Medical Term Glossary
Plain-language explanations of the medical terms that appear on CT, MRI and X-ray reports — what each one means, when it matters, and what to ask your doctor.
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Abscess
A walled-off pocket of pus that the body builds around an infection to stop it spreading. It is the immune system's way of containing trouble, but once it forms it usually cannot drain on its own. Most need either antibiotics, a drain placed under image guidance, or a small procedure to clear them properly.
Also: infected cavity, infected fluid collection, pocket of pus
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Adrenal gland
A small, triangular hormone-producing organ sitting on top of each kidney. It releases stress hormones such as cortisol and adrenaline, along with chemicals that help the body manage salt, water, and blood pressure. Small spots found here by chance on a scan are extremely common and the vast majority turn out to be harmless.
Also: adrenal, adrenals, gland above the kidney
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Aneurysm
A focal bulge in the wall of an artery, where the vessel has stretched outwards into a balloon-like pouch. Most are found by chance on scans done for another reason and are watched over years rather than treated immediately. Size, location, and growth rate decide whether monitoring, medication, or repair is the right plan.
Also: AAA, arterial aneurysm, ballooning artery
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Aorta
The body's largest artery. It carries oxygen-rich blood out of the heart, arches over the top of the chest, and then runs straight down through the chest and belly, branching off to supply every organ and limb along the way. Reports often mention it when measuring its width or describing changes in its wall.
Also: abdominal aorta, aortic vessel, great artery
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Ascites
Extra fluid that has collected inside the belly, in the space surrounding the bowel and organs. A small amount can be normal in some situations, but larger collections almost always point to a problem with the liver, heart, kidneys, or the lining of the abdomen itself. The cause matters far more than the fluid.
Also: abdominal effusion, abdominal fluid, fluid build-up in the belly
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Atelectasis
A small area of lung that has not fully inflated, so it looks denser than the air-filled tissue around it. It is one of the most common findings on a chest CT and is usually mild, temporary, and not a sign of disease on its own. The cause matters more than the finding itself.
Also: bibasilar atelectasis, collapsed lung, discoid atelectasis
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Atrophy
Loss of size or volume in a tissue or organ. It can affect the brain, muscles, kidneys, a gland, or almost anywhere else. Some volume loss is part of normal ageing; some reflects a specific condition such as disuse, nerve damage, reduced blood supply, or a longstanding disease. The pattern matters more than the word alone.
Also: atrophic change, reduced volume, shrinkage
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Basal ganglia
A cluster of structures sitting deep inside the brain, on both sides, that help coordinate smooth, planned movements and certain types of learning and habit. They are routinely checked on every brain scan because they are a common site for small strokes, mineral deposits, and changes seen in some long-standing conditions.
Also: caudate putamen globus pallidus, deep brain nuclei, deep gray matter
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Benign
A reassuring word in radiology meaning a finding is not cancerous. It describes growths, lumps, or spots that have the visual features of harmless tissue — smooth edges, slow or no growth, typical patterns. Some still need monitoring or treatment depending on size and location, but they are not cancer.
Also: benign-appearing, harmless, likely benign
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Biliary dilatation
A widening of the small tubes that carry bile from the liver to the bowel. It usually means something downstream is slowing or blocking the flow — a stone, a narrowing, an inflamed pancreas, or, less often, a mass. The location and degree of the widening tell the medical team where to look next.
Also: bile duct dilation, biliary dilation, biliary tree dilation
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Bone marrow edema
An area inside a bone where extra fluid has built up among the soft tissue that fills its core. It usually signals that the bone is reacting to something — a recent injury, repeated stress, inflammation, or a nearby joint problem — and shows up as a bright patch on MRI sequences sensitive to water.
Also: bone bruise, bone marrow edema syndrome, bone marrow lesion
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Bowel obstruction
A blockage that stops food, fluid, and gas from moving through the intestines as they normally would. The gut above the block stretches and fills with fluid and air, which is what shows up on a scan. It is almost always a problem that needs prompt medical attention, sometimes urgent surgery.
Also: blocked bowel, blocked intestine, gut blockage
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Brainstem
The stalk-like lower part of the brain that connects the larger brain above to the spinal cord below. It runs the basic, automatic functions the body cannot live without — breathing, heart rate, blood pressure, swallowing, and the level of wakefulness. Every brain scan checks this region carefully because of how vital it is.
Also: brain stalk, brain stem, lower brain stalk
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Bronchiectasis
Permanently widened airways in the lungs. The tubes that should taper smoothly as they branch deeper instead look stretched and baggy, which makes it harder to clear mucus and easier for infections to take hold. The damage itself does not reverse, but the symptoms it causes can usually be managed well with the right treatment.
Also: airway dilatation, bronchial dilatation, cylindrical bronchiectasis
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Bursitis
Inflammation of a bursa — one of the small fluid-filled cushions that sit between bone and the soft tissues around joints. When a bursa becomes irritated, it fills with extra fluid and shows up on imaging as a fluid pocket. Most cases settle with rest and time; a smaller number are infected and need treatment.
Also: bursa inflammation, bursal distension, bursal inflammation
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Calcification
A small deposit of calcium that has built up in soft tissue, blood vessels, or an old healed area. On a CT scan it shows up as a very bright white spot because calcium blocks x-rays. Most deposits are old, stable, and harmless — they are essentially scars made of mineral.
Also: calcifications, calcified, calcified lesion
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Cardiomegaly
An enlarged heart on imaging. The heart looks bigger than expected when compared with the inside of the chest. It is a sign, not a diagnosis — the heart can grow because its walls have thickened from years of high blood pressure, because its chambers have stretched from extra workload, or because fluid has built up around it.
Also: big heart on scan, cardiac enlargement, dilated heart
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Cerebellum
The smaller, rounded part of the brain tucked under the back of the larger hemispheres, just above where the neck meets the skull. It coordinates balance, posture, and the smooth timing of movements. Radiologists mention it routinely on brain imaging because it is one of the standard structures they check on every scan.
Also: balance center of the brain, cerebellar, hindbrain coordinator
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Cerebral atrophy
A general shrinking of brain tissue, with widened grooves on the surface and slightly larger fluid spaces in the centre. A small amount is a normal part of getting older. Larger amounts, or shrinkage that does not match a person's age, can be linked to specific neurological conditions and are usually viewed alongside symptoms.
Also: age-related atrophy, brain atrophy, brain shrinkage
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Cerebral edema
Extra water inside or around the brain tissue, making part of the brain look swollen on a scan. It is a reaction to many things — a bruise, a stroke, an infection, a tumour, or surgery — rather than a diagnosis by itself. How much swelling there is, and what is causing it, decides how worrying it is.
Also: brain edema, brain swelling, cerebral oedema
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Chronic
A radiology word meaning a finding has been present for a long time — usually weeks, months, or years — and looks stable rather than new. It is the opposite of acute, which describes something that has just appeared. The word says nothing about danger; it describes how long something has been there.
Also: chronic changes, established, long-standing
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Compression fracture
A break in one of the spine's bones where the front of the bone has collapsed and lost height, while the back wall typically stays intact. Most happen in the mid or lower back, and many occur from a small load — like a cough or a minor stumble — in bone that has been weakened by osteoporosis.
Also: VCF, collapsed vertebra, crushed vertebra
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Consolidation (lung)
An area of lung where the tiny air sacs are filled with something other than air — usually fluid, pus, blood, or inflammatory cells. On imaging it looks denser and whiter than normal lung, and pneumonia is the most familiar cause. The pattern, location, and your symptoms together point to what is filling those air spaces.
Also: airspace disease, airspace opacity, dense lung opacity
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Contrast enhancement
A special dye is injected into a vein during the scan to make blood vessels and certain tissues stand out more clearly. When an area soaks up the dye and looks brighter than its surroundings on the images, radiologists call that pattern enhancement. The pattern itself helps tell different kinds of tissue apart.
Also: IV contrast, contrast uptake, contrast-enhanced scan
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Cortical bone
The hard, dense outer layer of bone — the part you would feel if you tapped a bone with your knuckle. It surrounds and protects the softer, spongy inner bone (called trabecular or medullary bone). Most of the strength of a bone comes from this outer shell, and radiologists pay close attention to it for fractures.
Also: bone cortex, compact bone, cortex
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Cyst
A small sac filled with fluid, sitting inside an organ or in soft tissue. Most are harmless, very common, and pop up incidentally on scans done for other reasons. Radiologists describe them as simple when the fluid is clear and the walls are thin, which is the reassuring picture; complex ones earn a closer look.
Also: complex cyst, cystic lesion, fluid collection
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Degenerative changes
A general term radiologists use for the everyday wear-and-tear that accumulates in the spine over a lifetime — slightly flattened cushions between vertebrae, small bony ridges along the edges, and a bit of joint thickening. Extremely common after the mid-30s and found in plenty of people who have no back pain at all.
Also: age-related changes, degeneration, degenerative disease
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Diffusion-weighted imaging (DWI)
A special MRI sequence that measures how freely water molecules move inside tissue. When water movement is blocked — for example, in the first minutes of a stroke or inside very dense tissue — the area lights up brightly on the scan. It is one of the most sensitive tools in emergency brain imaging.
Also: ADC map, DWI, DWI sequence
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Disc bulge
A gentle, broad outward swell of one of the soft cushions that sit between the bones of the spine. The cushion stays intact — nothing has torn or leaked — but its outer edge pushes a little past its usual footprint. Extremely common with age and often found in people who have no symptoms at all.
Also: annular bulge, broad-based bulge, bulging disc
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Disc herniation
A small tear in the outer wall of one of the spinal cushions has let some of the soft inner core push outward into a focused lump. Unlike a broad, even bulge, this is a localized pocket that can press on a nearby nerve and cause arm or leg pain, tingling, or weakness along the nerve's path.
Also: disc extrusion, disc protrusion, herniated disc
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Dislocation
A joint where the bones are no longer lined up the way they should be. In the full form the bone surfaces have lost contact completely; in a partial form (subluxation) they are misaligned but still touch. Most need to be put back into place promptly, although the urgency varies by joint and whether nearby structures are injured.
Also: dislocated joint, displaced joint, joint displacement
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Diverticulosis
Small pouches that bulge outward from the wall of the large intestine, most often in the lower-left part. They are extremely common after middle age, usually cause no symptoms, and are typically found by chance on a scan or colonoscopy. They only become a concern if one of the pouches becomes inflamed or bleeds.
Also: bowel pouches, colon pouches, colonic diverticulosis
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Emphysema
Permanent damage to the tiny air sacs deep inside the lungs, where the walls between them have broken down and merged into bigger, less efficient pockets. On a CT scan it shows up as small black spaces scattered through the lung. Smoking is by far the most common cause, though some people develop it for other reasons.
Also: COPD changes, bullous emphysema, centrilobular emphysema
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Extra-axial
A location word meaning outside the brain tissue itself but still inside the skull — in the protective layers and spaces wrapped around the brain. Radiologists use it to separate findings sitting on or around the surface from those buried in the brain. The distinction matters because it often points to different causes and treatments.
Also: around the brain, extra axial, extra-axial compartment
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Facet joint
One of the small paired joints at the back of each level of the spine that link one vertebra to the next. They guide and limit movement — bending, twisting, leaning back — and share load with the disc at the front. Like every joint in the body, they can show wear over time.
Also: apophyseal joint, facet, facet arthropathy
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FLAIR hyperintensity
A bright spot or patch on a specific type of MRI image that is good at picking up subtle tissue changes. The brightness itself simply means the tissue holds a little more water than its neighbours. Such spots are extremely common, often age-related, and only meaningful when read together with their pattern, size, and the person's symptoms.
Also: FLAIR bright lesions, FLAIR hyperintensities, T2 FLAIR hyperintensity
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Focal
A descriptive word meaning a finding is limited to one specific spot rather than spread across a wider area. It is the opposite of diffuse, which means scattered or widespread. The word says where, not what — it tells you the finding is localised but says nothing on its own about whether it matters.
Also: circumscribed, discrete area, in one area
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Foraminal narrowing
A tightening of one of the small side-doors of the spine that each nerve uses to leave the spinal canal and travel out to the body. When the door is smaller than usual, the nerve passing through can be pinched, leading to pain, tingling, or weakness along that nerve's path — usually on one side.
Also: exit foramen narrowing, foraminal stenosis, narrowing of the nerve exit
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Fracture
A break, crack, or other loss of continuity in a bone. It can be a hairline split that's barely visible, a clean snap across the middle, or a more complicated pattern with multiple pieces. The location, pattern, and whether nearby structures are involved all shape how it is treated.
Also: Fx, bone break, bony injury
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Gallbladder
A small pear-shaped sac tucked under the liver that stores and concentrates bile, the greenish fluid the liver makes to help break down fats. It releases that bile into the small intestine after a fatty meal. People can live normally without it if it has to be removed, which is one of the most common abdominal surgeries.
Also: bile sac, bile storage pouch, biliary sac
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Gallstones
Small, hardened deposits that form inside the gallbladder — the little pear-shaped sac that stores bile beneath the liver. Many people have them without ever knowing, and a quiet stone often needs no treatment. They only become a medical problem when one moves, blocks a duct, or sets off inflammation.
Also: biliary stones, cholecystolithiasis, cholelithiasis
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Ground-glass opacity
A hazy area of lung on CT that looks like a faint cloud — denser than normal lung but not so dense that the underlying blood vessels and airways disappear. It is a non-specific finding with a long list of possible causes, ranging from a minor passing infection to inflammation, fluid, or early scarring. Context is everything.
Also: GGO, ground glass attenuation, ground glass changes
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Hemorrhage
Blood that has leaked outside the vessels meant to carry it. On a scan it shows up as a pool or streak of blood in tissue or a body cavity. Size, location, and whether the leak looks fresh or old all change how urgently it needs attention. Many small or old collections are watched rather than treated.
Also: active bleed, bleed, bleeding
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Hepatic cyst
A small, fluid-filled pocket sitting inside the liver. The vast majority are harmless, present from birth, and stay quiet for life. Many people have one without ever knowing — they tend to be found by chance on a scan ordered for something completely unrelated, and they rarely cause symptoms.
Also: benign liver cyst, biliary cyst, cyst in the liver
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Hepatic steatosis
Extra fat stored inside the cells of the liver. It is very common, often has no symptoms, and is usually picked up by chance on imaging done for other reasons. The amount of fat and the reason behind it — diet, weight, alcohol, or certain medications — guide how much it matters.
Also: MASLD, NAFLD, fat in the liver
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Hydrocephalus
A build-up of cerebrospinal fluid inside the brain's fluid chambers, making them larger than normal. It can develop slowly or come on quickly, and the cause matters far more than the word itself. Treatment ranges from watchful waiting to a small surgical drain, depending on how much pressure the extra fluid creates.
Also: CSF build-up, NPH, communicating hydrocephalus
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Hydronephrosis
A swelling of one or both kidneys caused by urine that cannot drain away properly. The backed-up fluid stretches the kidney's collecting system, which shows up clearly on imaging. The cause matters more than the swelling itself — kidney stones, narrowed tubes, and an enlarged prostate are typical reasons.
Also: dilated renal pelvis, kidney backup, kidney swelling
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Imaging planes (axial, sagittal, coronal)
The three standard directions radiologists use to slice the body when reviewing a scan. Axial slices cut across like a horizontal cross-section, sagittal slices run from side to side splitting left from right, and coronal slices run front to back like opening a book. Looking at the same area in all three helps the radiologist see things any single direction would miss.
Also: axial, axial view, coronal
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Impingement
A radiology word for pinching — when two structures inside a joint rub or compress each other during normal movement instead of gliding cleanly past each other. Most often described in the shoulder (between the bones at the top) and the hip (between the ball and the rim of the socket), and not always painful.
Also: FAI, femoroacetabular impingement, hip impingement
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Incidental finding
Something the radiologist noticed on a scan even though it was not what the scan was originally looking for. These pop-ups are very common in modern imaging because scans capture far more than the clinical question asked. Most are harmless background discoveries; a few deserve a closer look.
Also: additional finding, incidental lesion, incidentally noted
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Indeterminate
A careful word radiologists use when a finding doesn't fit neatly into the benign category or the worrying category. It means the current scan alone cannot decide what something is, so a follow-up scan or a different test is usually recommended. It does not mean the finding is dangerous.
Also: equivocal finding, incompletely characterised, indeterminate finding
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Infarct
An area of brain tissue that has been injured or has died because its blood supply was cut off, usually by a blocked artery. On imaging it shows up as a patch of tissue that no longer looks like its healthy neighbours. The size and location decide how the symptoms appear and how the team responds.
Also: brain attack, cerebral infarct, infarction
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Intracranial
An adjective meaning inside the skull. It describes the location of something — a structure, a finding, or a process — rather than what that thing is or whether it is a problem. The word appears constantly in brain reports because radiologists use it to point at where something sits.
Also: inside the brain cavity, inside the skull, intracranial compartment
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Intracranial hemorrhage
Blood that has leaked inside the skull, either into the brain tissue itself or into one of the spaces wrapped around it. It is an important and time-sensitive finding because fresh blood takes up room the brain does not have to spare. Exact location, size, and cause shape how urgently it has to be treated.
Also: ICH, bleeding in the brain, brain bleed
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Labral tear
A break in the labrum, the ring of soft fibrous cartilage that deepens the socket of the shoulder or hip and helps hold the ball of the joint in place. Tears can come from a sudden injury, from repeated load over years, or simply from the shape of the joint itself. Common, and often found on scans of pain-free adults.
Also: SLAP tear, hip labral tear, labrum tear
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Lesion
A general word radiologists use for any spot, area, or region of tissue that looks different from what surrounds it. By itself it does not mean cancer, infection, or anything specific — it simply flags a finding that stood out. The report's other adjectives (focal, well-defined, suspicious, benign) carry most of the meaning.
Also: abnormal area, focal lesion, growth
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Ligament tear
A break in one of the tough fibrous bands that hold two bones together at a joint. Tears range from a few stretched fibres (a sprain) to a complete rupture across the whole band. Most happen during a sudden twist, pivot, or impact, and the joint involved shapes how serious it is.
Also: ACL tear, MCL tear, ligament rupture
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Lymph nodes
Small, bean-shaped filters that sit along the body's drainage network for tissue fluid. Hundreds of them are scattered through the neck, armpits, chest, abdomen, pelvis, and groin. They trap bacteria, viruses, debris, and stray cells, then mount an immune response. Their presence on a scan is normal; size, shape, and pattern decide whether they need attention.
Also: glands, lymph glands, lymph node
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Lymphadenopathy
Lymph nodes that look larger than normal on imaging. The body has hundreds of these small, bean-shaped filters scattered through the chest, neck, armpits, and elsewhere. They swell when they are doing their job — fighting infection — but can also enlarge from inflammation, autoimmune conditions, or, less commonly, cancer.
Also: enlarged lymph nodes, hilar lymphadenopathy, lymph node enlargement
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Malignant
A heavy word in radiology meaning a finding has the appearance of cancer on imaging — irregular edges, invasion into nearby tissue, abnormal blood vessels, or other concerning features. It is a description of the picture, not a confirmed diagnosis. A biopsy is what actually proves cancer; imaging alone cannot.
Also: cancerous, concerning for cancer, concerning for malignancy
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Mass
A solid or partly solid lump of tissue, usually larger than three centimetres, that looks distinct from the tissue around it. The word flags something worth investigating, but it does not by itself mean cancer. Size, borders, growth over time, and how it behaves with contrast all carry far more meaning than the label alone.
Also: focal mass, growth, lump
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Mass effect
A phrase radiologists use when something inside the skull is taking up extra room and pushing on the brain tissue or fluid spaces nearby. It is a description of crowding, not a diagnosis on its own. The cause — swelling, bleeding, a tumour, or a fluid pocket — and how much pressure it creates is what matters most.
Also: compression effect, local mass effect, mass-like effect
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Mastoid air cells
Tiny honeycomb-like air pockets inside the bone just behind each ear, connected to the middle ear. They normally contain air and help regulate pressure in the ear. Because they sit right next to the brain, every head CT or MRI looks at them and notes whether they are clear or contain fluid.
Also: ear bone air spaces, mastoid, mastoid bone
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Mediastinum
The central compartment of the chest, sitting between the two lungs. It contains the heart, the great blood vessels, the windpipe, the food pipe, lymph nodes, and several nerves. When a chest scan mentions this area, it is usually pointing at something sitting in that central region rather than in the lungs themselves.
Also: central chest compartment, central chest space, mediastinal area
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Meniscal tear
A split in one of the two C-shaped pads of cartilage that sit between the thigh bone and the shin bone inside the knee. These pads cushion and stabilise the joint. Tears can follow a sudden twist or develop gradually with age, and not every tear seen on a scan causes pain.
Also: bucket-handle tear, lateral meniscus tear, medial meniscus tear
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Metastasis
A spot on imaging that looks like cancer that has spread from another part of the body. The word on a report is a description of appearance, not always a diagnosis. Many suspected spreads turn out, after biopsy or follow-up, to be benign — cysts, scars, or unrelated lesions. Biopsy is the gold standard for confirmation.
Also: metastases, metastatic disease, metastatic lesion
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Midline shift
A sign on brain imaging that something on one side is pushing the brain's central structures over toward the other side. It almost always points to swelling, bleeding, or a mass that needs attention soon. The amount of shift, measured in millimetres, is one of the strongest cues to how urgent the situation is.
Also: brain shift, deviation of the midline, mass effect with midline shift
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MRI signal intensity (T1, T2, FLAIR)
On an MRI scan, every tissue gives off a different brightness depending on which setting the scanner is using. The settings are called sequences — T1, T2, and FLAIR are the most common. Whether something looks bright or dark on each sequence is one of the main clues radiologists use to tell different tissues and problems apart.
Also: FLAIR, T1, T1 signal
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MRI vs CT — which does what
Two of the most common imaging tests, used for different jobs. CT is fast and great for bones, bleeding, and emergencies. MRI is slower but shows soft tissue, brain detail, and joints in much higher resolution. Neither is better overall — they answer different questions, and doctors choose based on what they need to see.
Also: CT or MRI, CT vs MRI, MRI or CT
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Mucosal thickening
A description used by radiologists when the soft inner lining of a hollow space looks puffier than usual. It is most commonly seen in the sinuses but also turns up in the bowel and other lined cavities. By itself it just means the lining is irritated; the cause varies from a recent cold to a more persistent inflammation.
Also: lining thickening, mucosal swelling, sinus lining thickening
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Nodule
A small, rounded spot of tissue, usually under three centimetres across, that looks different from what surrounds it. Most are harmless and very common — old scars, tiny benign growths, or healed inflammation. Size, shape, and behaviour over time decide whether one needs follow-up or can be ignored.
Also: pulmonary nodule, small focal lesion, small nodule
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Nonspecific
A hedging word radiologists use when a finding could be caused by several different things and the scan alone cannot decide between them. It is not a diagnosis — it is the radiologist being honest about the limits of imaging and asking your doctor to combine the picture with your symptoms and blood tests.
Also: etiology unclear, non-specific, nonspecific appearance
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Orbits
The bony eye sockets in the front of the skull, holding the eyeballs along with the muscles, nerves, fat, and blood vessels that surround them. They sit right next to the sinuses and the front of the brain, so head and brain scans routinely include them and comment on what is inside.
Also: bony orbit, eye socket, eye sockets
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Osseous
A medical word that simply means "of the bone" or "made of bone." Radiologists use it as a precise adjective when describing structures, findings, or changes that involve the skeleton itself rather than the surrounding soft tissues — muscles, tendons, organs, or nerves. On its own it carries no good or bad meaning.
Also: bone, bone-related, bony
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Osteoarthritis
The most common form of joint wear. The smooth cartilage that lines the ends of the bones inside a joint gradually thins, the joint space narrows, and small bony ridges form along the edges. Extremely common with age — most adults over 60 show some of it on imaging, and many feel nothing from it.
Also: DJD, OA, degenerative arthritis
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Osteophyte
A small extra ridge of bone that grows along the edge of a joint or vertebra as the body responds to years of wear and load. Very common after middle age, usually painless on its own, and most often a marker of ageing rather than a disease — though large ones can crowd nearby nerves.
Also: bone spur, bony outgrowth, bony ridge
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Paranasal sinuses
Air-filled spaces in the bones of the face around the nose, lightening the skull and warming and moistening the air you breathe. They sit in the forehead, behind the cheeks, between the eyes, and deep inside the head, and they all drain into the nose. Brain and head scans routinely include and comment on them.
Also: ethmoid sinus, facial sinuses, frontal sinus
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Parenchyma
The working tissue of an organ — the part that actually does the organ's job, as opposed to its supporting structures like blood vessels, ducts, or capsule. The brain has its own working tissue; so do the kidneys, liver, lungs, and pancreas. Radiologists use the word to be precise about which part of an organ they are describing.
Also: brain parenchyma, functional tissue, hepatic parenchyma
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Pericardial effusion
Extra fluid sitting in the thin sac that surrounds the heart. A small amount is often harmless and very common. A larger volume can press on the heart and stop it filling properly, which is why the size on the report — and how quickly it built up — matters more than the finding itself.
Also: cardiac effusion, fluid around the heart, fluid in heart sac
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Periventricular
A descriptive term meaning "around the fluid-filled spaces in the middle of the brain." It points to the region of brain tissue that lies just next to the ventricles, where a finding has been seen. The word itself only marks the location — what matters is what is found there.
Also: around the brain's fluid spaces, around the ventricles, next to the ventricles
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Pleural effusion
A build-up of fluid in the thin space between the lungs and the chest wall. Small amounts often cause no symptoms; larger collections can press on the lung and make breathing harder. The cause matters more than the fluid itself — infection, heart strain, and inflammation are the usual culprits.
Also: fluid around lung, fluid around the lungs, fluid in the chest
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Pneumoperitoneum (free air)
Air sitting inside the belly cavity where there should be none. Normally air stays inside the stomach and intestines; finding it loose in the surrounding space usually means a hole somewhere in the gut wall has let it escape. It is almost always treated urgently because the underlying leak needs prompt attention.
Also: free abdominal air, free air, free air in the belly
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Pneumothorax
Air that has leaked into the space between the lung and the inside of the chest wall, where there should be no air at all. The trapped air presses on the lung and stops it from inflating fully. Small leaks sometimes heal on their own, but larger ones need urgent treatment because they can make breathing difficult quickly.
Also: PTX, air around the lung, air leak in chest
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Pulmonary edema
Extra fluid leaking into the tiny air sacs and surrounding tissue of the lungs, making them heavy and less efficient at moving oxygen into the blood. It most often reflects strain on the left side of the heart, but inflammation, infection, kidney issues, and high altitudes can also cause it. Treatment focuses on the underlying reason.
Also: cardiogenic lung fluid, fluid in the lungs, lung congestion
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Pulmonary embolism
A blood clot that has travelled through the veins and lodged in one of the arteries supplying the lungs. Most start as a clot in a deep leg vein, break off, and ride the blood up through the heart before getting stuck. The size and location decide how serious it is, and the care team treats it promptly.
Also: PE, blood clot in the lung, clot in the lungs
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Pulmonary nodule
A small, rounded spot in the lung that stands out from the surrounding tissue. Most are smaller than a grape and most turn out to be harmless — leftover scars from old infections, tiny benign growths, or specks of inflammation. Size, shape, and whether it changes over time decide how closely it is watched.
Also: SPN, incidental lung nodule, lung nodule
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Renal cyst
A small, fluid-filled sac inside the kidney. Most are harmless, develop quietly with age, and are picked up by chance on a scan done for something else. The radiologist's job is to tell the simple, benign kind apart from the rare more complex variety that needs a closer look — and most of the time it is the simple kind.
Also: benign kidney cyst, cyst on the kidney, fluid-filled kidney lesion
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Rotator cuff tear
Damage to one of the four small muscle-tendons that wrap around the top of the shoulder and keep the arm bone seated in its socket. The tear can be a thin partial fray on the surface or a full break through the tendon. Many are gradual age-related wear; others follow a sudden injury.
Also: cuff tear, partial-thickness cuff tear, rotator cuff injury
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Sacroiliac joint
The paired joints that connect the lower spine (sacrum) to the back of the pelvis (iliac bones), one on each side. They sit deep in the lower back, transfer weight between the spine and the legs, and move very little. They are common to mention on scans and are a frequent source of low back and buttock pain.
Also: SI joint, SI joints, SIJ
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Soft tissue mass
A lump in the soft parts of the body — muscle, fat, fibrous tissue, nerves, or vessels — rather than in bone. It is a description of what was seen, not a diagnosis. Most are benign (lipomas, cysts, fibrous lumps); some are inflammatory; a smaller number turn out to be tumours that warrant further imaging or biopsy.
Also: fatty lump, muscle mass, non-bony mass
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Spinal canal stenosis
A narrowing of the bony tunnel that houses the spinal cord and nerve roots. The narrowing crowds the structures running through it, which can cause back pain, leg pain, numbness, or weakness depending on the level. Most cases develop slowly with age; the severity on imaging often correlates loosely with symptoms.
Also: central canal narrowing, central canal stenosis, cervical stenosis
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Splenomegaly
An enlarged spleen — the small, fist-sized organ tucked under the ribs on the left side. It is a sign, not a diagnosis: the spleen grows in response to many different things, from a recent viral infection to long-standing liver disease or a blood disorder. The reason behind the enlargement is what matters.
Also: big spleen, enlarged spleen, spleen enlargement
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Spondylolisthesis
One of the bones in the spine has shifted forward, backward, or sideways relative to the bone below it, so the stack no longer lines up perfectly. The slip is often small and stable, but a larger shift can narrow the spinal canal or pinch a nerve, causing back pain or symptoms down a leg.
Also: anterolisthesis, degenerative spondylolisthesis, isthmic spondylolisthesis
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normal
Spondylosis
A general term for the slow, age-related wear of the spine — drying cushions, small bony spurs, and stiffer joints. It is the back's version of grey hair: nearly universal after middle age, often visible on scans of people who feel completely fine, and usually a description of normal ageing rather than a disease.
Also: arthritis of the spine, cervical spondylosis, degenerative disc disease
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Study
In radiology, a single complete imaging examination of one patient on one day — for example, one MRI of the brain or one CT of the abdomen. A single examination is usually made up of several image sets, called series, captured from different angles or with different settings.
Also: DICOM study, current study, examination
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urgent
Subarachnoid hemorrhage
Bleeding into the thin, fluid-filled space that wraps around the brain, between two of its protective layers. It is a time-sensitive finding because the blood sits in the same space as the cerebrospinal fluid and can quickly affect the whole brain. The cause and the amount of bleeding decide how it is treated.
Also: SAH, aneurysmal bleed, bleed under the arachnoid
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Sulci
The grooves on the outer surface of the brain, between the raised folds. They are a normal part of how the brain is built — the wrinkled surface packs a much larger sheet of tissue into the limited space of the skull. Radiologists describe how deep or wide these grooves look as part of every brain scan.
Also: brain folds, brain grooves, cerebral sulci
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Suspicious
A hedging word radiologists use when a finding has some features that raise concern but the scan alone cannot prove a diagnosis. It usually triggers more workup — a follow-up scan, biopsy, or specialist referral — rather than a definite answer. The word is a flag, not a verdict.
Also: concerning, concerning for, raises concern for
T
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Tendinopathy
A catch-all term for a tendon that's been irritated, overloaded, or worn down over time. The tissue thickens, loses some of its tidy fibre pattern, and may show small areas of damage inside it. Common in shoulders, elbows, knees, and ankles, and often linked to repeated load rather than a single injury.
Also: tendinitis, tendinosis, tendon degeneration
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Thickening
A description that a wall, lining, or layer of tissue measures more than expected for that area. The word is purely a measurement — it does not say whether the cause is inflammation, infection, scarring, a benign change, or something more serious. The rest of the report and the clinical picture decide what it means.
Also: circumferential thickening, focal thickening, mural thickening
U
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Ultrasound
An imaging test that uses high-frequency sound waves rather than X-rays to look inside the body. A handheld probe sends sound pulses through the skin and listens for the echoes, building a live picture on a screen. It involves no radiation, is widely available, and is especially good at looking at soft, fluid-filled, and moving structures.
Also: US, doppler scan, echo
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Unremarkable
A reassuring word in radiology. It means the radiologist looked carefully at a structure and found nothing worth pointing out — no swelling, no abnormal spots, no concerning changes. Despite how it sounds in everyday English, on a scan report this is good news.
Also: grossly normal, negative study, no abnormality detected
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