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 edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

167 results found
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Adie pupil

Adie pupil (also known as tonic pupil) is caused by idiopathic degeneration of the ciliary ganglion, which sometimes occurs following a viral or bacterial illness. It is usually unilateral and typically affects young females 1. Adie pupil represents a large dilated "tonic pupil", which does not...
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Air bubble sign (tension pneumocephalus)

The air bubble sign is seen on CT of the brain and represents multiple small foci of air within the subarachnoid space, especially the Sylvian fissure.1 Although described as a sign of tension pneumocephalus it is also seen in pneumocephalus without elevated pressures.2 It should not be confus...
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Arc sign (CARASIL)

The arc sign has been described in late-stage CARASIL and is seen on axial T2 weighted images. It describes high signal extending from one middle cerebellar peduncle, across the pons, to the contralateral middle cerebellar peduncle 1. 
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Argyll Robertson pupil

Argyll Robertson pupil is usually bilateral and presents as bilaterally miotic and irregular pupils, which constrict briskly with accommodation but do not react to bright light therefore displaying light-near dissociation 1.  It is a highly specific sign of late neurosyphilis, however can also ...
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Barbell sign (progressive multifocal leukoencephalopathy)

The barbell sign has been described in a short series of patients with progressive multifocal leukoencephalopathy (PML) 1. This describes confluent FLAIR / T2w parieto-occipital abnormalities with a thin continuation of signal abnormality across the splenium. Given the lack of mass effect typi...
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Bare orbit sign (sphenoid wing)

The bare orbit sign, is described as a characteristic appearance of the orbit, seen when the innominate line is absent. The innominate line is a projection of the greater wing of the sphenoid, and its absence or destruction is responsible for this appearance. It is the classical frontal radiogr...
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Battle sign (base of skull fracture)

Battle sign is an eponymous term given to mastoid ecchymosis (bruising of the scalp overlying the mastoid process) and is strongly suggestive of a base of skull fracture, most commonly a petrous temporal bone fracture.  History and etymology Mr William Henry Battle (1855-1936) was an English s...
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Bat wing 4th ventricle

Bat wing 4th ventricle sign refers to the morphology of the fourth ventricle in the Joubert anomaly and related syndromes. The absence of a vermis with apposed cerebellar hemispheres give the fourth ventricle an appearance reminiscent of a bat with its wings outstretched. It is best demonstrate...
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Bifid postcentral gyrus sign

The bifid postcentral gyrus sign, also known as the pars deflection sign, is a landmark useful for identifying the central sulcus on cross-sectional imaging. The medial aspect of the postcentral gyrus splits in two before meeting the interhemispheric fissure. The two legs straddle the pars marg...
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Blend sign (brain)

The blend sign refers to a CT appearance of early intracranial hematoma growth. It is defined as blending of a hypoattenuating area and a hyperattenuating region with a well-defined margin.
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Boomerang sign (disambiguation)

Boomerang sign may refer to: boomerang sign (peroneus brevis tear) boomerang sign (medial meniscal tear) boomerang sign (splenium) History and etymology Boomerang is of course a curved projectile used originally by the Australian Aborigines, one of its various uses was as a hunting weapon 1.
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Boomerang sign (splenium)

The boomerang sign refers to a boomerang-shaped region of cytotoxic edema in the splenium of the corpus callosum typically seen in cytotoxic lesions of the corpus callosum (CLOCCs) 1-4.  See also boomerang sign in peroneus brevis split syndrome boomerang sign in horizontal meniscal flap tear
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Bracket sign (pars marginalis)

The bracket sign of the pars marginalis, also known as the pars bracket sign, refers to the appearances of the superior most extent of the pars marginalis of the cingulate sulcus on axial imaging. It forms two roughly symmetric brackets, open anteriorly. The next sulcus anteriorly is the central...
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Bracket sign (pericallosal lipoma)

The bracket sign refers to a radiographic appearance seen with the tubulonodular variety of pericallosal lipoma. It reflects calcification seen at the periphery of the midline lipoma. It is best seen on coronal imaging and historically was identified on frontal radiographs. It should not be con...
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Bright rim sign (DNET)

The bright rim sign, also known as the hyperintense ring sign, has been described in dysembryoplastic neuroepithelial tumors (DNET). It is described as a well defined rim of high signal around the DNET on FLAIR sequences. This T2/FLAIR hyperintense ring, whether complete or in complete, is fair...
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Brudzinski sign (meningism)

Brudzinski's sign occurs in meningitis (of any etiology) or meningism where passive flexion of a patient's neck elicits reflexive bilateral knee and hip flexion; it was originally known as the "nape of the neck sign" and was one of several physical exam maneuvers concurrently described to be cha...
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Burst lobe

A burst lobe is an uncommonly used description of traumatic lobar intraparenchymal hemorrhage of the brain that ruptures into the subdural space and communicates with subdural hemorrhage 1. As traumatic hemorrhages are more common in the frontal and temporal lobes, these lobes are the most affe...
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Butterfly glioma

Butterfly gliomas are a high grade astrocytoma, usually a glioblastoma (WHO grade IV), which crosses 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.  Most freq...
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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...
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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).  Method Ideally the angle should be measured on a cor...
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Caput medusae sign (developmental venous anomaly)

The caput medusae sign, refers to developmental venous anomalies of the brain, where a number of veins drain centrally towards a single drain vein. The appearance is reminiscent of Medusa, a gorgon of Greek mythology, who was encountered and defeated by Perseus. The sign is seen on both CT and ...
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Chasing the dragon sign (toxic leukoencephalopathy)

Chasing the dragon sign is seen in toxic leukoencephalopathy caused by the inhalation of heroin fumes.  Clinical presentation Three stages are recognized: cerebellar signs and motor restlessness pyramidal and pseudobulbar signs spasms, hypotonic paresis, and ultimately death Only a minorit...
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Cingulate sulcus sign

The cingulate sulcus sign has been proposed as being useful as an MRI feature of idiopathic normal pressure hydrocephalus (NPH). It denotes the posterior part of the cingulate sulcus being narrower than the anterior part. The divider between the anterior and posterior parts of the sulcus being a...
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Claw sign (mass)

The claw sign is useful in determining that a mass arises from a solid structure rather than is located adjacent to it and distorts the outline. It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. ...
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Copper beaten skull

Copper beaten skull, also known as beaten silver skull or beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault. Clinical presentation The appearance of a copper beaten skull is associated with...
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Cord sign (dural sinus thrombosis)

The cord sign 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 runs approximately in the axial plane s...
Article

Cortical vein sign

The cortical vein sign refers to the presence of superficial cortical veins seen on MRI and CT (particularly with contrast injection) traversing an enlarged subarachnoid space, differentiating it from the similar radiological appearance of a subdural hygroma. Although initially proposed as a me...
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Cotton wool appearance (bone)

The cotton wool appearance is a plain film sign of Paget disease and results from thickened, disorganized trabeculae which lead to areas of sclerosis in a previously lucent area of bone, typically the skull. These sclerotic patches are poorly defined and fluffy. See also Other Paget disease re...
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CSF cleft sign

The CSF cleft sign in neuroimaging can be used to distinguish an extra-axial lesion from an intra-axial lesion and is typically used in the description of a meningioma. Classically, the cleft was regarded as representing a thin rim of CSF between a tumor and brain parenchyma. However, it often ...
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CT angiographic spot sign (intracerebral hemorrhage)

The CT angiographic (CTA) spot sign is defined as unifocal or multifocal contrast enhancement within an acute primary intracerebral hemorrhage (ICH) visible on CTA source images and discontinuous from adjacent normal or abnormal blood vessels 1. It should not be present on pre-contrast images. I...
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CT comma sign (head)

The CT comma sign is a characteristic sign seen in head trauma. It is the presence of concurrent epidural and subdural hematomas, which gives the characteristic appearance of this sign as a "comma" shape.
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Cyst with dot sign (neurocysticercosis)

The cyst with dot sign is seen in neurocysticercosis and represents the parasitic cyst with, usually eccentric, scolex. It can be seen on both MRI and CT at: the vesicular stage (CSF density / intensity cyst - denser / hyperintense scolex) and colloidal vesicular stage (enhancement of wall an...
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Dawson fingers

Dawson fingers are a radiographic feature of demyelination characterized by periventricular demyelinating plaques distributed along the axis of medullary veins, perpendicular to the body of the lateral ventricles and/or callosal junction. This is thought to reflect perivenular inflammation. They...
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Dense vein sign

The dense vein sign 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 or pseudodelta sign. It is really the sa...
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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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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...
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Double density sign (osteoid osteoma)

The double density sign, also sometimes clumsily referred to as the hotter spot within hot area sign, is a bone scan sign of an osteoid osteoma. It refers to a central focus of intense uptake (the nidus) within a surrounding lower, but nonetheless increased uptake, rim. See also double densit...
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Double panda sign

The double panda sign refers to the combination of the face of the giant panda and face of the miniature panda (cub of the giant panda) seen on T2 weighted images of midbrain and pons respectively in Wilson disease. The midbrain face of the giant panda sign consists of normal intensity of red n...
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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...
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Dumbbell appearance of spinal tumors

The dumbbell appearance of spinal tumors refers to a tumor which has both a component within the canal and a component in the paravertebral space contiguous with each other via a thinner tumor component traversing the neural exit foramen. The appearance can be seen in: spinal nerve sheath tumo...
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Dural tail sign

The dural tail sign occurs as a result of thickening and enhancement of the dura and is most often seen adjacent to a meningioma. Initially, the sign was felt to be pathognomonic of meningiomas, however as experience grew, it has become increasingly noted to be present in many other conditions,...
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Ears of the lynx sign (brain)

The ear of the lynx sign refers to abnormal T2/FLAIR cone-shaped hyperintensity at the tip of the frontal horn of the lateral ventricles in the region of forceps minor which resembles the tufts of hair crowning the ears of a lynx. This sign is seen in hereditary spastic paraplegia associated wit...
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Eccentric target sign (cerebral toxoplasmosis)

The eccentric target sign is considered pathognomonic for cerebral toxoplasmosis. It is seen on postcontrast MRI/CT as a ring enhancing lesion with an eccentrically located enhancing mural nodule. It is believed that this mural nodule is an extension from the abscess wall itself with inflamed ve...
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Empty delta sign (dural venous sinus thrombosis)

The empty delta sign is a CT sign of dural venous sinus thrombosis of the superior sagittal sinus, where contrast outlines a triangular filling defect, which represents thrombus. It is only described with CECT-scan or MRI, not with NECT nor non-contrast MRI. An equivalent appearance can be note...
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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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Empty thecal sac sign

The empty thecal sac sign or empty sac sign is when the thecal sac appears empty on MRI of the lumbar spine, best seen on T2-weighted images. If the empty thecal sac sign is present, a diagnosis of adhesive arachnoiditis can be made.​ Radiographic features MRI There is usually no gadolinium c...
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État criblé

État criblé, also known as status cribrosum, is a term that describes the diffusely widened perivascular spaces (Virchow-Robin spaces) in the basal ganglia, especially in the corpus striatum on MRI. It is usually symmetrical, with the perivascular spaces showing CSF signal and without diffusion ...
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État lacunaire

État lacunaire is a term describing the presence of multiple lacunar infarcts, which are ischemic strokes due to occlusion of penetrating cerebral arterioles, especially in the basal ganglia. The term has been strongly described as a pathological substrate for a multi-infarct vascular dementia 4...
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Extracranial brain herniation

Extracranial brain herniation refers to herniation of brain tissue external to the calvaria through a skull bone defect, which may be post-traumatic or post-surgical. Unlike encephaloceles, brain herniation is not surrounded by the meninges.  The herniated brain tissue requires surgical reducti...
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Eye of the tiger sign (globus pallidus)

The eye of the tiger sign refers to abnormal low T2 signal on MRI (due to abnormal accumulation of iron) in the globus pallidus with a longitudinal stripe of high signal (due to gliosis and spongiosis).  The eye of the tiger sign is most classically associated with pantothenate kinase-associate...
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Figure of eight appearance

The following lesions may resemble a figure of eight (sometimes referred to as snowman shaped): supracardiac variety of total anomalous pulmonary venous return 1 pituitary macroadenoma with suprasellar extension 2 intraspinal neurofibroma with extraspinal extension through neural foramina di...
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Flame sign (spinal cord metastasis)

The flame sign has been described as a helpful MRI sign of spinal cord metastases, enabling them to be distinguished from other enhancing spinal cord lesions (e.g. ependymoma, astrocytoma and hemangioblastoma) 1.  Radiographic features MRI The flame sign is seen on sagittal post contrast T1 w...
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Flat floor of fourth ventricle sign

The flat floor of fourth ventricle sign is useful in detecting a pontine mass and is a sign of mass effect. The normal floor of the fourth ventricle (remember that the floor is anterior) normally slopes upwards towards the midline, with the facial colliculi visible on either side.  It is a non-...
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Fogging phenomenon (cerebral infarct)

The fogging phenomenon is seen on non-contrast CT of the brain and represents a transient phase of the evolution of cerebral infarct where the region of cortical infarction regains a near-normal appearance.  {{youtube:http://www.youtube.com/watch?v=LuX3VV__2w0}} During the first week following...
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Hematocrit effect

The hematocrit effect with fluid-fluid levels is the result by layering of heavier cellular elements of blood located dependent to a liquid supernatant. It can be seen on CT or MRI. It is most frequently seen in the setting of anticoagulation therapy or coagulopathy. See also signal flare phen...
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Hemosiderin cap sign

The hemosiderin cap sign refers to an MR imaging feature in some spinal tumors where a cap of T2 hypointense hemosiderin is above and/or below the tumor due to previous hemorrhage.  It is most often associated with spinal cord ependymomas (20-33% of cases) 1. It may also be seen in hemangioblas...
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Harlequin eye deformity

The harlequin eye deformity is characterized by elevation of the superolateral corner of the orbit. It may be seen in unilateral (plagiocephaly) or bilateral (brachycephaly) coronal suture synostosis. History and etymology The term harlequin eye derives from the appearance of the eyes on a har...
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Hockey stick sign (Creutzfeldt-Jakob disease)

The hockey stick sign refers to the hyperintense signal involving the pulvinar and dorsomedial thalamic nuclei bilaterally on FLAIR, in cases of variant Creutzfeldt-Jakob disease, which has the shape of a hockey stick. See also pulvinar sign (Creutzfeldt-Jakob disease) hockey stick sign (thyr...
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Hockey stick sign (disambiguation)

The hockey stick sign can refer to a variety of different signs and appearances: hockey stick sign (thyroid hemiagenesis) hockey stick sign (Creutzfeldt-Jakob disease) hockey stick sign (ureters)
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Hot cross bun sign (pons)

The hot cross bun sign refers to the MRI appearance of the pons in a variety of neurodegenerative diseases.  T2 hyperintensity forms a cross on axial images through the pons, representing selective degeneration of pontocerebellar tracts. It has been described in 1: multiple system atrophy (MSA...
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Hot nose sign

The hot nose sign refers to increased perfusion in the nasal region on nuclear medicine cerebral perfusion studies in the setting of brain death. The absent or reduced flow in the internal carotid arteries is thought to lead to increased flow within the external carotid arteries and subsequent i...
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Hummingbird sign (midbrain)

The hummingbird sign, also known as the penguin sign, refers to the appearance of the brainstem in patients with progressive supranuclear palsy (PSP).  The atrophy of the midbrain results in a profile of the brainstem (in the sagittal plane) in which the preserved pons forms the body of the bir...
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Hutchinson pupil

Hutchinson pupil is a fixed and dilated pupil caused by compression of the oculomotor nerve (CN III) as a result of uncal herniation. It should not be confused with any of the following: Hutchinson triad Hutchinson freckle Hutchinson teeth Hutchinson sign Hutchinson syndrome History and e...
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Hutchinson sign (disambiguation)

The Hutchinson sign can refer to two signs.  Hutchinson sign (ophthalmology) Relates to involvement of the tip of the nose from facial herpes zoster. It implies involvement of the external nasal branch of the nasociliary nerve (branch of the ophthalmic division of the trigeminal nerve) and thu...
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Hyperdense MCA sign (brain)

The hyperdense MCA sign refers to focal increased density of the middle cerebral artery (MCA) on CT and is a direct visualization of thromboembolic material within the lumen. It is thus the earliest visible sign of MCA infarction as it is seen within 90 minutes after the event 1. It is the longi...
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Hypomelanotic macules

Hypomelanotic macules are otherwise known as ash-leaf spots due to their resemblance to Sorbus aucuparia, or mountain-ash, leaves. These macules have a strong association with tuberous sclerosis and are often multiple and present in the vast majority of individuals with the condition (up to 97% ...
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Imaging psoas sign (spondylodiskitis)

The imaging psoas sign is an MRI finding specific for spondylodiskitis and is seen as T2 hyperintensity in the psoas major muscle. The sign has a high sensitivity (92%) and specificity (92%) for spondylodiskitis and in the clinical context of a suspected infective process of the spine supports c...
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Infundibulum sign (pituitary)

The infundibulum sign is helpful in distinguishing an empty pituitary sella from a cystic lesion of the pituitary region 1.  In the former, although the sella is enlarged, there is no mass as such and the pituitary infundibulum traverses the enlarged sella to its floor where residual pituitary ...
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Intracranial arterial beading

Intracranial arterial beading represents alternating areas of constriction in the intracranial arteries that gives the appearance of beads strung together. Differential diagnosis The various conditions where this is seen are: cerebral vasculitis radiation therapy cerebral vasospasm post sub...
Article

Inverted "V" sign (spinal cord)

The inverted "V" sign, also known as the inverted rabbit ears sign, is a radiological sign described in subacute combined degeneration of the spinal cord​. It refers to the appearance of the spinal cord on axial MRI slices 1-3. On these slices in a patient with subacute combined degeneration of...
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Ivy sign (brain)

The ivy sign refers to the MRI appearance of patients with moya moya disease or moya moya syndrome. Prominent leptomeningeal collaterals result in vivid contrast enhancement and high signal on FLAIR due to slow flow. The appearance is reminiscent of the brain having been covered with ivy. Diffe...
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J-shaped sella

A J-shaped sella is a variant morphology of the sella turcica, whereby the tuberculum sellae is flattened, thus forming the straight edge of the "J". The dorsum sellae remains rounded and forms the loop of the "J". Differential diagnosis Differential diagnosis for a J-shaped sella includes 1,2...
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Kernohan phenomenon

Kernohan notch phenomenon is an imaging finding resulting from extensive midline shift due to mass effect, resulting in indentation in the contralateral cerebral crus by the tentorium cerebelli. This has also been referred to as Kernohan-Woltman notch phenomenon and false localizing sign. Clini...
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Kissing carotids

The term kissing carotids refers to tortuous and elongated vessels which touch in the midline. They can be be found in:  retropharynx 2 intrasphenoid 1 within the pituitary fossa within sphenoid sinuses within sphenoid bones The significance of kissing carotids is two-fold: may mimic intr...
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Lemon sign

The lemon sign, noted on antenatal imaging, is one of the many notable fruit-inspired signs. It is a feature when there appears to be an indentation of the frontal bone (depicting that of a lemon). It is classically seen as a sign of a Chiari II malformation and also seen in the majority (90-98%...
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Lentiform fork sign (basal ganglia)

The lentiform fork sign has been described on MRI and is seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a hyperintense rim delineating the lentiform nucleus. It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage renal dise...
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Leopard skin sign (white matter)

The leopard skin sign (also known as tigroid pattern or stripe sign) results from dark-spots or stripes (spared perivascular white matter) within bright demyelinated periventricular white matter on T2W images. It is characteristically seen in: metachromatic leukodystrophy Pelizaeus-Merzbacher ...
Article

Lhermitte sign (spinal cord)

Lhermitte sign or the barber chair phenomenon is an electrical shock sensation running down the spine and into the limb on neck flexion. It suggests compression of the upper cervical spinal cord and/or brainstem. Pathology It is typically seen with multiple sclerosis but is also associated wit...
Article

Loss of the insular ribbon sign

The loss of the insular ribbon sign refers to a loss of definition of the gray-white interface in the lateral margin of the insular cortex ("insular ribbon") and is considered an early CT sign of MCA infarction. The insular cortex is more susceptible to ischemia following MCA occlusion than oth...
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Lower T sign (central sulcus)

The lower T sign is one of the features useful in identifying the central sulcus on cross-sectional imaging.  It relies on identifying the inferior frontal sulcus which intersects the precentral sulcus in a "T" junction, thus defining the precentral gyrus. The central sulcus is the next posteri...
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L sign (brain)

The L sign is one of the features useful in identifying the central sulcus on cross-sectional imaging. On axial images, the superior frontal gyrus at its posterior aspect meets the precentral gyrus in an "L" configuration (forwards on the left, backwards on the right). The central sulcus is the...
Article

Mamillopontine distance

Mamillopontine distance is defined as the distance between the inferior aspect of the mammillary bodies to the superior aspect of the pons. In normal subjects, it should be greater than 5.5 mm 1. It is decreased in conditions that either depress the floor of the third ventricle or change the po...
Article

Marcus Gunn pupil

Marcus Gunn pupil, also known as a relative afferent pupillary defect (RAPD), is a non-specific sign on physical examination that indicates partial optic nerve dysfunction. It is mainly due to unilateral optic neuropathy (e.g. optic neuritis), or rarely optic chiasm or optic tract lesions. This...
Article

MCA dot sign (brain)

The middle cerebral artery (MCA) dot sign, also known as the Sylvian fissure sign, is seen on CT of the head and represents the cross-sectional M2 equivalent of the hyperdense MCA sign. Rather than imaging a length of middle cerebral artery (typically the M1 segment), the dot sign represents a t...
Article

Mickey Mouse appearance

In medical imaging literature, a Mickey Mouse appearance has been given to imaging features that depict that of 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 ...
Article

Middle cerebellar peduncle sign

The middle cerebellar peduncle (MCP) sign is a feature of a number of conditions, particularly neurodegenerative diseases, and most commonly associated with fragile X-associated tremor/ataxia syndrome (FXTAS) although many other conditions are recognized.  It represents high T2 signal in the mi...
Article

Molar tooth sign (CNS)

The molar tooth sign refers to the appearance of the midbrain in an axial section in which the elongated superior cerebellar peduncles give the midbrain an appearance reminiscent of a molar or wisdom tooth. It was initially described in Joubert syndrome and related disorders (JSRD) 2 but is now...
Article

Moose head appearance

The moose head appearance refers to the lateral ventricles in coronal projection in patients with dysgenesis of the corpus callosum. The cingulate gyrus is everted into narrowed and elongated frontal horns. An alternative name is the viking helmet sign.
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 a axial image at the level of the midbrain by drawing 1:   a horizo...
Article

Morning glory syndrome (eye)

Morning glory disc anomaly (MGDA), also known as morning glory syndrome, is a rare congenital malformation of the optic nerve which is frequently associated with midline abnormalities of the brain and skull 1. Epidemiology Morning glory disc anomaly is rare and is more commonly found in female...
Article

Mosaic pattern of bone

The mosaic bone pattern, also referred to as the jigsaw pattern of bone is seen in Paget disease, where thickened, disorganized trabeculae lead to areas of sclerosis are interspersed with lucent and more normal bone. See also Other Paget disease related signs: blade of grass sign tam o' shan...
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Mother in law sign

The mother in law sign is perhaps uncharitably (depends on the mother in law I suppose) used to describe lesions that enhance early during the arterial phase and remain opacified well after the venous phase. The joke is that a mother in law comes early and stays late.  It is most frequently equ...
Article

Motor band sign

The motor band sign is a radiological sign described in amyotrophic lateral sclerosis (ALS). It refers to the appearance of the cortex on axial GRE and SWI MRI in patients with ALS 1,2. On these sequences, and in the axial plane, curvilinear bands of low signal may be appreciated within the cor...

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