CLASSICAL SIGNS IN GASTROINTESTINAL RADIOLOGY(PART 1 & 2)

Dr. Muhammad Bin Zulfiqar PGR IV FCPS SHL/SIMSAlnoor Diagnostic Centre

INTRODUCTION

Radiologists have established many classic imaging signs for visual manifestations of pathophysiologic processes.

The use of familiar objects to describe visual findings enables radiologists both to arrive at a correct diagnosis and to effectively convey such diagnostic findings to clinicians

The goal of this article is to review an array of classic signs associated with gastrointestinal tract pathologies whose imaging manifestations resemble everyday objects e.g. The “football” and “cobblestone” signs.

INTRODUCTION

This article organizes the gastrointestinal signs from proximal to distal within the gastrointestinal tract.

BIRD’S BEAK SIGN

The “bird’s beak” sign is a classic finding on esophagrams; it describes a dilated proximal esophagus with a smooth-tapered, distal esophagus at the level of the esophageal hiatus in the setting of achalasia.

Achalasia is further characterized by esophageal aperistalsis and failure of the lower esophageal sphincter to relax

Radiograph of the distal esophagus after oral contrast administration obtained in a patient with achalasia demonstrates marked proximal esophageal dilatation with tapering of the distal esophagus resembling a bird’s beak. Note the debris in the dilated proximal esophagus.

ACHALASIA

There are both primary and secondary forms of achalasia.

Primary achalasia, the more common etiology, is idiopathic

The lack of lower esophageal sphincter relaxation is likely due to a loss of inhibitory neurons in the esophageal myenteric plexus

ACHALASIA Proposed causes

1. Neuronal degeneration 2. Viral infection 3. Genetic inheritance 4. Autoimmune disease

ACHALASIA Secondary achalasia is much less common

Caused by1. Esophageal carcinoma2. Chagas disease.

CORKSCREW SIGN The “corkscrew” sign is the visual manifestation of

lumen-obliterating, simultaneous, nonperistaltic contractions within the esophagus

These abnormal contractions of varying amplitude occur in diffuse esophageal spasm, a rare esophageal motility disorder

Esophagram in a patient with diffuse esophageal spasm demonstrates non-peristaltic contractions within the esophagus resulting in a corkscrew appearance

DIFFUSE ESOPHAGEAL SPASM

Characterized on manometry by periods of normal peristalsis followed by simultaneous, repetitive, ineffective contractions.

These abnormal contractions segment the normal esophageal lumen, mimicking a corkscrew on barium studies of the esophagus

DOUBLE-BARREL ESOPHAGUS

The term “double-barrel esophagus” classically refers to the radiographic appearance of a dissection between the esophageal mucosa and submucosa without perforation.

The double-barrel radiographic appearance of the esophagus is due to the visualization of a barium-filled, intramural dissecting channel separated from the true esophageal lumen by a lucent line known as the mucosal stripe.

DOUBLE-BARREL ESOPHAGUS

Intramural esophageal dissection is most commonly seen in middle-aged or elderly women

This entity can occur in the setting of a 1. Coagulopathy, 2. Emetogenic injury, 3. Trauma, 4. Instrumentation, 5. Ingestion of foreign bodies6. Intramural esophageal abscess, 7. Intraluminal diverticulum8. Esophageal duplication

Esophagram demonstrates dissection of oral contrast between the esophageal mucosa and submucosa producing a double-barrel appearance

BULL’S EYE LESIONS Lesions within the stomach forming central

collections of oral contrast within ulcerated intramural masses can produce a target or bull’s eye appearance on upper gastrointestinal barium examinations

Differential diagnosis is broad and includes 1. Gastric metastatic lesions from melanoma and

lymphoma2. Kaposi’s sarcoma 3. Carcinoid tumors 4. Gastric lipomas may also ulcerate and produce a

bull’s eye appearance

Radiograph from an upper gastrointestinal series of a patient with metastatic melanoma demonstrates a bull’s eye lesion in the body of the stomach

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.

Crohn’s disease is notable for this appearance

Crohn’s disease affects the stomach and duodenum in 0.5% to 4.0% of patients

The antrum is the gastric region most frequently involved

Radiograph of the stomach following the oral administration of contrast in a patient with HIV/AIDS demonstrates somewhat tubular, conical shape of the distal stomach resembling a ram’s horn

LEATHER BOTTLE STOMACH The stiff, nondistensible wall gives the stomach a

leather bottle appearance, also known as linitis plastica

Differential diagnoses for the appearance of a leather bottle stomach include 1. Primary scirrhous adenocarcinoma of the stomach 2. Scirrhous metastases from lung, breast, colon3. Pancreatic carcinomas4. Lymphoma5. Crohn’s disease6. Sarcoidosis7. Syphilis.

LEATHER BOTTLE STOMACH Primary scirrhous adenocarcinoma of the stomach

spreads predominantly in the submucosa and muscularis propria

Scirrhous tumors constitute 5% to 15% of all gastric carcinomas

Scirrhous adenocarcinoma is thought to arise near the pylorus and spread proximally diffusely involving the entire stomach

Radiograph of the stomach following oral barium administration demonstrates a thickened, stiff wall of the stomach secondary to syphilis creating a leather water bottle-like appearance

WINDSOCK SIGN The windsock appearance is formed by passive

elongation of the intraluminal diverticulum due to continual peristalsis of the duodenum.

The windsock appearance is most commonly located in the second portion of the duodenum and consists of the barium-filled diverticulum that lies entirely within the duodenum

Appearance most commonly caused by Intraluminal Duodenal Diverticulum

WINDSOCK SIGN Intraluminal duodenal diverticulum is a rare congenital

cause of duodenal obstruction

These intraluminal diverticula are believed to arise from an improper luminal recanalization of the foregut in the 7th week of embryogenesis.

A residual tissue diaphragm may span the entire circumference of the duodenum and only allow passage of enteric contents through fenestrations

Duodenal wind sock sign in a patient with duodenal diverticulum. Image from an upper gastrointestinal series clearly demonstrates an intraluminal duodenal diverticulum (arrows) surrounded by a narrow radiolucent line (arrowheads). The diverticulum, arising in the second portion of the duodenum and extending to the third portion, was confirmed at surgery.

DOUBLE BUBBLE SIGN The “double bubble” sign represents the appearance

of 2 gas-filled structures in the upper abdomen of newborns and infants on plain films of the abdomen

The left-sided, proximal bubble is the distended gas and fluid-filled stomach.

The second, right-sided, more distal bubble is the distended duodenum.

The double bubble sign indicates the presence of duodenal obstruction that can be caused by a number of intrinsic or extrinsic etiologies

DOUBLE BUBBLE SIGN The intrinsic causes include 1. Duodenal webs 2. Duodenal atresia3. Duodenal stenosis

The extrinsic etiologies include 1. Preduodenal portal vein 2. Malrotation of the gut with a midgut volvulus 3. Ladd bands4. Annular pancreas

DOUBLE BUBBLE SIGN Duodenal atresia is the causative entity most

commonly linked with a double bubble sign.

Duodenal atresia is found in 1 in 10,000 newborns and is typically associated with other congenital anomalies

30% of children with duodenal atresia have Down’s syndrome

Plain radiograph of the abdomen in a patient with duodenal atresia creates a double bubble appearance of the stomach and duodenum

WHIRLPOOL SIGN The “whirlpool” sign is found on both cross-sectional

imaging as well as abdominal ultrasound in the presence of midgut volvulus

The whirlpool appearance represents the swirling pattern of the gut and the superior mesenteric vein as they wrap around the superior mesenteric artery (SMA) in a clockwise rotation

It is the clockwise rotation of the bowel loops that result in the whirlpool sign on cross-sectional imaging

WHIRLPOOL SIGN Embryological explanation

Normally, the midgut undergoes a 270-degree counterclockwise rotation during embryologic development.

Malrotation of the midgut represents a spectrum of developmental anomalies that result in either an insufficient or total lack of counterclockwise rotation of the midgut around the axis of the SMA.

These anomalies all lead to a shortened mesenteric base.

The shortened mesentery predisposes to volvulus that may result in bowel obstruction.

Midgut volvulus is the most common complication of malrotation of the small bowel in adults.

CT maximal intensity projection (MIP) demonstrates the whirlpool appearance of the superior mesenteric artery and vein wrapping around one another in a patient with mid-gut volvulus.

STRING OF PEARLS The “string of pearls” sign indicates the presence of a

small-bowel obstruction. This sign is also commonly referred to as the “string of beads” sign.

It represents a row of small gas bubbles oriented in a relatively linear fashion within the abdomen on plain films

STRING OF PEARLS The observed rows of gas bubbles represent gas

trapped between the valvulae conniventes of the nondependent wall of small bowel.

These loops of small bowel are dilated and filled with fluid in the setting of a small-bowel obstruction, thus the meniscal effect of the surrounding fluid gives these pockets of gas a rounded or ovoid appearance.

String of pearls sign in a patient with small-bowel obstruction (SBO). Left lateral decubitus radiograph of the abdomen demonstrates a row of small air bubbles (arrows), which represents air trapped between the valvulae conniventes.

STACK OF COINS The “stack of coins” sign typically indicates the

presence of a small-bowel hematoma

This sign is seen on plain films or MDCT images and represents adjacent, thickened folds with sharp demarcation and crowding of the valvulae conniventes

STACK OF COINS Over-anticoagulation with warfarin is the most common

cause of spontaneous intramural small-bowel hematoma

Other Causes include1. Idiopathic thrombocytopenic purpura2. Leukemia3. Pancreatitis4. Pancreatic cancer5. Hemophilia6. Lymphoma7. Myeloma8. Chemotherapy9. Vasculidites

Plain radiograph of the abdomen following the oral administration of barium to a patient with a small bowel hematoma demonstrates a stack of coins sign.

STRING SIGN

The string sign represents the marked narrowing of the terminal ileum lumen secondary to symmetric, transmural granulomatous inflammation and subsequent fibrotic thickening of the bowel wall

Bowel-wall thickening is the most common manifestation of Crohn’s disease on MDCT scans, occurring in up to 82% of patients

STRING SIGN In the setting of Crohn’s disease, the terminal ileum

often becomes markedly stenotic secondary to bowel-wall inflammation and fibrosis.

This results in the lumen of this portion of the small bowel resembling a piece of string on plain radiographs after ingestion of high-density oral contrast material

A thin line of barium is seen in the terminal ileum (long arrows), which resembles a frayed cotton string (the gastrointestinal string sign). Small mesenteric border ulceration is seen (small arrow).

RIBBON SIGN Fluoroscopic examinations performed with high-density

oral contrast material in patients with GVHD of the GI tract may demonstrate marked fold thickening, luminal narrowing, separation of folds, and ultimately complete effacement of the valvulae conniventes. The latter causes the so-called “ribbon sign”

Donor lymphoid cells damage host tissues in graft-versus-host disease (GVHD).

The organs most commonly affected by GVHD include the gastrointestinal tract, liver, and skin.

Marked bowel-wall thickening can occur both in the small and large bowel

GVHD: Graft versus host disease

RIBBON SIGN The ribbon bowel appearance can also occur with

multiple other clinical settings, such as 1. Infection2. Irradiation3. Allergy4. Ischemia5. Ingestion of corrosives or medications6. Amyloid7. Mastocytosis8. Lymphoma9. Crohn disease10. Celiac disease

Plain radiograph of a small bowel follow through in a patient with graft versus host disease illustrates marked luminal narrowing and effacement of the valvulae conniventes producing a ribbon like appearance of the small bowel

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COMB SIGN

The “comb sign” is seen in the presence of Crohn’s disease.

This sign is observed on contrast-enhanced

CT or magnetic resonance imaging (MRI) scans.

The teeth of the comb in this instance represent engorged small arteries, the vasa recta, perfusing the small bowel

COMB SIGN The vasa recta of the small bowel seen in Crohn’s

disease become tortuous and enlarged.

They appear as prominent opacities on the mesenteric side of the small bowel.

These small arteries become engorged due to increased blood flow to the inflamed small bowel and are accentuated due to the fibrofatty proliferation in the mesentery.

Contrast-enhanced CT image in a patient with Crohn’s disease demonstrating engorged vasa recta secondary to hyperemia of the bowel producing the comb sign.

TARGET SIGN The target sign is classically seen in patients with

Crohn’s disease.

This pattern of bowel wall enhancement has been observed in patients with

1. Radiation enteritis2. GVHD 3. Ischemic bowel4. Intramural hemorrhage5. Vasculitides such as Henoch-Schonlein purpura, and 6. Pseudomembranous colitis

TARGET SIGN It represents an enhancement pattern of the

bowel wall seen in various disease processes on contrast-enhanced CT or MRI scans.

This appearance is formed when a thickened bowel wall demonstrates alternating degrees of attenuation, with an inner and outer layer of higher attenuation and a middle layer of lower attenuation

TARGET SIGN The higher-attenuation inner and outer layers

represent the mucosa and muscularis propria, respectively.

The high attenuation of these layers is believed to be secondary to contrast enhancement from inflammation.

The lower attenuation middle layer is thought to be due to submucosal bowel wall edema.

Contrast-enhanced CT image of the small bowel in a patient with Crohn’s disease reveals rings of high attenuation representing the hyperemic mucosa and muscularis propria of the small bowel. The hypodense ring represents the edematous submucosa. This enhancement pattern creates the target sign.

COILED SPRING SIGN The “coiled spring” sign can be seen

anywhere in the bowel where an intussusception has occurred.

These ring shadows represent contrast reflux within the lumen between the walls of the intussusceptum and intussuscipiens

COILED SPRING SIGN Classically, this sign describes the

appearance of the cecum in the presence of appendiceal intussusception, a rare entity.

It is thought that the coiled-spring appearance results from intussusception of the cecal tip with the invaginated appendix acting as the lead point for variable amounts of cecocecal or cecocolic intussusception

Plain radiograph of the abdomen following the administration of contrast through a feeding tube in a patient who is status postgastric bypass demonstrates a coiled-spring appearance of the small bowel secondary to intussusception

ARROWHEAD SIGN This perceived arrowhead shape is secondary

to focal, symmetric thickening of the cecal wall secondary to spreading inflammation from appendicitis

The cecal wall thickening causes funneling of oral or rectal contrast material within the upper cecum, which points to the obstructed appendiceal orifice

ARROWHEAD SIGN The arrowhead sign, which is obtained after

the administration of oral and/or rectal contrast material, is seen on computed tomographic (CT) images as an arrowhead-shaped collection of contrast medium localized to the upper part of the cecum near the orifice of the appendix

Contrast-enhanced CT image in a patient with right lower-quadrant pain demonstrates arrowhead-shaped inflammatory changes of the cecal base secondary to acute appendicitis. Note the thickened appendix.

THUMBPRINT SIGN This sign is seen in roughly 75% of cases of

transient, nongangrenous ischemic colitis

Other conditions that may also produce the thumbprint sign include

1. Pseudomembranous colitis2. Ulcerative colitis3. Lymphoma4. Leukemia5. Coagulopathies

THUMBPRINT SIGN This sign describes smooth, rounded

impressions causing filling defects classically seen in barium studies of ischemic colitis.

These nodular densities represent edema and hemorrhage into the wall of the colon most commonly secondary to ischemia

Plain radiograph of the abdomen in a patient with ischemic colitis demonstrates thickening of the haustra secondary to edema and hemorrhage resulting in the appearance of multiple thumbprints in the wall of the colon

COBBLESTONE SIGN The “cobblestone sign” is classically seen

within the small and large bowel on fluoroscopic studies in the presence of active Crohn’s disease

The cobblestone appearance of the bowel wall is due to a combination of extensive, broad, linear transverse and longitudinal ulcerations within an inflamed mucosal surface. Only scattered islands of normal mucosa remain in this setting

Radiograph of a small bowel follow-through in a patient with Crohn’s disease demonstrates scattered islands of normal intestinal mucosa adjacent to multiple ulcerations resulting in the cobblestone appearance of the distal ileum

BOWLER HAT SIGN The “bowler-hat sign” represents the

appearance of a sessile colonic polyp on a double contrast barium enema

A colonic diverticulum can partially fill with barium and also produce a bowler hat appearance

BOWLER HAT SIGN The bowler-hat sign is formed by a ring of

barium adjacent to the base of the polyp surrounding a domed layer of barium coating the surface of the polyp

The orientation of the dome of the bowler hat sign can help differentiate a polyp from a diverticulum.

An intraluminal polyp will result in a bowler-hat sign with its dome pointed inward toward the lumen, while a diverticulum will produce a bowler hat sign pointed outward

Magnified view of the sigmoid colon demonstrates " the bowler hat sign" of the mid-sigmoid sessile polyp seen obliquely (arrowhead) and diverticula en face (arrow).

MEXICAN HAT SIGN Pedunculated colonic polyps form the “Mexican

hat sign”

The Mexican hat sign is formed by the appearance of 2 concentric rings

The outer ring represents the “en face” visualization of barium coating the surface of the head of a pedunculated polyp, while

The inner ring represents a meniscus of barium surrounding the stalk of the polyp visualized through the head

Radiograph of an upper gastrointestinal series demonstrates a pedunculated gastric polyp demonstrating a close resemblance to a Mexican hat.

COLLAR BUTTON SIGN “Collar button ulcers” are manifestations of

inflammatory processes within the bowel.

These deep ulcerations are classically seen in the colon associated with active ulcerative colitis

However they have also been observed in the setting of other inflammatory bowel processes, such as

1. Crohn’s disease 2. Ischemic colitis3. Shigellosis

COLLAR BUTTON SIGN The collar button appearance is formed by

mucosal ulceration with associated undermining of the ulcer’s edge by lateral submucosal extension

Vertical penetration into the bowel wall is limited due to the resistance of the underlying muscularis mucosa, thus resulting in the discoid collar button appearance of these ulcers

Radiograph from a single contrast barium enema in a patient with active ulcerative colitis shows a deep ulcer within the descending colon that demonstrates a collar button appearance

APPLE CORE SIGN The apple core sign is classically seen in cases of

colon carcinoma

This appearance is most commonly located in the sigmoid colon as well as in the ascending, transverse, and descending colon.

The apple core sign is not seen in the larger-caliber cecum.

APPLE CORE SIGN The differential diagnosis of a lesion with an

apple core appearance is 1. Focal diverticulitis2. Ischemic colitis 3. Ulcerative colitis 4. Endometriosis5. Amebiasis6. Serosal metastatic implants7. Infectious colitis

APPLE CORE SIGN The apple core appearance is the visual

manifestation of an annular lesion of the bowel with irregular overhanging edges and shouldered margins

Fluoroscopic image from a double contrast barium enema in a patient with changing bowel habits reveals an annular lesion with overhanging edges within the colon closely resembling an apple core.

ACCORDION SIGN The “accordion sign” describes the

appearance of colonic wall thickening in the setting of colitis

The accordion sign has also been observed with

1. colonic edema secondary to cirrhosis 2. Crohn’s disease3. Ischemic colitis4. Lupus vasculitis5. Infectious colitis.

ACCORDION SIGN This sign describes the appearance of

alternating, edematous haustral folds that are due to transmural edema and are separated by transverse mucosal clefts filled with oral contrast .

Oral contrast is trapped between thickened, edematous colonic folds and pseudomembranes in the setting of C. difficile-induced pseudomembranous colitis

White oval highlights markedly thickened bowel wall with oral contrast trapped between haustral folds in a patient with known C difficle colitis. This is the "accordion sign."

LEAD PIPE SIGN The lead pipe appearance of the colon is

classically seen with chronic, smoldering ulcerative colitis.

The differential diagnosis for a lead pipe appearance of the colon includes

1. Crohn’s disease2. Tuberculosis3. Amebiasis

LEAD PIPE SIGN The lead pipe appearance likely represents

the visual manifestation of multiple pathophysiological processes

There is increased regeneration of the colonic mucosa in ulcerative colitis.

This mucosal regeneration may lead to hypertrophy of the muscularis mucosae.

Contraction of this hypertrophic muscle layer gives the colon the lead pipe-like narrowed, ahaustral, and foreshortened appearance

Radiograph from a double contrast barium enema in a patient with chronic, smoldering ulcerative colitis demonstrates an ahaustral, pipe-like appearance of the colon

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