Endoscopic MRI Using 3D-Spoiled GRASS (SPGR) Sequence for Local Staging of Rectal Carcinoma

Objective: Magnetic resonance imaging was performed with an MR endoscope to evaluate the depth of invasion of rectal carcinomas. Materials and Methods: Twenty-two patients with rectal carcinomas were studied prior to surgery with MRI using a 3D-fast spoiled GRASS (SPGR) sequence, a nonmagnetic endoscope and an antenna probe. Results: The MR images on 3D-fast SPGR sequence showed that the normal bowel mucosa had a high signal intensity, the submucosal layer had a low signal intensity, and the muscularis propria had moderate signal intensity. Small tumors had moderate signal intensity similar to the muscularis propria. Advanced tumors with considerable volume revealed heterogeneous findings with intermediate and low signal intensities. The depth of wall invasion by rectal carcinoma was correctly staged with endoscopic MRI in 16 of 22 patients. Conclusion: This technique may be useful for the accurate staging of the depth of invasion by rectal carcinomas.