Rectal carcinoma: Double-contrast MR imaging for preoperative staging

PURPOSE: To evaluate and compare the imaging findings and staging of rectal carcinoma by using conventional magnetic resonance (MR) imaging, MR imagin g with an enema of superparamagnetic ferristene-based contrast material, an d MR imaging with an enema of ferristene solution plus intravenous injectio n of gadodiamide. MATERIALS AND METHODS: Twenty-nine patients (17 women, 12 men; age range, 3 9-91 years) referred with a diagnosis of rectal carcinoma were examined. An alysis of the rectal wall and staging of the tumor were performed. In all p atients, the MR imaging findings were correlated with the histopathologic f indings. RESULTS: The contrast material enema caused distention of the rectum and an intraluminal signal void, whereas the gadodiamide injection caused enhance ment of the mucosa on T1-weighted images. This enhancement enabled evaluati on of the normal rectal wall and differentiation of the mucosa, tunica musc ularis, and perirectal space, which was not possible on the nonenhanced ima ges. Double-contrast (ferristene solution plus gadodiamide) MR imaging was superior to imaging with only ferristene-based contrast material and had a sensitivity of 100%, specificity of 70%, and accuracy of 90% in distinguish ing tumor stages worse than Dukes A. CONCLUSION: Double contrast material-enhanced MR imaging enables accurate r ectal carcinoma staging, which is not possible at nonenhanced imaging.