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.

125 results found
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Abnormal bowel wall attenuation patterns

Abnormal bowel wall attenuation patterns on CT scan can be grouped under five categories: white enhancement gray enhancement water halo sign fat halo sign black attenuation The first three patterns are seen on contrast studies. White enhancement It is defined as uniform enhancement of th...
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Accordion sign (colon)

The accordion sign (also known as concertina sign) is seen on CT examinations 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 mar...
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Antral nipple sign

The antral nipple sign refers to redundant pyloric mucosa protruding into the gastric antrum and is seen in pyloric stenosis. See also cervix sign of pyloric stenosis target sign of pyloric stenosis shoulder sign of pyloric stenosis
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Antral pad sign

The antral pad sign is a feature seen on a spot radiograph of the upper gastrointestinal tract obtained with orally-administered contrast material. It refers to the extrinsic impression or indentation on the posteroinferior aspect of the antrum. The impression is generally arcuate and smooth, an...
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Apple core sign (colon)

The apple core sign, also known as the napkin ring sign (bowel), is most frequently associated with constriction of the lumen of the colon by a stenosing annular colorectal carcinoma. Differential diagnosis The appearance of the apple-core lesion of the colon also can be caused by other diseas...
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Apple-peel intestinal atresia

Apple-peel intestinal atresia, also known as type IIIb or Christmas tree intestinal atresia, is a rare form of small bowel atresia in which the duodenum or proximal jejunum ends in a blind pouch and the distal small bowel wraps around its vascular supply in a spiral resembling an apple peel. Oft...
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Arrowhead sign (cecum)

The arrowhead sign refers to the focal cecal thickening centered on the appendiceal orifice, seen as a secondary sign in acute appendicitis. The contrast material in the cecal lumen assumes an arrowhead configuration, pointing at the appendix.   The arrowhead sign is applicable only when enteri...
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Backwash ileitis

Backwash ileitis is seen in patients with ulcerative colitis (UC), where the entire colon is involved. In such cases the terminal ileum is edematous. Backwash ileitis extends contiguously backward from the cecum without skip regions. One source estimates it to occur in 6% of patients with UC, a...
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Ball of wool sign (hydatid cyst)

The ball of wool sign, also referred to as the yarn sign or congealed water lily sign, is an ultrasound appearance, representing degeneration of hydatid cysts (WHO class CE 4). The inner side of the cyst detaches from the cyst wall and folds on itself, causing a change from anechoic (fluid) to a...
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Beak sign (pyloric stenosis)

Beak sign in pyloric stenosis is one of the fluoroscopic (barium meal) findings which is useful in the diagnosis of congenital hypertrophic pyloric stenosis.  Radiographic features Barium meal A beak-like tapering projection of barium is seen entering into the narrowed and compressed pyloric ...
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Bilateral adrenal gland hyperenhancement

Bilateral adrenal gland hyperenhancement or intense adrenal enhancement may be a feature of hypotension and forms part of the CT hypoperfusion complex. Adrenal gland hyperenhancement has been described in pediatric and small adult series or individual cases of hemorrhagic shock, pancreatitis, s...
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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 (although it is difficult to see the similarity) is also referred to as the rat-tail sign. The appearance, although classically occurring in primary achalasia, can ...
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Bird beak sign (right colon)

The bird beak sign of the right colon is tapering obstruction of the inferior part of right colon seen on contrast enema or CT scan with rectal contrast indicating cecal volvulus. This sign can help to differentiate cecal volvulus from cecal bascule, in particular on a contrast/barium enema stu...
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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 ...
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Cecal bar sign (acute appendicitis)

The cecal bar sign is a secondary sign in acute appendicitis. It refers to the appearance of inflammatory soft tissue at the base of the appendix, separating the appendix from the contrast-filled cecum. See also arrowhead sign
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Carman meniscus sign

The Carman meniscus sign describes the lenticular shape of barium in cases of large and flat gastric ulcers, in which the inner margin is convex toward the lumen. It usually indicates a malignant ulcerated neoplasm; in cases of benign gastric ulcers, the inner margin is usually concave toward th...
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Caterpillar sign

The caterpillar sign is a radiological sign described in pyloric stenosis. It refers to the appearance of stomach on an upper gastrointestinal radiographic series or plain abdominal radiograph 1,2. On these imaging modalities in a patient with pyloric stenosis, the stomach appears distended, ai...
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Centipede sign (mesentery)

The centipede sign is seen as engorged mesenteric vessels in cases of acute sigmoid diverticulitis which gives an appearance similar to a centipede 1.
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Cervix sign of pyloric stenosis

The cervix sign of pyloric stenosis describes indentation of the pylorus into the fluid-filled antrum, seen in pyloric stenosis. See also antral nipple sign target sign of pyloric stenosis shoulder sign of pyloric stenosis
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Chilaiditi sign

Chilaiditi sign refers to the interposition of bowel, usually colon, between the inferior surface of the right hemidiaphragm and the superior surface of the liver. It may be misinterpreted as a true pneumoperitoneum resulting in unnecessary further investigations and/or therapy (so-called pseudo...
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Cobblestone appearance (hollow viscera)

Cobblestoning (having a cobblestone appearance) can occur in a number of hollow organs with mucosa, most commonly the bowel, in the setting of Crohn disease.  Longitudinal and circumferential fissures and ulcers separate islands of mucosa, giving it an appearance reminiscent of cobblestones.  ...
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Cockade sign (disambiguation)

There are several described cockade signs in radiology: cockade sign (intraosseous lipoma) cockade sign (aorto-left ventricular tunnel) 1 cockade sign (appendicitis) 2 cockade sign (hypertrophic pyloric stenosis) 3 cockade sign (GI tumors) 4
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Coffee-bean sign (sigmoid colon)

The coffee-bean sign (also known as the kidney bean sign or bent inner tube sign 4) is a sign on an abdominal plain radiograph of a sigmoid volvulus although some authors have also used the term to refer to closed loop small bowel obstructions. Cecal volvulus may be mistaken with sigmoid volvulu...
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Collar sign in diaphragmatic rupture

The collar sign, also called the hourglass sign, is a helpful sign for diagnosis of diaphragmatic rupture on coronal or sagittal CT/ MR images and barium studies. It refers to a waist-like or collar-like appearance of herniated organs at the level of the diaphragm. See also dependent viscera s...
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Colon cut-off sign

Colon cut-off sign describes gaseous distension seen in proximal colon associated with narrowing of the splenic flexure in cases of acute pancreatitis. Though originally described in abdominal radiographs, this sign has also been demonstrated in contrast enemas and computed tomography 1. This a...
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Comb sign (mesentery)

The comb sign refers to the hypervascular appearance of the mesentery in active Crohn disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel,...
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Cone-shaped cecum (differential)

A cone-shaped cecum refers to a loss of the normal rounded appearance of the cecum, which instead becomes narrow and cone-shaped with the apex pointing towards the base of the appendix. It is encountered in a number of conditions including: inflammatory infective blastomycosis amoebiasis Ye...
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Corkscrew sign

The corkscrew sign describes the spiral appearance of the distal duodenum and proximal jejunum seen in midgut volvulus 1. In patients with malrotation and volvulus, the distal duodenum and proximal jejunum do not cross the midline and instead pass in an inferior direction. These loops twist on ...
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Crescent in a doughnut sign (intestinal intussusception)

The crescent in a doughnut sign refers to the transverse ultrasound appearance of intestinal intussusception, and is a variation of the target sign (which is also known as the doughnut sign) The doughnut is formed by concentric alternating echogenic and hypoechogenic bands. The echogenic bands ...
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Cupola sign (pneumoperitoneum)

The cupola sign is seen on a supine chest/abdominal radiograph in the presence of pneumoperitoneum.  It refers to non-dependent gas that rises within the abdominal cavity of the supine patient to accumulate underneath the central tendon of the diaphragm in the midline. It is seen as lucency ove...
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Dependent viscera sign

The dependent viscera sign is one of the signs of diaphragmatic rupture on axial CT or MR images, where herniated viscera lie against the posterior thoracic wall in a dependent position, as they are no longer supported by the diaphragm. See also  collar sign (or hourglass sign)
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Dog ear sign (abdomen)

The dog ear sign represents the presence of fluid or blood in the pelvic peritoneal recess on a supine abdominal radiograph. The appearance of the sign comes from a convex soft-tissue density representing fluid or blood in the lateral pelvic peritoneal recess separated from the bladder by a thin...
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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 gas lucency or can be crescent shaped, or semicircular is usually bound by the 11th rib in the right upper quadrant on abdominal radiographs due to air in the...
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Double barrel sign (disambiguation)

Double barrel sign is an imaging appearance of two lumens adjacent to each other. It can be seen in: dilated bile duct adjacent to portal vein double barrel aorta: aortic dissection double barrel esophagus: esophageal dissection
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Double bubble sign (duodenum)

The double bubble sign is seen in infants and represents dilatation of the proximal duodenum and stomach. It is seen in both radiographs and ultrasound, and can be identified antenatally 2. Pathology Causes include 1,2: congenital obstruction duodenal web duodenal atresia duodenal stenosis...
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Double duct sign

The double duct sign refers to the presence of simultaneous dilatation of the common bile and pancreatic ducts. Being an anatomical sign it can be seen on all modalities that can visualize the region, including: MRI, CT, ultrasound and endoscopic retrograde cholangiopancreatography (ERCP).  The...
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Double track sign (pyloric stenosis)

The double track sign is a radiological sign described in pyloric stenosis on various imaging modalities.  Barium study Double streaks of barium passing through the narrow pylorus 1. Ultrasound On fluid aided real-time examination, the pyloric fluid is compressed into smaller tracks as it is...
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Double wall sign (pneumoperitoneum)

The double wall sign is another name for the Rigler sign. It is a sign of pneumoperitoneum with gas outlining both sides of the bowel wall. It is seen when large amounts of free gas, >1000 mL, are present. It should be distinguished from the false double wall sign which refers to two dilated lo...
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Doughnut sign (disambiguation)

The doughnut sign can refer to a variety of different signs: doughnut sign (bone) doughnut sign (bowel) crescent in a doughnut sign (bowel)
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Duct penetrating sign (pancreas)

The duct penetrating sign is a radiographic sign which can be useful in differentiating between focal pancreatitis (inflammatory pancreatic mass) from pancreatic carcinoma. A positive sign is when a mass is penetrated by an unobstructed pancreatic duct; this makes focal pancreatitis the most li...
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Falciform ligament sign

The falciform ligament sign, also called the Silver sign, is characterized by the falciform ligament being outlined with free abdominal gas in cases of pneumoperitoneum of a large amount.  It is almost never seen in isolation as, if there is enough free gas to outline the falciform ligament, th...
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Fascial tail sign

The fascial tail sign is the linear extension along the fascia/muscular aponeurosis from a deeper tumor, typically seen in desmoid tumors. It can be seen in other soft tissue tumors containing collagen fibers such as fibrosarcoma leiomyoma neurofibroma It is also a characteristic sign in no...
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Fat halo sign (inflammatory bowel disease)

The fat halo sign refers to a feature seen on CT examination of the abdomen, and represents infiltration of the submucosa with fat, between the muscularis propria and the mucosa. It is characterized by an inner (mucosa) and outer (muscularis propria and serosa) ring of enhancing bowel wall along...
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Fat ring sign (mesenteric panniculitis)

The fat ring sign (also known as a fat halo sign) describes preservation of fat around the mesenteric vessels and around soft tissue nodules on a background of diffuse fat stranding in patients with mesenteric panniculitis or mesenteric lipomas.  This finding may help distinguish mesenteric pan...
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Fat stranding on CT

Fat stranding is a common sign seen on CT wherever fat can be found. It is most commonly seen in abdomen/pelvis, but can also be seen in retroperitoneum, thorax and subcutaneous tissues. It can be helpful in localizing both acute and chronic pathology. Radiographic features CT Fat stranding c...
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Fat stranding (summary)

This is a basic article for medical students and other non-radiologists Fat stranding is a sign that is seen on CT. It describes the change in attenuation of fat around an inflamed structure and is a very helpful signpost for intra-abdominal pathology. Reference article This is a summary arti...
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Fishtail pancreas

Fishtail pancreas (also known as pancreas bifidum or bifid tail of the pancreas) is a rare anatomical variant of the pancreas produced by a branching anomaly during its development. It is named as such due to the fishtail-like appearance of the pancreas. Epidemiology It is a rare anatomical an...
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Fissure for ligamentum teres sign

The fissure for ligamentum teres sign or extrahepatic ligamentum teres sign is a radiographic sign of pneumoperitoneum. It represents the outline of the ligamentum teres (remnant of an obliterated left umbilical vein) with free abdominal gas in a supine patient, as seen on a plain abdominal radi...
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Fleischner sign (disambiguation)

Fleischner sign can refer to two distinctly separate signs: Fleischner sign (enlarged pulmonary artery) Fleischner sign (tuberculosis of ileocecal junction)
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Fleischner sign (tuberculosis of ileocecal junction)

The Fleischner sign (also known as the inverted umbrella sign), refers to a widely gaping, thickened, patulous ileocecal valve and a narrowed, ulcerated terminal ileum associated with tuberculous involvement of the ileocecum. See also gastrointestinal tuberculosis Stierlin sign not to be con...
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Floating aorta sign

The floating aorta sign refers to the displacement of the abdominal aorta away from the vertebral column. It is a radiographic sign of retroperitoneal masses. Radiographic findings On lateral lumbar spine radiographs, the expected location of the posterior aortic wall is expected to be ≤10 mm...
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Foamy esophagus sign

Foamy esophagus is an appearance seen on a single contrast barium study in Candida esophagitis with associated scleroderma/achalasia (stasis). Pathology Pathophysiologic basis of the foamy esophagus is uncertain. Stasis is a predisposing factor. Foam is produced directly by the fungal organism...
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Football sign (pneumoperitoneum)

The football sign is seen in cases of massive pneumoperitoneum, where the abdominal cavity is outlined by gas from a perforated viscus. The median umbilical ligament and falciform ligament are sometimes included in the description of this sign, as representing the sutures. Which football is use...
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Frimann-Dahl sign

The Frimann-Dahl sign is a diagnostic sign demonstrated when three dense lines, representing the sigmoid walls, are seen converging to the site of obstruction in sigmoid volvulus and associated with empty rectal gas 1. History and etymology Johan Frimann-Dahl (1902-82) was a Norwegian Professo...
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Frostberg inverted 3 sign

Frostberg inverted 3 sign is a radiological sign seen on a barium examination where there is effacement and distortion of the mucosal pattern on the medial wall of the second part of the duodenum due to focal mass and local edema. It is most commonly associated with carcinoma of the head of the ...
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Gut signature sign

The gut signature sign is an ultrasound term used to describe the appearance of the gastrointestinal wall. Radiographic features  Ultrasound The bowel wall has five layers, composed of alternating hyperechoic and hypoechoic appearances. Anatomically these layers are as follows (innermost to o...
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Hampton line

The Hampton line is a thin millimetric radiolucent line seen at the neck of a gastric ulcer in barium studies (profile view), indicating its benign nature. It is caused by a thin line of mucosa overhanging the ulcer's crater. History and etymology It was originally described by Aubrey Otis Ham...
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Hepatic edge sign

The hepatic edge sign is a radiographic sign of pneumoperitoneum seen on a supine plain abdominal radiograph. It is represented by a cigar-shaped pocket of free air in the subhepatic region, which tracks superomedial following the contour of the liver.
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Hide-bound sign (bowel)

The hide-bound bowel sign refers to an appearance on a barium study of the small bowel in patients with scleroderma. The sign describes the narrow separation between the valvulae conniventes which are of normal thickness despite dilatation of the bowel lumen.   Although the term hide-bound is u...
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Howship-Romberg sign

The Howship-Romberg sign refers to obturator nerve neuropathy due to compression of the obturator nerve by an obturator hernia. Patients present with pain and paraesthesia along the inner aspect of the thigh, down to the knee. History and etymology Named after Moritz Heinrich Romberg (1795-187...
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Hyperattenuating ring sign in epiploic appandagitis

The hyperattenuating ring sign is a sign that has been described with epiploic appendagitis and refers to a hyperattenuating ring of visceral peritoneum surrounding an inflamed epiploic appendage 1. On CT it can be seen as a ring of soft tissue surrounding a region of fat attenuation adjacent to...
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Hypercontracting (nutcracker) esophagus

Hypercontracting (nutcracker) esophagus is a motility disorder of the esophagus. This condition is primarily diagnosed with manometry with high intra-esophageal pressure and normal peristalsis. Most patients will have a normal barium swallow.  Hypercontracting esophagus ("nutcracker esophagus")...
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Ice pick sign

The ice pick sign is a smooth tapered narrowing of the upstream pancreatic duct distal to the pancreatic lesion seen frequently in benign pancreatic lesions such as a focal autoimmune pancreatitis, this is due to the extrinsic narrowing of the duct secondary to periductal fibrosis and inflammati...
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Intramural bowel gas

Intramural bowel gas, also known as pneumatosis intestinalis, refers to the clinical or radiological finding of gas within the wall of the bowel. Terminology There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cystoid...
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Inverted "V" sign (pneumoperitoneum)

The inverted "V" sign, also known as the lateral umbilical ligament sign, is a sign of pneumoperitoneum manifested by the visualization of an inverted "V"  shape in the pelvis on supine view of abdominal radiographs. It represent free gas outlining the lateral umbilical ligaments. In infants, th...
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Jejunoileal fold pattern reversal

Jejunoileal fold pattern reversal (a.k.a. jejunisation of the ileum) is one of the signs of celiac disease, and is seen on small bowel follow-through studies as well as CT. The pattern is one of increased number of ileal folds and reduced number of jejunal folds 1,2, and is considered positive w...
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Kirklin complex

The Kirklin complex is a combination of the Carman meniscus sign associated with a radiolucent semicircular zone surrounding the elevated ridge of the ulcer. This complex is seen in cases of gastric adenocarcinoma on barium studies. History and etymology Byrl Raymond Kirklin, (1888-1957 2) an ...
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Kirklin sign

The Kirklin sign refers to a deformity of the normal gastric bubble on an upright chest radiograph due to a mass lesion of the gastric cardia or fundus. The Kirklin sign is different from the Kirklin complex, a gastric finding on upper GI fluoroscopy. History and etymology Byrl Raymond Kirkli...
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Lateral crescent sign (inguinal hernia)

The lateral crescent sign is a useful diagnostic sign of a direct inguinal hernia on CT scan, the hernia causing compression and lateral displacement of the inguinal canal contents (ductus deferens, testicular vessels, fat, etc.) to form a semicircle of tissue that resembles a moon crescent seen...
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Lead pipe sign (colon)

The lead pipe appearance of colon is the classical barium enema finding in chronic ulcerative colitis, and is also seen with other modalities such as CT or MRI. There is a complete loss of the haustral markings in the diseased segment of the colon, appearing smooth-walled and cylindrical.  This...
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Leaping dolphin sign

The leaping dolphin sign (also known as the diaphragm muscle slip sign) may be seen in pneumoperitoneum on a supine abdominal radiograph. It represents the outlining of the diaphragmatic muscle slips by free intraperitoneal gas and usually requires a moderate to large volume of pneumoperitoneum ...
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Light bulb sign (pheochromocytoma)

The light bulb sign of an adrenal pheochromocytoma is an MRI feature of this tumor. It refers to marked hyperintensity on T2 weighted sequences, however, this finding is neither sensitive nor specific and pheochromocytomas are more often heterogeneous with intermediate or high T2 signal intensit...
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Liver overlap sign

The liver overlap sign can be seen in sigmoid volvulus wherein the sigmoid loop is seen, usually on an abdominal radiograph, ascending to the right upper quadrant and projecting over the liver shadow. In one study of 21 patients with confirmed sigmoid volvulus, the sign was present in 9 patient...
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Low attenuation lymphadenopathy

Low attenuation lymphadenopathy suggests underlying necrosis and can be seen in: metastatic carcinoma (or lymphoma) infections (tuberculous or fungal) Whipple disease celiac sprue inflammatory necrotic disorders (e.g. Kikuchi-Fujimoto disease) extra adrenal myelolipoma See also lymphaden...
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Lucent liver sign

The lucent liver sign is represented by a reduction of hepatic radiodensity on supine radiograph when there is a collection of free intraperitoneal gas located anterior to the liver.
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Mercedes-Benz sign (gallbladder)

In the gallbladder, the Mercedes-Benz sign describes a star-shaped pattern of gas-fissuring within gallstones initially described on an abdominal radiograph 2. Fissures, usually fluid-filled, are present in close to 50% of gallstones. Less than half of these fissured gallstones contain some amo...
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Moulage sign (bowel)

The moulage sign is related to sprue, in particular celiac disease. It occurs where there is a dilated jejunal loop with complete loss of jejunal folds 1. It is said to appear like a tube into which wax has been poured. History and etymology Moulage (French: casting/molding) is the art of appl...
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Mushroom cap sign

Mushroom cap sign is one of the important signs of deep rectosigmoid endometriosis seen on T2 weighted MRI sequence. It indicates the submucosal involvement in the rectosigmoid colon. The hypertrophic muscularis propria appears as heterogeneous low signal intensity surrounded by the high signal...
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Mushroom sign (pyloric stenosis)

The mushroom sign (also called umbrella sign) is a radiological sign described in pyloric stenosis on barium examination. This sign refers to the impression made by the hypertrophic pylorus on the duodenal cap. See also shoulder sign cervix sign of pyloric stenosis target sign of pyloric st...
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Neuhauser sign (distal ileum)

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 ileocecal valve or with small-bowel follow-through. Although classically described with m...
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Northern exposure sign

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.
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Esophageal intubation

Esophageal intubation refers to the incorrect placement of an endotracheal tube in the esophagus. Within minutes its consequences can be catastrophic with the seriousness of its outcome depending largely on the timeliness of its diagnosis. Epidemiology Accidental esophageal intubation can happ...
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Periportal free gas sign

The periportal free gas sign has been described as being strongly suggestive for upper gastrointestinal hollow viscus perforation. See also bowel perforation (summary) pneumoperitoneum
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Peritoneal stripe sign (pneumoperitoneum)

The peritoneal stripe sign in abdominal ultrasonography is considered indicative of intraperitoneal free air, present in pneumoperitoneum. Free air in the abdomen will collect in an anti-dependent manner, typically the anterior prehepatic space in the supine patient, settling against the parieta...
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Polo mint sign (venous thrombosis)

The polo mint sign is a description given to a venous thrombosis on contrast-enhanced CT imaging.  When viewed in the axial plane, a thin rim of contrast persists around a central filling defect due to thrombus. This gives an appearance like that of the popular UK mint sweet, the Polo (figure 1)...
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Pseudokidney (intussusception)

The pseudokidney of intussusception is an ultrasound finding 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 which is dragged into the intussusception, co...
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Pseudovein sign (bowel)

The pseudovein sign can occur with active gastrointestinal bleeding where contrast extravasation during angiography may have a curvilinear appearance as it pools in the gastric rugae or mucosal folds of bowel, mimicking the appearance of a vein. However, contrast in the “pseudovein” persists bey...
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Psoas sign (abdominal x-ray)

The psoas sign is a classic non-specific finding on the abdominal radiograph, potentially representing retroperitoneal pathology. Normally on an abdominal radiograph, the lateral margins of both the psoas muscles are clearly visible due to adjacent fat. When the lateral edge of one, or both, ps...
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Pyrexia

Pyrexia (or fever) is a clinical sign, indicated by an abnormally elevated core body temperature, which is defined by several medical societies as ≥38.3°C (≥101°F). The temperature elevation may be persistent or episodic. The commonest cause of fever is infection, in one study of hospital inpati...
Article

Rat-tail sign (esophagus)

The rat-tail sign is used to refer to the tapering of the inferior esophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the ​bird beak sign (esophagus). 
Article

Reverse figure 3 sign (esophagus)

The reverse figure 3 sign (also known as the E sign) is seen on barium swallows in patients with a coarctation of the aorta and is the medial equivalent of the figure 3 sign seen on plain chest radiographs. It is formed by prestenotic dilatation of the ascending aorta, indentation of the coarcta...
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Rigler sign (bowel)

The Rigler sign, also known as the double wall sign, is seen on a radiograph of the abdomen when the air is present on both sides of the intestine, i.e. when there is air on both the luminal and peritoneal side of the bowel wall. Pneumoperitoneum may be a result of perforation or, recent instru...
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Rigler triad (gallstone ileus)

Rigler triad consists of three findings seen in gallstone ileus: pneumobilia small bowel obstruction ectopic gallstone, usually in the right iliac fossa History and etymology It is named after Leo George Rigler, American radiologist (1896-1979) 1. Practical points Rigler triad should not ...

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