Prospective Evaluation of Preoperative 3 Tesla MRI in the Diagnosis of Rectal Carcinoma

Purpose: The purpose of this study was to prospectively investigate the ability of Magnetic Resonance Imaging at 3 Tesla to depict the topographical anatomical relations and tumor stage of rectal carcinoma compared to histology.

Methods: Fifteen patients with suspected or histologically confirmed adenocarcinoma of the rectum, who were referred for elective staging underwent an MRI of the pelvis. Because of stenotic and painful endoluminal tumor tissue a phased-array surface coil was used. Sagittal and transversal T1 and T2 weighted images were acquired with fast-spin-echo technique. Diagnostic quality of the images, T- and N stage and distance from anorectal margin were assessed in a prospective and blinded fashion. The results were correlated with clinical and histologic findings after TME.

Results: MRI of the pelvis at 3 Tesla was capable to produce images of diagnostic quality in all cases. Malignancy was identified in all cases and confirmed histologically. The accuracy in determining the logitudinal extent and distance to the anorectal margin was 80% and 87% respectively. T- and N-stage were correctly diagnosed in 93% and 87% respectively.

Conclusion: MRI of rectal cancer at 3 Tesla showed a high accuracy in determining the stage of rectal carcinoma. It enables the radiololgist and surgeon to identify the anatomical relation of the tumor to surgically relevant pelvic structures such as mesorectal fascia. Especially in case of locally advanced tumors and failure of endoscopic procedures it may be used to select patients for neoadjuvant treatment regimes.