Preoperative detection of local extension of carcinoma of the rectum using magnetic resonance imaging.

Background: We evaluated the ability of magnetic resonance imaging (MRI) to define local extension of rectal carcinoma.

Study Design: Thirty-three patients with rectal carcinoma were preoperatively assessed by MRI.

Results: When sagittal or coronal images, or both, were added to transverse images as needed, the sensitivity rate was 84.2 percent and the specificity rate was 92.9 percent. False-positive results when using only transverse images were mainly related to slight extramural spread, to an anterior location in the lower rectum (partial volume effect), and to massive extramural spread of the middle rectal tumors.

Conclusion: Preoperative MRI was helpful to define tumor extension three-dimensionally.