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.
1,141 results found
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...
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Hypodense vessel sign
The hypodense vessel sign, or hypodense artery sign, is a radiological sign appreciated on non-contrast CT brain in acute ischemic stroke due to the rare entity of fat macroembolism causing large vessel occlusion. Notably, this is a distinct sign to the hyperdense vessel sign.
The sign describe...
Article
Hyperdense vessel sign
The hyperdense vessel sign is a radiological sign appreciated on non-contrast CT brain whereby there is focal hyperattenuation (mean of approximately 55 HU) within an intracranial blood vessel 1,2. Notably, this is a distinct sign to the hypodense vessel sign.
The hyperdense vessel sign is ofte...
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Disappearing basal ganglia sign
The disappearing basal ganglia sign is one of the early signs of a middle cerebral artery (MCA) infarction. It is defined as the loss of delineation of the basal ganglia, due to blurring of their grey-white matter interface and hypoattenuation, consequent to cytotoxic edema at the time of an isc...
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Cord sign (dural sinus thrombosis)
The cord sign is a type of hyperdense vessel sign and refers to cordlike hyperattenuation within a dural venous sinus on non-contrast enhanced CT of the brain due to dural venous sinus thrombosis. The sign is most commonly seen in the transverse sinus because along the origin of the tentorium it...
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Dense vein sign
The dense vein sign is a type of hyperdense vessel sign and refers to hyperattenuating thrombus within a cortical vein or dural venous sinus due to acute venous thrombosis.
When located in the superior sagittal sinus, particularly posteriorly, it is sometimes referred to as the delta, triangle ...
Article
MCA dot sign (brain)
The middle cerebral artery (MCA) dot sign, also known as the Sylvian fissure sign, is a type of hyperdense vessel sign seen on non-contrast brain CT and represents the cross-sectional M2 equivalent of the hyperdense MCA sign. Rather than imaging a length of middle cerebral artery (typically the ...
Article
Air-tissue interface sign - breast
Air-tissue interface sign on mammography in cases where the mass is located on the skin helps to distinguish it from intra-mammary mass so that in the skin-based lesion, due to the presence of air in the vicinity of a part of the margin, its border is pretty sharp and a narrow lucent rim around ...
Article
Cascade sign (Behçet disease)
The cascade sign, also known as the waterfall sign, is a radiological sign appreciated on MRI brain that is described in patients with neuro-Behçet disease involving the mesodiencephalic junction.
The sign describes the involvement of the mesodiencephalic junction as seen on coronal T2/FLAIR se...
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Bird’s nest sign (lungs)
The bird’s nest sign refers to the appearance created by a reverse halo sign with associated irregular and intersecting areas of stranding or irregular lines within the area of ground-glass opacity 1.
Both bird's nest sign and reverse halo signs are suggestive of invasive pulmonary fungal infec...
Article
Bagel sign (Behçet disease)
The bagel sign is a radiological sign appreciated on MRI spine that is described in patients with neuro-Behçet disease-associated myelitis.
The sign describes the involvement of the spinal cord as seen on axial T2 sequences in patients with myelitis, whereby there is a round hyperintense lesion...
Article
Food inspired signs
There are many food-inspired signs in radiology:
bagel sign (disambiguation)
bagel sign (Behçet disease)
bagel sign (tubal ectopic pregnancy)
bloomy rind sign (leptomeningeal metastases)
bunch of grapes sign (disambiguation)
bunches of grapes sign (hepatic abscess)
bunch of grapes sign (b...
Article
Layer cake skull
The layer cake skull refers to the CT appearance of layered diffuse calvarial hyperostosis in a distinct concentric pattern deep to the inner table of the skull seen most frequently in the setting of spontaneous intracranial hypotension although it is also sometimes encountered in normal individ...
Article
Trident sign (neurosarcoidosis)
The trident sign is a radiological (MRI) sign described in spinal cord neurosarcoidosis.
The sign is formed by the axial appearance of a longitudinally extensive transverse myelitis due to spinal cord neurosarcoidosis, whereby on a T1 post-contrast (gadolinium) MRI sequence, there is central ca...
Article
Murphey's teat
Murphey’s teat, also known as Murphey’s tit or Murphey’s excrescence, refers to the cerebral angiographic finding of a focal outpouching within an intracranial aneurysm that indicates the likely site of rupture in a patient with subarachnoid hemorrhage 1,2. This sign, when present, is particular...
Article
Codman triangle periosteal reaction
A Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. The periosteum does not have time to ossify with shells of new bone (e.g. as seen in a single layer and multilayered periosteal reaction) in aggressive lesions, so only the edge of the raised periosteum will os...
Article
Hair on end sign (mnemonic)
The hair on end sign refers to a radiographic appearance of the diploic space of the skull vault which results from a thickening of trabeculae as the diploic space expands. These trabeculae are perpendicular in orientation, interspersed by radiolucent marrow hyperplasia along with skull vault.
...
Article
Bright tree appearance (brain)
The bright tree appearance is a radiological pattern appreciated on MRI brain diffusion-weighted sequences in pediatric patients with severe encephalopathy syndromes. The appearance describes widespread restricted diffusion affecting the subcortical white matter, giving the appearance of multipl...
Article
Gasless abdomen
A gasless abdomen refers to a paucity of gas on abdominal radiography, and the specific cause can usually be identified when the patient's history is known. Common causes include:
proximal obstruction: gastric outlet obstruction, esophageal atresia
small bowel obstruction
bowel ischemia
asci...
Article
Small bowel feces sign
The small bowel feces sign can be observed on abdominal CT. The sign has been described as a finding specific for small bowel obstruction or another severe small bowel abnormality (e.g. metabolic or infectious disease).
While the reported prevalence of the sign in small bowel obstruction is low...
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