Quantitative proton MRI and MRS of the rat brain with a 3 T clinical MR scanner

SummaryObjectiveTo demonstrate the capability of a clinical 3 T human scanner in performing quantitative MR experiments in the rat brain.Material and methodsIn vivo, measurements on eight Wistar rats were performed. Longitudinal relaxation time (T1) and transverse relaxation time (T2) measurements were set up at a spatial resolution of 0.3 × 0.3 × 1 mm3. Diffusion-weighted imaging was also applied and the evaluation included both mono- and biexponential approaches (b-value up to 6000 s/mm2). Besides quantitative imaging, the rat brain was also scanned at a microscopic resolution of 130 × 130 × 130 μm3. Quantitative proton spectroscopy was also carried out on the rat brain with water as internal reference.ResultsT1 and T2 for the rat brain cortex were 1272 ± 85 ms and 75 ± 2 ms, respectively. Diffusion-weighted imaging yielded accurate diffusion coefficient measurements at both low and high b-value ranges. The concentrations of MR visible metabolites were determined for the major resonances (i.e., N-acetyl-aspartate, choline and creatine) with acceptable accuracy.ConclusionThe results suggest that quantitative imaging and spectroscopy can be carried out on small animals on high-field clinical scanners.