Magnetic Resonance Imaging of the Common Marmoset Head

Abstract

This study evaluated the changes in the intrinsic magnetic resonance (MR) relaxation parameter values (T_1; T₂, proton density, magnetisation transfer and apparent diffusion coefficient) of the marmoset head, imaged before and after death. Knowing the absolute values of the MR parameters makes it possible to choose an imaging protocol for optimal structural differentiation. The changes between the ante-mortem and post-mortem MR parameters provide an insight into the changing biophysical microenvironment of the post-mortem brain, and allow some of the changes that occur in pathological conditions to be predicted. Diffusion-weighted MR imaging (MRI) was used to map quantitative apparent diffusion coefficient values, and to investigate diffusional anisotropy along the fibre tracts in pre-mortem and post-mortem brain tissue. A three-dimensional data set of the entire marmoset brain demonstrates the ability of three-dimensional MRI to differentiate internal brain structures. MRI is a non-invasive technique which, in principle, permits the same animal to be re-imaged serially and has the potential to probe in vivo brain structural and biophysical changes over an extended period of time. Serial imaging, where each animal acts as its own control, reduces the number of animals required to detect a significant change by minimising the effects of inter-subject variance. MRI therefore provides important scientific and ethical benefits.