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.

2,245 results found
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Cystic leukoencephalopathy without megalencephaly

Cystic leukoencephalopathy without megalencephaly, is an autosomal-recessive inherited condition that manifests in the early childhood with moderate to severe psychomotor retardation and spasticity. On imaging, it is characterised by bilateral anterior subcortical temporal lobe cysts and extens...
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Cystic meningioma

The term cystic meningioma is applied to both meningiomas with intratumoral degenerative cyst formation as well as those with peritumoral arachnoid cysts or reactive intraparenchymal cysts.  They should not be confused with microcystic meningiomas, a distinct variant, in which the cysts are mic...
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Cystic spinal lesions

A cystic spinal lesion can result from a number of disease entities. They include: Primary Chiari malformations Dandy walker malformation diastematomyelia spinal dysraphism certain skeletal dysplasias 2 achondroplasia tricho-rhino-phalangeal syndrome type I Acquired due to a tumour as...
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Cyst of the medullary conus

Cyst of the medullary conus is a rare benign ependymal cyst of the conus medullaris which probably relates to abnormal persistence and cystic dilatation of the ventriculus terminalis or "5th ventricle". This entity can be symptomatic and present in adulthood with bladder or bowel sphincter distu...
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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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Cytomegalovirus encephalitis

Cytomegalovirus (CMV) encephalitis is a CNS infection that almost always develops in the context of profound immunosuppression.  This article focus on adult infection, CMV is also one of the most frequent prenatal infections. Please, refer on congenital CMV infection for further discussion on t...
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Cytotoxic cerebral oedema

Cytotoxic cerebral oedema refers to a type of cerebral oedema, most commonly seen in cerebral ischaemia, in which extracellular water passes into cells, resulting in their swelling.  The term is frequently used in clinical practice to denote the combination of both true cytotoxic (cellular) oed...
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Cytotoxic lesions of the corpus callosum (CLOCCs)

Cytotoxic lesions of the corpus callosum (CLOCCs) represent a collection of disparate conditions that can cause signal change in the corpus callosum, usually involving the splenium.  Terminology The term cytotoxic lesions of the corpus callosum (CLOCCs) has been proposed recently 12 as a more ...
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Dandy-Walker continuum

Dandy-Walker continuum, also referred as Dandy-Walker spectrum or Dandy-Walker complex, corresponds to a group of disorders believed to represent a continuum spectrum of posterior fossa malformations, characterised by inferior vermian hypoplasia and incomplete formation of the fourth ventricle w...
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Dandy-Walker malformation

Dandy-Walker malformation (DWM) is the most common posterior fossa malformation, characterised by the triad of: hypoplasia of the vermis and cephalad rotation of the vermian remnant cystic dilatation of the fourth ventricle extending posteriorly  enlarged posterior fossa with torcular-lambdoi...
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Dandy-Walker variant

Dandy-Walker variant (DWv) is a less severe posterior fossa anomaly than the classic Dandy-Walker malformation (DWM) and is considered being on the lesser end of the disease spectrum in the Dandy-Walker continuum. Terminology This term was created to include those malformations that do not mee...
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Dawson fingers

Dawson fingers are a radiographic feature of demyelination characterised 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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Deep brain stimulation

Deep brain stimulation is used in a variety of clinical settings, predominantly in patients with poorly controlled movement disorders. Although effective, its exact mode of function continues to be poorly understood 2.   Careful patient selection and target selection are essential if the proced...
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Deep cerebral veins

The deep cerebral veins drain the deep white matter and grey matter that surround the basal cisterns and ventricular system. The deep veins are responsible for the outflow of approximately the inner 80% of the hemisphere. They provide useful landmarks for skull base and intraventricular surgery ...
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Deep cerebral vein thrombosis

Deep cerebral vein thrombosis is a subset of cerebral venous thrombosis involving the internal cerebral veins, often coexisting with cortical vein thrombosis or dural venous sinus thrombosis, and with different clinical presentations relying on which segment is involved. As such please refer to...
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Dé​jerine-Roussy syndrome

Dé​jerine-Roussy syndrome, or thalamic pain syndrome, is type of central post-stroke pain syndrome caused by a stroke to the thalamus. This syndrome should not be confused with Déjerine syndrome or Déjerine-Sottas syndrome. Epidemiology Approximately 25% of all patients with sensory strokes d...
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Déjerine-Sottas disease

Déjerine-Sottas disease, also known as hereditary motor and sensory neuropathy type III or hypertrophic interstitial polyneuritis, is a rare hereditary motor and sensory neuropathy (HMSN). This syndrome should not be confused with Déjerine syndrome or Déjerine-Roussy syndrome. Clinical present...
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Delayed cerebral ischaemia

Delayed cerebral ischaemia (DCI) is a frequent complication of subarachnoid haemorrhage. It contributes substantially to the morbidity and mortality following subarachnoid haemorrhage. It is defined as symptomatic vasospasm related to subarachnoid haemorrhage or cerebral infarction demonstrated ...
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Delta resistive index

The delta resistive index (delta RI or Δ RI) is a measurement that can be made when performing Doppler ultrasound. In preterm babies who have hydrocephalus secondary to intraventricular haemorrhage, the delta RI can be used to determine whether decompression of the ventricular system with a...
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Dementia with Lewy bodies

Dementia with Lewy bodies (DLB), also known as Lewy body disease, is a neurodegenerative disease (a synucleinopathy to be specific) related to Parkinson disease (PD). It is reported as the second most common form of dementia following Alzheimer disease (AD), accounting for 15-20% of cases at aut...
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Demyelinating disorders

Demyelinating disorders are a subgroup of white matter disorders characterized by the destruction or damage of normally myelinated structures. These disorders may be inflammatory, infective, ischaemic or toxic in origin and include 1-7: autoimmune demyelination multiple sclerosis (MS) Marburg...
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Demyelination

Demyelination is incorrectly often equated to multiple sclerosis, whereas in reality it is a generic pathological term simply describing, as the word suggests, the loss of normal myelin around axons in the central nervous system. This should be distinguished from dysmyelination where the formati...
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Demyelination protocol (MRI)

MRI protocol for demyelinating diseases is a group of MRI sequences put together to best approach these white matter disorders characterized by the destruction or damage of normally myelinated structures. These disorders may be inflammatory, infective, ischaemic or toxic in origin.  Generally, ...
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Denervation changes in muscles

Denervation changes in muscles can be observed in a number of settings. Radiographic features MRI in the very early stage, muscle signal may be normal earliest change is increased T2 signal (best seen on a fat saturated T2WI such as STIR) chronic changes are marked by muscle atrophy and fat...
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Dentate gyrus

The dentate gyrus is located in the mesial temporal lobe and forms part of the hippocampal formation, along with the hippocampus proper and subiculum.  The dentate gyrus receives fibres from the entorhinal cortex via the perforant path and projects fibres to the CA3 portion of the hippocampus. ...
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Dentate nucleus

The dentate nucleus is the largest and most lateral of the cerebellar nuclei, located medially within each cerebellar hemisphere, just posterolateral to the fourth ventricle 1.  It is part of the triangle of Guillain and Mollaret, connected to the contralateral red nucleus via the superior cere...
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Denticulate ligaments

The denticulate ligaments are bilateral triangular lateral extensions of pia mater that anchor the spinal cord to the dura mater. They are formed by pia mater of the spinal cord coursing in-between the dorsal and ventral nerve roots bilaterally. They function to provide stability to the spinal ...
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Denver criteria for blunt cerebrovascular injury

The Denver criteria are a set of screening criteria for blunt cerebrovascular injury (BCVI) in trauma used to reduce the need for CT angiography and its associated radiation exposure.  Screening criteria The screening protocol criteria 1,3 for BCVI are divided into signs and symptoms of BCVI a...
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Desmoplastic infantile astrocytoma and ganglioglioma

Desmoplastic infantile astrocytoma and gangliogliomas are a rare intracranial tumour, which despite their aggressive appearances tend to have a good prognosis and are considered WHO grade I tumours.  Terminology Previously considered separate entities, desmoplastic infantile astrocytoma and de...
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Developmental stages of the spheno-occipital synchondrosis

Developmental stages of the spheno-occipital synchondrosis take place in a number of predictable steps.  Fusion of the spheno-occipital synchondrosis was well underway by the age of 15 years and is complete by 17-18 years.  Fusion begins superiorly and progresses inferiorly. Persistence of a ...
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Developmental venous anomaly

Developmental venous anomaly (DVA), also known as cerebral venous angioma, is a congenital malformation of veins which drain normal brain. They were thought to be rare before cross-sectional imaging but are now recognised as being the most common cerebral vascular malformation, accounting for ~5...
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Dialysis disequilibrium syndrome

The dialysis disequilibrium syndrome (DDS) is a situation characterised by development of neurological symptoms caused by rapid removal of urea during hemodialysis. It develops primarily from an osmotic gradient that develops between the brain and the plasma as a result of rapid haemodialysis. I...
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Diaphragma sellae

The diaphragma sellae is one of the folds (or reflections) of the dura mater. It covers the sella turcica and forms the roof over the pituitary fossa 1. Gross anatomy The diaphragma sellae consists of two horizontal leaves of dura mater on the sphenoid bone. It extends from the tuberculum sell...
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Diastematomyelia

Diastematomyelia, also known as a split cord malformation, refers to a type of spinal dysraphism (spina bifida occulta) when there is a longitudinal split in the spinal cord.  Terminology Although traditionally it has been distinguished from diplomyelia (in which the cord is duplicated rather ...
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Diencephalon

The diencephalon is connected above and in front with the cerebral hemispheres; behind with the mid-brain. Its upper surface is concealed by the corpus callosum, and is covered by a fold of pia mater, named the tela chorioidea of the third ventricle; inferiorly it reaches to the base of the brai...
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Differential diagnoses for temporal lobe tumours

Most tumours of the CNS can potentially occur in the temporal lobe, but entities with a predilection for being diagnosed in this location include: pleomorphic xanthoastrocytoma (PXA) ganglioneuroma ganglioglioma pilocytic astrocytoma dysembryoplastic neuroepithelial tumour (DNET) multinodu...
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Diffuse astrocytoma

Diffuse astrocytomas, also referred to as low-grade infiltrative astrocytomas, are designated as WHO II tumours of the brain. The term diffuse infiltrating means there is no identifiable border between the tumour and normal brain tissue, even though the borders may appear well-marginated on imag...
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Diffuse astrocytoma grading

Diffuse astrocytomas can be graded in according to a number of systems, the most popular being the WHO grading system. In general these grading systems focus on the presence or absence of a number of histological features 3: cellular atypia/anaplasia  mitotic activity microvascular proliferat...
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Diffuse axonal injury

Diffuse axonal injury (DAI), also known as traumatic axonal injury (TAI), is a severe form of traumatic brain injury due to shearing forces. It is a potentially difficult diagnosis to make on imaging alone, especially on CT as the finding can be subtle, however, it has the potential to result in...
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Diffuse axonal injury (grading)

Grading of diffuse axonal injury has been described histologically according to the anatomic distribution of injury, which correlated with outcome 1-3. The classification was first proposed by Adams in 1989 4 and divides diffuse axonal injury (DAI) into three grades: grade I: involves grey-whit...
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Diffuse brainstem gliomas

Diffuse brainstem gliomas, also known as diffuse intrinsic brainstem glioma (DIBG), is a term used to describe infiltrating astrocytomas, no longer recognised as a distinct entity in the 2016 update to the WHO classification of CNS tumours. It encompassed a variety of tumours, ranging from WHO g...
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Diffuse cerebellar atrophy

Diffuse atrophy of the cerebellum refers to degeneration/reduction from a previously normal cerebellar volume. Terminology Cerebellar atrophy slightly differs from cerebellar hypoplasia meaning the cerebellum was not well formed to start with. Pathology Aetiology Diffuse atrophy can result ...
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Diffuse cutaneous neurofibroma

Diffuse cutaneous neurofibromas are a rare neurofibroma variant, similar to plexiform neurofibromas which may be co-existent. Both neurofibromas and plexiform neurofibromas are discussed separately.  Terminology There are variable uses and some confusion about the distinction between plexiform...
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Diffuse dural calcification

Diffuse dural calcification can occur in a number of settings. These include parathyroid abnormalities hyperparathyroidism secondary hyperparathyroidism 2 tertiary hyperparathyroidism 3 renal failure ref nephrogenic systemic fibrosis 1 congenital syndromes basal cell naevus syndrome Dif...
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Diffuse glioma

Diffuse glioma is a term used to encompass a variety of tumours of the central nervous system, which histologically appear similar to glial cells, specifically astrocytomas, oligodendrogliomas and oligoastrocytomas, ranging from WHO grade II to grade IV tumours 1. Importantly, it does not includ...
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Diffuse leptomeningeal glioneuronal tumour

Diffuse leptomeningeal glioneuronal tumour (also previously known as disseminated oligodendroglial-like leptomeningeal tumour of childhood) is a rare and only recently described tumour of the central nervous system included in the WHO classification of CNS tumours in the 2016 update 2,5. Morphol...
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Diffuse midline glioma H3 K27M–mutant

Diffuse midline glioma H3 K27M–mutant is a specific entity added to the 2016 update of the WHO classification of CNS tumours, that represents the majority of diffuse intrinsic pontine gliomas, although identical tumours are also found elsewhere in the midline (e.g. brainstem, spinal cord and tha...
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Diffusion kurtosis imaging

Diffusion kurtosis imaging (DKI) is an advanced neuroimaging modality which is an extension of diffusion tensor imaging by estimating the kurtosis (skewed distribution) of water diffusion based on a probability distribution function. It provides a high order diffusion of water distribution and a...
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Diffusion tensor imaging

Diffusion tensor imaging (DTI) is an extension of diffusion weighted imaging (DWI) that allows data profiling based upon white matter tract orientation. DWI is based on the measurement of Brownian motion of water molecules. This motion is restricted by membranous boundaries. In white matter, di...
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Diffusion-tensor MRI imaging and fiber tractography

Diffusion-tensor imaging (DTI) is an MRI technique that uses anisotropic diffusion to estimate the axonal (white matter) organisation of the brain. Fiber tractography (FT) is a 3D reconstruction technique to access neural tracts using data collected by DTI. Within cerebral white matter, water m...
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Diffusion weighted MRI in acute stroke

Diffusion weighted imaging (DWI) is a commonly performed MRI sequence for evaluation of acute ischaemic stroke, and is sensitive in the detection of small and early infarcts. Conventional MRI sequences (T1WI, T2WI) may not demonstrate an infarct for 6 hours, and small infarcts may be hard to app...
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Diplomyelia

Diplomyelia is a rare spinal cord malformation in which the cord is duplicated. It should be distinguished from diastematomyelia in which a single cord is split. Having said that it has been proposed that the term be abandoned in favour of split cord malformation, which encompasses both diastema...
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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 oedema at the time of an is...
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Distal dural ring

The distal dural ring is an anatomical landmark that separates the extradural from the intradural intracranial internal carotid artery (ICA). It is located at the junction of the cavernous, clinoid and ophthalmic segments of the ICA. Gross anatomy Anatomy of this region is complex and varied a...
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Dolichoectasia

The term dolichoectasia means dilated and elongated. It is used to characterise arteries that have shown a significant deterioration of their tunica intima (and occasionally the tunica media), weakening the vessel walls and causing the artery to elongate and distend. Epidemiology Dolichoectasi...
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Dopaminergic pathways

Dopaminergic pathways include: mesolimbic  mesocortical  striatonigral  tuberoinfundibular 
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Dorsal brainstem syndrome

Dorsal brainstem syndrome is a rare subset of hypoxic ischaemic encephalopathy in neonates limited to the isolated involvement of the brainstem with sparing of the supratentorial brain. Due to its subtle imaging features it is often undiagnosed. Clinical presentation Injuries involving the teg...
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Dorsal columns

The dorsal columns, or posterior columns, are ascending pathways primarily concerned with sensory function. They are responsible for transmitting vibration, conscious proprioception, and fine (discriminative) touch 1,2. The dorsal columns are divided two tracts, which are discussed separately 2...
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Dorsal cord syndrome

Dorsal cord syndrome, also known as posterior spinal cord syndrome, is one of the incomplete cord syndromes resulting from pathology affecting the posterior part of the spinal cord, particularly the dorsal columns and potentially (in larger lesions) the lateral corticospinal tracts 1.  Clinical...
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Dorsal cyst of holoprosencephaly

The dorsal cyst of holoprosencephaly is a large cerebrospinal fluid cavity present in holoprosencephaly that occupies the area above the dorsocaudal aspect of the diencephalon. This communicates directly with the prosencephalic, telencephalic, or diencephalic ventricle. This cavity usually abuts...
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Dorsal dermal sinus

Dorsal dermal sinus (DDS) is an epithelium-lined tract from the skin to the spinal cord, cauda equina, or arachnoid. Pathology Dorsal dermal sinus is caused by incomplete separation of the superficial ectoderm from the neural ectoderm, resulting in a focal segmental adhesion. Later during emb...
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Dorsal horn

The dorsal horn of the spinal cord is one of the grey longitudinal columns found within the spinal cord. It primarily acts as the termination of primary afferent fibres via the dorsal roots of the spinal nerves. Gross Anatomy On transverse section of the spinal cord the spinal grey matter is d...
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Dorsal root ganglion

The dorsal root ganglia are an enlargement of the dorsal root of spinal nerves representing the cell bodies of the primary somatosensory neurons. Gross anatomy Each dorsal root ganglion is oval and proportional in size to its related root. They are usually found just distal to the intervertebr...
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Dorsal thoracic arachnoid web

Dorsal thoracic arachnoid web refers to a thickened band of arachnoid over the dorsal aspect of the cord. It usually causes a focal thoracic cord distortion with consequent neurological dysfunction.  On imaging, it is characterised by a focal dorsal indentation and anterior displacement of the ...
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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 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...
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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 inversion recovery sequence

Double inversion recovery (DIR) is a MRI pulse sequence which suppresses signal from the CSF as well as from the white matter and hence enhances any inflammatory lesion. To obtain such sequence in 3T MRI scanner, two inversion times are required. TI1 which is used for suppression of CSF and usu...
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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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Down syndrome

Down syndrome (or trisomy 21) is the most common trisomy and also the commonest chromosomal disorder. It is a major cause of intellectual disability, and also has numerous multi-system manifestations. Epidemiology According to the world health organisation (WHO), the approximate worldwide inci...
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Dravet syndrome

Dravet syndrome, previously known as severe myoclonic epilepsy of infancy (SMEI), is a rare form of epilepsy usually presenting in the first 1-2 years of life. Clinical presentation The typical presentation occurs during the first six months to one year of life as tonic-clonic seizures in a fe...
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Dual rim sign

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 (GBM).  On both susceptibility weighted imaging (SWI) and T2WI it consists of two concentric rims surrounding the abscess cavity, outer one of wh...
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Duane syndrome

Duane syndrome, also known as Duane retraction syndrome, is a rare congenital disease characterised by non-progressive strabismus. It is caused by a variable degree of abnormal development of one or both 6th cranial nerves (CN VI). Epidemiology It presents during childhood and it accounts for ...
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Dumbbell appearance of spinal tumours

The dumbbell appearance of spinal tumours refers to a tumour which has both a component within the canal and a component in the paravertebral space contiguous with each other via a thinner tumour component traversing the neural exit foramen. The appearance can be seen in: spinal nerve sheath t...
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Duplicated middle cerebral artery

The duplicated middle cerebral artery is an anatomical variant in which there are two middle cerebral arteries originating from the distal end of the internal carotid artery. Supply The duplicated artery supplies the anterior temporal lobe. Differential diagnosis It should not be confused wi...
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Dural arteriovenous fistula

Dural arteriovenous fistulas (dAVF) are a heterogeneous collection of conditions that share arteriovenous shunts from dural vessels. They present variably with haemorrhage or venous hypertension, and can be challenging to treat. Epidemiology Most dural arteriovenous fistulas present in adultho...
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Dural arteriovenous shunts

Dural arteriovenous shunts (DAVS) are rare congenital arteriovenous malformations (CAVMs). On the basis of clinical and anatomical features DAVS have three different types: dural sinus malformations (DSMs) infantile or juvenile DAVS (IDAVS) adult DAVS (ADAVS)
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Dural ectasia

Dural ectasia refers to ballooning or widening of the dural sac which can result in posterior vertebral scalloping and is associated with herniation of nerve root sleeves. Clinical presentation Patients with dural ectasia may present with low back pain or radicular pain in the buttocks or legs...
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Dural enhancement

Pachymeningeal enhancement, also known as dura-arachnoid enhancement 4, refers to a dural and outer layer of arachnoid pattern of enhancement seen following contrast administration and may occur in the conditions listed below: infection intracranial tumour metastases intracranial hypotension...
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Dural masses

Dural masses can be the result of a number of different tumours and conditions, although meningiomas are by far the most common. The differential of a dural mass includes: meningioma haemangiopericytoma primary dural lymphoma Rosai-Dorfman disease solitary fibrous tumour of the dura EBV-as...
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Dural metastases

Dural or pachymeningeal metastases are a relatively common cause of dural masses, although they are less common than brain metastases and meningiomas. They can occur both within the spine and intracranially - this article is focussed on intracranial dural masses.  Clinical presentation Patient...
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Dural osteoma

Dural osteomas are a cause of focal intracranial calcification (colloquially known as brain stones). They are difficult to differentiate from an ossified "burnt out" meningiomas and ossification of the falx. Some reports are actually contradictory 1,4, suggesting that at least some lesions have ...
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Dural sinus malformations

Dural sinus malformations (DSMs) are congenital vascular malformations characterized by massive dilatation of one or more dural venous sinuses. This condition is typically associated with arteriovenous shunts (DAVS). Sub types There are two types of DSMs DSM involving the confluence of sinuse...
Article

Dural sinus occlusive disease

Dural sinus occlusive disease (DSOD) is an infective form of dural sinus thrombosis (thrombophlebitis) commonly seen in the setting of acute otomastoiditis. It typically presents with: severe headaches high fevers sixth nerve palsy - due to involvement of Dorello's canal altered conscious st...
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,...
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Dural venous sinuses

Dural venous sinuses are venous channels located intracranially between the two layers of dura mater (endosteal layer and meningeal layer). They can be conceptualised as trapped epidural veins. Unlike other veins in the body they run alone, not parallel to arteries. Furthermore, they are valvele...
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Dural venous sinus thrombosis

Dural venous sinus thrombosis is a subset of cerebral venous thrombosis, often coexisting with cortical or deep vein thrombosis, and presenting in similar fashions, depending mainly on which sinus is involved. As such, please refer to the cerebral venous thrombosis article for a general discuss...
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Dura mater

The dura mater, also known as the pachymeninx, is the tough outer layer of the meninges that surrounds the central nervous system and is pierced by the cranial nerves, the internal carotid arteries and the vertebral arteries.  Intracranially it is formed by two layers: outer endosteal layer, c...
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Duret haemorrhage

Duret haemorrhage is a small haemorrhage (or multiple haemorrhages) seen in the medulla or pons of patients who are rapidly herniating.  Pathology Raised supratentorial pressure causes the brainstem and mesial temporal lobes to be forced downwards through the tentorial hiatus. As a result of t...
Article

Dyke-Davidoff-Masson syndrome

Dyke-Davidoff-Masson syndrome (DDMS) is a condition characterised by hemicerebral atrophy/hypoplasia secondary to brain insult usually in fetal or early childhood period and is accompanied by ipsilateral compensatory osseous hypertrophy and contralateral hemiparesis. It is characterised by: th...
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Dynamic contrast enhanced (DCE) MR perfusion

Dynamic contrast-enhanced (DCE) MR perfusion, sometimes also referred to as permeability MRI, is one of the main MRI perfusion techniques which calculates perfusion parameters by evaluating T1 shortening induced by a gadolinium-based contrast bolus passing through tissue. The most commonly calcu...
Article

Dynamic susceptibility contrast (DSC) MR perfusion

Dynamic susceptibility contrast (DSC) MR perfusion is one of the most frequently used techniques for MRI perfusion, and relies on the susceptibility induced signal loss on T2* weighted sequences which results from a bolus of gadolinium-based contrast passing through a capillary bed.  The most co...
Article

Dysembryoplastic neuroepithelial tumour

Dysembryoplastic neuroepithelial tumours (DNET) are benign (WHO Grade I) slow growing glioneuronal tumours arising from either cortical or deep grey matter. The vast majority are centred in cortical grey matter, arise from secondary germinal layers, and are frequently associated with cortical dy...
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Dysgenesis of the corpus callosum

Dysgenesis of the corpus callosum may be complete (agenesis) or partial and represents an in utero developmental anomaly. It can be divided into: primary agenesis: the corpus callosum never forms secondary dysgenesis: the corpus callosum forms normally and is subsequently destroyed Epidemiolo...

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