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.
86 results found
Article
Comet tail sign (phleboliths)
The comet tail sign (in urological imaging) helps distinguish a ureteric calculus from a phlebolith and strongly favors the latter.
The sign refers to a tail of soft tissue extending from a calcification, representing the collapsed/scarred/thrombosed parent vein. When well seen, it is said to ...
Article
Susceptibility vessel sign
The susceptibility vessel sign is a radiological sign appreciated on susceptibility-sensitive MRI brain sequences that is described in patients with acute ischemic stroke. It correlates well with the hyperdense vessel sign (e.g. hyperdense MCA sign) that may be seen on CT brain, but is considere...
Article
Psoas sign (abdominal x-ray)
The psoas sign is a classic albeit non-specific finding on the abdominal radiograph, potentially representing retroperitoneal pathology.
Normally on an abdominal radiograph, the lateral margins of both the psoas muscles are clearly visible due to adjacent fat. When the lateral edge of one, or b...
Article
Concentric ring sign
The concentric ring sign is a pathognomonic sign for a subacute hematoma on MRI. A subacute hematoma may show three characteristic layers of signal intensity:
a thin peripheral rim of low signal intensity on all pulse sequences corresponding to hemosiderin
an inner peripheral high-signal inten...
Article
Signal flare phenomenon
The signal flare phenomenon is a useful sign to identify active bleeding in a liquefied hematoma with hematocrit effect on dynamic CT scan images.
When active arterial hemorrhage is present in a liquefied hematoma that has a hematocrit effect, a signal flare phenomenon may be seen as a linear, ...
Article
Reverse figure 3 sign (esophagus)
The reverse figure 3 sign (also known as the E sign) is seen on barium swallows in patients with coarctation of the aorta and is the medial equivalent of the figure 3 sign seen on plain chest radiographs. It is formed by prestenotic dilatation of the ascending aorta, indentation of the coarctati...
Article
Renal arterial cut-off sign
Renal arterial cut-off sign, as the name suggests, is an abrupt termination of the contrast-opacified lumen of the renal artery. It may or may not be associated with contrast extravasation.
It is seen in a vascular injury, e.g. segmental or main renal artery thrombosis or occlusion.
Article
Tangential calcium sign
A tangential calcium sign is a sign seen with an aortic aneurysm rupture. The calcified intimal rim is discontinuous and is seen to tangentially point away from the aneurysmal lumen. This sign is seen at the point of breach. There is associated retroperitoneal leakage.
Article
Shmoo sign
Shmoo sign refers to the appearance of a prominent, rounded left ventricle and dilated aorta on a plain PA chest radiograph giving the appearance of Shmoo, a fictional cartoon character in the comic strip Li'l Abner, which first appeared in 1948 5. This sign is indicative of left ventricular enl...
Article
Scimitar (disambiguation)
The term scimitar, referring to the characteristic shape of the Middle Eastern sword, may refer to the following:
scimitar syndrome (lungs)
scimitar sign (cystic adventitial disease)
scimitar sacrum (bones)
Article
Spider web appearance
Spider web appearance is a classic appearance seen on venography in a patient with hepatic venous outflow obstruction. It refers to the dense network of hepatic venous collaterals seen.
Article
Dog leg sign (popliteal artery)
The "dog leg" sign is a secondary angiographic sign on popliteal angiography, which demonstrates an irregular lumen of the popliteal artery with acute bend in the course of the popliteal artery. It is characteristically seen in popliteal artery aneurysms with mural thrombus.
It is an important ...
Article
Acceleration index
Acceleration index is an indirect sonographic sign to assess renal artery stenosis 1.
Usage
Acceleration index is used in the Doppler assessment of the renal arteries when assessing for renal artery stenosis.
Measurement
Acceleration index is calculated by subtracting the initial systolic ve...
Article
Light bulb sign (pheochromocytoma)
The light bulb sign of an adrenal pheochromocytoma is an MRI feature of this tumor. It refers to marked hyperintensity on T2 weighted sequences, however, this finding is neither sensitive nor specific and pheochromocytomas are more often heterogeneous with intermediate or high T2 signal intensit...
Article
Griesinger sign (mastoid)
The Griesinger sign refers to edema of the postauricular soft tissues overlying the mastoid process as a result of thrombosis of the mastoid emissary vein. It is a complication of acute otomastoiditis and may be associated with dural sinus occlusive disease (DSOD). It is said to be a pathognomon...
Article
Walnut kernel microbleed pattern
The walnut kernel microbleed pattern along with the starfield pattern and corpus callosum diffusion restriction appears to be the most important imaging markers of cerebral fat embolism 1-3.
In this pattern, there is a diffuse presence of round microbleeds (punctate focal hypointensities) of si...
Article
Hyperdense MCA sign (brain)
The hyperdense MCA sign, also known as Gács sign, is a type of hyperdense vessel sign and refers to focal hyperattenuation of the middle cerebral artery (MCA) on non-contrast brain CT and is due to intraluminal thromboembolic material. It is the earliest visible sign of MCA infarction and is see...
Article
Stag's antler sign (lungs)
The stag's antler sign, also known as the hands-up or inverted moustache sign, refers to upper lobe pulmonary venous diversion in pulmonary venous hypertension or pulmonary edema as seen on an erect frontal chest radiograph.
The prominence of upper lobe pulmonary veins resembles a stag's antler...
Article
Double barrel sign (disambiguation)
Double barrel sign is an imaging appearance of two lumens adjacent to each other.
It can be seen in:
dilated bile duct adjacent to portal vein
double barrel aorta: aortic dissection
double barrel esophagus: esophageal dissection
Article
Figure 3 sign (aortic coarctation)
The figure 3 sign is seen in aortic coarctation and is formed by prestenotic dilatation of the aortic arch and left subclavian artery, indentation at the coarctation site (also known as the "tuck"), and post-stenotic dilatation of the descending aorta.
On barium studies of the esophagus in pati...
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