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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
16,924 results
Article
Ejaculatory duct obstruction
Ejaculatory duct obstruction refers to the congenital or acquired obstruction of the ejaculatory ducts.
Epidemiology
Ejaculatory duct obstruction is rare, accounting for approximately 5% of infertile patients, but thought to be underdiagnosed 2.
Clinical presentation
Patients may complain ab...
Article
Spinal dura mater
The spinal dura mater is the outermost layer of the meninges that surround the spinal cord.
Gross Anatomy
The spinal dura mater is a fibrous, non-adherent, tough layer surrounding the spinal cord. Unlike the intracranial dura mater, it only has a single layer which is continuous with the inner...
Article
Ganglion
A ganglion (plural: ganglia) is a group of neuronal cell bodies and processes located in the peripheral nervous system 1.
Ganglia can be categorized into two groups - sensory ganglia and autonomic ganglia. Sensory ganglia primarily contain the cell bodies of neurons as well as their central and...
Article
Parasympathetic ganglia in the head and neck
The parasympathetic ganglia are a group of 4 bilateral autonomic ganglia in the head and neck. Each has three roots entering the ganglion and a variable number of exiting branches, but only parasympathetic fibers synapse within the ganglion. Sensory and sympathetic fibers only traversing through...
Article
Parasympathetic nervous system
The parasympathetic nervous system (PaNS/PNS), mediated by the head and neck ganglia and pelvic splanchnic nerves, is a major division of the autonomic nervous system. It is composed of general visceral afferent and efferent axons that allow for involuntary control of bodily functions via severa...
Article
Diffuse midline glioma, H3 K27-altered
Diffuse midline glioma, H3 K27-altered is a specific entity that represents the majority of diffuse intrinsic pontine gliomas, although identical tumors are also found elsewhere in the midline (e.g. brainstem, spinal cord and thalamus) 1. They are aggressive tumors with a poor prognosis and are ...
Article
Cranial nerve nuclei
The cranial nerve nuclei are a series of bilateral grey matter motor and sensory nuclei located in the midbrain, pons and medulla that are the collections of afferent and efferent cell bodies for many of the cranial nerves.
Some nuclei are small and contribute to a single cranial nerve, such as...
Article
Cystic bronchiectasis
Cystic bronchiectasis is one of the less common morphological forms of bronchiectasis. It may be present on its own or may occur in combination with other forms of bronchiectasis.
For a general discussion, please refer to the article on bronchiectasis.
Radiographic features
It is characterize...
Article
Taylor dysplasia
Taylor dysplasia is a type of focal cortical dysplasia and a common cause of refractory epilepsy. Under both the Palmini classification and the Blumcke classification of focal cortical dysplasia, Taylor dysplasia is classified as type II.
For further discussion of the radiographic features ple...
Article
Elastofibroma dorsi
Elastofibroma dorsi, a benign soft-tissue tumor, is distinctly situated in the infrascapular or subscapular region, being bilateral close to a third of cases. On imaging, it presents as a poorly defined soft-tissue mass with CT attenuation closely resembling adjacent skeletal muscle.
Epidemiolo...
Article
Menstrual cup
The menstrual cup is a reusable silicone device designed to be an alternative to tampons and sanitary pads. Various different brands are available but they all have the same shape.
It can be observed on all forms of abdominal imaging and it is worth being familiar with its normal appearances.
...
Article
Sesamoid
Sesamoids, also known as sesamoid bones, are focal areas of ossification within tendons as they pass over joints 1. They can also occur in ligaments and usually measure a few millimeters in diameter. Their function is purported to be to alter the direction of the tendon and modify pressure, ther...
Article
Mirizzi syndrome
Mirizzi syndrome refers to an uncommon phenomenon that results from extrinsic compression of an extrahepatic biliary duct from one or more calculi within the cystic duct or gallbladder. It is a functional hepatic syndrome but can often present with biliary duct dilatation and can mimic other hep...
Article
Total knee arthroplasty
Total knee arthroplasty (TKA), or total knee replacement (TKR), or tricompartmental knee replacement is an orthopedic procedure whereby the three articular surfaces of the knee (femoral, tibial, and patellar) are replaced by prosthetic components.
TKA is the most common joint arthroplasty perfo...
Article
Microtia
Microtia refers to a small pinna of the ear, when is it completely absent it is termed anotia.
Epidemiology
The estimated incidence at around 1:9000 live births. It is more common in males and there is a recognized right sided predilection.
Pathology
Associations
Microtia can be associated ...
Article
de Carvalho index (knee)
The de Carvalho index is used to measure patellar height and identify patella alta. It is similar to the Caton-Deschamps index and relies upon the length of the patellar articular surface and its distance from the tibia. This helps in reducing erroneous measurements in those with long patella bo...
Article
Adrenal washout
Adrenal washout can be calculated using the density value of an adrenal mass on non-enhanced, portal venous phase and 15-minute delayed CT scans (density measured in Hounsfield units (HU)). It is primarily used to diagnose adrenal adenoma.
absolute washout
[(HUportal venous phase) - (HUdelayed...
Article
External auditory canal atresia
External auditory canal atresia, also known as congenital aural atresia, is characterized by complete or incomplete bony atresia of the external auditory canal (EAC), often in association with a dysplastic auricle and an abnormal middle ear cavity or ossicles.
Epidemiology
The incidence is 1 i...
Article
Proximal radio-ulnar synostosis
Proximal radio-ulnar synostosis is an upper limb skeletal malformation characterized by bony fusion at the proximal aspect of the radius and ulna. The proximal third is considered the most common site of the radio-ulnar synostoses.
Epidemiology
Proximal radioulnar synostoses are rare occurren...
Article
Crescent sign (osteonecrosis)
The crescent sign refers to a linear cleft due to a subchondral fracture in the setting of osteonecrosis.
It was originally described as a radiographic finding, however, it can also be seen on cross-sectional imaging.
In the setting of Legg-Calve-Perthes disease, it heralds the beginning of th...
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