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
Air bronchogram
An air bronchogram occurs when endobronchial air is visible against a background of increased lung opacity. Expulsion of gas from the parenchyma is partial or complete and can be due to atelectasis and/or replacement by fluid, inflammatory cells, blood, tumor or interstitial thickening. The pers...
Article
Periwinkle sign (supratentorial ependymoma)
The periwinkle sign has been coined to describe what has been claimed to be a characteristic appearance of intraparenchymal supratentorial ependymomas on non-enhanced CT axial images.
The central solid component sometimes demonstrates centripetal calcification surrounding the central necrotic c...
Article
Obturator sign
Obturator sign is a clinical sign of acute appendicitis, it is defined as discomfort felt by the subject/patient on the slow internal movement of the hip joint, while the right knee is flexed. It indicates an inflamed pelvic appendix that is in contact with the obturator internus muscle 1-3.
Se...
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Dual rim sign (brain abscess)
The dual or double rim sign is seen on MRI in approximately 75% of cerebral abscesses and is helpful in distinguishing an abscess from a glioblastoma.
On both susceptibility weighted imaging (SWI) and T2WI it consists of two concentric rims surrounding the abscess cavity, outer one of which is...
Article
Hairy kidney sign (Erdheim-Chester disease)
The hairy kidney sign refers to the soft tissue ring of perirenal infiltration seen on cross-sectional imaging studies in Erdheim-Chester disease and is considered to be pathognomonic of this disease. The ‘‘hairy’’ description refers to the associated thickening of the bridging perirenal septa (...
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
Pellegrini-Stieda lesion
Pellegrini-Stieda lesions refer to ossified post-traumatic lesions at (or near) the medial femoral collateral ligament adjacent to the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femo...
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Steelpan sign (sigmoid volvulus)
The steelpan sign refers to the close resemblance of sigmoid volvulus on CT to the percussion instrument known as the steelpan. The steelpan, also known as steel drum or pan, is a Caribbean musical instrument invented in Trinidad and Tobago by the mid-1930s, which became very popular in Trinidad...
Article
Toothpaste sign
The toothpaste sign in spinal imaging represents an extrusion of an intervertebral disc into the epidural space. It is called after the shape of extruded material relatively to the parent disc in a sagittal plane.
Article
Raccoon eyes sign (base of skull fracture)
Raccoon eyes sign (or panda eyes in the UK and Ireland) refers to periorbital ecchymosis with sparing of the tarsal plate 3 and is a physical examination finding indicative of a base of skull fracture of the anterior cranial fossa.
However it is not pathognomonic for trauma, and there are sever...
Article
Salt and pepper sign (disambiguation)
The salt and pepper sign is used to refer to a speckled appearance of tissue on imaging. It is used in many contexts, but most commonly for the appearance of certain lesions on MRI, especially paragangliomas.
salt and pepper noise (MRI artifact) 9
salt and pepper sign (ARPCKD) 8
salt and pepp...
Article
Spinnaker sign (mediastinum)
The spinnaker sign (also known as the angel wing sign) is a sign of pneumomediastinum seen on neonatal chest radiographs. It refers to the thymus being outlined by air with each lobe displaced laterally and appearing like spinnaker sails. This is distinct from the sail sign appearance of the nor...
Article
Cloaca (osteomyelitis)
A cloaca (pl. cloacae or cloacas) is a gap in the cortex of a bone affected by chronic osteomyelitis that allows the drainage of pus or other material from the bone into the adjacent tissues.
Terminology
The use of the term cloaca should be reserved for cortical breaches that are the result of...
Article
Teardrop sign (superior mesenteric vein)
The teardrop sign of the superior mesenteric vein is one of the important signs in the local staging of pancreatic adenocarcinoma. Its importance lies in its diagnostic, as well as prognostic, significance. This sign is used in assessing the resectability of pancreatic cancer.
Radiographic feat...
Article
Pseudokidney sign (colonic carcinoma)
The pseudokidney sign is a non-specific sonographic sign that describes the reniform shape of a mass with a hypoechoic region (representing bowel wall thickening) surrounding a central hyperechoic portion or echogenic stripe (which represents the apposition of the mucosal surfaces) 1,2.
It can...
Article
Flashlight sign (B-flow)
The flashlight sign is a B-flow vascular ultrasound sign caused by wall adherent and floating thrombi and emboli in arteries, which appear as bright spots on imaging.
Radiographic features
Ultrasound
The flashlight sign is described as a moving, very bright intraluminal focus of signal on B-f...
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
Antral nipple sign (pyloric stenosis)
The antral nipple sign refers to redundant pyloric mucosa protruding into the gastric antrum and is seen in hypertrophic pyloric stenosis on ultrasound examination.
See also
cervix sign (pyloric stenosis)
target sign (pyloric stenosis)
Article
Dyspepsia
Dyspepsia is a group of upper abdominal gastrointestinal symptoms often described as a burning sensation, discomfort, nausea and bloating, especially after meals.
Epidemiology
Dyspepsia is a common condition affecting up to 25% of the population in the United States.
Clinical presentation
bl...
Article
Black hole sign (intracerebral hemorrhage)
The black hole sign refers to the non-contrast CT appearance of acute extravasation of blood into a hematoma, for example, an intracerebral hemorrhage, and therefore is a predictor of hemorrhage expansion 3. It can be thought of as an encapsulated swirl sign.
Radiographic features
The black ho...
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