Development and clinical application of MR endoscopy

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In an attempt to develop MR endoscopy, we performed the following imaging experiments using 1.5-T clinical MR system and 4.7-T experimental MR system : (1) we designed and made new surface and quadrature RF coils for MR endoscopy ; (2) we tested these coils in phantom experiments using various pulse sequences (spin-echo, fast spin-echo, gradient-echo, and fast gradient-echo methods) ; (3) we investigated the spatial resolution, contrast resolution, and time resolution in MR endoscopy ; (4) we imaged various organs of animals using MR endoscopy with various pulse sequences (spin-echo, fast spin-echo, gradient-echo, and fast gradient-echo methods) ; and, (5) we investigated optimal pulse sequence, repetition time, echo time, flip angle, field of view, and matrix size for each organ of animals in MR endoscopy.We performed MR endoscopy for gastric and esophageal carcinomas and compared the findings with histopathologic findings. MR endoscopy clearly depicted the normal gastric and esophageal walls as several layers, which corresponded well with the histologic layers. In gastric and esophageal carcinomas, the depth of mural invasion visualized with MR endoscopy correlated well with the histologic staging. MR endoscopy showed a high diagnostic accuracy for evaluating the mural invasion of gastric and esophageal carcinomas and thus potentially enabled preoperative histopathologic staging.We are performing MR endoscopy for many patients with various diseases. Furthermore, we are planning to develop new methods for MR endoscopy and optimize the imaging methods for each organ in MR endoscopy.