1. Apple core sign
- Apple core sign - describes a short segment irregular circumferential stricture of the large bowel that has abrupt "shouldered" margins resembling an apple core.
- The appearance is classically described on contrast enema studies.
- The appearance is most commonly located in the sigmoid colon as well as in the ascending, transverse, and descending colon. The apple core sign is classically seen in cases of colon carcinoma.
- The differential diagnosis are Focal diverticulitis, Ischemic colitis, Ulcerative colitis and Infectious colitis.
Fig. 1: Apple core sign- Contrast study showing the appearance of an annular constricting carcinoma of the colon, from circumferential involvement of the lumen.
References: http://casesjournal.com/casesjournal/article/view/7275
2.Accordian sign
- The accordion sign is described as alternating edematous haustral folds separated by mucosal ridges filled with oral contrast material in CT abdominal study.
- The sign is due to the marked degree of colonic wall thickening caused by the pseudomembranes and edematous tissues that develop in Clostridium difficile colitis.
- The differential diagnosis are Cirrhosis with colonic edema and Ischemic colitis.
Fig. 2: Accordion sign- Markedly thickened bowel wall with oral contrast trapped between haustral folds in a Pseudomembranous colitis.
References: Case courtesy by Dr Maxime St-Amant,Radiopaedia.org,rID: 20366.
3.Arrowhed sign
- The arrowhead sign, which is obtained after the administration of oral contrast material, is seen on CT images as an arrowhead shaped collection of contrast medium localized to the upper part of the cecum near the orifice of the appendix.
- The cecal wall thickening causes funneling of oral contrast material within the upper cecum, which points to the obstructed appendiceal orifice.
Fig. 3: Arrowhead sign- Arrowhead shaped inflammatory changes of the cecal base secondary to acute appendicitis.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 2-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
4. Bird's beak sign
- Bird's beak sign describes a dilated proximal esophagus with a smooth-tapered, distal oesophagus (short segment tapering) at the level of oesophageal hiatus, resembling bird's beak- Achalasia.
- The differential diagnosis are Oesophageal malignancy commonly referred to as pseudoachalasia.
Fig. 4: Bird’s Beak sign - contrast study showing appearance of achalasia like a smooth tapering of the gastro-oesophageal junction.
References: Chakraborty, A., Ayoob, A. & DiSantis, D. Abdom Imaging (2015) 40: 3338.
5.Bull's eye lesions
- Lesions within the stomach forming entral collections of oral contrast within ulcerated intramural masses can produce a target or bull's eye appearance on upper gastrointestinal barium examinations.
- The differential diagnosis are gastric metastatic lesions from melanoma, lymphoma, Kaposi's sarcoma and carcinoid tumors.
Fig. 5: Bull's eye sign- A small pit of barium contained within an ulcer cavity in the body of the stomach.
References: Case courtesy by Dr Ian Bickle,Radiopaedia.org,rID: 19519.
6.Bowler hat sign
- This sign represents the appearance of a sessile colonic polyp observed at an oblique angle on a double contrast barium enema.
- It is formed by a ring of barium seen adjacent to the base of the polyp surrounding a domed layer of barium coating the surface of the polyp.
- An intraluminal polyp will result in a bowler hat sign with its dome pointed inward towards the lumen, while a diverticulum will produce a bowler hat sign pointed outwards.
Fig. 6: Bowler hat sign- Double contrast study showing cup-shaped filling defects that pointed inward towards the lumen.
References: Miller Jr WT, Levine MS, Rubesin SE, Laufer I. Bowler-hat sign: a simple principle for differentiating polyps from diverticula. Radiology. 1989 Dec;173(3):615-7.
7.Collar button sign
- Collar button ulcers are manifestations of inflammatory processes within the bowel.
- These deep ulcerations are classically seen in colon associated with active ulcerative colitis.
- It is formed by the mucosal ulceration with associated undermining of the ulcer’s edge by lateral sub-mucosal extension.
- However they have also seen in Crohn's disease and Ischemic colitis.
Fig. 7: Collar button sign- Contrast barium enema shows mucosal ulceration with associated undermining of the ulcer's edge by lateral submucosal extension.
References: Starcevic, V., Myers, D.T. & Williams, T.R. Abdom Radiol (2018) 43: 3536.
8.Cobblestone sign
- This sign is typically seen in the small and large bowels on fluoroscopic studies in the presence of active Crohn’s disease.
- The cobblestone appearance of the bowel wall is due to the combination of extensive, broad, linear transverse and longitudinal ulcerations within an inflamed mucosal surface. Only scattered islands of normal mucosa remains to form this sign.
Fig. 8: Cobblestone sign- Small bowel follow through shows scattered islands of normal intestinal mucousa adjacent to multiple ulcerations in terminal ileum.
References: Leshchinskiy, S., Ali, N. & D’Agostino, R. Abdom Radiol (2018) 43: 3532.
9.Comb sign
- The vasa recta of the small bowel seen in Crohn's Disease become tortuous and enlarged.
- The increased number of visible vessels on the mesentery of the affected segments of the small bowel gives the resemblance of teeth comb.
- These small arteries become engorged due to increased blood flow to the inflamed small bowel and are accentuated due to the fibrofatty proliferation of the mesentery.
Fig. 9: Comb sign- CECT image shows engorged vasa recta secondary to hyperemia of the bowel forms the comb sign.
References: http://www.svuhradiology.ie/case-study/comb-sign-target-sign-crohn-disease/
10.Coiled spring sign
- It is described by concentric ring shadows in a barium-filled cecum with a central filling defect.
- This sign describes the appearance of the cecum in the presence of appendiceal intussusception, a rare entity.
- These ring shadows represent contrast reflux within the lumen between the walls of the intussusceptum and intussuscipiens.
Fig. 10: Coiled spring sign- Plain radiograph of the abdomen following the administration of contrast through feeding tube demonstrate a coiled spring appearance of the small bowel secondary to intussusception.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 2-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
11.Corkscrew sign
- The corkscrew sign describes the spiral appearance of the distal duodenum and proximal jejunum seen in midgut volvulus.
- It is the visual manifestation of the lumen obliterating, simultaneously, non-peristaltic within the esophagus.
Fig. 11: Corkscrew sign- describes the spiral appearance of the distal duodenum and proximal jejunum in the setting of midgut volvulus on contrast studies.
References: Case courtesy by Dr Andrew Dixon,https://radiopaedia.org/blog/corkscrew-sign-of-midgut-volvulus?lang=us
12.Double-barrel esophagus
- This sign describes the appearance of a dissection between esophageal mucosa and submucosa without perforation.
- The double-barrel radiographic appearance is due to the visualization of barium filled, intramural dissecting channel separated from the true esophageal lumen by a lucent line known as the mucosal stripe.
- This sign can also occur in coagulopathy and trauma.
Fig. 12: Double-barrel esophagus- Contrast study demonstrates dissection of oral contrast between the esophageal mucosa and submucosa without perforation.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 1-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
13.Double bubble sign
- This sign represents the appearance of 2 distended gas and fluid-filled stomach and duodenum.
- The double bubble sign indicates the presence of duodenal obstruction that can be caused by duodenal web or atresia or stenosis and extrinsic factors include malroatation of the gut with midgut volvulus or annular pancreas.
Fig. 13: Double Bubble Sign- abdominal radiography showing two air-filled structures in the upper abdomen, with no air distally. The proximal bubble in the left side filled with air represents the stomach and the second bubble to the right of the midline represents the proximal duodenum.
References: Case courtesy by Dr Tamsir Rongpipi,Radiopaedia.org,rID: 72590.
14.Lead pipe sign
- This sign is due to increased regeneration of the colonic mucosa in ulcerative colitis which leads to hypertrophy of the muscularis mucosae causing lead pipe like narrowed, loss of haustral marking and foreshortened appearance of colon.
- Classically seen in chronic ulcerative colitis.
- The differential diagnosis includes Crohn's disease, tuberculosis,Amebiasis.
Fig. 14: Lead pipe sign— Abdominal X-ray showing narrowed and ahaustral segment of the colon.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 2-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
15. Leather bottle stomach
- Primary scirrhous adenocarcinoma of the stomach spreads in the submucosa and muscularis propria.
- The thickened, stiff, nondistensible gastric wall gives the stomach a leather bottle appearance also known as linitis plastica.
- The differential diagnosis includes Scirrhous metastases and Crohn's disease
Fig. 15: Leather bottle stomach- Radiograph of the stomach following oral barium demonstrates thickened, stiff, nondistensibe gastric wall gives the stomach a leather bottle appearance.
References: Case courtesy by Dr Chris O'Donnell,Radiopaedia.org, rID:18189.
16.Mexican hat sign
- Pedunculated colonic polyps form the Mexican hat sign.
- The Mexican hat sign is formed by the appearance of 2 concentric rings.
Fig. 16: Mexican hat sign- Radiograph of an upper GI demonstrates 2 concentric rings. The outer ring formed by barium coating the surface of the head of pedunculated polyp and inner ring represents a meniscus of barium surrounding the stalk of the polyp.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 2-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
17.Ram's horn
- The unusual shape of the stomach resembling the horn of the ram is due to combination of gastric deformity causing a tubular shape, conical narrowing and limited distensibility of the stomach seen in Crohn's disease.
- It affects the antrum of the gastric region more frequently.
Fig. 17: Ram's horn sign- Radiograph of the stomach following oral contrast shows tubular,conical shape of the distal stomach resembling a ram's horn.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 1-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
18.Ribbon sign
- In patients with GVHD of the GI tract in fluoroscopic examination may demonstrate marked fold thickening, luminal narrowing, separartion of folds and ultimately complete effacement of the valvulae conniventes called as ribbon sign.
- It can also occur in infection,ischemia,Crohn's and celiac disease.
Fig. 18: Ribbon sign- Marked luminal narrowing and effacement of the valvulae conniventes producing a ribbon like appearance of the small bowel.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 1-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
19.Stack of coins
- This sign typically indicates small bowel hematoma and represent adjacent, thickened folds with sharp demarcation and crowding of the valvulae conniventes.
- The most common cause is over anticoagulation with warfarin others include Idiopathic thrombocytopenic purpura,leukemia and pancreatitis.
Fig. 19: Stack of coins- Radiograph of the abdomen following oral contrast represent adjacent,thickened folds with sharp demarcation and crowding of the valvulae conniventes.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 1-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
20.String of pearls
- This sign typically indicates small bowel obstruction.
- It represents a row of small gas bubbles oriented in a relatively linear fashion within the abdomen on plain films.
Fig. 20: String of pearls- Left lateral decubitus radiograph of the abdomen shows a row of small air bubbles,represents air trapped between the valvulae conniventes.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 1-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
21.String sign
- In Crohn's disease the terminal ileum often becomes markedly stenotic secondary to bowel wall inflammation and fibrosis, this resembles a piece of string on barium enema study.
Fig. 21: String sign- A thin line of barium is seen in the terminal ileum and also small mesenteric border ulceration noted.
References: https://pubs.rsna.org/doi/pdf/10.1148/radiol.2422041244
22.Thumbprint sign
- This sign describes smooth, rounded impressions causing filling defect classically seen in barium studies of Ischemic colitis.
- These nodular densities represent edema and hemorrhage into the wall of the colon.
- This sign can also seen in Ulcerative colitis,lymphoma and leukemia.
Fig. 22: Thumbprint sign- Thickening of the haustra secondary to edema and hemorrhage resulting in multiple thumbprints in the wall of colon.
References: Moishe Liberman MD, Chris Labos, Jeff Wiseman MD.https://www.mja.com.au/journal/2003/179/2/bowel-wall-thumbprinting-pseudomembranous-colitis
23.Target sign
- Target sign is classically seen in Crohn's disease.
- It represent an enhancement pattern of bowel wall in CECT, it is formed by thickened bowel wall with hyperdense inner and outer layer and hypodense middle layer.
Fig. 23: Target sign- Hyperdense ring represents the hyperemic mucosa and muscularis propria of the small bowel. The hypodense ring represents the edematous submucosa.
References: http://www.svuhradiology.ie/case-study/comb-sign-target-sign-crohn-disease/
24.Windsock sign
- This appearance is most commonly located in 2nd portion of the duodenum consists of barium filled diverticulum that lies within the duodenum.
- Intraluminal duodenal diverticulum is rare congenital cause of duodenal obstruction.
Fig. 24: Windsock sign- Intraluminal duodenal diverticulum surrounded by narrow radiolucent line.
References: Baldwin M, Genant J, Braver J, Mortele KJ. Part 1-Classic signs in gastrointestinal radiology. Applied Radiology. 2011;40(12):22
25.Whirlpool sign
- It represents the swirling pattern of the gut and the superior mesenteric vein as they wrap around the superior mesenteric artery.
- This sign is seen in midgut volulus.
Fig. 25: Whirlpool sign- superior mesenteric artery and vein wrapping around one another in mid-gut volvulus.
References: Case courtesy by Dr Laughlin Dawes,Radiopaedia.org, rID:8490.