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.

124 results found
Article

Bare orbit sign

Bare orbit sign, is described as a characteristic appearance of orbit, where 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 radiograph sign of ...
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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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Blend sign

Early haematoma growth is not uncommon in patients with intracerebral haemorrhage and is an independent predictor of poor functional outcome. In nonenhanced cranial CT the blend sign is defined as blending of a hypoattenuating area and a hyperattenuating region with a well-defined margin.
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Boomerang sign

The boomerang sign refers to boomerang shaped splenial lesion (splenium of corpus callosum) which is seen as hyperintense lesion on T2-WI, FLAIR and DWI 1. This sign can be seen in: transient lesion in splenium ischemia posterior reversible encephalopathy syndrome diffuse axonal injury mul...
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Bracket sign

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.
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Bright rim sign in DNETs

The bright rim sign has been described in DNETs and is seen, as the name so aptly describes, as a rim of high signal around the DNET on FLAIR sequences.
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Brudzinski sign

Brudzinski sign occurs in meningitis, where passive flexion of one leg causes flexion in the opposite leg. Passive flexion of the neck brings about flexion of the legs as well. Historical context First described by Jósef Brudziñski (1874-1917), Paediatrician from Warsaw, Poland 2.
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Bull's eye sign: general

There are many bull's eye signs, also referred to as target signs: red bone marrow located in shaft of long bone with central yellow marrow on MRI peripheral plexiform neurofibromas on MRI intussusception: see target sign of intussusception choledocholithiasis: see target sign of choledochol...
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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

Butterfly sign refers to the normal appearance of bilateral 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 mistaken by butterfly glioma, which is a glioblastoma ...
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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 anomalies

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 ...
Article

Chasing the dragon - toxic leukoencephalopathy

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

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

Claw sign

The claw sign is useful in determining whether a mass arises from a solid structure or 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. As su...
Article

Copper beaten skull

Copper beaten skull, also known as beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault. Demographics and clinical presentation The appearance of copper beaten skull is associated with raised ...
Article

Cord sign

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...
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Cotton wool appearance of 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...
Article

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 tumour and brain parenchyma. However, it often ...
Article

CT angiographic spot sign

The CT angiographic (CTA) spot sign is defined as unifocal or multifocal contrast enhancement within an acute primary intracerebral haemorrhage (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. ...
Article

CT comma sign

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

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...
Article

Dawson fingers

Dawson fingers are a radiographic feature depicting demyelinating plaques through the corpus callosum, arranged at right angles along medullary veins (callososeptal location). They are a relatively specific sign for multiple sclerosis (MS), which presents as T2 hyperintensities. History and ety...
Article

Disappearing basal ganglia sign

The disappearing basal ganglia sign is one of the early signs of an 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 oedema at the time of an ischaemic event. It is be...
Article

Double density sign of berry aneurysms

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 calibre. 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...
Article

Double density sign of 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...
Article

Double panda sign

The double panda sign refers to combination of 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 nuclei an...
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Double rim sign

Double rim sign is best described on T2WI MRI, in the early capsule stage of brain abscess. It consists two concentric rims surrounding the abscess cavity, one of which is hypointense (outer rim), and the other relatively more hyperintense (inner rim). It is described in more than 75% of cases.
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Dual rim sign

The dual rim sign is seen on susceptibility weighted imaging (SWI) in cerebral abscesses and is helpful in distinguishing an abscess from a gliblastoma (GBM).  Pathology It has been postulated that granulation tissue lines the inner part of fibrocollagenous abscess capsule and together they fo...
Article

Dumbbell appearance of spinal tumours

Dumbbell appearance of spinal tumours refers to a tumour which has both a component within the canal and a component in the paravertebral space linked by tumour traversing the neural exit foramen. The appearance can be seen in: spinal nerve sheath tumours spinal schwannoma (90%) 1 spinal neu...
Article

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, ...
Article

Eccentric target sign

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...
Article

Empty delta sign

The empty delta sign is CT sign of dural venous sinus thrombosis of the superior sagittal sinus, where contrast outlines a triangular filling defect (clot). It is only described with CECT-scan or MRI, not with NECT nor non-contrast MRI. Pathology The exact mechanism for this appearance is unce...
Article

Empty light bulb sign in brain death

In brain death, on HMPAO-Tc99m 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 '...
Article

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...
Article

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. It is usually symmetrical, with the perivascular spaces showing CSF signal and without diffusion restric...
Article

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...
Article

Extracranial brain herniation

Extracranial brain herniation refers to herniation of brain tissue outside the calvarium through a skull bone defect, which may be post traumatic or post surgery. Unlike encephalocoeles, brain herniation is surrounded by the meninges.  The herniated brain tissue requires surgical reduction as i...
Article

Eye of tiger sign

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) that can be seen in: Hallervorden-Spatz syndrome: classical but not 100% pathognomonic progr...
Article

Figure of eight appearance

Following lesions may resemble a figure of eight (sometimes referred to as snowman shaped): supracardiac variety of total anomalous pulmonary venous return (TAPVR) 1 pituitary macroadenoma with suprasellar extension2 intraspinal neurofibroma with extraspinal extension through neural foramina ...
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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

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 a c...
Article

Haematocrit effect

The haematocrit effect with fluid-fluid levels is the result by layering of heavier cellular elements of blood located dependent to liquid supernatant may be seen on CT or MRI. It is most frequently seen in the setting of anticoagulation therapy or coagulopathy. See also signal flare phenomenon
Article

Haemosiderin cap sign

The haemosiderin cap sign refers to an MR imaging feature in some spinal tumours where a cap of T2 hypointense haemosiderin is above and/or below the tumour due to previous haemorrhage.  It is most often associated with spinal cord ependymomas, being seen in 20-33% of these cases 1. The sign ho...
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Harlequin eye deformity

The harlequin eye deformity may seen in unilateral (plagiocephaly) or bilateral (brachycephaly) coronal suture synostosis, and refers to the elevation of the superolateral corner of the orbit.
Article

Hockey stick sign

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 (vCJD), which has the shape of a hockey stick. The hockey stick sign is also used sometimes to describe thyroid hemi...
Article

Hot cross bun sign

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...
Article

Hummingbird sign

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...
Article

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's triad Hutchinson freckle Hutchinson teeth Hutchinson's sign Hutchinson syndrome History a...
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Hutchinson sign

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 nasal branch of the nasociliary nerve (branch of the ophthalmic division of the trigeminal nerve) and thus raises ...
Article

Hyperdense MCA sign

The hyperdense MCA sign refers to the appearance of the middle cerebral artery (MCA) on CT. It has been associated with poor outcome, although this is by no means established 5. Radiographic features There is increased attenuation of the proximal portion of the MCA and it is often associated w...
Article

Infundibulum sign

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 ...
Article

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

Ivy sign

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 configuration of the sella turcica, where 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-shap...
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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 localising sign. Clini...
Article

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 intra-sphenoid 1 within the pituitary fossa within sphenoid sinuses within sphenoid bones The significance of kissing carotids is two-fold: may mimic int...
Article

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

The lentiform fork sign has been described on MRI seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a more/brightly hyperintense rim delineating the lentiform nucleus. It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage ren...
Article

Leopard skin sign

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

Lhermitte sign is a clinical finding that typically seen with multiple sclerosis (MS) but can also be seen in other entities which affect the dorsal columns of the spinal cord: cervical cord tumours cervical spondylosis, e.g. after a fracture 3 vitamin B12 deficiency It is characterised by a...
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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 ischaemia following MCA occlusi...
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Mamillopontine distance

Mamillopontine distance is defined as the distance between the inferior aspect of the mammillary bodies to superior aspect of the pons. In normal subjects, it should be >5.5 mm. It is decreased in conditions such as intracranial hypotension: it is one of the helpful quantitative signs helpf...
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Marcus Gunn pupil

Marcus Gunn pupil, also known as afferent pupillary defect, is a nonspecific finding that indicates partial optic nerve dysfunction. It is mainly due to unilateral optic neuropathy, or rarely optic chiasm or optic tract lesions. In response to light input to the affected eye, both eyes do not c...
Article

MCA dot sign

The middle cerebral artery (MCA) dot 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 thromboembolus within a segmental branch o...
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Mickey mouse appearance

In medical imaging literature, a mickey mouse appearance has been given to imaging features that depict that of a Mickey mouse when viewed from the front. It has been described with: anencephaly 2 progressive supranuclear palsy 1 synonymously with a finger in glove sign the flared shape of t...
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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 recognised.  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 axial section 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 reco...
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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.
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Morning glory sign

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

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' sha...
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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...
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Mount Fuji sign

Mount Fuji sign is seen on cross sectional imaging and implies tension pneumocephalus is present.  The sign refers to the presence of air (pneumocephalus) between the tips of the frontal lobes giving the appearance of Mount Fuji. It suggests that the pressure of the air is at least greater than...
Article

Non-accidental injuries

Non-accidental injuries (NAI) represent both ethical and legal challenges to treating physicians. Radiologists are often the first to suspect NAI when confronted with particular injury patterns, and a knowledge of these is essential if the opportunity to save a child from future neglect is not ...
Article

Notch sign

There are many so-called notch signs. They include: focal notch in the wall (or tail extending from) a 2nd branchial cleft cyst between the internal and external carotid artery.  peripheral notches in the contour of a solitary pulmonary nodule (SPN) suggests malignancy thymic notch sign
Article

Onion bulb formation

Onion bulb formation is seen in hypertrophic neuropathies such as Charcot-Marie-Tooth type 1A (CMT1A) and chronic inflammatory demyelinating polyneuropathy (CIDP). It is the result of from the proliferation of Schwann cells and deposition of collagen 1.  Radiographic features MRI The nerve ro...
Article

Open ring sign

The open ring sign is a relatively specific sign for demyelination, most commonly multiple sclerosis (MS), and is helpful in distinguishing between the causes of ring enhancing lesions. Interestingly open ring enhancement is not seen in neuromyelitis optica (NMO).  Radiographic features The en...
Article

Owl's eye sign

The owl's eye 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 T2-weighted signal extending usually over...
Article

Pancake brain

Pancake brain, is the classical sign of alobar holoprosencephaly. It is due to fusion of cerebral hemisphere leaving a single ventricle in its center. It is the most severe form of holoprosencephaly. It is associated with multiple facial abnormality See also pancake vertebra vegetable and fru...
Article

Panda sign

The humble panda has a few signs to its name: panda sign of the midbrain panda sign of sarcoidosis See also animal and animal produce inspired signs
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Panda sign of the midbrain

The panda sign in neuroimaging refers to the appearance of the midbrain, when the red nucleus and substantia nigra are surrounded by high T2 signal. It is classically seen in Wilson disease, although whenever the white matter is diffusely abnormal in the region a similar appearance will be perc...
Article

Papilloedema

Papilloedema is essentially an ophthalmoscopic diagnosis and refers to swelling of the optic disc. The MRI appearance relates to the dural anatomy of the optic nerve, which is continuous with the subarachnoid space, thereby allowing increased intracranial pressure (ICP) to be transmitted to the ...
Article

Peg like tonsils

Peg like tonsils refer to CT or MR appearances of pointed cerebellar tonsils on sagittal scans.  The may help distinguish tonsillar ectopia from a Chiari 1 malformation.
Article

Posterior pituitary bright spot

The posterior pituitary bright spot (PPBS) is a MRI feature of the normal pituitary gland. It refers to the intrinsically high T1 signal of the posterior pituitary thought to be from the storage of vasopressin, which has a T1-shortening effect 2. It is important to note that a posterior pituita...
Article

Powers ratio

Powers ratio is a measurement of the relationship of the foramen magnum to the atlas, used in the diagnosis of atlanto-occipital dissociation injuries. The ratio, AB/CD, is measured as the ratio of the distance in the median (midsagittal) plane between the: basion (A) and the posterior spinola...
Article

Prévost sign

The Prévost sign refers to deviation of the eyes away from the hemiparesis in acute cortical hemiparetic stroke. Therefore, the eyes are deviated towards the involved hemisphere and may be exaggerated when the head is turned in the same direction. It is most pronounced with non-dominant hemisphe...
Article

Pseudo-subarachnoid haemorrhage

Pseudo-subarachnoid haemorrhage is the a sign related to apparent increased attenuation within the basal cisterns which simulates a true subarachnoid haemorrhage (SAH). Pathology Causes and associations The most common cuase is cerebral oedema where there is a decrease in parenchyma attenuati...
Article

Puff of smoke sign

The puff of smoke sign describes the characteristic angiographic appearance of tiny abnormal intracranial collateral vessel networks in moyamoya disease. Progressive narrowing of the supraclinoid internal carotid arteries and circle of Willis vessels results in extensive small collateral arteria...
Article

Pulvinar sign

The pulvinar sign refers to bilateral FLAIR hyperintensities involving the pulvinar thalamic nuclei. It is classically described in variant Creutzfeldt-Jakob disease (vCJD). It is also described in other neurological conditions: Fabry disease (although the hyperintense signal is seen on T1WI) ...
Article

Putaminal rim sign

The putaminal rim sign, also known as putaminal slit sign,  is a relatively specific sign of multiple system atrophy - parkinsonism (MSA-P), and refers to a linear region of high T2 signal surrounding the lateral aspect of the putamen at 1.5T MRI. Importantly this appearance can be seen in norma...
Article

Racing car sign

The racing car sign refers to widely spaced lateral ventricles due to agenesis of the corpus callosum with intervening Probst bundles. Appearances on axial MRI or CT are reminiscent of a formula one car seen from above, with the tires represented by the widely spaced frontal horns, and the dilat...
Article

Radial bands sign

The radial bands sign 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 are thought to relate to dysfuction or...

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