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.

16,919 results
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Ann Arbor staging system (historical)

The Ann Arbor staging system was the landmark lymphoma staging classification system for both Hodgkin lymphoma and non-Hodgkin lymphoma. It is named after the town of Ann Arbor in the US state of Michigan where the Committee on Hodgkin's Disease Staging Classification met in 1971 to agree on it....
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Pancreatic duct stone

A pancreatic duct stone, also known as calculus, is a stone embedded within the pancreatic ducts. They typically arise in the setting of chronic pancreatitis. Terminology Three terms other than pancreatic stones or calculi have been used to refer to calculi in the pancreatic ducts; primarily t...
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Detective quantum efficiency

Detective quantum efficiency (DQE) is one of the fundamental physical variables related to image quality in radiography and refers to the efficiency of a detector in converting incident x-ray energy into an image signal. The words "quantum efficiency" have a precise meaning, because the DQE mea...
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Bremsstrahlung radiation

X-rays are produced by high-energy electrons bombarding a target, especially targets with a high proton number (Z). When bombarding electrons penetrate the target, some electrons travel close to the nucleus due to the attraction of its positive charge and are subsequently influenced by its elect...
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Managing editor

Managing editors at Radiopaedia.org are part of the senior editorial team and have specific roles in developing the site and its content. As of 2024, there are three managing editors: Joachim Feger Andrew Murphy Vikas Shah Responsibilities Between 2007 (launch) and 2014, Radiopaedia.org ha...
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Wyburn-Mason syndrome

Wyburn-Mason syndrome (also known as Bonnet-Dechaume-Blanc syndrome) is a rare, nonhereditary neurocutaneous disorder that typically presents with unilateral vascular malformations that primarily involve the brain, orbits and facial structures. It is classified as a cerebrofacial arteriovenous m...
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Neurodegenerative disease

Neurodegenerative disease is a blanket term encompassing a wide variety of disorders, typically slowly progressive, with variable gradual neurologic dysfunction.  Over the years numerous classification schemas have been described, each adding a layer of confusion for students. The main distinct...
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Acute renal transplant rejection

Acute renal transplant rejection is a renal transplant complication that occurs within <5-7 days of the placement of the transplant. Although part of a spectrum of closely-related rejection disorders, the term is meant to distinguish this type of rejection from chronic renal transplant rejection...
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Helicobacter pylori

Helicobacter pylori (H. pylori) is a gram-negative spiral flagellate microaerophilic bacterium found in the human gastric mucosa 1. It is classified as a group I carcinogen and is considered necessary but insufficient alone to cause gastric adenocarcinoma. More often than not, it results in chro...
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Fluoroscopy

Fluoroscopy is an imaging modality that allows real-time x-ray viewing of a patient with high temporal resolution. It is based on an x-ray image intensifier coupled to a still/video camera. In years, flat panel detectors (like those used in direct digital radiography) have been replacing image i...
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Angiocentric glioma

Angiocentric gliomas are rare, superficial slow-growing WHO grade 1 brain tumors typically presenting in pediatric patients with intractable focal epilepsy 1-6. They are often considered part of the heterogeneous group of tumors known as long-term epilepsy-associated tumors (LEATs). Epidemiolog...
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Investigating strabismus (summary)

This is a basic article for medical students and other non-radiologists Strabismus, commonly known as "crossed eyes" or "squint," is a visual disorder characterized by the misalignment of the eyes 1. Reference article This is a summary article; there is no more in-depth reference article. Su...
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Renal abscess

Renal abscess is a collection of infective fluid in the kidney. It is usually a sequela of acute pyelonephritis, where severe vasospasm and inflammation may occasionally result in liquefactive necrosis and abscess formation. Epidemiology It can affect all ages and has no recognized gender pred...
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Leadless cardiac pacemaker

Leadless cardiac pacemakers are a type of cardiac conduction device. These pacemakers are self-contained right ventricular single-chamber pacemakers that are implanted percutaneously via a femoral approach 1-3. There are two leadless cardiac pacemakers on the market: Nanostim™️ (Abbott Medical) ...
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Final FRCR Part A examination

The Final FRCR Part A examination (colloquially known as Part 2A exam) is part of the standard set of examinations taken by radiology registrars in their 3rd year of training who have completed the First FRCR examination. The exam format was updated in 2017, returning to a single examination rat...
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Neurosyphilis

Neurosyphilis results from infection of the central nervous system by the spirochete Treponema pallidum, subspecies pallidum. The disease has a heterogeneous spectrum of early and late manifestations. For a general discussion, and for links to other system-specific manifestations, please refer ...
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Leber hereditary optic neuropathy

Leber hereditary optic neuropathy (LHON) is a mitochondrial genetic disorder characterized by bilateral, progressive, central vision loss secondary to loss of the retinal ganglionic cell layer 1,2. Epidemiology Leber hereditary optic neuropathy classically presents in young, Caucasian, adult m...
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Gamma camera

Gamma cameras (also called scintillation cameras or Anger cameras) are the predominant nuclear medicine imaging machine in use. They permit the acquisition of planar images. They are also central to single photon emission computed tomography (SPECT). Design From the exterior to interior a came...
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Chemical shift

The chemical shift is the local change in resonant frequency due to different chemical environments. The external magnetic field causes the electron cloud surrounding the nucleus to induce an electron current, which in turn produces a local magnetic field at the nucleus opposed in direction to t...
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Left atrial appendage thrombus

Left atrial appendage thrombus is a site of intra-cardiac thrombus and refers to the presence of thrombus within the left atrial appendage. The left atrial appendage is considered the main location of thrombus formation, predominantly in patients with non-valvular atrial fibrillation. Radiogra...

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