Gastrointestinal

Gastrointest Radiol 9:263-268 (1984)

Radiology 9 Springer-Verlag 1984

Computed Tomography of Diverticulitis George Pillari 1' 3, Bernard Greenspan 1' 3, Frances M. Vernace 1' 3, and Gilbert Rosenblum 2 Departments of i Radiology, and 2 Medicine, Long Island Jewish-Hillside Medical Center, New Hyde Park, New York, and 3 State University of New York at Stony Brook, Stony Brook, New York, USA

Abstract. Six cases of diverticulitis were studied by means of pelvic computed tomography (CT) and contrast enema. CT is effective in defining the intramural and extracolonic component of diverticulitis; abscess formation in the extracolonic space resulted in consistent changes in the contour of the opacified urinary bladder. Inflammatory extracolonic masses were imaged on CT as low or mixed-attenuation lesions frequently containing pockets of gas. Bladder wall thickening and edema, as well as contour asymmetry of the opacified and distended bladder, were reliable indicators of pericolonic or extracolonic extension of diverticular disease. Contrast enema and sigmoidoscopy are inherently limited in the evaluation of diverticulitis; CT of the pelvis reveals secondary changes outside the mucosa and bowel wall, CT directly images the inflammatory mass and associated changes in pelvic anatomic relationships. CT findings of pelvic inflammatory mass are not specific for abscess of diverticular origin; however, CT interpretation is reliable and confident since it is directed by the supporting findings on contrast enema. Integrated study by CT and contrast enema effectively defines the extent of disease in patients with diverticulitis. Summary evaluation of these studies has a serious impact on the choice of medical or surgical management.

Key words: Diverticulitis - Cross-sectional imaging - Computed tomography Pelvis - Inflammatory bowel disease.

The efficacy of computed tomography (CT) applied to the study of hollow organs has been estabAddress reprint requests to: George Pillari, M.D., Department

of Radiology, Long Island Jewish-Hillside Medical Center, New Hyde Park, NY 11042, USA

lished in several recent reports. Cross-sectional images are useful in the evaluation of the stomach, colon, and urinary bladder. Previous reports recognize that CT in the study of hollow organs is limited and complementary to conventional examinations such as gastrointestinal series and contrast enema [1-14]. In the present report we note the complementary, but essential, role of CT in 6 cases of diverticulitis.

Case Reports Case 1 A 65-year-old woman entered the hospital because of urinary frequency and urgency; she also reported seeing fecal material in the urine. Urinary cultures were positive for E. coli and Enterococcus and the white blood cell count was 11,000 mm 3. Barium enema revealed the presence of diverticula with extraluminal tracking and barium collection in the extracolonic space (Fig. 1 A). Sigmoidoscopy showed mucosal changes consistent with diverticulitis, but failed to demonstrate a fistulous communication. CT study demonstrated a large left paravesical mass of mixed attenuation. Irregular thickening of the bladder wall, edematous changes, and the presence of free air in the ventral aspect of the bladder confirmed the presence of pericolonic and paravesical abscess with fistulous communication (Fig. 1 B). Findings were also confirmed at surgery; the abscess was resected and drained and a colostomy performed.

Case 2 A 58-year-old woman with a 5-year history of myelofibrosis complained of crampy suprapubic pain, fatigue, night sweats, and fever of 102 ~ F of i-day's duration. Barium enema showed diverticula and contrast extravasation in the pericolonic region in the midsigmoid colon (Fig. 2A). CT study of the pelvis revealed bladder asymmetry with encroachment on the left posterolateral aspect of the bladder by a mass of mixed attenuation (Fig. 2 B). Noteworthy within the mass were gas pockets. Displacement of the air-filled rectum to the left was noted. The patient was treated surgically by means of abscess and sigmoid resection and diverting colostomy.

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Fig. 1. A Contrast enema: diverticulitis in midsigmoid colon with barium extravasation into the extracolonic space; associated midsigmoid spasm is present. B Pelvic CT study demonstrates mass of mixed attenuation in the left paravesical region with notable contiguous bladder wall edema and irregularity. Air within the ventral aspect of the urinary bladder confirms fistulous communication Fig. 2. A Extracolonic extravasation of barium during barium enema; diverticula are demonstrated in the sigmoid colon. B Mass density with pockets of gas encroaches on the left lateral and posterior margin of the opaque urinary bladder. Nonspecific edematous changes about the posterolateral bladder wall are consistent with edema and bladder wall thickening secondary to diverticulitis and extracolonic abscess

Case 3 A 45-year-old man was admitted because of poorly localized suprapubic pain associated with chills and fever of 102 ~ F of 2 day's duration. On rectal examination a tender mass was palpated anterior to the upper margin of the rectum; white blood cell count was 19,000 mm 3. Sigmoidoscopy showed pus and mucosal inflammatory change in the mid- and distal sigmoid colon. Diverticulitis was suspected and the first examination performed was a CT of the pelvis. CT study showed a mass of mixed attentuation within which pockets of gas were demonstrated. The mass encroached on the posterior left lateral margin of the urinary bladder (Fig. 3 A). The bladder wall-mass

junction was poorly marginated, suggesting considerable urinary bladder wall edema. Contrast enema showed diverticula throughout the distal and midsigmoid colon with fine spiculation of the mucosal pattern. On evacuation study, an extracolonic collection of barium was demonstrated originating from the midsigmoid colon (Fig. 3B, C). The patient was treated surgically by means of a diverting colostomy and resection of the abscess.

Case 4 A 48-year-old man complained of lower abdominal and rectal pain with associated constipation of 3 weeks duration. Physical

G. Pillari et al. : CT of Diverticulitis

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examination revealed guarding and tenderness in the lower abdomen. No masses were palpable. Results of a rectal examination were unremarkable. Sigmoidoscopy confirmed inflammatory mucosal changes and diverticula in the sigmoid colon. Barium enema study showed numerous diverticula through the proximal and midsigmoid colon. There was no evidence of contrast intravasation or extravasation about the colon wall. CT scan clearly showed an irregularly marginated mass indenting the contrast-opacified urinary bladder in its posterior right margin (Fig. 4). The mass contained numerous pockets of gas. The patient has been managed effectively on antibiotic therapy over a follow-up period of 6 months. The patient has refused a follow-up CT scan.

Case 5 A 57-year-old alcoholic man was admitted to the hospital because of generalized weakness and an 88-kg weight loss over 1 year. On physical examination the abdomen was soft and not tender; results of rectal examination were negative. The white blood cell count was 3,800 mm a hemoglobin9.6 g, and hematocrit 29.3%. Urine culture was strongly positive for E. coli. Barium enema study showed immediate contrast extravasation about the sigmoid colon (Fig. 5A). Diverticula were numerous through the distal and midsigmoid colon. Sigmoidoscopy confirmed inflammatory changes and pus about the wall of the mid- and distal sigmoid colon consistent with diverticulitis. CT scan showed a paravesical mass with displacement of the opaque bladder from left to right in its lateral and posterior margins left side. Extravasated barimn was visualized within the mixed-attenuation paravesical and prerectal mass (Fig. 5 B).

Case 6 A 46-year-old man complained of aching pain in the pubic and suprapubic region of 2 week's duration. The patient had an associated low-grade fever of 100 ~ to 101~ and urinary frequency for 2 weeks prior to admission. Following contrast

Fig. 3. A Pelvic CT examination describes mass of mixed attenuation with pockets of gas encroaching on the left lateral and posterior margins of the urinary bladder. Associated bladder wall edema is reflected by the poorly marginated bladder wallmass junction. B Contrast enema: marked spasm in the midsigmold colon occurs with associated intramural tracking of barium and fine spiculation of intramural barium collections. C Lateral view of barium enema. Presigmoid and prerectal collection of barium in the extracolonic space is demonstrated on evacuation study

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Fig. 4. CT of the pelvis reveals gas-containing mass which is poorly marginated and intruding on the mid and right posterior bladder wall. Posterior bladder wall contour is sharply interrupted by inflammatory mass and associated bladder wall edema Fig. 5. A Barium enema: immediate contrast extravasation is present about the mid- and distal sigmoid colon. Diverticula are seen in association with colon wall irregularity and edema. Intramural tracking is also demonstrated. B CT scan of the pelvis shows marked distortion of the left lateral and posterior bladder wall contour; the bladder is displaced from left to right by a mixed-attenuation mass which contains barium. Bladder wall-mass junction is markedly irregular, with advanced bladder wall thickening and edema Fig. 6. A Barium enema: midsigmoid colon spasm is secondary to segmental diverticulitis with associated extravasation of barium in the pericolonic space. B Pelvic CT scan demonstrated left paravesical mass of mixed attenuation containing pockets of gas. Bladder wall contour distortion is secondary to edema and thickening

G. Pillari et al. : CT of Diverticulitis administration during barium enema, the patient experienced severe lower abdominal cramps and pain in the suprapubic area; marked spasm was visualized through the midsigmoid and numerous diverticula were demonstrated in the midsigmoid colon. Intramural and pericolonic extravasation of barium was present (Fig. 6A). CT study showed a mixed-attenuation mass encroaching on the left lateral and posterior aspect of the opacifled urinary bladder. Bladder wall thickening and edema were present; pockets of gas were seen within the mass (Fig. 6B). Findings on contrast enema and CT scan were confirmed by sigmoidoscopy performed at admission and 1 month after treatment. The patient has been treated with antibiotics with a good clinical response over a 2-month follow-up period. Follow-up contrast enema and CT scan are planned.

Discussion

The extraluminal component of diverticulitis is demonstrated on contrast enema only in the presence of intramural or extramural collections of contrast and by signs of extrinsic bowel contour distortion or compression. Contrast enema illustrates mucosal changes such as spiculation and ulceration. Spasm and associated pain on filling the inflamed segment are helpful diagnostic signs in diverticulitis, but are seriously limited in the evaluation of pericolonic changes, specifically peri- or extracolonic abscess formation. The limitations of sigmoidoscopy are essentially the same as contrast enema. Both examinations provide only an indirect index of extracolonic disease, inherently limited to an "inside-out" view of the hollow organ. Cross-sectional imaging with CT adequately quantitates and characterizes the extraluminal component of diverticulitis, providing a direct image of pericolonic extension of disease (the "outside-in" view). Contour distortion of the opaque distended urinary bladder was the most consistent finding on CT in the 6 cases of diverticulitis presented in this report. Asymmetry of the bladder was constant in all cases, characterized by deformity of the left lateral and/or posterior bladder wall. The contiguous bladder mass contained areas of low attenuation frequently containing pockets of gas. Within the pelvic space, bladder wall and contour changes reflect accurately the extension of benign and malignant disease [15-17]. The junction of contrast, bladder wall, and extrinsic mass is variable and certainly not specific for abscess of diverticular origin. In fact, bladder configuration on CT is difficult to interpret as an intrinsic or extrinsic mass. However, CT interpretation is reliable and confident since it is directed by supporting findings on contrast enema and the patient's physical signs and symptoms.

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Diverticulitis is commonly insidious in onset and occult in clinical manifestation. Classification of diverticulitis as acute, subacute, or chronic is often arbitrary and lacks support from anatomic changes. Correlation of findings on contrast enema and CT scan in cases of diverticulitis more accurately defines the patient's clinical status. Contrast enema alone is seriously limited and frequently describes only mucosal and intramural disease. Essential for clinical grading and treatment planning is information regarding the pericolonic and extracolonic extension of inflammatory disease. Crosssectional study interprets changes in pelvic anatomic relationships and measures the frequently unsuspected quantity of disease outside the colon. Integrated imaging by means of contrast enema and CT study of the pelvis effectively defines the extent of disease in diverticulitis. Summary evaluation of these studies has a serious impact on the choice of medical or surgical management. Acknowledgements. The authors gratefully acknowledge the assistance of Janice Viccora in the preparation of the manuscript. We also thank Richard Matthias and Fred Liebman, Department of Audiovisual Resources.

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Received: October 18, 1983; accepted: December 4, 1983