Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

975 results found
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Broken heart sign

The broken heart sign, also known as the Y sign in older otorhinolaryngology literature 2,3, describes the appearances of incudomalleolar disarticulation. This sign is identified on CT in the coronal plane, being formed by the widening of the incudomalleolar joint and lateral displacement of th...
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Bronchial cut-off sign

The bronchial cut-off sign refers to the abrupt truncation of a bronchus from obstruction, which may be due to cancer, mucus plugging, trauma or foreign bodies. Typically, there is associated distal lobar collapse. 
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Bronchorrhea

Bronchorrhea is the expectoration of copious amounts of mucus from the lungs. It has been defined as production of more than 100 mL of mucus in 24 hours, which is more than is usually seen in chronic lung disease (e.g. chronic bronchitis typically produces 25 mL/24 hrs) 2. It may be a feature of...
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Brudzinski sign (meningism)

Brudzinski sign occurs in meningitis (of any etiology) or meningism where passive flexion of a patient's neck elicits reflexive bilateral knee and hip flexion; it was originally known as the "nape of the neck sign" and was one of several physical exam maneuvers concurrently described to be chara...
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Bubbly consolidation

Bubbly consolidation describes internal or central lucencies which represent normal aerated lung lobule within infarcted, consolidated, lung parenchyma. It is one of the highly specific imaging appearances of focal pulmonary hemorrhage or possibly pulmonary infarct secondary to pulmonary embolis...
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Bulging fissure sign (lobar consolidation)

The bulging fissure sign refers to lobar consolidation where the affected portion of the lung is expanded causing displacement of the adjacent fissure. Any type of pneumonia or space-occupying process can lead to bulging (sagging) fissure sign. Classically, it has been described in right upper l...
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Bullet and bodkin sign

Bullet and bodkin sign is the appearance of the ureter when there is an abrupt transition in the ureteral caliber. Bullet in the name is represented by the dilated proximal ureteric segment which appears to be perched on the constricted / non-dilated encased ureter which gives an appearance of a...
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Bullet-shaped vertebra

Bullet-shaped or ovoid vertebra refers to the anterior beaking of the vertebral body. It is seen in the following conditions: mucopolysaccharidosis (Morquio disease, Hurler disease) achondroplasia congenital hypothyroidism  See also weapons and munitions inspired signs
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Bunch of grapes sign (bronchiectasis)

The bunch of grapes sign, a.k.a. cluster of grapes sign, is a characteristic imaging finding on CT seen in bronchiectasis. Closely apposed dilated bronchi may look like multiple adjacent thin walled cysts which mimic the appearance of a bunch of grapes.
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Bunch of grapes sign (disambiguation)

Bunch of grapes sign refers to the imaging appearance of multiple cystic spaces or lesions and it has been described for multiple pathologies: bunch of grapes sign (hydatidiform mole) 7 bunch of grapes sign (bronchiectasis) 3 bunch of grapes sign (IPMN) 6 bunch of grapes sign (botryoid rhabd...
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Bunny waveform sign

Bunny waveform sign refers to the biphasic morphology of the pulsed wave Doppler spectral waveform in the vertebral artery in early (occult/latent or partial) subclavian steal phenomenon (sometimes called a "presteal" state, before it progresses to frank flow reversal). There is a sharp decelera...
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Burst lobe

A burst lobe is an uncommonly used description of traumatic lobar intraparenchymal hemorrhage of the brain that ruptures into the subdural space and communicates with subdural hemorrhage 1. As traumatic hemorrhages are more common in the frontal and temporal lobes, these lobes are the most affe...
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Butterfly glioma

Butterfly gliomas are a high grade astrocytoma, usually a glioblastoma (WHO grade IV), which crosses the midline via the corpus callosum. Other white matter commissures are also occasionally involved. The term butterfly refers to the symmetric wing-like extensions across the midline.  Most freq...
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Butterfly sign (choroid plexus)

The butterfly sign refers to the normal appearance of the choroid plexuses on axial imaging of the fetal brain, commonly observed on the antenatal ultrasound. Its absence may suggest holoprosencephaly 1. In the CNS, the term should not be confused with a butterfly glioma, which is a glioblastom...
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Butterfly vertebra

Butterfly vertebra is a type of vertebral anomaly that results from the failure of fusion of the lateral halves of the vertebral body because of persistent notochordal tissue between them. Pathology Associations anterior spina bifida +/- anterior meningocele can be part of the Alagille syndr...
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Button sequestrum

A button sequestrum is a small sequestrum of devascularised bone surrounded by lucency. Although classically described in osteomyelitis and eosinophilic granuloma it is also occasionally seen in fibrosarcoma and lymphoma. Differential diagnoses osteoid osteoma tuberculous osteomyelitis radi...
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Cecal bar sign (acute appendicitis)

The cecal bar sign is a secondary sign in acute appendicitis. It refers to the appearance of inflammatory soft tissue at the base of the appendix, separating the appendix from the contrast-filled cecum. See also arrowhead sign
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Callosal angle

The callosal angle has been proposed as a useful marker of patients with idiopathic normal pressure hydrocephalus (iNPH), helpful in distinguishing these patients from those with ex-vacuo ventriculomegaly (see hydrocephalus versus atrophy).  It should be noted that there is nothing magical abou...
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Calyceal crescent sign (intravenous pyelogram)

The calyceal crescent sign (Dunbar crescents) refers to the early intravenous pyelogram (IVP) appearance of markedly dilated renal calyces. It is formed by early contrast opacification of the dilated collecting ducts and ducts of Bellini with the characteristic shape as a result of the associate...
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Cannonball metastases (lungs)

Cannonball metastases refer to multiple large, well-circumscribed, round pulmonary metastases that appear not unsurprisingly like cannonballs. The French terms "envolée de ballons" and "lâcher de ballons",  which translate to "balloons release", are also used to describe this same appearance. M...
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Capps triad

The Capps triad refers to the constellation of clinical and imaging findings in patients with spontaneous retropharyngeal hematomas, and consists of: tracheal and esophageal compression anterior displacement of the trachea subcutaneous bruising over the neck and anterior chest History and et...
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Caput medusae sign (developmental venous anomaly)

The caput medusae sign refers to developmental venous anomalies of the brain, where a number of veins drain centrally towards a single drain vein. The appearance is reminiscent of Medusa, a gorgon of Greek mythology, who was encountered and defeated by Perseus. The sign is seen on both CT and M...
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Caput medusae sign (disambiguation)

Caput medusae sign can refer to: caput medusae sign (portal hypertension) caput medusae sign (developmental venous anomaly) History and etymology The appearance is reminiscent of Medusa, a gorgon of Greek mythology, who was encountered and defeated by Perseus.
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Caput medusae sign (portal hypertension)

The caput medusae sign is seen in patients with severe portal hypertension. It describes the appearance of distended and engorged paraumbilical veins, which are seen radiating from the umbilicus across the abdomen to join the systemic veins.  History and etymology The appearance is reminiscent...
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Carman meniscus sign

The Carman meniscus sign describes the lenticular shape of barium in cases of large and flat gastric ulcers, in which the inner margin is convex toward the lumen. It usually indicates a malignant ulcerated neoplasm; in cases of benign gastric ulcers, the inner margin is usually concave toward th...
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Cartilage interface sign

Cartilage interface sign, also referred to as double cortex sign, refers to the sonographic presence of a thin markedly hyperechoic line at the interface between the normally hypoechoic hyaline articular cartilage of the humeral head and an abnormally hypoechoic supraspinatus tendon. This arises...
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Caterpillar sign (pyloric stenosis)

The caterpillar sign is a radiological sign described in pyloric stenosis. It refers to the appearance of the stomach on an upper gastrointestinal radiographic series or plain abdominal radiograph 1,2. On these imaging modalities in a patient with pyloric stenosis, the stomach appears distended...
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Caton-Deschamps index (knee)

The Caton-Deschamps index is used to measure patellar height and identify patella alta and patella baja. The Caton-Deschamps index relies upon the length of the patellar articular surface and its distance from the tibia, reducing erroneous measurements in those with long patella bodies, as measu...
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Celery stalk (disambiguation)

Celery stalk appearance can refer to the following: celery stalk anterior cruciate ligament celery stalk metaphysis
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Celery stalk metaphysis

Celery stalk metaphysis refers to a plain film appearance of the metaphyses in a number of conditions characterized by longitudinally aligned linear bands of sclerosis. They are seen in: congenital infections congenital rubella congenital syphilis congenital cytomegalovirus (CMV) osteopathi...
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Celery stalk sign (anterior cruciate ligament)

The celery stalk sign is a term given to the appearance of the anterior cruciate ligament which has undergone mucoid degeneration and has been likened to that of a celery stalk. Its low signal longitudinal fibers are separated from each other by higher signal mucinous material, best appreciated ...
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Centipede sign (mesentery)

The centipede sign is seen as engorged mesenteric vessels in cases of acute sigmoid diverticulitis which gives an appearance similar to a centipede 1.
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Central vein sign

The central vein sign is a marker for multiple sclerosis (MS) and is the imaging manifestation of the perivenular nature of demyelinating plaques. It is not pathognomonic but can be useful in helping differentiate multiple sclerosis from mimics, such as cerebral small vessel disease, neuromyelit...
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Centrilobular micronodules

Centrilobular micronodules are an image descripter which refer to centrilobular nodules when the nodules are very small and present in a centrilobular distribution in the lungs. They are usually seen with a bronchiolitis and can blend into tree-in-bud opacities.  Image interpretation Postproce...
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Cerebral paragonimiasis

Cerebral paragonimiasis refers to brain infection with a specific genus of flukes and is a serious manifestation of paragonimiasis, which is primarily a lung disease caused by trematodes of the genus Paragonimus. Epidemiology Paragonimiasis is endemic in Asia, West Africa, and Latin America. I...
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Cervicothoracic sign

The cervicothoracic sign is a variation of the silhouette sign on frontal chest radiography used to determine whether a superior (para)mediastinal soft tissue mass is anterior or posterior to the trachea. A positive cervicothoracic sign occurs when a thoracic lesion contacts the neck or extends...
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Cervix sign (pyloric stenosis)

The cervix sign of pyloric stenosis describes the indentation of the pylorus into the fluid-filled antrum, seen in pyloric stenosis on ultrasound examination. See also antral nipple sign (pyloric stenosis) target sign (pyloric stenosis)
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Chain of lakes sign

The chain of lakes sign is a radiological finding describing the appearance of the pancreatic ducts in cases of chronic pancreatitis. Due to repeated inflammation, fibrosis occurs and results in damage and atrophy of the pancreatic tissue as well as dilatation and beading of the main pancreatic ...
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Champagne glass pelvis (achondroplasia)

The champagne glass pelvis is a helpful sign in achondroplasia in which the iliac blades are flattened, giving rise to a pelvic inlet that resembles a champagne glass. The acetabular angles are flattened (horizontal) and the sacrosciatic notch is small.
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Chang sign (pulmonary embolism)

The Chang sign refers to the dilatation and abrupt change in caliber of the main pulmonary artery due to pulmonary embolism 1. It is one of several described signs of pulmonary embolus on chest radiographs. History and etymology It is named after C H Joseph Chang, (July 7 1929 - November 15 20...
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Charcot triad

Charcot triad is the finding of pyrexia, right upper quadrant pain and jaundice, and is a traditional clinical sign of acute cholangitis. A meta-analysis of 4288 patients in 16 studies found that the sensitivity of Charcot triad for acute cholangitis was poor (36.3%) with a much better specific...
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Cheerio sign (disambiguation)

The Cheerio sign has been described in two different scenarios: Cheerio sign (pulmonary nodule) Cheerio sign (shoulder)
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Cheerio sign (pulmonary nodule)

Cheerio sign in thoracic imaging relates to pulmonary nodules with a central lucent cavity supplied by a patent bronchus as seen on CT 3. It is due to proliferation of (malignant or non-malignant) cells around an airway. They are so named because of their resemblance to the breakfast cereal, Che...
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Cheerio sign (shoulder)

The Cheerio sign has been described as a sign seen in a type III superior labral anterior posterior tear (SLAP lesion) of the glenoid labrum. In the Cheerio sign, a rounded core of soft tissue is surrounded by a rim of contrast material and gas.  SLAP type III is the bucket handle tear of the s...
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Chen sign

Chen sign on chest radiography is the prominence of the left basal pulmonary vasculature, compared to the right, seen in valvular pulmonary stenosis. It is due to the asymmetric increase in pulmonary blood flow to the left lung due to preferential blood flow into the left pulmonary artery after ...
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Chicken intestine appearance

The chicken intestine is a term used to describe the appearance of a hypersegmented barium column. This appearance is characteristic of intestinal tuberculosis 1. Other radiographic findings such as accelerated intestinal transit, flocculation and dilution of the barium and, luminal stenosis wi...
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Chilaiditi sign

Chilaiditi sign refers to the interposition of the bowel, usually colon, between the inferior surface of the right hemidiaphragm and the superior surface of the liver. It may be misinterpreted as a true pneumoperitoneum resulting in unnecessary further investigations and/or therapy (so-called ps...
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Chinese dragon sign (vascular)

Chinese dragon sign is a radiological sign in abdominal radiograph and CT describing the radiologic appearance of calcified tortuous splenic artery that resembles the Chinese dragon. The tortuous splenic artery segment on the splenic hilum side represents the dragon head while the other arterial...
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Chorionic bump

Chorionic bump is a finding that can be uncommonly seen in a first-trimester scan. It may represent a small hematoma bulging into the gestational sac or an anembryonic (failed) second pregnancy that is being resorbed. It is also seen in some patients undergoing infertility treatment. Epidemiolo...
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Cingulate island sign

The cingulate island sign is a highly specific radiological sign described in dementia with Lewy bodies. It refers to the pattern of metabolism seen on FDG-PET in patients with dementia with Lewy bodies 1-3. On FDG-PET, there is occipital hypometabolism with relative sparing of the posterior ci...
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Cingulate sulcus sign

The cingulate sulcus sign has been proposed as being useful as an MRI feature of idiopathic normal pressure hydrocephalus (NPH). It denotes the posterior part of the cingulate sulcus being narrower than the anterior part. The divider between the anterior and posterior parts of the sulcus being a...
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Claustrum sign

The claustrum sign refers to the bilateral claustral involvement seen in febrile infection-related epilepsy syndrome (FIRES). This sign is described in T2 and FLAIR sequences, seen as hyperintensity of both claustra during the acute phase and posterior hypointensity during the chronic phase if ...
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Claw sign (disambiguation)

A claw sign has been named in multiple contexts: claw sign indicating the organ of origin of a mass claw sign of degenerative spondylosis lobster claw sign of renal papillary necrosis
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Claw sign (mass)

The claw sign is useful in determining that a mass arises from a solid structure rather than is located adjacent to it and distorts the outline. It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. ...
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Claw sign (spine)

The claw sign on diffusion weighted imaging refers to a pattern of hyperintensity seen in degenerative changes in the spine (Modic type 1): well-defined, paired band-like regions of restricted diffusion affecting two contiguous vertebral bodies, resembling a claw surrounding the disc space on sa...
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Cliff sign (hip micro-instability)

The cliff sign in hip microinstability is a steep drop-off and loss of normal sphericity of lateral femoral head. Radiographic features Plain radiograph Shenton line distortion subluxation of the femoral head sclerosis of the femoral neck MRI <3 mm anterior lateral capsule >5 mm anterior...
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Cloaca (osteomyelitis)

A cloaca (pl. cloacae/cloacas) can be found in chronic osteomyelitis. The cloaca is an opening in an involucrum which allows drainage of purulent and necrotic material out of the dead bone. If the tract extends to the skin surface, the portion extending beyond the involucrum to the skin surface...
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Cloverleaf skull (craniosynostosis)

Cloverleaf skull, also known as kleeblattschädel syndrome or deformity, refers to a type of severe craniosynostosis which gives the skull a cloverleaf shape. It is very rare, with less than 130 case reports globally. It typically results from intrauterine premature closure of the sagittal, coron...
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Cluster of black pearls sign

The "cluster of black pearls" sign refers to a finding on contrast-enhanced CT useful in differentiating sarcoidosis from other causes of lymphadenopathy such as tuberculosis, lymphoma and metastatic adenocarcinoma. The sign is depicted by the presence of multiple tiny round nodules (1-2 mm) di...
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Cluster sign

The cluster sign is a finding on MRI and CT that is associated with pyogenic hepatic abscesses and can help differentiate pyogenic abscesses from other types of liver lesions. Radiographic features The cluster sign is best seen on MRI T2-weighted and postcontrast T1-weighted sequences. Small n...
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Cobblestone appearance (hollow viscera)

Cobblestoning (having a cobblestone appearance) can occur in a number of hollow organs with mucosa, most commonly the bowel, in the setting of Crohn disease.  Longitudinal and circumferential fissures and ulcers separate islands of mucosa, giving it an appearance reminiscent of cobblestones.  ...
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Cobra head sign (ureter)

The cobra head sign, also known as the spring onion sign, refers to dilatation of the distal ureter, surrounded by a thin lucent line, which is seen in patients with an adult-type ureterocele. The cobra head appearance indicates an uncomplicated ureterocele. During an excretory phase of an intr...
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Cobweb sign of arterial dissection

The cobweb sign is seen in cases of arterial dissection (usually aortic dissection) on CT angiogram (CTA) examinations and represents strands or ribbons of media crossing the false lumen, and appearing as thin filiform filling defects. Although it is a specific sign for the false lumen, it is i...
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Coca-Cola bottle sign (thyroid eye disease)

The Coca-Cola bottle sign refers to the appearance of the muscles of the orbit in thyroid eye disease.  The belly of the muscle enlarges with sparing of the tendinous insertion, giving the appearance of the traditional Coca-Cola bottle. The enlargement of the muscles follows the I'M SLOW format...
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Cockade sign (disambiguation)

There are several described cockade signs in radiology: cockade sign (intraosseous lipoma) cockade sign (aorto-left ventricular tunnel) 1 cockade sign (appendicitis) 2 cockade sign (hypertrophic pyloric stenosis) 3 cockade sign (GI tumors) 4
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Cockade sign (intraosseous lipoma)

The cockade sign describes the classic appearance of a calcaneal intraosseous lipoma seen as a well-defined lytic lesion with a central calcification. History and etymology It is named after a cockade, which is a badge, usually in the form of a rosette or knot, generally worn on the hat.
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Codman triangle periosteal reaction

A Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. The periosteum does not have time to ossify with shells of new bone (e.g. as seen in a single layer and multilayered periosteal reaction) in aggressive lesions, so only the edge of the raised periosteum will os...
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Coffee-bean sign (sigmoid colon)

The coffee-bean sign (also known as the kidney bean sign or bent inner tube sign 4) is a sign on an abdominal plain radiograph of a sigmoid volvulus although some authors have also used the term to refer to closed loop small bowel obstructions. Cecal volvulus may be mistaken with sigmoid volvulu...
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Cogwheel sign

The cogwheel sign refers to an imaging appearance in pelvic imaging of thickening loops of the Fallopian tube seen on cross-section. There are infolding projections (sometimes looking like nodules) into the Fallopian tube lumen which is likened to that of a cogwheel. The sign is typically descri...
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Coin lesion (lung)

A coin lesion refers to a round or oval, well-circumscribed solitary pulmonary lesion. It is usually 1-5 cm in diameter and calcification may or may not be present 1,3. Typically but not always the patient is asymptomatic 1.  Differential diagnosis The differential diagnosis for such lesions i...
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Collar sign in diaphragmatic rupture

The collar sign, also called the hourglass sign, is a helpful sign for diagnosis of diaphragmatic rupture on coronal or sagittal CT/ MR images and barium studies. It refers to a waist-like or collar-like appearance of herniated organs at the level of the diaphragm. Small tear on the right side ...
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Colon cut-off sign

The colon cut-off sign describes gaseous distension seen in the proximal colon associated with abrupt termination of gas within the colon usually at the level of the splenic flexure and decompression of the more distal part of the colon. Though originally described in abdominal radiographs, this...
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Color bruit artifact

The color bruit or tissue vibration artifact is a type of color Doppler ultrasound artifact which results in color signal overflowing to the perivascular tissues most often caused by stenosis, AV fistulas, or shunts. Thus, this artifact is useful by pinpointing areas of potentially pathological ...
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Comb sign (mesentery)

The comb sign refers to the hypervascular appearance of the mesentery in active Crohn disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel,...
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Comet tail (disambiguation)

The distinctive appearance of a comet's tail has been used for several signs: comet tail artifact (ultrasound) color comet tail artifact comet tail sign (chest) comet tail sign (phleboliths)
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Comet tail sign (chest)

The comet tail sign is a finding that can be seen on CT scans of the chest. It consists of a curvilinear opacity that extends from a subpleural "mass" toward the ipsilateral hilum. The comet tail sign is produced by the distortion of vessels and bronchi that lead to an adjacent area of round ate...
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Comet tail sign (phleboliths)

The comet tail sign (in urological imaging) is helpful in distinguishing a ureteric calculus from a phlebolith and strongly favors the latter.  The sign refers to a tail of soft tissue extending from a calcification, representing the collapsed/scarred/thrombosed parent vein. When well seen, it ...
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Concentric ring sign

The concentric ring sign is a pathognomonic sign for a subacute hematoma on MRI. A subacute hematoma may show three characteristic layers of signal intensity: a thin peripheral rim of low signal intensity on all pulse sequences corresponding to hemosiderin an inner peripheral high-signal inten...
Article

Concentric target sign (cerebral toxoplasmosis)

The concentric target sign is a typical sign for cerebral toxoplasmosis. It is seen on T2 weighted MR imaging as a deep parenchymal lesion showing a series of concentric rings with hyperintense and hypointense/isointense signal alternatingly. Strong perifocal edema is usually visible on T2/FLAIR...
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Cone-shaped cecum (differential)

A cone-shaped cecum refers to a loss of the normal rounded appearance of the cecum, which instead becomes narrow and cone-shaped with the apex pointing towards the base of the appendix. It is encountered in a number of conditions including: inflammatory infective blastomycosis amoebiasis Ye...
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Congenital hallux valgus

Congenital hallux valgus is a very rare finding wherein a fetus or newborn shows lateral deviation of the first toe(s). When found on prenatal imaging, bilateral congenital/foetal hallux valgus is highly suggestive of fibrodysplasia ossificans progressiva 1,2.
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Continuous diaphragm sign

The continuous diaphragm sign is a chest radiograph sign of pneumomediastinum or pneumopericardium if lucency is above the diaphragm, or of pneumoperitoneum if lucency is below the diaphragm.  Normally the central portion of the diaphragm is not discretely visualized on chest radiographs as it ...
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Convoluted cerebriform pattern

A convoluted cerebriform pattern is a term used to denote the appearance of a sinonasal inverted papilloma on MRI. The appearance is seen on both T2 and post contrast T1 images and appears as alternating roughly parallel lines of high and low signal intensity. This sign has been reported as pre...
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Cookie bite skeletal metastases

Cookie bite metastases are characterized by small focal eccentric lytic external cortical destruction in long tubular bones. This type of destruction is typically described for metastases from lung cancer; however, they can also occur with other tumors.
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Copper beaten skull

Copper beaten skull, also known as beaten silver skull or beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault. Clinical presentation The appearance of a copper beaten skull is associated with...
Article

Cord sign (dural sinus thrombosis)

The cord sign refers to cordlike hyperattenuation within a dural venous sinus on non-contrast enhanced CT of the brain due to dural venous sinus thrombosis. The sign is most commonly seen in the transverse sinus because along the origin of the tentorium it runs approximately in the axial plane s...
Article

Corduroy sign (vertebral hemangioma)

The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous hemangiomas of the spine. It is the sagittal and coronal equivalent of the polka-dot sign seen on axial imaging.  It is caused by the replacement of the normal cancellous bone by thickened vertical trabec...
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Corkscrew sign (disambiguation)

Corkscrew sign can refer to: corkscrew sign (midgut volvulus) corkscrew sign (tertiary esophageal contractions) corkscrew sign (corkscrew cochlea)
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Corkscrew sign (midgut volvulus)

The corkscrew sign describes the spiral appearance of the distal duodenum and proximal jejunum seen in midgut volvulus 1. In patients with malrotation and volvulus, the distal duodenum and proximal jejunum do not cross the midline and instead pass in an inferior direction. These loops twist on ...
Article

Cortical rim sign (kidneys)

The cortical rim sign describes the thin, viable rim of subcapsular cortex seen on contrast-enhanced CT or MRI in major renal vascular compromise including: renal artery obstruction from embolism, thrombosis or dissection renal vein thrombosis acute tubular necrosis acute cortical necrosis ...
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Cortical vein sign

The cortical vein sign refers to the presence of superficial cortical veins seen on MRI and CT (particularly with contrast injection) traversing an enlarged subarachnoid space, differentiating it from the similar radiological appearance of a subdural hygroma. Although initially proposed as a me...
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Costal hook sign (flail chest)

The costal hook sign is a chest x-ray feature seen in some cases of flail chest. It represents the rotation of a fractured rib along its long axis, something that is only possible if a second fracture is present along its length, even if the second fracture is not visible 1. 
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Cottage loaf sign (liver)

The cottage loaf sign occurs as a result of a right-sided diaphragmatic rupture with partial herniation of the liver through the diaphragmatic defect. The herniated component is separated by a waist at the diaphragm from the larger intra-abdominal component. This shape is reminiscent of a cottag...

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