Preoperative computed tomography staging of rectal carcinoma

Pelvic computed tomography (CT) was analyzed in 48 patients with rectal carcinoma. Air was insufflated into the rectum before CT scanning. The areas of tumor (T) and rectosigmoid lumen (L) were determined for T/L ratio. Changes of the perirectal fatty tissues on CT were classified into five patterns: shaggy, granular, linear, clubbed, and wavy appearances. The T/L ratio and changes of the perirectal fatty tissue were correlated with transmural tumor extension. When the T/L ratio was above 1, tumors were frequently classified as Dukes' staging B and C, whereas a T/L ratio above 2 suggested Dukes' C classification. Clubbed or wavy appearance in the perirectal fatty tissues suggested that the tumor extended beyond the submucosa involving the muscularis propria. These findings were very useful for surgery.