Magnetic resonance imaging for local staging of gastric carcinoma: results of an in vitro study.

Objective: Preoperative staging of gastric carcinoma is limited by the fact that available imaging modalities do not enable accurate evaluation of the depth of infiltration of the gastric wall. The aim of this study was to evaluate the efficiency of conventional magnetic resonance imaging (MRI) in local staging of gastric carcinoma.

Methods: Sixty-five specimens of patients with proven gastric carcinoma were examined immediately after gastrectomy. Examination was performed with a 1-T MRI and included T1-weighted, T2-weighted, and opposed phase images. Images were analyzed for the number of visible wall layers and their signal intensity characteristics, for tumor localization and depth of infiltration. T-stage was classified according to the TNM system. Finally, the staging by MRI was compared with the histopathological staging of the specimens.

Results: The mucosal, submucosal, and proper muscle layers could be differentiated by the typical signal intensities. Depiction of the subserosa or serosa was not possible. In 65 specimens, 67 carcinomas were found by the pathologist. Sixty-four of 67 (96%) histologically proven carcinomas were correctly localized by MRI; T-staging accuracy was 50% only, mainly because of overstaging pT2 tumors as T3.

Conclusions: MRI enables differentiation of gastric wall layers and, therefore, technically allows the evaluation of the local tumor stage of gastric carcinomas. However, infiltration of the subserosal and serosal layer cannot be proved accurately. Overstaging pT2 tumors is one of the most predominant problems. Yet further technical developments in high-resolution imaging of the gastric wall may improve T-staging in the near future and overcome today's staging limitations.