Whole-brain, ultra-high spatial resolution ex vivo MRI with off-the-shelf components

Ultra-high spatial resolution imaging of whole, ex vivo brains provides new opportunities to understand neurological disease. Recent work has demonstrated that 100 μm isotropic resolution can reveal anatomical details that are otherwise difficult to appreciate, but relied on fabrication facilities, fabrication expertise and programming expertise that is not available at clinical imaging sites that lack a dedicated research staff and resources. The purpose of this work is to describe a whole-brain, ultra-high spatial resolution imaging procedure for ex vivo specimens using equipment that can be purchased, assembled and implemented by most clinical sites. We provide enough detail so that other groups can readily reproduce the approach.

A container and hardware for holding the brain fixed for long scan times was developed, along with a procedure for removing bubbles, which can cause artifact. Imaging was performed on a standard knee coil on a whole-body 7 T MRI at 170 μm isotropic spatial resolution. Five specimens were examined in Fomblin or formalin to evaluate consistency of image quality.

High quality images were acquired on all specimens. Anatomical features that are not readily observed at standard resolution, such as subthalamic nuclei, are readily observed. Disease-related features such as microscopic infarcts are also readily observed.

Ultra-high spatial resolution, whole-brain images can be readily achieved without specialized hardware and software development. The approach is expected to be valuable as a complement to histology and to discover relationships among pathology located at different places throughout the brain.