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.
73 results found
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
Starry sky appearance (ultrasound)
A starry sky appearance, also known as a centrilobular pattern 7, refers to a sonographic appearance of the liver parenchyma with bright echogenic dots throughout a background of decreased liver parenchymal echogenicity. Although usually associated with acute hepatitis, this sign has been found ...
Article
Phrygian cap
Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance.
Radiographic findings
A Phrygian cap may be identified on ultrasound, multiphase CT/MRI, or c...
Article
Atoll sign (liver MRI)
The atoll sign in hepatic imaging has been described when a liver lesion shows a peripheral rim of high T2 signal intensity with the center of the lesion appearing isointense to the background of non-cirrhotic liver on T2WI mimicking an atoll. The peripheral rim shows hyperenhancement in the por...
Article
Sonographic halo sign (disambiguation)
Sonographic halo sign can be useful in a number of situations:
hypoechoic halo sign (also known as target or bull's eye sign) in liver metastases: used in hepatobiliary imaging, is a concerning feature for malignant lesion if the lesion is a hyperechoic liver lesion 1,2
ultrasound halo in angi...
Article
Water lily sign (hydatid cyst)
The water lily sign, also known as the camalote sign, is seen in hydatid infections when there is detachment of the endocyst membrane which results in floating membranes within the pericyst that mimic the appearance of a water lily.
It is classically described on plain radiographs (mainly chest...
Article
Porcelain gallbladder
Porcelain gallbladder refers to extensive calcium encrustation of the gallbladder wall. The term has been used to emphasize the blue discolouration and brittle consistency of the gallbladder wall at surgery but is often an incidental finding on multiple different imaging modalities.
Clinical p...
Article
Intrahepatic arterioportal shunt
Intrahepatic arterioportal shunts, also known as arterioportal fistulas, represent abnormal flow between the portal venous system and a hepatic arterial system within the liver. They can be a reversible cause of portal hypertension.
Clinical presentation
Clinical features will depend on the si...
Article
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...
Article
Deer horn sign
The deer horn sign is a reliable sign and an important diagnostic clue of passive congestive hepatopathy due to heart failure on ultrasonography 1. In the deer horn sign, the head is formed by a dilated inferior cava, and the engorged hepatic veins resemble horns. It has also been described as t...
Article
Rim sign (choledocholithiasis)
The rim sign of choledocholithiasis is a finding seen on contrast-enhanced CT and comprises a faint rim of increased density along the margin of a low-density area of calculus 1.
Article
Intrabiliary rupture of hepatic hydatid cyst
Intrabiliary rupture of hepatic hydatid cyst is a common complication associated with hepatic hydatid cysts. It is important to appreciate the direct and indirect signs of this condition.
Radiographic features
The radiological features of intrabiliary rupture of a hepatic hydatid cyst can be c...
Article
Focal hepatic hot spot sign
The focal hepatic hot spot sign, also known as the hot quadrate sign can be seen on technetium 99m sulfur colloid scans of the liver and spleen, as well as CT studies.
Radiographic features
It occurs as a focal area of increased radiopharmaceutical uptake, or iodinated contrast accumulation, i...
Article
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...
Article
Serpent sign
The serpent sign, (also knowns as the snake sign), is a sign described in hydatid disease. The WHO classification (2001) or Gharbi classification (1985) of hydatid disease describe several stages on ultrasound 1.
During the active stage, the cyst is composed of three layers: the outer (pericyst...
Article
Nutmeg liver
A nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of hepatic venous congestion. When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner. This results in a mottled pattern of contrast enhancement in the a...
Article
Spoke wheel sign (focal nodular hyperplasia)
The spoke wheel sign is described in focal nodular hyperplasia (FNH) and describes the pattern of internal vasculature of FNHs seen on color Doppler ultrasound when multiple arteries radiate peripherally from the center of the lesion.
This sign was classically applied to the color/power Doppler...
Article
Pseudocalculus sign (common bile duct)
The pseudocalculus sign is a term coined to describe a mimic of a distally impacted common bile duct (CBD) stone on ERCP, MRCP and the various forms of cholangiography, including T-tube, CT, intraoperative, and percutaneous 1.
It results from the forceful contraction of the choledochal sphincte...
Article
Sonographic Murphy sign
Sonographic Murphy sign is defined as maximal abdominal tenderness from the pressure of the ultrasound probe over the visualized gallbladder 1,2. It is a sign of local inflammation around the gallbladder along with right upper quadrant pain, tenderness, and/or a mass 2.
It is one of the most im...
Article
Turtleback sign
Turtleback sign, also known as tortoise shell appearance, represents a characteristic appearance of chronic hepatic schistosomiasis in which liver margins are irregular and nodular. Dystrophic calcifications within a polygonal network of fibrous septa are seen in the periphery, often perpendicul...
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