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.
More than 200 results
Article
Perilymphatic fistula
A perilymphatic fistula (also known as a labyrinthine fistula) is a pathologic communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, most commonly occurring at either the round or oval window.
Clinical presentation
Symptoms of perilymphatic ...
Article
Napkin-ring sign (heart)
The napkin-ring sign is a feature of high-risk coronary artery atherosclerotic plaque on CT coronary angiogram (coronary CTA). It has been shown to possess a high predictive value in predicting future cardiac events and is considered one of the imaging correlates of an unstable plaque. It is one...
Article
Crescent sign of arterial dissection
The crescent sign refers to the high signal crescent seen in the wall of a vessel when dissected. This may be seen both on T1 or T2 sequences depending on the age of the blood (see aging blood on MRI). It is classically referred to in internal carotid artery dissection.
It should not be confuse...
Article
Stener-like lesion of the medial collateral ligament of the knee
Stener-like lesions of the medial collateral ligament (MCL) occur when a tear involves the distal fibers of the superficial medial collateral ligament (sMCL) are displaced superficially to the pes anserinus, which can result in compromised healing.
Pathology
Usually, the sMCL runs deep to the p...
Article
Athelia
Athelia is a rare congenital condition characterized by the absence of the nipple. This may occur unilaterally or bilaterally.
Associations
Poland syndrome
ectodermal dysplasia 2
Article
Absent bow tie sign (knee)
The absent bow tie sign represents the loss of the normal appearance of the menisci on parasagittal MRI images and is suggestive of meniscal injury.
Normally the medial and lateral menisci appear as low signal triangular structures linked by a thin body located between the femoral condyles and ...
Article
Tulip bulb sign
The tulip bulb sign refers to the characteristic appearance of annuloaortic ectasia as seen on CT angiography.
There is symmetric dilatation of the three sinuses of Valsalva, with extension into the ascending aorta and effacement of the sinotubular junction.
It is seen especially in Marfan sy...
Article
Vertebral body squaring (differential)
Vertebral body squaring refers to the loss of normal concavity of the anterior border of the vertebral body. It is seen in a variety of conditions, some of which are listed below.
Differential diagnosis
Ankylosing spondylitis
Ankylosing spondylitis is the most common cause of vertebral body ...
Article
Cogwheel sign
The cogwheel sign refers to the pelvic imaging appearance of dilated loops of fallopian tube seen in cross-section. It represents infolding projections (sometimes looking like nodules) into the fallopian tube lumen which are likened to that of a cogwheel. The sign is typically described on ultra...
Article
Apple-peel intestinal atresia
Apple-peel intestinal atresia, also known as type IIIb or Christmas tree intestinal atresia, is a rare form of small bowel atresia in which the duodenum or proximal jejunum ends in a blind pouch and the distal small bowel wraps around its vascular supply in a spiral resembling an apple peel. Oft...
Article
Double density sign (berry aneurysm)
Double density sign of berry aneurysms refers to the angiographic appearance of a small intracranial aneurysm projecting in front or behind a vessel of similar caliber. As such, the border of the aneurysm cannot easily be seen, but the extra contrast within it can be seen as a rounded area of in...
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
Ballet sign (eyeball)
The ballet sign refers to the paralysis of voluntary movements of the eyeball with preservation of the automatic movements. Sometimes this sign is present with exophthalmic goiter and hysteria.
Article
Double density sign (left atrium)
The double-density sign, also known as the double right heart border, is seen on frontal chest radiographs in the presence of left atrial enlargement, and occurs when the right side of the left atrium extends behind the right cardiac shadow, indenting the adjacent lung and forming its own distin...
Article
Lateral femoral notch sign (knee)
The (deep) lateral femoral notch sign describes a depression on the lateral femoral condyle at the terminal sulcus, a junction between the weight-bearing tibial articular surface and the patellar articular surface of the femoral condyle. It is occasionally referred to as a deep sulcus sign, not ...
Article
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...
Article
Scaphoid abdomen
Scaphoid abdomen is the term given to an inward concavity of the anterior abdominal wall. It is used both for the clinical appearance and its radiological equivalent.
In children it maybe a sign of congenital diaphragmatic hernia. In both adult and pediatric patients, it raises the possibility...
Article
Bear paw sign (kidney)
The bear paw sign refers to the cross-sectional appearance of the kidney affected by xanthogranulomatous pyelonephritis. There is a radial arrangement of multiple, low attenuation rounded spaces representing dilated calyces, surrounded by thin renal parenchyma that has higher attenuation or cont...
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, ...
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