There is great interest in the non-destructive capabilities of magnetic resonance microscopy (MRM) for studying small animal models of human disease. Continuing technological advances in MRM have led to MR "histology" as a new tool for the pathologist. These high-resolution techniques permit a nondestructive interpretation of complex spatial relationships between tissue substructures, in vivo and in specimens, in a digital 3D format which circumvents the need for serial sectioning and staining necessary for conventional optical histology.

Typically, dedicated small animal imagers with high magnetic and gradient field strengths and optimized bore sizes are utilized to achieve maximal image quality and spatial resolution for MRM of rodents and specimens. Unfortunately many investigators do not have access to such facilities and, therefore, clinical scanners are often used for small animal studies. Using such scanners, MRM studies are often limited by suboptimal gradient strength, leading to compromised spatial resolution or velocity/diffusion sensitivity.

In this project we are developing new tools for implementing a custom-built high-strength gradient coil insert in a clinical MR scanner. Such inserts can produce the strong gradient fields required for MRM and also introduce the possibility of accessing an experimental mode of operation, for advanced MRI studies of small animals, using a clinical whole-body MR scanner.

With a number of interfacing and optimizing methods developed, we were able to obtain spatial resolution as high as 50x50x200 microns, within reasonable scan time, on a clinical 1.5T MR imager. Modifications to the MR system were minimized to allow for efficient transition between clinical and experimental (insert) modes and vice versa. Preliminary results show the method to be advantageous and cost effective.

We believe that high-strength, insertable gradient coil is a promising tool and may one day be used commonly by medical and basic science researchers.