Anatomy of the brainstem: correlation of in vitro MR images with histologic sections.

MR imaging was performed on three formaldehyde-fixed brainstem specimens that were sectioned in the axial plane and myelin stained. The histologic sections were used to identify and label the structures demonstrated on short TR/TE axial MR images. Fiber tracts and nuclei that cannot be resolved on in vivo scans were well delineated by in vitro MR. Improved gray-white differentiation may be due to much greater T1 shortening of gray matter relative to white matter after fixation. The excellent anatomic detail provided by these scans should facilitate comparison of clinical scans with histologic sections.