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.
169 results found
Article
Northern exposure sign (sigmoid volvulus)
The northern exposure sign has been described as a high specificity sign in sigmoid volvulus. On a supine abdominal radiograph, the apex of the sigmoid volvulus is seen above (cranial to) the transverse colon.
Article
Bird beak sign (esophagus)
The bird's beak sign of the esophagus is used to refer to the tapering of the inferior esophagus in achalasia. The same appearance is also referred to as the rat's tail sign.
The appearance, although classically occurring in primary achalasia, can also occur in pseudoachalasia due to a gastric ...
Article
Torricelli-Bernoulli sign
The Torricelli-Bernoulli sign denotes non-dependent air trapped in a necrotic ulcer in a gastrointestinal tumor seen on axial CT or MRI. Occasionally, a vertical stream of bubbles can be seen issuing from the orifice of the ulcer.
Terminology
Torricelli's theorem gives the relation of the velo...
Article
Mackler's triad
Mackler's triad consists of the clinical symptoms of vomiting, followed by severe pain in the chest, usually retrosternal, lower thoracic, and upper abdominal, associated with subcutaneous emphysema detected on physical examination, which is suggestive of esophageal rupture (Boerhaave syndrome) ...
Article
Anderson triad
The Anderson triad consists of the clinical findings of tachypnea and abdominal rigidity with lower thoracic or epigastric pain, associated with subcutaneous emphysema, which is usually related to esophageal rupture.
Article
Pseudokidney sign (intussusception)
The pseudokidney sign is a characteristic ultrasound appearance in some cases of intestinal intussusception. It refers to the longitudinal ultrasound appearance of the intussuscepted segment of bowel which mimics a kidney.
The fat-containing mesentery, containing vessels, which is dragged into ...
Article
Bird beak sign (sigmoid colon)
Bird's beak sign of the sigmoid is one of the signs of sigmoid volvulus. It represents gradual narrowing/tapering of the sigmoid colon up to the level of obstruction during contrast/barium insertion to the rectum or on CT.
When located in the sigmoid colon, it suggests the diagnosis of sigmoid ...
Article
Saber sign (pneumobilia)
The saber sign refers to a pattern of gas distribution seen in supine abdominal radiographs of patients with pneumobilia. A sword-shaped lucency is apparent in the right paraspinal region of the upper abdomen representing arching gas extending from the common bile duct into the left hepatic duc...
Article
Rat's tail sign (esophagus)
The rat's tail sign refers to tapering of the inferior esophagus on barium swallow study. Many sources use this sign synonymously with the bird beak sign (esophagus) and indicate that it is characteristic of achalasia 1. It is important to remember that if a "rat tail" involves more than just t...
Article
Gasless abdomen
A gasless abdomen refers to a paucity of gas on abdominal radiography, and the specific cause can usually be identified when the patient's history is known. Common causes include:
proximal obstruction: gastric outlet obstruction, esophageal atresia
small bowel obstruction
bowel ischemia
asci...
Article
Accordion sign (colon)
The accordion sign (also known as concertina sign) is seen on CT of the abdomen and refers to the similarity between the thickened edematous wall of pseudomembranous colitis and the folds of an accordion. This appearance is the result of hyperemic enhancing mucosa stretched over markedly thicken...
Article
Lipoma
Lipomas are benign tumors composed of mature adipocytes. They are the most common soft tissue tumor, seen in ~2% of the population.
Epidemiology
Patients typically present in adulthood (5th-7th decades).
Associations
In some cases, multiple lipomas are associated with syndromes and other di...
Article
X-marks-the-spot sign (large bowel volvulus)
The X-marks-the-spot sign of large bowel volvulus refers to the crossing loops of the bowel at the site of the transition. It has been reported to improve diagnostic confidence in detecting cecal and sigmoid volvulus. This is in contrast to the split-wall sign which indicates partial obstruction...
Article
Doge cap sign (pneumoperitoneum)
The doge cap sign, also referred to as Morison pouch sign, is a radiographic sign of pneumoperitoneum. It presents as a triangular-shaped (although may also be crescentic or semicircular) gas lucency, usually bound by the 11th rib in the right upper quadrant on abdominal radiographs due to air i...
Article
Zebra sign (disambiguation)
The evocative appearance of the coat of a zebra has been used for several distinctive signs in radiology:
zebra sign: cerebellar hemorrhage 1
zebra sign: amyotrophic lateral sclerosis 2
zebra spleen: arterial phase appearance of normal spleen 4,5
zebra stripe sign: treated osteogenesis imper...
Article
Boas sign
Boas sign is a clinical sign that is defined as hyperesthesia felt by the patient to light touch in the right lower scapular region or the right upper quadrant of the abdomen. It is classically seen in patients with acute cholecystitis.
History and etymology
Ismar Isidor Boas (1858–1938), was ...
Article
Thumbprinting
Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by edema, related to an infective or inflammatory process (colitis). The normal haustra become thickened at regular intervals appearing like thumbprints projecting into the aerated lumen.
Pathology
Etiology
Th...
Article
Obturator sign
Obturator sign is a clinical sign of acute appendicitis, it is defined as discomfort felt by the subject/patient on the slow internal movement of the hip joint, while the right knee is flexed. It indicates an inflamed pelvic appendix that is in contact with the obturator internus muscle 1-3.
Se...
Article
Steelpan sign (sigmoid volvulus)
The steelpan sign refers to the close resemblance of sigmoid volvulus on CT to the percussion instrument known as the steelpan. The steelpan, also known as steel drum or pan, is a Caribbean musical instrument invented in Trinidad and Tobago by the mid-1930s, which became very popular in Trinidad...
Article
Teardrop sign (superior mesenteric vein)
The teardrop sign of the superior mesenteric vein is one of the important signs in the local staging of pancreatic adenocarcinoma. Its importance lies in its diagnostic, as well as prognostic, significance. This sign is used in assessing the resectability of pancreatic cancer.
Radiographic feat...
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