USEFULNESS OF CT IN PATIENTS WITH ISCHEMIC COLITIS PROXIMAL TO COLONIC-CANCER

OBJECTIVE. The purpose of this study was to assess the usefulness of C T scans for distinguishing ischemic from tumoral segments in patients with colonic carcinoma complicated by proximal bowel ischemia. MATERIA LS AND METHODS. CT scans of 20 patients with ischemic colitis proximal to obstructing colonic carcinoma were reviewed retrospectively. The c oncomitant presence of ischemia was proven on pathologic examinations in 12 patients and on barium enema studies in the remaining eight pati ents. CT scans were analyzed for the involved site and length, bowel w all thickness, enhancing pattern of both tumoral and ischemic segments , and changes in the pericolic space, The results of tumor staging on CT scans were compared with those of pathologic findings. RESULTS. Dis tinction of ischemic from tumoral segments could be made on CT in 15 ( 75%) of the 20 patients, Of the 20 patients, 18 had ischemic segments contiguously proximal to the tumoral segment, and the remaining two pa tients had a skipped zone with intervening normal mucosa. Tumoral segm ents were irregularly thickened in most patients, Maximum thickness ra nged from 0.8 to 45 cm (mean, 2.0 cm). Most often the ischemic segment was concentrically and smoothly thickened, ranging from 0.6 to 1.5 cm (mean, 1.0 cm). The tumoral segments enhanced heterogeneously in 12 p atients and enhanced homogeneously in the remaining eight, whereas isc hemic segments enhanced homogeneously in 14 (70%) patients and heterog eneously in six. On CT scans, we saw the target or double halo sign in four (20%) patients, Pericolic vascular engorgement was seen in 19 pa tients, two of whom were overstaged because pericolic vascular engorge ment was interpreted as tumor infiltration. CONCLUSION. Although CT fi ndings are not specific for certain groups of patients, they are often helpful in distinguishing tumoral from ischemic segments in patients with ischemic colitis proximal to colonic carcinoma. An understanding of this pathologic entity may increase the accuracy of CT for staging colonic carcinoma.