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.

16,885 results found
Article

Optic perineuritis

Optic perineuritis, also known as perioptic neuritis, refers to inflammation of the optic nerve sheath. Optic perineuritis may manifest on its own, or together with inflammation of adjacent ocular or orbital structures. Epidemiology Optic perineuritis is likely rare 1, but the exact incidence ...
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Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD)

Myelin oligodendrocyte glycoprotein​ antibody-associated disease (MOGAD) represents a group of inflammatory demyelinating disorders united by the presence of IgG antibodies to myelin oligodendrocyte glycoprotein (MOG). MOGAD represents a distinct clinical entity that clinically overlaps but is n...
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Optic nerve sheath meningioma

Optic nerve meningiomas are benign tumors arising from the arachnoid cap cells of the optic nerve sheath and represent ~20% of all orbital meningiomas, the majority of which are direct extensions from intracranial meningiomas.  These tumors typically appear as masses within the optic nerve, iso...
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Optic neuritis

Optic neuritis denotes inflammation of the optic nerve and is one of the more common causes of optic neuropathy. It can be thought of as broadly divided into infectious and non-infectious causes, although the latter is far more frequent. On imaging, optic neuritis is most easily identified as a ...
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Doughnut sign (orbit)

The doughnut sign of optic nerve sheath meningioma refers to the appearance of this tumor on coronal CT/MRI. The meningioma forms a thick cuff of enhancing tumor around the central non-enhancing optic nerve, mimicking the appearance of a ring doughnut. It is the coronal equivalent of the tram-tr...
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Prostate specific antigen

Prostate specific antigen (PSA) is currently used as a tumor marker for prostate adenocarcinoma. PSA is a 33 kilodalton glycoprotein produced in prostate epithelial cells. Its normal physiologic role is as a liquefying agent for seminal fluid; only a tiny amount leaks into the blood, therefore ...
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PSA velocity

The PSA velocity (PSAV) is a statistically derived measure of how prostate specific antigen (PSA) levels change over time and has been used as a marker of how prostate cancer progresses or regresses.  Calculation Calculating PSA velocity, or similar measures of PSA kinetics, is fraught with di...
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Shoulder protocol (MRI)

The MRI shoulder protocol encompasses a set of different MRI sequences for the routine assessment of the shoulder joint. Note: This article aims to frame a general concept of an MRI protocol for the assessment of the shoulder joint. Protocol specifics will vary depending on MRI scanner type, sp...
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Caton-Deschamps index (knee)

The Caton-Deschamps index is used to measure patellar height and identify patella alta and patella baja. The Caton-Deschamps index relies upon the length of the patellar articular surface and its distance from the tibia, reducing erroneous measurements in those with long patella bodies, as measu...
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Intracerebral hemorrhage

Intracerebral hemorrhage (ICH), or intraparenchymal cerebral hemorrhage, is a subset of an intracranial hemorrhage as well as of stroke, defined by the acute accumulation of blood within the brain parenchyma. This article concerns non-traumatic intracerebral hemorrhages; traumatic hemorrhagic c...
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Urinoma

Urinomas, or uriniferous fluid collections, are urine collections usually found in the retroperitoneum, most commonly in the perirenal space, as a consequence of renal tract leakage caused by urinary obstruction, trauma, or post-instrumentation.  Terminology As there is no definitive distincti...
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Spontaneous rupture of the renal pelvis

Spontaneous rupture of the renal pelvis, also known as pyelosinus backflow, is a rare complication that can occasionally occur with obstructive urolithiasis (usually in the distal third of the ureter) or occasionally infection 1. Leakage of urine can result in a urinoma, and there is an increase...
Article

Flow-diverter stent

Flow-diverter stents are important devices in the management of intracranial aneurysms in both acute and elective settings, especially ones that are large, broad-necked, or fusiform. Complications Understanding the complication rates is important in obtaining informed consent from patients. In...
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Non-ischemic cerebral enhancing (NICE) lesions

Non-ischemic cerebral enhancing (NICE) lesions are an uncommon delayed complication of cerebrovascular procedures, including aneurysm coiling, thrombectomy and placement flow-diverter stent placement 1,2,4,5. Epidemiology As NICE lesions are seen following endovascular procedures most commonly...
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Male urethra

The male urethra is a fibromuscular tube that drains urine from the bladder. It has a longer, more complicated, course than the female urethra and is also more prone to pathology. Gross anatomy The male urethra measures, on average, 18-20 cm in length 6. It commences at the internal urethral o...
Article

Hydrops fetalis

Hydrops fetalis is excessive fluid into the third space in a fetus, which could be due to heart failure, volume overload, decreased oncotic pressure, or increased vascular permeability. Epidemiology The estimated incidence is at ~1 in 2000 births, although this can significantly vary according...
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Ivor Lewis procedure

Ivor Lewis procedure (also known as a gastric pull-up) is a type of esophagectomy, an upper gastrointestinal tract operation performed for mid and distal esophageal pathology, usually esophageal cancer. Due to the necessity of removing a significant length of the esophagus, the stomach is "pull...
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Exophytic sinonasal papilloma

Exophytic sinonasal papillomas (ESP) or fungiform sinonasal papillomas are a benign sinonasal tumor arising from the nasal septum, and one of the three main histological forms a Schneiderian papilloma can take. Epidemiology Exophytic sinonasal papillomas are the second most common form of sino...
Article

Tram-track sign (orbit)

Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve sheath meningioma. It may, however, also be seen in 1: orbital pseudotumor optic perineuritis orbital sarcoidosis orbital leukemia orbital lym...
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Optic nerve

The optic nerve is the second (CN II) cranial nerve (TA: nervus opticus or nervus cranialis II). It is a purely sensory nerve that conveys visual information from the eye to the brain.  The nerve arises from the back of the globe exiting the orbit via the optic canal. It joins the contralateral...

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