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
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
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
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 ...
Article
Target sign (choledocholithiasis)
The target sign of choledocholithiasis is a finding seen on contrast-enhanced CT and comprises:
central density within the bile duct: stone
surrounding low density: bile or mucosa
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
Saber sign (pneumobilia)
The saber sign refers to a pattern of gas distribution seen in supine abdominal radiographs of patients with pneumobilia. A sword-shaped lucency is apparent in the right paraspinal region of the upper abdomen representing arching gas extending from the common bile duct into the left hepatic duc...
Article
Zebra sign (disambiguation)
The evocative appearance of the coat of a zebra has been used for several distinctive signs in radiology:
zebra sign: cerebellar hemorrhage 1
zebra sign: amyotrophic lateral sclerosis 2
zebra spleen: arterial phase appearance of normal spleen 4,5
zebra stripe sign: treated osteogenesis imper...
Article
Enlarged hilar periportal space sign
The enlarged hilar periportal space sign refers to the widening of the periportal space seen on MRI in early liver cirrhosis.
Usage
Enlarged hilar periportal space sign is one of the early signs of cirrhosis and may be used to detect fibrotic changes in the liver in patients who do not yet hav...
Article
Hepatic atrophy
Hepatic atrophy is a common appearance on imaging of the liver. It may result from obstruction of a major branch of the portal vein, bile ducts or hepatic veins. It does not usually occur secondary to hepatic arterial flow compromise. Compensatory hypertrophy of the unaffected segments/lobes is ...
Article
Lollipop sign (hepatic epithelioid hemangioendothelioma)
The lollipop sign is seen in hepatic epithelioid hemangioendothelioma (HEHE). It represents hepatic/portal vein and/or their tributaries/branches tapering and terminating at or just within the edge of a well defined peripherally enhancing (or non-enhancing) lesion with an avascular core on CT or...
Article
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...
Article
Rolling stone sign
The rolling stone sign refers to the presence of gallstones within the gallbladder that are mobile when the patient moves.
Small gallstones can sometimes be difficult to diagnose due to the absence of posterior shadow artefact but the presence of a rolling stone sign increases the confidence of...
Article
Nodule-in-nodule appearance (liver)
In hepatic imaging, a nodule-in-nodule appearance represents foci of abnormal arterial enhancement within a liver lesion, in cases of a liver regenerative nodule with a focus of hepatocellular carcinoma or high-grade dysplastic nodule. It is so called because of the nodular arterial enhancement ...
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
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
Caput is the Latin for head, ...
Article
Rosary sign (gallbladder)
The rosary sign is a CT finding in adenomyomatosis of the gallbladder. It is formed by the enhanced proliferative mucosal epithelium, with the intramural diverticula surrounded by the unenhanced hypertrophied muscle coat of the gallbladder. The rosary sign is similar to the pearl necklace sign.
Article
Double target sign (hepatic abscess)
The double target sign is a characteristic imaging feature of liver abscess on contrast-enhanced CT scans, in which a central, fluid-filled low attenuation lesion is surrounded by a high attenuation inner rim and a low attenuation outer ring 1,2.
The inner ring (abscess membrane) demonstrates e...
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
Tensile gallbladder fundus sign
The tensile gallbladder fundus sign is positive when the gallbladder fundus is seen to bulge into, and distort, the anterior abdominal wall and is a feature of acute cholecystitis.
It is particularly useful as an early sign of the condition on CT as it has around a 75% sensitivity and 95% speci...
Article
Target sign (tuberculosis)
The target sign of tuberculosis refers to the bull's eye appearance of some parenchymal tuberculomas involving the brain (see: CNS tuberculosis) and solid abdominal organs (see: hepatic and splenic tuberculosis) on cross-sectional imaging.
Radiographic features
Ultrasound
hypoechoic nodules ...
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