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.

1,984 results found
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Arachnoid cyst (fetal presentation)

A fetal arachnoid cyst is term given when an arachnoid cyst is diagnosed in utero. For a general discussion of arachnoid cysts refer to the parent article. Pathology They can be classified as being primary or secondary 2. primary (congenital) arachnoid cysts: result from a benign accumulation...
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Arachnoid granulation

Arachnoid granulations, also known as a Pacchionian granulation, are projections of the arachnoid membrane (villi) into the dural sinuses that allow CSF entrance from the subarachnoid space into the venous system. They most frequently occur in a parasagittal location with the transverse and sup...
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Arachnoid mater

The arachnoid mater forms the middle layer of the meninges and together with the pia mater is sometimes referred to as the leptomeninges.  Gross anatomy The arachnoid mater is a membrane that comes into direct contact with the dura mater and is separated from the pia mater by a CSF filled spac...
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Arachnoiditis

Arachnoiditis is a broad term encompassing inflammation of the meninges and subarachnoid space. Terminology Arachnoiditis affecting the cauda equina may be referred to as spinal/lumbar adhesive arachnoiditis.  Clinical presentation Lumbar spine arachnoiditis can result in leg pain, sensory c...
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Area postrema

The area postrema is one of the so-called circumventricular organs located on the dorsal inferior surface of the medulla oblongata at the caudal end of the fourth ventricle. The specialised ependymal cells in the area postrema detect toxins in the blood and act as a vomit-inducing centre, along...
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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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Arterial spin labelling (ASL) MR perfusion

Arterial spin labelling (ASL) MR perfusion is an MR perfusion technique which does not require intravenous administration of contrast (unlike DSC perfusion and DCE perfusion). Instead it exploits the ability of MRI to magnetically label arterial blood below the imaging slab. The parameter most c...
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Arterial supply of the head and neck

The arteries of the head and neck are branches of the common carotid and subclavian arteries. common carotid artery carotid body carotid bifurcation internal carotid artery (segments) caroticotympanic artery persistent stapedial artery ophthalmic artery supraorbital artery lacrimal arte...
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Artery of Adamkiewicz

The artery of Adamkiewicz, also known as the great anterior radiculomedullary artery or arteria radicularis anterior magna, is the name given to the dominant thoracolumbar segmental artery that supplies the spinal cord. Gross anatomy Origin The artery of Adamkiewicz has a variable origin but ...
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Artery of Percheron

The artery of Percheron is a rare variant of the posterior cerebral circulation characterised by a solitary arterial trunk that supplies blood to the paramedian thalami and the rostral midbrain bilaterally. Gross anatomy The term is used to refer to a solitary arterial trunk that branches from...
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Artery of Percheron territory infarct

Artery of Percheron territory infarct is rare, on account of the relative rarity of the artery of Percheron, and presents with a variety of signs and symptoms collectively termed the paramedian thalamic syndrome. It is a type of posterior circulation infarction. On imaging, it is classically ch...
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Ascending ramus of the lateral sulcus

Ascending ramus of the lateral sulcus, is located at the anterior end of the lateral sulcus (sylvian fissure), just posterior to the anterior ramus, and passes superiorly into the inferior frontal gyrus separating the pars triangularis from the pars opercularis of the frontal operculum.  Termin...
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Ascending transtentorial herniation

Ascending transtentorial herniation is a situation where space occupying lesions in the posterior cranial fossa cause superior displacement of superior parts of the cerebellum through the tentorial notch.  Clinical presentation nausea and/or vomiting  rapid progression toward decreased level ...
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ASIA impairment scale for spinal injury

The American Spinal Injury Association (ASIA) was developed by the American Spinal Injury Association in 2006, and at the time of writing (July 2016), remains the most widely used scale. This scale is part of the ASIA spinal cord injury classification. It divides spinal cord injuries into 5 cat...
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Astroblastoma

Astroblastomas are rare glial tumours usually found in the cerebral hemispheres of young adults and children.  Epidemiology They occur at all ages range from early childhood to 6th decade but are most commonly seen in children, adolescents, and young adults with a mean age between 10-30 years ...
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Astrocytes

Astrocytes are cells of the central nervous system which act as both physical and physiological support for the neurones that are embedded between them. They are particularly abundant in the grey matter, where they are the most abundant glial cells 1. They are highly branched and contribute to ...
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Astrocytic tumours

Astrocytic tumours are primary central nervous system tumours that either arises from astrocytes or appear similar to astrocytes on histology having arisen from precursor cells. They are the most common tumours arising from glial cells. They can be divided into those that are diffuse in growth ...
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Asymmetric fatty bone marrow of the petrous apex

Asymmetric pneumatisation of petrous apex results in asymmetric fatty bone marrow within the petrous apex. It is a common incidental finding on brain and skull base MRI. Clinical presentation Asymptomatic. Pathology Asymmetric pneumatisation of the petrous apex results in the presence of bon...
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Asymmetric ventriculomegaly, interhemispheric cyst and dysgenesis of the corpus callosum (AVID)

Asymmetric ventriculomegaly, interhemispheric cyst and dysgenesis of the corpus callosum (AVID) is a triad of congenital cerebral anomalies. Radiographic features markedly asymmetric enlargement of the lateral ventricles may be the initial finding on routine fetal morphology ultrasound. inter...
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Asymmetrically large jugular bulb

Asymmetrically large jugular bulbs are entirely normal and asymptomatic; its only significance is to distinguish it from pathology. The size of the jugular bulbs is variable, with the right side being significantly larger than the left in two-thirds of people. A normal but large bulb will have...
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Ataxia telangiectasia

Ataxia telangiectasia is a rare multisystem disorder which carries an autosomal recessive inheritance, sometimes classified as a phakomatosis. It is characterised by multiple telangiectasias, cerebellar ataxia, pulmonary infections and immunodeficiency.  On brain imaging, it usually demonstrate...
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Atelencephaly

Atelencephaly (also termed atelencephalic microcephaly) is a rare and extreme disorder with only a handful of published cases. In this anomaly, the derivatives of the telencephalon are absent or dysplastic, while more caudal structures are normal or mildly deformed. It falls under the aprosencep...
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Atlantodental interval

The atlantodental interval (ADI), as the name suggests, is the horizontal distance between the anterior arch of the atlas and the dens of the axis, used in the diagnosis of atlanto-occipital dissociation injuries and injuries of the atlas and axis. It is the distance (in mm) between the posteri...
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Atretic parietal cephalocoele

Atretic parietal cephalocoeles (APC) also known as atretic cephalocele, refers to small subscalp lesions that consist of dura, fibrous tissue, and dysplastic brain tissue. Epidemiology Common presentation in infants and young children.  Clinical presentation Palpable midline parietal soft ti...
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Atypical callosal dysgenesis

Atypical callosal dysgenesis is a term used to denote an unusual pattern of dysgenesis of the corpus callosum. The development of the corpus callosum occurs between the 12th and 16-20th weeks of gestation 2-3. It begins with the genu and then continues posteriorly along the body to the splenium...
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Atypical choroid plexus papilloma

Atypical choroid plexus papillomas are WHO grade II tumours derived from choroid plexus epithelium with intermediate clinical and pathological features between the much more common, and more indolent, WHO grade I choroid plexus papilloma and the more aggressive WHO III choroid plexus carcinoma. ...
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Atypical meningioma

Atypical meningioma refers to a more aggressive form of meningioma and denotes a WHO grade II tumour (along with two histological variants clear cell meningioma and chordoid meningioma). Atypical meningiomas account for 20-30% of all meningiomas 1,3.  It should be noted that epidemiology, clini...
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Atypical teratoid/rhabdoid tumour

Atypical teratoid/rhabdoid tumours (AT/RTs) are an uncommon WHO Grade IV tumour, which in the vast majority of cases occurs in young children less than two years of age. It most frequently presents as a posterior fossa mass.  AT/RTs were until relatively recently classed as medulloblastomas, al...
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Autoimmune encephalitis

Autoimmune encephalitis (also known as autoimmune limbic encephalitis) is an antibody-mediated autoimmune-mediated inflammation of the brain, typically involving the limbic system, although all parts of the brain can be involved.  Autoimmune encephalitis can be divided broadly into two groups, ...
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Autosomal recessive spastic ataxia of Charlevoix-Saguenay

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a rare autosomal recessive spastic ataxia unique to the region of Charlevoix-Saguenay, in the Province of Quebec, Canada. It is due to a mutation on the SACS gene locus q12 of chromosome 13. It has been reported in other regio...
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AVAglio criteria for glioblastoma

The AVAglio criteria were developed to assess response to first-line treatment of glioblastoma, treated with radiotherapy and temozolomide with or without bevacizumab 1-2. These were adapted from the older Macdonald criteria, but have since been superseded by they RANO criteria (2010) 1.  The A...
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Azygos anterior cerebral artery

An azygos anterior cerebral artery is uncommon to rare variant of the circle of Willis where the two A1 segments of the anterior cerebral artery (ACA) join to form a single trunk. As a result, there is no anterior communicating artery. This organisation is similar to that seen in lower primates ...
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Babinski-Nageotte syndrome

Babinski-Nageotte syndrome is thought to be a brainstem stroke syndrome in between that of the hemimedullary syndrome (Reinhold syndrome) and the lateral medullary syndrome (Wallenberg syndrome) 1,2. It is considered to be a spreading of the “Wallenbergian” lateral lesion, often due to occlusion...
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Balint syndrome

The Balint syndrome is characterised by: simultanagnosia (inability to perceive more than one object at a time) optic ataxia oculomotor apraxia It typically results from damage to the parieto-occipital regions, and has been associated with 1-3: corticobasal degeneration posterior cortical ...
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Balo concentric sclerosis

Balo concentric sclerosis (BCS) is a rare and severe monophasic demyelinating disease, considered a subtype of multiple sclerosis, appearing as a rounded lesion with alternating layers of hyper and hypoattenuation giving it a characteristic 'bullseye' or 'onion bulb' appearance 1,9. Epidemiolog...
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Band heterotopia

Band heterotopia, also known as double cortex syndrome, is a form of diffuse grey matter heterotopia affecting almost only women. Refractory epilepsy is present in nearly all affected patients, with partial complex and atypical absence epilepsy being the most common syndromes. On imaging, this ...
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Band of Giacomini

The band of Giacomini, also known as the tail of the dentate gyrus is the anteromedial continuation of the dentate gyrus, which in turn is part of the hippocampal formation, along with the hippocampus, subicular complex and entorhinal cortex. It is an important anatomical landmark of the inferio...
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Bannayan-Zonana syndrome

Bannayan-Zonana syndrome is a rare hamartomatous disorder.  Epidemiology Inheritance is by autosomal dominant transmission with few reported sporadic cases. Male predominance is reported. 1 Presentation Bannayan-Zonana syndrome characterised by  : macrocephaly  multiple lipomas haemangiom...
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Bannayan–Riley–Ruvalcaba syndrome

Bannayan–Riley–Ruvalcaba syndrome (BRRS or BRR syndrome) is a very rare autosomal dominant hamartomatous disorder caused by a mutation in the PTEN gene. It is considered in the family of hamartomatous polyposis syndrome. There are no formal diagnostic criteria for this disease, but characterist...
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Bardet-Biedl syndrome

Bardet-Biedl syndrome (BBS), previously known as the Laurence-Moon-Bardet-Biedl syndrome (LMBBS), is a rare autosomal recessive hereditary condition. Clinical presentation The clinical spectrum includes: retinal anomalies: similar to that of retinitis pigmentosa mental retardation renal str...
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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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Barkovich classification of focal cortical dysplasia

Barkovich classifies focal cortical dysplasias among the his extensive classification system for malformations of cortical development, distributing them as follows: Type I and type IIb (transcortical dysplasia - Taylor type with balloon cells) as non-neoplastic malformations due to abnormal ne...
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Barrow classification of caroticocavernous fistulae

Barrow caroticocavernous fistula classification divides caroticocavernous fistulas into direct (type A) or indirect (types B-D). This classification was proposed by Barrow et al. in 1985 1 and at the time of writing (mid 2016) remains the most widely used system for describing caroticocavernous ...
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Basal ganglia

The basal ganglia are a group of nuclei in the deep white matter of the brain that is interconnected with the cerebral cortex, thalami and brainstem. In a strict anatomical sense, it contains three paired nuclei that together comprise the corpus striatum: caudate nucleus putamen globus palli...
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Basal ganglia and thalamus signal abnormalities

Basal ganglia and thalamus signal abnormalities occur in a wide variety of conditions. Ischaemia/hypoxia, metabolic disorders and toxins, particularly those that affect the respiratory chain, have a predilection for affecting the basal ganglia as they are highly metabolically active.  They can ...
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Basal ganglia calcification

Basal ganglia calcification is common and is seen in approximately 1% of all CT scans of the brain, depending on the demographics of the scanned population. It is seen more frequently in older patients and is considered a normal incidental and idiopathic finding in an elderly patient but should ...
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Basal ganglia haemorrhage

Basal ganglia haemorrhage is a common form of intracerebral haemorrhage, and usually as a result of poorly controlled long-standing hypertension. The stigmata of chronic hypertensive encephalopathy are often present (see cerebral microhaemorrhages). Other sites of hypertensive haemorrhages are ...
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Basal ganglia T1 hyperintensity

There are many causes of basal ganglia T1 hyperintensity, but the majority relate to deposition of T1-intense elements within the basal ganglia such as: calcium idiopathic calcification calcium and phosphate abnormalities hepatic failure acquired non-wilsonian hepatocerebral degeneration W...
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Basal ganglia T1 hypointensity

Hypointensity on T1 weighted images of the basal ganglia, as a general rule is in itself of limited value, and should be correlated with T2 signal, which is usually more informative. Most causes of T2 hyperintensity in the basal ganglia will result in T1 hypointensity (most are afterall due to o...
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Basal ganglia T2 hyperintensity

The causes of basal ganglia T2 hyperintensity can be remembered using the mnemonic LINT: lymphoma ischaemia hypoxia venous infarction (internal cerebral vein thrombosis) neurodegenerative / metabolic Wilson disease Huntington disease: especially caudate heads methylmalonic acidaemia mit...
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Basal ganglia T2 hypointensity

Basal ganglia T2 hypointensities can be caused by any of the following and is commonly remembered using the mnemonic ChOMP. childhood hypoxia old age multiple sclerosis Parkinson disease: more in globus pallidus Parkinson-plus syndrome: more in putamen deoxyhemoglobin of hemorrhage haemos...
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Basal nucleus of Meynert

The basal nucleus of Meynert, also known as the nucleus basalis of Meynert, is formed by a group of cells that lies in the substantia innominata. It is rich in acetylcholine and its degeneration has been correlated to Alzheimer disease. It lies anterior to the anterior commissure. 
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Basal vein of Rosenthal

The basal veins, also known as the veins of Rosenthal, are paired, paramedian veins which originate on the medial surface of the temporal lobe and run posteriorly and medially. It passes lateral to the midbrain through the ambient cistern to drain into the vein of Galen with the internal cerebra...
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Basilar artery

The basilar artery is part of the posterior cerebral circulation. It artery arises from the confluence of the left and right vertebral arteries at the base of the pons as they rise towards the base of the brain. Summary origin: vertebral artery confluence course: ventral to pons in the pontin...
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Basilar artery fenestration

Basilar artery fenestration (or more simply, basilar fenestration) is the most common intracranial arterial fenestration. It refers to duplication of a portion of the artery. Its reported prevalence is highly variable depending on the technique used: ~0.5% (0.3-0.6%) at angiography (presumably ...
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Basilar artery hypoplasia

Basilar artery hypoplasia is a rare vascular anomaly of the basilar artery. Pathology Associations Basilar artery hypoplasia is usually accompanied by one or more fo the following: persistent carotid-vertebrobasilar anastomoses hypoplastic V4 segments of the vertebral arteries unilateral o...
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Basilar invagination

Basilar invagination, also called basilar impression, is a congenital or acquired craniocervical junction abnormality where the tip of the odontoid process projects above the foramen magnum.  Terminology The terms basilar invagination and basilar impression are often used interchangeably becau...
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Basilar invagination (mnemonic)

A mnemonic to help recall the causes of basilar invagination is: PF ROACH Mnemonic P: Paget disease of bone F: fibrous dysplasia R: rheumatoid arthritis, rickets O: osteogenesis imperfecta, osteomalacia A: achondroplasia C: Chiari I and Chiari II, cleidocranial dysostosis H: hyperparath...
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Basilar venous plexus

The basilar venous plexus lies between the endosteal and visceral layers of the dura on the inner surface of the clivus. It connects the: inferior petrosal sinuses cavernous sinuses intercavernous sinuses superior petrosal sinuses internal vertebral venous plexus marginal sinus (around the...
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Basion

The basion is the median (midline) point of the anterior margin of the foramen magnum. The apical ligament attaches to it. It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement. Clinical importance Various lines and measurements using the ...
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Basion-axial interval

The basion-axial interval (BAI), as the name suggests, is the horizontal distance between the basion and the posterior cortex of the axis, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance (in mm) between the basion and the superior extension of the posterior ...
Article

Basion-dens interval

The basion-dens interval (BDI), as the name suggests, is the distance between the basion and the tip of the dens, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance from the most inferior portion of the basion to the closest point of the superior aspect of the ...
Article

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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Behavioural variant frontotemporal lobar degeneration

Behavioural variant frontotemporal lobar degeneration (bvFTLD), also known as behavioural variant frontotemporal dementia, is one of the clinical neurodegenerative diseases associated with frontotemporal lobar degeneration (FTLD).  In the older literature, it is also referred to as Pick disease...
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Behçet disease (CNS manifestations)

CNS manifestations of Behçet disease, also known as neuro-Behçet disease, corresponds to the neurological involvement of the systemic vasculitis Behçet disease and has a variety of manifestations.  For a discussion of the disease in general please refer to Behçet disease article.  Epidemiology...
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Bell palsy

Bell palsy, also known as idiopathic peripheral facial paralysis, is characterised by rapid onset facial nerve paralysis, often with resolution in 6-8 weeks. As there are numerous causes of facial nerve palsy, many of which can be acute in onset, it is currently a diagnosis of exclusion supporte...
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Benedikt syndrome

Benedikt syndrome, or paramedian midbrain syndrome, is a midbrain stroke syndrome that involves the fascicles of the oculomotor nerve and the red nucleus resulting in an ipsilateral CN III palsy and crossed hemiataxia and choreoathetosis 1-4. Using imaging alone, it is difficult to distinguish ...
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Benign enlargement of the subarachnoid space in infancy

Benign enlargement of the subarachnoid spaces in infancy (BESS or BESSI) also known as benign external hydrocephalus (BEH) is, as the name implies, a benign enlargement of subarachnoid spaces seen in infancy. It usually involves the frontal lobe subarachnoid spaces, and it is characterised clini...
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Benign metastasising meningioma

Benign metastasising meningiomas are a rare occurrence, encountered as a complication of a tiny fraction of all meningiomas diagnosed. It refers to spread of the tumour via metastases to distant sites, analogous to benign metastasising leiomyoma from uterine fibroids.  Epidemiology The inciden...
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Benign metastasising tumours

There are a number of benign metastasising tumours: benign metastasising meningioma 1,2 benign metastasising leiomyoma 3 primary adenoma of thyroid 4 giant cell tumour of bone 5
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Benign regressive post-infectious neurological disorders

Benign regressive post-infectious neurological disorders (BRPINDs) refer to a group of neurological disorders and must be differentiated from the more malignant and progressive post-infectious neurological disorders such as SSPE (subacute sclerosing panencephalomyelitis) or rubella panencephalit...
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Beta-propeller protein-associated neurodegeneration

Beta-propeller protein-associated neurodegeneration (BPAN) is a rare subtype of neurodegeneration with brain iron accumulation disease (NBIA). It was previously known as static encephalopathy with neurodegeneration in childhood (SENDA), but it was renamed after the underlying genetic abnormalit...
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Betz cells

Betz cells are pyramidal cell neurons located within the fifth layer of the primary motor cortex. They are some of the largest in the central nervous system, sometimes reaching 100 µm in diameter and send their axons down the corticospinal tracts to the anterior horn cells of the spinal cord.  ...
Article

Bicaudate index

The bicaudate index is the ratio of width of two lateral ventricles at the level of the head of the caudate nucleus to distance between outer tables of skull at the same level. It can be a useful marker of ventricular volume and in the diagnosis of hydrocephalus. 
Article

Bickers Adams Edwards syndrome

Bickers Adams Edwards syndrome is a rare x-linked disorder with profound mental retardation, adducted thumb and large head which is comprising of a constellation of congenital CNS anomalies including :  congenital aqueductal stenosis corpus callosum agenesis absence of the medullary pyramids ...
Article

Bickerstaff encephalitis

Bickerstaff encephalitis is a rare immune-mediated condition believed to be one of a number of conditions sharing a similar immunological mechanism, and collectively termed anti-GQ1b IgG antibody syndrome.   Clinical presentation Bickerstaff encephalitis is often seen following varicella zoste...
Article

Biffl scale for blunt cerebrovascular injury

The Biffl scale or grade illustrates the spectrum of blunt cerebrovascular injury (BCVI) seen on angiography (both CTA and DSA). Some authors refer to the grading scale as the Denver scale, which is not to be confused with the Denver criteria, a set of clinical and risk factors for BCVI.  Class...
Article

Bilateral frontoparietal polymicrogyria

Bilateral frontoparietal polymicrogyria (BFPP) is a rare genetic condition consisting of extensive bilateral perisylvian polymicrogyria. So far (as of 2015) only a single gene association has been identified; GPR56 gene located on chromosome 16q12.2–21 1. It is inherited as an autosomal recessiv...
Article

Bilateral megalencephaly

Bilateral megalencephaly refers to megalencephaly affecting both cerebral hemispheres. Pathology Associations achondroplasia acromegaly Alexander disease Canavan disease mucopolysaccharidoses neurofibromatosis type 1 (NF1) Proteus syndrome Tay-Sachs disease tuberous sclerosis (TS) va...
Article

Bilateral middle cerebellar peduncle lesions

Involvement of both middle cerebellar peduncles is uncommon, but has a relatively long differential, including 1: neurodegenerative diseases multiple systemic atrophy (MSA) olivopontocerebellar atrophy Shy-Drager syndrome spinocerebellar atrophy metabolic diseases  adrenoleukodystrophy ...
Article

Bing Neel syndrome

Bing-Neel syndrome is an extremely rare neurological complication of Waldenström macroglobulinemia where there is malignant lymphocyte infiltration into the central nervous system (CNS). Treatment and prognosis It is considered potentially treatable with cranial radiation therapy alone or in c...
Article

Biotinidase deficiency

Biotinidase deficiency is a rare autosomal recessive condition in which the body is unable to break down the conjugated form of the vitamin B7 (biotin), resulting in low levels of available biotin. Epidemiology Profound deficiency (<10% of normal level) is estimated at ~1:100,000 of newborns. ...
Article

Birth trauma

Birth trauma relates to those conditions caused by both physical/mechanical and hypoxic injuries. Epidemiology Birth trauma occurs in ~5 per 1000 births 2. Pathology Aetiology There are a wide range of conditions related to birth trauma, ranging from superficial and minor injuries through t...
Article

Bithalamic lesions

Bilateral thalamic lesions usually seen in combination with basal ganglia and /or white matter and sometimes cortical lesions. Symmetrical bilateral involvement of the thalami has relatively limited differential diagnosis, including metabolic, vascular, toxic, ischaemic, infectious, or hypoxic c...
Article

Blend sign (brain)

The blend sign refers to a CT appearance of early intracranial haematoma growth. It is defined as blending of a hypoattenuating area and a hyperattenuating region with a well-defined margin.
Article

Blood brain barrier

The blood brain barrier (BBB) forms a physical resistance to the passage of lipophobic substances from cerebral capillaries into the brain and is a key reason why there is no CSF enhancement following IV contrast media in CT and MR imaging. Gross anatomy The BBB is formed by a combination of e...
Article

Blood supply of the meninges

The blood supply of the meninges generally concerns the blood supply of the outer layer of dura mater rather than the inner layer of dura mater, arachnoid or pia mater which do not require a large blood supply. There are several arteries that supply the dura in the anterior, middle, and posterio...
Article

Blumcke classification of focal cortical dysplasia

Blumcke et al. proposed the most recent (2011) 2 and now widely adopted consensus classification system for focal cortical dysplasia, which shares many features with the previously described classifications system by Palmini (2004) and Barkovich (2005).  Unfortunately, as is the case with many ...
Article

Blunt cerebrovascular injury

Blunt cerebrovascular injury (BCVI) is an uncommon but serious consequence of blunt trauma to the head and neck. Epidemiology It is often part of multi-trauma with a significant series of blunt trauma CTA reporting an incidence of approximately 1% 3. A large systematic review and meta-analysis...
Article

Bochdalek's flower basket

Bochdalek's flower basket is the eponymous name for the incidental finding of protrusion of the choroid plexus through the foramina of Luschka. This is a relatively common finding. It is an important normal variant to recognise as the presence of protruding calcified choroid tissue in the fourt...
Article

BOLD imaging

Blood oxygenation level dependent (BOLD) imaging is the standard technique used to generate images in functional MRI (fMRI) studies, and relies on regional differences in cerebral blood flow to delineate regional activity.  Blood flow in the brain is highly locally controlled in response to oxy...
Article

Boomerang sign (splenium)

The boomerang sign refers to a boomerang-shaped splenial lesion (splenium of corpus callosum) which is seen as a hyperintense lesion on T2-WI, FLAIR and DWI 1. This sign can be seen in: transient lesion of the splenium ischaemia posterior reversible encephalopathy syndrome (PRES) diffuse ax...
Article

Borden classification of dural arteriovenous fistulas

The Borden classification of dural arteriovenous fistulas (DAVF) groups these lesions into three types based upon the site of venous drainage and the presence or absence of cortical venous drainage. It was first proposed in 1995 1. At the time of writing (July 2016), it is probably less popular ...

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