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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
1,140 results found
Article
Bowl of grapes sign
The bowl of grapes sign has been described in synovial sarcoma. It refers to the characteristic multilobulated lesion subdivided by multiple septa, forming large cystic foci with regions of hemorrhage.
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Small heart sign
The small heart sign represents a rarely encountered but critical sign on chest caused by a sudden reduction of heart size caused by cardiac tamponade due to either tension pneumopericardium or pneumomediastinum.
A sudden, >2 cm reduction in the transverse cardiac diameter is considered highly...
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Caput medusae sign (developmental venous anomaly)
The caput medusae sign also sometimes known as a palm tree sign refers to developmental venous anomalies of the brain, where a number of veins converge centrally into a single draining vein.
The sign is seen on both CT and MRI when contrast medium is administered. Angiographically the caput me...
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Flame sign (carotid)
The flame sign refers to a gradual tapering of contrast opacification in the mid-cervical internal carotid artery, sparing the carotid bulb. The sign can be observed on angiography (digital subtraction angiography 1, CT angiography 1, or contrast-enhanced MR angiography 2) in either of two scena...
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Perinephric stranding
Perinephric stranding refers to the appearance of edema within the fat of the perirenal space on CT or MRI. While a degree of symmetric bilateral perinephric stranding is common, particularly in the elderly, asymmetric or unilateral perinephric stranding is an important sign of renal inflammatio...
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Northern exposure sign (sigmoid volvulus)
The northern exposure sign has been described as a high specificity sign in sigmoid volvulus. On a supine abdominal radiograph, the apex of the sigmoid volvulus is seen above (cranial to) the transverse colon.
Article
The crisscross sign
The crisscross sign is a fetal ultrasound sign that describes the normal relationship between the ventricular outflows tracts of the fetal heart. The left ventricular outflow tract (LVOT); represented by the take-off of the aorta (Ao) from the left ventricle, is perpendicular (90o) to the right ...
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Echogenic fetal bowel
Echogenic fetal bowel is an observation in antenatal ultrasound imaging, in which fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. When observed, it needs to be interpreted in the context of other associated abno...
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Ring of fire sign (adnexa)
The ring of fire sign, also known as ring of vascularity, signifies a hypervascular lesion with peripheral vascularity on color or pulsed Doppler examination of the adnexa due to low impedance high diastolic flow 1.
This sign can be seen in:
corpus luteum cyst (more commonly)
ectopic pregnancy
Article
Mickey Mouse sign (disambiguation)
In medical imaging, a Mickey Mouse sign or appearance has been given to imaging features that mimic Mickey Mouse when viewed from the front. It has been described in the following:
anencephaly 2
progressive supranuclear palsy 1
synonymously with a finger in glove sign
the flared shape of the...
Article
Pleural mouse
A pleural mouse (plural: pleural mice), also known as a fibrin body is a 1-2 cm mobile rounded clump of fibrin left over after resolution of a pleural effusion 1.
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Retroaortic anomalous coronary sign (echocardiography)
The retroaortic anomalous coronary (RAC) sign describes the sonographic appearance of an anomalous left coronary artery traveling posteriorly to the aortic root. It is most commonly observed with anomalous origin of the left circumflex artery from the right sinus of Valsalva, but is also describ...
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Reynolds pentad
Reynolds pentad is a combination of clinical signs found in acute cholangitis. It consists of Charcot triad 2-4:
fever and/or chills
RUQ pain
jaundice
as well as:
delirium or lethargy, and
shock
Usefulness
Sensitivity of Reynolds pentad from a large systematic review of nine studies was ...
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Parasellar dark T2 signal sign
The parasellar dark T2 signal sign is a MRI feature where there is parasellar low T2 signal. Some authors describe it as a specific finding in differentiating lymphocytic hypophysitis from a pituitary adenoma.
Article
Dragonfly sign
Dragonfly sign describes the appearance of the cerebellum on coronal images, which is seen secondary to cerebellar atrophy in pontocerebellar hypoplasia 1.
The sign is so called as the whole cerebellum resembles the shape of a dragonfly if one imagines the vermis is the body of the insect and t...
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Meniscus sign (disambiguation)
A meniscus sign has been named in multiple contexts:
air meniscus sign in chest imaging most commonly due to invasive aspergillosis 1
Carman meniscus sign in barium studies due to an ulcerated gastric cancer 2
clot meniscus sign in angiography due to large vessel occlusion acute ischemic stro...
Article
Harris ring
A Harris ring is a ring-like shadow observed at the base of the odontoid process on a lateral radiograph of the cervical spine. It is formed by the superimposition of the lateral masses of the C2 vertebra (axis) on its body.
Disruption of the Harris ring is seen in type III, and less commonly, ...
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Double panda sign
The double panda sign refers to the combination of the face of the giant panda and face of the miniature panda (cub of the giant panda) seen on T2 weighted images of midbrain and pons respectively, most commonly seen in Wilson disease.
The midbrain face of the giant panda sign consists of norma...
Article
Extrapleural fat sign
The extrapleural fat sign is an imaging feature which can be seen on CT under certain circumstances. It occurs from the inward displacement of extrapleural fat by an extrapleural fluid collection, extrapleural hematoma or extrapleural mass. The presence of the extrapleural fat sign is indicative...
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Pooping duck sign
Pooping duck sign indicates the presence of a triquetral fracture on a lateral wrist radiograph, where an avulsed fracture fragment from the dorsal cortex of the triquetrum projects along the dorsal aspect of the osseous structures of the wrist.
In this sign, the fracture fragment represents th...
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