Ulcerative Colitis

 Terminal ileum affected in minority of patients



• Toxic megacolon
image Colon is dilated with loss of fold and mucosal pattern

image Ascites is common ± pneumatosis, pneumoperitoneum




TOP DIFFERENTIAL DIAGNOSES




• Granulomatous colitis (Crohn disease)

• Infectious (including Clostridium difficile) colitis
image D egree of mucosal enhancement  and  submucosal edema is usually greater than seen in ulcerative colitis

• Ischemic colitis
image Rectum is almost always spared in ischemic colitis

• Cathartic colon

• Neutropenic enterocolitis

• Diverticulitis


PATHOLOGY




• Associated pathology
image Greater risk of colorectal cancer in UC than Crohn colitis
– Multiple carcinomas in 25% of UC cases

image Primary sclerosing cholangitis, uveitis

image Ankylosing spondylitis, rheumatoid arthritis


CLINICAL ISSUES




• Most common signs/symptoms
image Relapsing bloody mucus diarrhea

image Fever, weight loss, abdominal pain and cramps

• Initial onset: 15-25 years (small peak at 55-65 years)

• Begins in rectum with proximal continuous extension to part or all of colon


DIAGNOSTIC CHECKLIST




• Consider UC in any patient with sclerosing cholangitis

• Consider other causes of colitis, especially infectious and Crohn disease

image
(Left) Graphic illustration demonstrates innumerable “collar button” ulcers and a loss of haustra throughout the descending and sigmoid colon.


image
(Right) Single-contrast barium enema shows innumerable “collar button” ulcers image and loss of haustra throughout the descending colon.

image
(Left) This 51-year-old woman has an acute flare of chronic ulcerative colitis. Coronal CECT shows pancolitis with mucosal hyperenhancement and submucosal edema image, with blunted transverse folds image.


image
(Right) Axial CT in the same patient shows the mucosal hyperenhancement and submucosal edema image. Note the prominent vessels image supplying the inflamed colon.


TERMINOLOGY


Abbreviations




• Ulcerative colitis (UC)


Definitions




• Chronic, idiopathic, diffuse, inflammatory disease primarily involving colorectal mucosa


IMAGING


General Features




• Best diagnostic clue
image Distal or pancolitis with mucosal hyperenhancement and only moderate submucosal edema

• Location
image Rectum only (30%), rectum and distal colon colon (40%), pancolitis (30%)
– Terminal ileum affected in minority of patients

• Morphology
image Moderate wall thickening and luminal narrowing in acute phase

image Foreshortened and ahaustral colon in chronic phase
– Described as “lead pipe” or “windowpane”


Fluoroscopic Findings




• Barium enema
image Acute
– Colorectal narrowing, incomplete filling (spasm + irritability)

– Fine mucosal granular pattern (edema/hyperemia)

– Mucosal stippling: Punctate barium collections and ulcers due to mucosal erosion and crypt abscesses

– Flask-shaped “collar button” ulcers 
image Ulcers may progress to widespread mucosal sloughing

image Residual or hyperplastic mucosa may appear as pseudopolyps

– Thickened transverse folds due to submucosal edema

image Chronic
– Shortened, less redundant colon

– “Lead pipe” or “windowpane” colon

– Blunted or complete loss of transverse folds

– Luminal narrowing and widened presacral space > 1.5 cm

– Benign or malignant strictures


CT Findings




• CECT
image Target or halo sign
– Enhancing inner ring of bowel wall (mucosa)

– Nonenhancing middle ring of bowel wall (submucosa)

– Enhancing outer ring of bowel wall (muscularis propria and serosa)

image Enhancement of mucosal islands or inflammatory pseudopolyps

image Wall thickening generally < 10 mm

image Perirectal fibrofatty proliferation and narrowing of rectal lumen
– Results in widening of presacral (retrorectal) space

image Toxic megacolon
– Colon is dilated, often > 8 cm (on CT, more on plain films)
image Small bowel also dilated (ileus)

– Colonic wall may be thick or thin

– Loss of normal transverse folds and mucosal pattern
image Mucosal islands or pseudopolyps may be seen

– Ascites is common ± pneumatosis, pneumoperitoneum


Imaging Recommendations




• Best imaging tool
image CECT with multiplanar reformations

image Air-contrast barium enema provides excellent depiction of colonic mucosal disease
– Rarely requested or performed in era of easy access to CT and colonoscopy


DIFFERENTIAL DIAGNOSIS


Granulomatous Colitis (Crohn Disease)




• Granulomatous colitis (GC) is transmural inflammation while UC is generally more limited to mucosa

• More often has skip lesions and involvement of small bowel

• Barium enema
image Aphthous ulcers: Shallow collection of barium in mucosal ulceration with surrounding edema

image “Cobblestoning”: Longitudinal and transverse ulcerations with paving stone appearance

image Segmental distribution: Colon and small bowel (60% of cases); isolated to colon (20% of cases)

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Rectal Prolapse and Intussusception Neutropenic Colitis (Typhlitis) Colonic Diverticulosis Biliary Cystadenocarcinoma Choledochal Cyst Crohn Disease

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Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Ulcerative Colitis

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