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.

30 results found
Article

Bailey classification of second branchial cleft cysts

This classification was intially proposed by Bailey in 19292 and remains the most widely used classification system at time of writing (July 2016). Bailey classification of second branchial cleft cysts provides a structure for classing second branchial cleft cysts into four types. It is no long...
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Ballet sign

The Ballet sign refers paralysis of voluntary movements of the eyeball with preservation of the automatic movements. Sometimes this sign is present with exophthalmic goitre and hysteria.
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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 ...
Article

Base of skull

The base of skull (or skull base) forms the floor of the cranial cavity and separates the brain from the structures of neck and face. Gross anatomy The base of skull is a bony diaphragm composed of number of bones including (from anterior to posterior): frontal bone ethmoid bone sphenoid bo...
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Basion

The basion is the median (midline) point of the anterior margin of the foramen magnum. It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement. Clinical importance Various lines and measurements using the basion are made in the diagnosis of ...
Article

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

Behavioural changes in obstructive sleep apnoea (mnemonic)

A mnemonic used to remember the behavioural changes of obstructive sleep apnoea (OSA) is: APRIL Mnemonic A: aggression P: poor school performance R: restlessness I: irritability L: lack of concentration
Article

Behçet disease

Behçet disease is a multi-systemic and chronic inflammatory vasculitis of unknown aetiology. Epidemiology The mean age at which Behçet disease occurs is 20-30 years. The disease is most prevalent in the Mediterranean region, Middle East and east Asia. The highest incidence has been reported in...
Article

Benign lymphoepithelial lesions

Benign lymphoepithelial lesions (BLL or BLEL), also misleadingly known as AIDS-related parotid cysts (ARPC), are mixed solid and cystic lesions that enlarge the parotid glands, and are usually associated with cervical lymph node enlargement, and nasopharyngeal lymphofollicular hyperplasia. Epid...
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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
Article

Benign minor salivary gland pathology

Benign minor salivary gland pathology is a broad term that encompasses a number of relatively uncommon pathologies that affect the minor salivary glands of the head and neck: salivary retention cysts benign neoplasms pleomorphic adenoma
Article

Bezold abscess

A Bezold abscess is a complication of acute otomastoiditis where the infection erodes through the cortex medial to the attachment of sternocleidomastoid , at the attachment site of the posterior belly of the digastric muscle, and extends into the infratemporal fossa. Due to it being deep to the ...
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 thinning of the parietal bones

Bilateral thinning of the parietal bones (also known as biparietal osteodystrophy) is an uncommon, slowly progressive acquired disease of middle-aged people with slight female predilection. It is typically an incidental finding. The aetiology is unknown but is thought to be an age-related proces...
Article

Bill's bar

Bill's bar is a landmark that divides the superior compartment of the internal acoustic meatus into an anterior and posterior compartment. Anterior to Bill bar, in the anterior superior quadrant, are the facial nerve (CN VII) and nervus intermedius, and posterior to it in the posterior superior ...
Article

Bimastoid line

The bimastoid line has been described and used to evaluate basilar invagination on frontal skull plain film and coronal recontructed CT image. The bimastoid line is drawn between right and left tip of mastoids. The tip of  the odontoid process of C2 normally projects less than or equal to 10 mm...
Article

Binocular distance

The binocular distance (BOD) is a measurement between the two lateral (outer) canthi of each eye. It is sometimes used as a accessory fetal biometric parameter where it is often documented on both 2nd trimester anatomy scans on axial brain scans. The largest diameter of the orbit should be used ...
Article

Black eyebrow sign

Black eyebrow sign is the description given on plain facial radiographs to intra-orbital air 1. Air rises into the most superior aspect of the orbit, almost always in the context of a facial fracture, in a linear fashion, giving the appearance of a eyebrow. The fracture is usually an orbital bl...
Article

Black turbinate sign

The black turbinate sign refers to an area of non-enhancing mucosa on MRI in a patient with angioinvasive fungal sinus infection / rhinocerebral mucormycosis. Mucormycosis is caused by fungi that include Mucor, Rhizopus, and Absidia species.  It is seen in diabetic and immunocompromised patient...
Article

Body of sphenoid

The body of the sphenoid bone is a cubical portion, hollowed by the sphenoid air sinuses.  Gross anatomy The body has superior, inferior, anterior, posterior, and lateral surfaces. The superior surface features: ethmoidal spine: prominent spine that articulates with the cribiform plate and g...
Article

Bogorad syndrome

Bogorad syndrome also known as the syndrome of crocodile tears, is characterized by residual facial paralysis with profuse lacrimation during eating. It is caused by a misdirection of the regenerating autonomic fibers to the lacrimal gland instead of to the salivary gland. Etymology Named afte...
Article

Bouthillier classification of ICA segments

Bouthillier et al described (in 1996) 1 a seven segment internal carotid artery (ICA) classification system. It remains the most widely used system for describing ICA segments at the time of writing (mid 2016). There are few others classifications systems including proposed by Fisher (1938), Gi...
Article

Brachycephaly

Brachycephaly refers to a calvarial shape where the bi-parietal diameter to fronto-occipital diameter approaches the 95th percentile. It can result from a  craniosynostosis involving the bicoronal and/or bilambdoid sutures. Pathology Associations Brachycephaly can be associated with numerous ...
Article

Branchial cleft anomalies

Branchial cleft anomalies comprise of a spectrum of congenital defects that occur in the head and neck. Pathology The anomalies result from branchial apparati (six arches; five clefts), which are the embryologic precursors of the ear and the muscles, blood vessels, bones, cartilage, and mucosa...
Article

Branchio-oto-renal dysplasia

Branchio-oto-renal (BOR) dysplasia is a rare syndromic disorder characterised by: otic malformations can involve the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment preauricular pits branchial fistulae and branchial cleft cysts renal malfo...
Article

Bregma

The bregma is the midline bony landmark where the coronal and sagittal sutures meet, between the frontal and two parietal bones. It is the anterior fontanelle in the neonate and closes in the second 2 (typically around 18 months after birth). It is one of the skull landmarks, craniometric poin...
Article

Buccal space

The buccal space (or buccinator space) is one of the seven suprahyoid deep compartments of the head and neck. Gross anatomy  The buccal spaces are paired fat contained spaces on each side of the face forming cheeks. Each space is enveloped by the superficial (investing) layer of the deep cervi...
Article

Buccinator artery

The buccinator artery is a small branch from the second part of the maxillary artery. It runs obliquely forward, between the medial pterygoid and the insertion of the temporalis, to the outer surface of the buccinator, to which it is distributed, anastomosing with branches of the facial artery a...
Article

Buphthalmos

Buphthalmos is a descriptive term which simply means an enlarged eyeball or ocular globe (usually without deformation or and intrinsic mass lesion).  Epidemiology It typically manifests in infants and young children. Pathology It usually indicates the presence of congenital (infantile) glauc...

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