Structural and quantitative neuroimaging of the common marmoset monkey using a clinical MRI system

Purpose was to adapt structural and quantitative magnetic resonance imaging (MRI) from humans to common marmoset monkeys on a clinical 3T scanner and to demonstrate the value for translational research. Three-dimensional T1- and T2-weighted MRI and gradient echo-based multi-parameter mapping was performed on nine adult animals using a wrist coil. Structural MRI was applied in a model of targeted experimental autoimmune encephalomyelitis (EAE). Magnetization transfer (MT) and T1 parameter maps were used to depict axon-rich cortical areas. After intraveneous triple dose of gadobutrol, the excretion half-time was determined from consecutive measurements of R1=1/T1. Diffusion tensor imaging (DTI) was performed at 1mm resolution. At 0.4mm resolution, total measurement time (30 min) was compatible with injection anesthesia, permitting rapid screening and frequent follow-up. Structural MRI depicted the EAE lesion in white matter. Quantitative values of T1, MT, and R2* in marmoset brain were comparable to humans, except for smaller R2* indicating lower iron content in basal ganglia. The middle temporal V5 area and the cortical layer IV could be identified, but were considerably better delineated when averaging two images at 0.33 mm resolution (70 min). A similar distribution volume (23%), but a shorter excretion half time than in humans (30 min) was observed. DTI was feasible only in larger structures, such as major axonal tracts. High-resolution MRI of common marmosets proved feasible using clinical MRI hardware. A rapid 3D examination protocol was established for screening under injection anesthesia, thus avoiding the adverse effects of inhalation anesthesia.