COMPARISION BETWEEN TRANSRECTAL ULTRASONOGRAPHY AND COMPUTED-TOMOGRAPHY WITH RECTAL INFLATION OF GAS IN PREOPERATIVE STAGING OF LOWER RECTAL-CANCER

Computed tomography with rectal air insufflation was compared with tra nsrectal ultrasonography (TRUS) in 63 patients. The CT protocol involv ed pre- and postcontrast scans with 5 mm slice thickness following air insufflation in IV antiperistaltic agent. Of the patients, 79% were s canned in the prone position. Results of the preoperative examinations were compared with the histological findings. The CT examination had an accuracy rate of 74%, predicting perirectal spread with a sensitivi ty of 83% and a specificity of 62%, whereas the corresponding figures for TRUS were 83, 91 and 67%. The accuracy, sensitivity and specificit y of CT and TRUS for nodal involvement were 57, 56, 57, 66, 68 and 64% -respectively. These findings confirm that TRUS is more accurate than CT in local tumour (T) staging and in detecting nodal (N) spread. Howe ver, the appropriate CT technique shows spread of tumour outside the r ectal wall and locoregional lymph nodes with reasonable size. TRUS and CT correctly staged only 57 and 43%, respectively, of cases with noda l metastases with maximum diameter of 5 mm. TRUS sometimes overstaged perirectal growth of tumour in 7 patients, due to inflammation (5 pati ents) or incorrect positioning of the balloon in relation to the tumou r surface (2 patients).