Medical Term Glossary

C

• Calcaneus

  The heel bone — the large, sturdy bone at the back of your foot that you stand and land on. It forms the heel and anchors the Achilles tendon from your calf. On a report it is usually just naming the back of the foot. The word itself is plain anatomy.

  Also: calcanei, heel, heel bone

• Calcific tendinopathy

  A buildup of calcium deposits within a tendon, most often in the rotator cuff of the shoulder, which can range from a silent incidental finding to a source of sharp, sudden pain. It results from a natural cycle of calcium formation and reabsorption within the tendon tissue.

  Also: calcific tendinitis, calcific tendinosis, calcifying tendinopathy

• 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

• Calcified granuloma

  A small area of old, healed inflammation in the lung that has hardened with calcium deposits over the years. It typically marks a past infection the immune system successfully contained, such as tuberculosis or a fungal exposure. On a CT scan it shows up as a dense, bright white spot and is considered a stable, benign finding.

  Also: calcified granulomas, calcified lung granuloma, calcified pulmonary granuloma

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• Calvarium

  The dome-shaped top part of the skull — the smooth bony cap that covers and protects the brain. It does not include the bones of the face or the base of the skull. Radiologists use the word to point specifically at the upper skull bone when describing its thickness, shape, or any findings within it.

  Also: calvaria, cranial vault, dome of the skull

• Cardiac silhouette

  The outline of the heart as it appears on a chest image, seen as a solid shadow because the heart is full of blood and blocks the rays. Radiologists study its size and shape to judge whether the heart looks normal. The word describes the shadow, not a problem in itself.

  Also: cardiac outline, cardiac shadow, heart outline

• 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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• Cardiothoracic ratio

  A simple comparison of the heart's width to the width of the chest on a chest X-ray, written as a fraction or percentage. A value up to about half is generally considered normal. It is a rough screening number, easily thrown off by how the image was taken, not a precise measure of heart health.

  Also: CT ratio chest x-ray, CTR, cardio-thoracic ratio

• Carina

  The ridge at the point where the windpipe splits into the two main airways, one heading to each lung. It sits in the middle of the chest behind the breastbone. Radiologists use it as a fixed landmark, and check that nearby structures and any breathing tubes are sitting in the right place.

  Also: airway fork, carina of trachea, tracheal bifurcation

• Carotid artery stenosis

  Narrowing of one of the major neck arteries that supply blood to the brain, usually caused by a buildup of fatty plaque along the artery wall. It is one of the most important imaging findings for stroke risk and is graded by how much of the artery's opening is blocked.

  Also: carotid artery blockage, carotid artery disease, carotid artery narrowing

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• Carpal bones

  These are the eight small bones of your wrist, packed in two rows between the forearm and the hand. They let your wrist bend, tilt, and rotate smoothly. Reports name them to point to the wrist region, or to a specific little wrist bone, when describing a finding.

  Also: carpals, carpus bones, small wrist bones

• Carpal tunnel syndrome

  A pinched nerve at the wrist that causes numbness, tingling, and weakness in the thumb and first three fingers. It happens when the median nerve is squeezed as it passes through a narrow tunnel of bone and ligament, and it is one of the most common nerve problems in the hand.

  Also: CTS, carpal tunnel compression neuropathy, median nerve compression

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• Cartilage

  The smooth, slippery tissue that caps the ends of bones inside a joint and cushions them so they glide without grinding. It also forms structures like the meniscus, ear, and windpipe rings. Reports mention it when describing thinning, wear, or damage, best seen on MRI.

  Also: articular cartilage, chondral surface, gristle

• Cauda equina

  The bundle of nerve roots that fills the lower spinal canal below where the spinal cord itself ends, carrying signals to the legs, bladder, bowel, and pelvic organs. It is a normal anatomical structure, but severe compression of it is a surgical emergency.

  Also: CES, cauda equina compression, cauda equina nerve bundle

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• Cecum

  The first, pouch-like part of the large bowel, sitting low in the right side of the belly where the small intestine empties in. The appendix hangs from it. Its name comes from a word meaning blind, as it is a dead-end pouch. Reports often name it to locate a finding in the lower right belly.

  Also: blind pouch of colon, caecum, cecal pouch

• Cellulitis

  A bacterial infection of the skin and the soft tissue just beneath it, causing redness, swelling, warmth, and pain. On a scan it shows up as thickened, inflamed tissue rather than a solid mass. It usually responds well to antibiotics, especially when caught early.

  Also: SSTI, peri-incisional inflammation, skin and soft tissue infection

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• Cerebellopontine angle

  A small, fluid-filled space deep in the skull where the cerebellum, brainstem, and hearing/balance nerves all come together on each side. It is checked closely on brain and ear MRI because it is the classic location for an acoustic neuroma.

  Also: CP angle, CPA angle, acoustic neuroma region

• 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

• Cerebral aneurysm

  A weak, bulging spot in the wall of an artery inside the brain, shaped like a small balloon or berry. Most are small, found by chance on a scan done for another reason, and never cause a problem. The report will describe its size and location, which drive the decision to watch it or treat it.

  Also: berry aneurysm, brain aneurysm, cerebrovascular aneurysm

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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

• 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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• Cerebral microbleed

  A tiny spot of old bleeding in the brain, only a few millimeters across, visible on specialized MRI sequences but far too small to have caused any symptoms on its own. Microbleeds become more common with age and are linked to small blood vessel changes, high blood pressure, or past head trauma.

  Also: brain microbleed, cerebral microbleeds, microbleed

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• Chiari malformation

  A structural finding where the lowest part of the cerebellum extends slightly below the base of the skull into the top of the spinal canal. Many people have a mild version with no symptoms at all, discovered only by chance on a scan done for another reason.

  Also: Arnold-Chiari malformation, cerebellar tonsillar ectopia, chiari 1 malformation

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• Cholecystectomy

  Surgical removal of the gallbladder, most often done to treat gallstones or gallbladder inflammation. When a scan report mentions this term, it usually means the gallbladder is absent because it was already removed in a prior operation, which is a normal and expected finding rather than a new problem.

  Also: gallbladder removal, gallbladder removal surgery, gallbladder resection

• Cholesteatoma

  An abnormal growth of skin cells inside the middle ear, behind the eardrum, that can slowly enlarge and erode the delicate bones and structures nearby. It's not a cancer, but left untreated it can damage hearing, balance, or the facial nerve, so it's usually found on a CT scan of the temporal bone.

  Also: choleastoma, cholesteatoma of the middle ear, cholesteotoma

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• Chondromalacia

  Softening, thinning, or fraying of the smooth cartilage that caps the ends of bones in a joint, most often under the kneecap. It is a very common cause of front-of-knee pain, ranges from mild to advanced, and usually improves with strengthening and activity changes rather than surgery.

  Also: cartilage softening, chondromalacia patella, chondromalacia patellae

• 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

• Circle of Willis

  A ring-shaped network of arteries at the base of the brain that connects the major vessels supplying blood to both hemispheres. Radiologists check it on MRA or CTA scans mainly to look for aneurysms or narrowing, and a normal, symmetric circle is a reassuring finding.

  Also: arterial circle of the brain, cerebral arterial circle, circle of Willis anatomy

• Clavicle

  The collarbone — the slim, slightly S-shaped bone you can feel running across the top of your chest from the breastbone to the shoulder. It props the shoulder out to the side and links the arm to the body. On a report it is usually just naming where near the shoulder or upper chest a finding sits.

  Also: clavicles, collar bone, collarbone

• Coccyx

  The tailbone — the small, triangular tip at the very bottom of the spine, just below the sacrum. It is the leftover of what would be a tail, made of a few tiny fused bones. On a report it is usually just naming the lowest point of the spine. The word itself is plain anatomy.

  Also: bottom of the spine, coccygeal bone, tail bone

• Collateral ligament

  A strong band along the side of a joint that stops it bending sideways. In the knee, the MCL runs on the inner side and the LCL on the outer side. Similar ligaments brace the elbow and ankle. Reports mention them when describing a sprain or tear, best seen on MRI.

  Also: LCL, MCL, collateral ligaments

• 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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• Condyle

  This is the smooth, rounded knob at the end of a bone where it meets another bone to form a joint. You have them at the knee, elbow, jaw, and more. Reports use the word to point to that bulging, rounded end of a particular bone when describing a finding.

  Also: bone knob, condyles, knuckle of bone

• 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

• Conus medullaris

  This is the tapered, cone-shaped lower tip of the spinal cord, where the cord narrows and ends before splitting into a bundle of nerve roots. Reports usually note the vertebral level where it sits, since that level is checked to confirm it looks normal.

  Also: conus, cord terminus, medullary cone

• Coprostasis (stool retention)

  A buildup of hardened stool sitting in the colon, most often the result of slow bowel transit, low fiber intake, or reduced mobility. It shows up clearly on CT as a colon packed with stool and gas, and is usually a benign, manageable finding rather than a sign of serious disease.

  Also: colonic stool loading, constipation on CT, fecal loading

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• Coronary artery calcification

  Small deposits of calcium within the walls of the heart's own arteries, visible as bright specks on a CT scan. It is a marker of underlying plaque buildup and cardiovascular risk rather than a diagnosis in itself, and it is frequently spotted incidentally on chest scans done for unrelated reasons.

  Also: Agatston score, calcified coronary plaque, cardiac calcification

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• Corpus callosum

  A thick band of nerve fibers running front to back through the middle of the brain, connecting the left and right hemispheres so they can share information. Radiologists check its shape and signal routinely, and it is a key structure looked at in multiple sclerosis.

  Also: brain bridge, callosal body, callosum

• 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

• Costophrenic angle

  The sharp corner at the bottom edge of each lung, where the curved chest wall meets the dome of the breathing muscle below. On a normal scan this corner looks crisp and pointed. Radiologists watch it closely because it is one of the first places fluid or scarring tends to show up.

  Also: CP angle, costophrenic angles, costophrenic recess

• Cruciate ligament

  One of two strong bands deep inside the knee that cross each other like an X and stop the shin bone sliding too far forward or back on the thigh bone. The front one is the ACL, the back one the PCL. Reports mention them when describing a sprain or tear, best seen on MRI.

  Also: ACL, PCL, anterior cruciate ligament

• Cryptorchidism

  A condition in which one or both testicles have not descended into the scrotum and instead sit somewhere along the path from the abdomen, most often found in infants but occasionally noted incidentally on imaging in older children or adults. It is common, usually correctable, and worth monitoring for a small increase in long-term risks.

  Also: cryptorchism, ectopic testicle, hidden testicle

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• CSF leak

  Escape of cerebrospinal fluid, the clear liquid that cushions the brain and spinal cord, through a tear or hole in its surrounding membrane. It most often follows spine surgery, a spinal tap, or trauma, and causes a distinctive headache that typically needs medical treatment to seal.

  Also: CSF fistula, cerebrospinal fluid leak, dural leak

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• CT angiography (CTA)

  An imaging test that pairs a CT scanner with a fast injection of contrast dye to produce detailed, three-dimensional pictures of blood vessels. It is commonly used to look for blockages, aneurysms, or blood clots in arteries throughout the body, and is usually completed within a few minutes.

  Also: CT angiogram, CTA, angio CT

• Cubital tunnel syndrome (ulnar neuritis)

  Irritation or compression of the ulnar nerve as it passes through a narrow tunnel on the inner side of the elbow, the same nerve responsible for the "funny bone" sensation. It's a common cause of tingling, numbness, or weakness in the ring and little fingers.

  Also: cubital tunnel neuropathy, funny bone nerve syndrome, ulnar nerve compression

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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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