright on T2, which helps tell tissues apart.

MRI

A Tarlov cyst is a small fluid-filled sac on a nerve root, usually at the base of the spine (the sacrum). It is common and almost always harmless.

MRI

Tendinosis means a tendon has become thickened and worn from long-term strain or age. It is a wear change, not a tear.

MRI, Ultrasound

Theranostics pairs a scan and a treatment aimed at the same target: the scan shows whether a tumor carries it, and a related radioactive drug treats it.

PET and nuclear medicine

A thrombus is a blood clot that has formed inside a blood vessel or a heart chamber. In a deep leg vein it is called deep vein thrombosis (DVT).

Ultrasound, CT

A thyroid nodule is a lump or spot in the thyroid gland in the neck. Thyroid nodules are very common, and most are benign.

Ultrasound, CT

TI-RADS is a points-based score for thyroid nodules on ultrasound. With the nodule's size, it guides whether a needle sample or follow-up is needed.

Ultrasound

Tree-in-bud is a CT pattern of tiny branching spots in the lung, like a twig with buds. It usually means small airways are filled with mucus or pus.

CT

Unremarkable means normal: the radiologist looked at that part of the scan and found nothing worth pointing out.

Any scan

A uterine fibroid is a benign (non-cancerous) growth of muscle in the wall of the uterus. Fibroids are very common and often cause no symptoms.

Ultrasound, MRI

A V/Q mismatch is an area of lung that gets air but little blood on a ventilation-perfusion scan, a pattern that can point to a blood clot.

PET and nuclear medicine

Vascularity means blood flow within a structure. On ultrasound it is checked with Doppler, which shows moving blood in color.

Ultrasound

A vertebral hemangioma is a benign growth of small blood vessels and fat inside a vertebra. It is very common and almost always harmless.

MRI, CT

Wall thickening means the wall of a hollow organ, such as the bowel, bladder or gallbladder, looks thicker than usual on a scan.

CT, MRI, Ultrasound

Washout means a lesion loses its contrast brightness faster than expected on the later images of a CT or MRI scan. Its meaning depends on the organ.

CT, MRI

Well-circumscribed means a finding has sharp, clear edges that separate it neatly from the tissue around it. It is usually a reassuring feature.

Any scan

White matter hyperintensities are bright spots or patches in the brain's wiring (the white matter) on MRI. They are very common, especially with age.

MRI

Within normal limits means a measurement or appearance falls inside the range expected for healthy people, often matched to age and sex.

Any scan