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.

53 results found
Article

Spinal cord tuberculoma

Spinal cord tuberculomas are rare compared to intracranial tuberculomas and can be challenging to diagnose particularly in individuals who are not from endemic areas.  Epidemiology Only 0.2% of central nervous system tuberculosis shows evidence of spinal cord involvement, and among tuberculosi...
Article

CT angiography of the circle of Willis (protocol)

CT angiography of the circle of Willis (CTA COW) is a technique that allows visualization of the intracranial arteries; specifically the circle of Willis. While digital subtraction angiography (DSA) remains the gold standard for the diagnosis of intracranial aneurysms especially, CTA is a less i...
Article

Febrile seizure

Febrile seizures are a largely idiopathic phenomenon which may occur between 6 and 60 months of age, defined by a seizure occurring concomitantly with a temperature over 38C (100.4F). This entity excludes seizures associated with infections of the central nervous system such as bacterial meningi...
Article

Retrosigmoid craniotomy

Retrosigmoid craniotomy also known as a suboccipital lateral craniotomy refers to the neurosurgical procedure in which lateral section of the occipital bone is removed to gain surgical access to the wide range of neoplastic and vascular pathologies in the cerebellopontine angle.
Article

Radiotracers for SPECT brain imaging

Radiotracers for SPECT brain imaging are divided into two classes: diffusible and not-diffusible radiotracers; this distinction lies in the ability (or not) to cross the blood-brain barrier (BBB). The not-diffusible radiotracers - composed of ions or polar molecules - are unable to cross the li...
Article

Microvascular decompression

Microvascular decompression is a surgical procedure for cranial nerve compression syndrome, most often carried out for trigeminal neuralgia, or less frequently hemifacial spasm and glossopharyngeal neuralgia. It is usually carried out via a retrosigmoid craniotomy. The culprit blood vessel, eit...
Article

Interpeduncular angle

The interpeduncular angle is defined as the angle formed by the posterior half of the cerebral peduncles on axial images. The interpeduncular angle has been proposed as a sensitive and specific measure of intracranial hypotension (reduced) and progressive supranuclear palsy (PSP) (increased)1,2....
Article

Head ultrasound

Head ultrasound (HUS), also called cranial ultrasound (CUS), is obtained for the diagnosis and follow-up of premature and sick neonates. Advantages Head ultrasound has the advantages of: accessibility mobility, i.e. bedside scanning at the NICU and neonatal ward requiring no sedation enabl...
Article

Optic nerve sheath diameter

Optic nerve sheath diameter has significance in the assessment of papilledema in cases of elevated intracranial pressure. Pathology The optic nerve sheath demonstrates changes in diameter with CSF pressure changes as there is a layer of subarachnoid space between the nerve and its sheath, whic...
Article

CT angiography of the cerebral arteries (protocol)

CT angiography of the cerebral arteries (also known as a CTA carotids or an arch to vertex angiogram) is a noninvasive technique allows visualization of the internal and external carotid arteries and vertebral arteries and can include just the intracranial compartment or also extend down to the ...
Article

Vermian maturity assessment (approach)

Radiological evaluation of the posterior fossa is an essential part of the routine fetal assessment, including vermian maturity assessment. Radiographic features Ultrasonography is a readily available diagnostic tool in the assessment of the fetal posterior fossa but is sometimes limited due t...
Article

Interseptal distance

The interseptal distance (ISD) is a measurement used to assess septal area atrophy as a marker for neurodegenerative conditions in patients with memory problems 1. It is proposed that atrophy of the septal nuclei can commonly be seen in conditions associated with hippocampal atrophy, particular...
Article

Concurrent suprasellar and pineal region lesions (differential)

Concurrent suprasellar and pineal region lesions have a relatively short differential to be considered, including:  germinoma other germ cell tumors choriocarcinoma embryonal cell carcinoma yolk sac tumor (endodermal sinus tumor) primary CNS lymphoma cerebral metastasis quadrilateral ret...
Article

Cerebral edema (summary)

This is a basic article for medical students and other non-radiologists Cerebral edema describes the collection of additional fluid within the white matter of the brain. It is the brain's response to an insult and may take one of two broad forms: vasogenic (white matter) and cytotoxic (grey and...
Article

CHALICE rule

The Children’s Head injury ALgorithm for prediction of Clinically Important Events (CHALICE) clinical decision rule was developed to predict clinically important brain injuries in children with head trauma. This rule identifies high-risk criteria and divides them into history, examination and me...
Article

Canadian CT head rule

The Canadian CT head rule (CCTHR) is a validated clinical decision rule to determine the need for CT head in adult emergency department patients with minor head injuries. Inclusion criteria Patient has suffered minor head trauma with resultant: loss of consciousness GCS 13-15 confusion amn...
Article

PECARN traumatic brain injury algorithm

The PECARN (Pediatric Emergency Care Applied Research Network) traumatic brain injury algorithm is a clinical decision rule that aims to identify children at very low risk of clinically important traumatic brain injury (ci-TBI) 1. This validated pediatric algorithm predicts likelihood of the abo...
Article

ABC/2

ABC/2, also confusingly written as 1/2ABC in some literature, is a fast and simple method for estimating the volume of intracerebral hemorrhage (or any other ellipsoid lesion for that matter) which does not require volumetric 3D analysis or software. Intracerebral hemorrhage volume is an import...
Article

CT head (subdural window)

The subdural (blood) window can be used when reviewing a CT brain as it makes intracranial hemorrhage more conspicuous, and may help in the detection of thin acute subdural hematomas that are against the calvaria that are similar density to adjacent bone. It is a wider setting than the standard ...
Article

Glioblastoma vs cerebral metastasis

Differentiating a glioblastoma (GBM) from a cerebral metastasis is a frequent challenge, with profound surgical, workup and treatment implications. Unfortunately distinguishing between the two entities is not always straightforward.  This article addresses helpful imaging features to aid in dis...
Article

Supratentorial intracranial mass in an adult (an approach)

The identification of a supratentorial intracranial mass in an adult is a fairly common clinical scenario, the appropriate management of which relies heavily on preoperative imaging. Often important clues will be present in the clinical history (e.g. immunosuppression, systemic malignancy, durat...
Article

Hemorrhagic infarct vs intracerebral hemorrhage

Hemorrhagic infarct or hemorrhagic transformation of an infarct is seen following breakdown of the lamina of the microvessels. Intracerebral hemorrhage (ICH) may overlap with a hemorrhagic infarct and hence needs to be differentiated as the line of treatment will vary. Differentiating points ...
Article

Intracranial non-neoplastic cysts

Intracranial non-neoplastic cysts are common findings on MRI and CT brain scans. Location-based diagnostic approach A location-based approach is useful in establishing an appropriate diagnosis; some locations are virtually pathognomonic for certain lesions e.g. colloid cyst. Many cysts may oc...
Article

Denver criteria for blunt cerebrovascular injury

The Denver criteria are a set of screening criteria used to determine when CT angiography of the neck is indicated to detect blunt cerebrovascular injury (BCVI) in trauma patients.  Screening criteria The Denver criteria were initially developed in 1996 1, modified in 2005 to limit the types o...
Article

Atlantodental interval

The atlantodental interval is used in the diagnosis of atlanto-occipital dissociation injuries and injuries of the atlas and axis. Measurement The anterior atlantodental interval is the horizontal distance between the posterior cortex of the anterior arch of the atlas (C1) and the anterior cor...
Article

Extradural hematoma vs subdural hematoma

Differentiating extradural (EDH) from subdural (SDH) hemorrhage in the head is usually straightforward, but occasionally it can be challenging. SDHs are more common and there are a few distinguishing features which are usually reliable. Pathology History and mechanism of injury Extradural hem...
Article

Sagittal midline of the brain (an approach)

The sagittal midline of the brain is one of the most important sectional planes in neuroimaging. A good working knowledge of the normal neuroanatomy of the sagittal midline is essential so that the subtle abnormalities that may manifest here can be recognized. The neuroembryological development...
Article

Global cortical atrophy scale

The global cortical atrophy (GCA) scale, also known as the Pasquier scale, is a qualitative rating system developed to assess cerebral atrophy, especially in the context of neurodegenerative diseases. It evaluates atrophy in 13 brain regions assessed separately in each hemisphere and resulting i...
Article

Tumor pseudoresponse

Tumor pseudoresponse, also known just as pseudoresponse, refers to the phenomenon of tumors appearing to respond to a specific treatment on imaging criteria when the lesion actually remains stable or has even progressed. Terminology The term is largely used for brain tumors during imaging foll...
Article

Ventral cord syndrome

Ventral cord syndrome (also known as anterior cord syndrome) is one of the incomplete cord syndromes and affects the anterior parts of the cord resulting in a pattern of neurological dysfunction dominated by motor paralysis and loss of pain, temperature and autonomic function. Anterior spinal ar...
Article

Spinal cord injury

Spinal cord injury (SCI) can be traumatic or non-traumatic (e.g. neoplastic compression or degenerative stenosis) but the syndromes associated with spinal cord injury can be seen in all etiologies. Injuries to the spinal cord can be incomplete or complete and are graded on the ASIA impairment s...
Article

Focal areas of signal intensity (brain)

Focal areas of signal intensity (FASI), also known as focal abnormal signal intensity or unidentified bright objects (UBO), are bright areas on T2-weighted images commonly identified in the basal ganglia (often the globus pallidus), thalamus, brainstem (pons), cerebellum, and subcortical white m...
Article

Glioma treatment response assessment in clinical trials

Glioma treatment response assessment in clinical trials has undergone numerous revisions with a number of criteria having been developed over the years. This has been necessary as a result of a number of factors: improved understanding of tumor biology (e.g. appreciating the importance of non-e...
Article

RANO criteria for glioma

Response assessment in neuro-oncology criteria (RANO), published in 2010 1, are used to assess response to first-line treatment of glioblastoma (as well as lower grade astrocytoma 3) and have largely superseded the older Macdonald criteria (which only dealt with glioblastoma multiforme) 2. For ...
Article

Intercaudate distance to inner table width ratio

Intercaudate distance to inner table width ratio (CC/IT) is used in assessing patients with neurodegenerative diseases that affect the caudate nuclei. It is best known for assessing individuals with suspected Huntington disease but is in no way specific for the diagnosis, also seen in other less...
Article

Frontal horn width to intercaudate distance ratio

Frontal horn width to intercaudate distance ratio (FH/CC) is used in assessing patients with suspected Huntington disease. An alternative measurement is intercaudate distance to inner table width ratio (CC/IT). Measurement On the same axial plane obtained on the ACPC (anterior commissure and p...
Article

Medial temporal lobe atrophy score

The medial temporal lobe atrophy (MTA) score, also known as Scheltens' scale, is useful in distinguishing patients with mild cognitive impairment and Alzheimer disease from those without impairment 2 is helpful in the assessment of patients with possible dementia (see neurodegenerative MRI brain...
Article

Neurodegenerative MRI brain (an approach)

Imaging of the brain in patients with suspected neurodegenerative conditions is common and challenging, as in patients with subtle and equivocal signs and symptoms, the imaging findings are also often subtle and equivocal. In many instances, by the time imaging findings are clear cut, then the p...
Article

Hemorrhagic intracranial tumors

Various types of brain tumors may cause hemorrhage. Increased tumor vascularization with dilated, thin-walled vessels and tumor necrosis are the most important mechanisms of hemorrhage. The list includes: glioblastoma pituitary adenoma ependymoma central neurocytoma choroid plexus carcinoma...
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.  See also Evans' index
Article

CT cisternography

Computed tomography (CT) cisternography is a minimally-invasive imaging technique used to visualize the intracranial CSF cisterns using iodinated contrast medium injected into the subarachnoid space. Indications detect and localize active CSF leaks through the skull base (CSF rhinorrhea or CSF...
Article

CT perfusion in ischemic stroke

CT perfusion in ischemic stroke has become established in most centers with stroke services as an important adjunct, along with CT angiography (CTA), to conventional unenhanced CT brain imaging. It enables differentiation of salvageable ischemic brain tissue (the penumbra) from the irrevocably ...
Article

Cases in radiology (video tutorials)

The cases featured in these video lectures are specifically selected to teach important concepts in radiology over a broad range of topics. The tutorials vary in difficulty from basic to advanced. For maximum learning, try the cases for yourself in Radiopaedia quiz mode first.  We love this ser...
Article

National Institutes of Health Stroke Scale

The National Institutes of Health Stroke Scale (NIHSS) is a score calculated from 11 components and is used to quantify the severity of strokes. The 11 components are:  level of consciousness (1a: 0-3, 1b: 0-2 and 1c: 0-2) best gaze (0-2) visual fields (0-3) facial palsy (0-3) arm motor (0-...
Article

Pineal region (an approach)

A systematic approach to the pineal region is crucial as it is at the confluence of many intracranial structures/regions and is the site of origin of a number of unique pathologies as well as playing host to many entities which are more frequently encountered elsewhere. As such an understanding ...
Article

Intraventricular masses (an approach)

The ventricular system of the brain plays host to a variety of unique tumors, as well as tumors that are more frequently seen elsewhere (e.g. meningiomas). Besides, some intra-axial (parenchymal) masses can be mostly exophytic and thus appear mostly intraventricular. A systematic approach taking...
Article

Intradural spinal mass lesions (an approach)

Intradural spinal mass lesions are relatively uncommon, compared to intracranial or extradural masses, and can be challenging to diagnose. Additionally, the need for a pre-operative/non-operative diagnosis is in many ways greater as biopsy of lesions within the cord has the potential of devastat...
Article

Pituitary MRI (an approach)

A systematic approach to the pituitary region is crucial as small lesions can have a profound impact on the patient, and can be subtle even on high quality dedicated MRI imaging. Successful assessment of the pituitary region relies not only on a clear understanding of the local anatomy but also ...
Article

Gunshot injuries

Gunshot injuries often require imaging assessment, and this evaluation has both clinical relevance (assessment of organ damage, surgical planning, and prognostication), and often also forensic implications. Epidemiology Incidence of gunshot injuries to the head is increasing in some countries,...
Article

CT head (an approach)

The approach taken to interpreting a CT scan of the head is no doubt different depending on the circumstances and the reading clinician, however, most radiologists will go through the same steps, although order may vary. What follows is merely a suggested approach to interpreting a CT of the hea...
Article

Tentorial angle

The tentorial angle is measured between a line connecting the nasion with the tuberculum sellae and the angle of the straight sinus. Normally it should measure between 27° and 52°. Abnormalities of the posterior fossa or base of skull can alter this. For example, this angle is elevated in achon...
Article

Hemorrhage on MRI

Hemorrhage on MRI has highly variable imaging characteristics that depend on: the age of the blood the type of hemoglobin present: oxy-, deoxy- or met- whether or not the red blood cell walls are intact: i.e. intra- vs extracellular the MRI sequence Although MRI is often regarded...
Article

Subfalcine herniation

Subfalcine herniation, also known as midline shift or cingulate hernia, is the most common cerebral herniation pattern. It is generally caused by unilateral frontal, parietal or temporal lobe disease that creates a mass effect with medial direction of the ipsilateral cingulate gyrus beneath the ...

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.