Colonic Diverticulosis

 CT shows diverticula as outpouchings from colonic wall, filled with gas or feces


image Circular muscle hypertrophy (myochosis coli) causes irregularly spaced indentations and narrowing of lumen of colon





TOP DIFFERENTIAL DIAGNOSES




• Giant sigmoid diverticulum
image Represents chronic, walled-off abscess that communicates with colonic lumen

• Diverticulitis
image Due to perforation of 1 or more diverticula


PATHOLOGY




• Etiology
image Sedentary lifestyle, high-fat, low-fiber diet predispose to diabetes, obesity, and diverticulosis among other ailments


CLINICAL ISSUES




• Affects > 50% of population > 60 years of age in USA

• Most common colonic disease in Western world 
image Diverticulosis is increasing in prevalence parallel to obesity epidemic

image Diverticulosis in patients 20-40 years old is no longer rare

• Most common signs/symptoms
image Most often asymptomatic

image Alternating constipation and diarrhea (with circular muscle hypertrophy)

image Most common cause of rectal bleeding in patients > 40 years of age

image Diverticulitis or abscess


DIAGNOSTIC CHECKLIST




• Consider
image Diverticulitis, if pericolonic fat stranding and pericolonic fluid are present

image Colon cancer if rectal bleeding is present

image
(Left) Axial NECT in a 74-year-old man with a 10-year history of obstipation presenting with lower abdominal pain shows a large amount of stool in the sigmoid colon image and a cluster of gas-filled diverticula image in the descending colon.


image
(Right) Axial CECT in the same patient illustrates the normal fat planes of the sigmoid mesocolon image and the small bowel mesentery image, without evidence of mural thickening or pericolonic stranding to suggest diverticulitis.

image
(Left) Axial CECT in a patient presenting with constipation and intermittent painful lower abdominal cramps shows thickening of the sigmoid colon wall image due to myochosis, a combination of hypertrophy of the circular muscle layer, shortening of the taeniae, and lumen narrowing.


image
(Right) Spot film from an air-contrast BE shows distortion of the colonic lumen. The luminal outpouchings image are diverticula, while the irregularly spaced infoldings of the wall image represent myochosis (circular muscle hypertrophy).


TERMINOLOGY


Synonyms




• Diverticular disease


Definitions




• Outpouching of colonic mucosa and submucosa, most commonly in sigmoid colon

• Myochosis coli is uncommonly used term to describe foreshortening of colon and circular muscle hypertrophy that commonly occurs along with diverticulosis


IMAGING


General Features




• Best diagnostic clue
image Rounded or oval colonic wall outpouchings

• Location
image Primarily sigmoid colon, but may occur in any segment except rectum
– Lack of diverticula in rectum is due to fusion of taenia providing strong supporting coat to rectal wall

• Size
image 5-10 mm in diameter

• Morphology
image Oval or rounded


Imaging Recommendations




• Best imaging tool
image CT and barium enema (BE)

• Protocol advice
image Good bowel preparation is necessary to avoid misdiagnosis of polyp vs. diverticula on air-contrast barium enema


Fluoroscopic Findings




• Contrast enema
image Diverticula project out beyond wall of colon

image Circular muscle hypertrophy (myochosis coli) causes irregularly spaced indentations and narrowing of lumen of colon

image Easier to distinguish colonic diverticula from polyps on single contrast BE than on air-contrast BE
– Diverticula fill with barium on single contrast BE

– Diverticulum with large neck; may resemble sessile polyp on air-contrast BE

– May cause “bowler hat” sign
image If “bowler hat” points to lumen, polyp likely

– Air-filled diverticula project out from bowel lumen

– Appearance of diverticula varies depending on degree of air vs. barium in diverticulum


Radiographic Findings




• Radiography
image “Bubbly” appearance of sigmoid in 50% of cases
– Associated with calcified pelvic phleboliths

image Diverticula arise adjacent to taenia coli
– Weakness in bowel wall due to penetration of vasa rectae


CT Findings




• Outpouchings (diverticula) filled with air, stool, or contrast agent

• Mural thickening due to myochosis (circular muscle hypertrophy) usually > 4 mm 
image Causes irregular narrowing of colonic lumen

• No pericolonic fluid, gas, or fat stranding

Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Colonic Diverticulosis
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