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.

11 results found
Article

Naclerio V sign

The Naclerio V sign is a sign described on the plain film in patients with a pneumomediastinum occurring often secondary to an oesophageal rupture.  It is seen as a V-shaped air collection. One limb of the V is produced by mediastinal air outlining the left lower lateral mediastinal border. The...
Article

Naked facet sign

The naked facet sign (also known as the hamburger sign or reverse hamburger bun sign) refers to the CT appearance of an uncovered vertebral articular facet when the facet joint is dislocated, most often in cases of locked facet.  This CT sign is characteristic of a flexion-distraction injury an...
Article

Napkin-ring sign

The napkin-ring sign (cardiac) is a recently described sign encountered on CT coronary angiogram (coronary CTA) performed on modern MDCT. It has been shown to possess a high predictive value in predicting future cardiac events and is considered one of the imaging correlates of an unstable plaque...
Article

Neuhauser sign

Neuhauser sign refers to a soap bubble appearance seen in the distal ileum in cases of meconium ileus, related to the air mixed with meconium. It may be seen with barium enema if contrast passes beyond the ileocaecal valve or with small-bowel follow-through. Although classically described with ...
Article

Nightstick fracture

Nightstick fractures are isolated fractures of the ulna, typically in the mid-diaphysis, usually resulting from a direct blow. It is a characteristic defensive fracture when the patient tries to ward off an overhead blow from an assailant. Treatment and prognosis Although typically a closed fr...
Article

Nodule-in-nodule appearance: liver

In hepatic imaging, a nodule-in-nodule appearance represents foci of abnormal arterial enhancement within a liver lesion, in cases of a liver regenerative nodule with a focus of hepatocellular carcinoma or high-grade dysplastic nodule. It is so called because of the nodular arterial enhancement ...
Article

Non-accidental injuries

Non-accidental injuries (NAI) represent both ethical and legal challenges to treating physicians. Radiologists are often the first to suspect NAI when confronted with particular injury patterns, and a knowledge of these is essential if the opportunity to save a child from future neglect is not ...
Article

Northern exposure sign

The northern exposure sign has been described as a high specificity sign in sigmoid volvulus. The sigmoid colon will be dilated and the apex of the volvulus is seen cephalic to gas in the transverse colon on supine abdominal radiography. 
Article

Notch sign

There are many so-called notch signs. They include: focal notch in the wall (or tail extending from) a 2nd branchial cleft cyst between the internal and external carotid artery.  peripheral notches in the contour of a solitary pulmonary nodule (SPN) suggests malignancy thymic notch sign
Article

Nubbin sign

Nubbin sign (also called as cystic duct sign) is an important sign in a HIDA scan (cholescintigraphy using iminodiacetic acid analogues) that may be seen in cases of gallbladder neck obstruction. The "nubbin" refers to a small amount of radiotracer activity in the cystic duct, with abs...
Article

Nutmeg liver

A nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of hepatic venous congestion. When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner. This results in a mottled pattern of contrast enhancement in the a...

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