Visualization of cerebellar peduncles using diffusion tensor imaging.

The cerebellum communicates with the cerebral cortex via the superior, middle, and inferior cerebellar peduncles (CPs). To preserve the structure and function of the brainstem and cerebellum, which is compressed in various pathological conditions, it is important to delineate the spatial interrelationship of the CPs for presurgical planning and intraoperative guidance. Diffusion tensor tractography (DTT) is a technique capable of depicting the major fiber bundles in CPs. However, routine use of this technology for brainstem visualization remains challenging due to the anatomical smallness and complexity of the brainstem and susceptibility-induced image distortions. Here, we attempt to visualize CPs using high-resolution DTT in a commercial equipment for the application of this technique in normal clinical settings. DTT and fast imaging employing steady-state acquisition-cycled phases (FIESTA) of the whole brainstem were performed. We rendered the DTT fiber bundle using a region-of-interest-based fiber tracking method onto the structural image generated in FIESTA by automatic image coregistration. Fibers of the CPs were clearly visualized by DTT. The DTT-FIESTA overlaid image revealed the cross-sectional and three-dimensional anatomy of the pyramidal tract and the ascending sensory fibers, in addition to the CPs. This could indicate a geometrical relationship of these fibers in the brainstem. The CPs could be visualized clearly using DTT within clinically acceptable scanning times. This method of visualizing the exact pathway of fiber bundles and cranial nerves in the skull base helps in the planning of surgical approaches.