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.
242 results found
Article
Morning glory sign (midbrain)
Morning glory sign of progressive supranuclear palsy (PSP) and multisystem atrophy, not to be confused with morning glory syndrome, refers to the appearance of the midbrain on axial imaging 1.
Graphically this is identified on an axial image at the level of the midbrain by drawing 1:
a horiz...
Article
Tram-track sign (orbit)
Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve sheath meningioma.
It may, however, also be seen in 1:
orbital pseudotumor
optic perineuritis
orbital sarcoidosis
orbital leukemia
orbital lym...
Article
Doughnut sign (orbit)
The doughnut sign of optic nerve sheath meningioma refers to the appearance of this tumor on coronal CT/MRI. The meningioma forms a thick cuff of enhancing tumor around the central non-enhancing optic nerve, mimicking the appearance of a ring doughnut. It is the coronal equivalent of the tram-tr...
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...
Article
Transmantle sign (brain)
The transmantle sign is an MRI feature of focal cortical dysplasia (FCD), almost exclusively seen in type II (ILAE/Blumcke classification), and especially in type IIb 1-5.
Pathology
The transmantle sign is believed to be related to abnormal function of, or injury to radial glial fibers (which ...
Article
Radial bands sign (tuberous sclerosis)
The radial bands sign, also known as radial migration bands, refers to linear bands seen on MRI, radiating from the periventricular white matter to the subcortical region, thought to be specific for tuberous sclerosis 1,2.
Pathology
The exact pathogenesis of radial bands is uncertain, but they...
Article
Owl-eyes sign (spinal cord)
The owl-eyes sign, also known as snake-eyes sign or fried-eggs sign, represents bilaterally symmetric circular to ovoid foci of high T2-weighted signals in the anterior horn cells of the spinal cord and is seen on axial MR imaging. The sagittal corollary is a "pencil-like" vertical linear high T...
Article
Swallow tail sign (substantia nigra)
The swallow tail sign describes the normal axial imaging appearance of a hyperintensity within the substantia nigra on high-resolution T2*/SWI weighted MRI. It was previously thought that this sign was caused by nigrosome-1, but this has not been found to be correct in subsequent studies, and th...
Article
CT angiographic spot sign (intracerebral hemorrhage)
The spot sign is a CTA sign in acute intracerebral hemorrhage representing the focal accumulation/pooling/extravasation of contrast containing blood within the hematoma. It is an important feature to identify during the evaluation of acute intracerebral hemorrhage as it significantly increases t...
Article
Eye of the tiger sign (globus pallidus)
The eye of the tiger sign refers to symmetric bilateral abnormal low signal on T2-weighted MRI (due to abnormal accumulation of iron) in the globus pallidus with central high signal (due to gliosis and spongiosis).
The eye of the tiger sign is most classically associated with pantothenate kinas...
Article
Hot cross bun sign (pons)
The hot cross bun sign refers to the MRI appearance of the pons when T2 hyperintensity forms a cross on axial images, representing selective degeneration of transverse pontocerebellar tracts and median pontine raphe nuclei 1.
It has been described in a variety of neurodegenerative and other con...
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
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
Suspected physical abuse
Suspected physical abuse (SPA), also known as non-accidental injury (NAI) or inflicted injury, in infants and young children represents both ethical and legal challenges to treating physicians.
Radiologists may be the first clinical staff to suspect non-accidental injuries when confronted with ...
Article
Prévost sign (eyes)
The Prévost sign, also known as the Vulpian sign or eye sign, refers to conjugate eye deviation in patients with acute stroke. The direction is variable, depending on the location of the stroke 3.
In a hemispheric stroke, the eyes deviate ipsilaterally towards the stroke (i.e. contralateral to ...
Article
Butterfly sign (choroid plexus)
The butterfly sign refers to the normal appearance of the choroid plexuses on axial imaging of the fetal brain, commonly observed on the antenatal ultrasound. Its absence may suggest holoprosencephaly 1.
In the CNS, the term should not be confused with a butterfly glioma, which is a glioblastom...
Article
Butterfly glioma
Butterfly gliomas are high-grade astrocytomas, IDH-mutant or glioblastomas, IDH-wildtype that cross the midline via the corpus callosum. Other white matter commissures are also occasionally involved. The term butterfly refers to the symmetric wing-like extensions across the midline.
Butterfly ...
Article
Lipoma
Lipomas are benign tumors composed of mature adipocytes. They are the most common soft tissue tumor, seen in ~2% of the population.
Epidemiology
Patients typically present in adulthood (5th-7th decades).
Associations
In some cases, multiple lipomas are associated with syndromes and other di...
Article
Cerebral paragonimiasis
Cerebral paragonimiasis is a serious manifestation of paragonimiasis, and refers to a parasitic brain infection caused by a the Paragonimus genus of trematodes (flukes).
Epidemiology
Paragonimiasis is endemic in Asia, West Africa, and Latin America. Infections can occur after ingesting underco...
Article
Empty light bulb sign (brain death)
In brain death, on Tc-99m HMPAO imaging there is absent or reduced flow in the internal carotid arteries and increased flow within the external carotid arteries. This leads to absent uptake in the brain with subsequent increased perfusion in the nasal region. This appearance has been called the ...
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