PREOPERATIVE STAGING OF RECTAL-CARCINOMA USING DOUBLE-CONTRAST MR-IMAGING - TECHNICAL ASPECTS AND EARLY CLINICAL-EXPERIENCES

Purpose: To improve preoperative staging of rectal carcinoma with MR i maging, using a double-contrast technique. Material and Methods: Imagi ng was performed in 12 patients before and after i.v. injection of Gd- DTPA and rectal administration of a superparamagnetic contrast medium, mainly containing magnetite. The diagnostic information was evaluated and compared with findings at surgery and histopathological analysis. Results: The superparamagnetic contrast medium enema caused a distens ion of the rectum and intraluminal signal void, whereas Gd-DTPA enhanc ed the mucosa in T1-weighted images. This allowed an evaluation of the normal rectal wall and separation of the mucosa, tunica muscularis an d perirectal space in all cases, which was not possible in T1- or T2-w eighted precontrast images. The rectal carcinoma could be delineated a nd tumor invasion to the rectal wall determined in all cases. The find ings in postcontrast MR corresponded with the findings at histopatholo gical examination in 11 of 12 patients. The histopathological examinat ion in one patient revealed metastases (< 1 cm) in regional lymph node s, too small to be identified in pre- or postcontrast MR images. Concl usion: Double-contrast-enhanced MR imaging allows evaluation of the no rmal rectal wall and preoperative staging of rectal carcinoma.