3433 Gallbladder wall layer displayed by mr endoscopy.

Abstract

Introduction: Imaging of gallbladder wall layers is almost performed by endoscopic ultrasonography. Standard magnetic resonance (MR) imaging of gallbladder by body and surface coils often inadequately depict extension into the gallbladder wall. Endocavitary coils have been developed to help solve this problem. Aims: To investigate MR endoscopic imaging of gallbladder wall layer compared to histopathologic appearance. Methods: We used an MR endoscope, type XGIF-MR30, developed by the Olympus Optical Co. Ltd. (Tokyo, Japan), with a 3-cm-long receive-only coil embedded in its tip. All imaging is currently performed on a 1.5-T system (Signa 5.6; GE Yokogawa Medical Systems, Tokyo, Japan). Patients were sedated intravenously in a standard fashion, and anticholinergic agent is administered intravenously to minimize gut motility and spasm. The tip of the MR endoscope was placed in the duodenal bulb. Then, axial MR examinations were performed in the following sequences: T1-weighted imaging, fast-spin-echo T2-weighted imaging, MRCP imaging, and gadolinium enhanced spin-echo T1-weighted imaging. Supplemental sagittal or coronal images were obtained, depending on lesion morphology and the patient's clinical stability. We performed endoscopic examinations with this endoscope in 10 subjects, seven subjects with control and three subjects with gallbladder cancer. The study was accepted by the Ethics Committee of the institutions, and every participating patient gave an informed consent. Results: In the control subjects, we identified three tissue layers in the normal gallbladder. The mucosa and submucosa were depicted as the first layer with high intensity imaging, muscularis propria corresponded to the second layer with low intensity, and subserosa and serosa consisted the third layer with high intensity. On the basis of these findings by MR endoscopy, gallbladder tumors were identified and staged in all patients: subserosa invasion in all patients. A good histopathologic correlation was obtained. Conclusion: We are investigating the optimal combination of a phased-array surface coil with the endoscopic coil to improve signal-to-noise ratio in our images. We believe that there are important potential advantages with this technique in staging gallbladder cancer and in planning patient treatment.