Rapid high-resolution three-dimensional mapping of T1 and age-dependent variations in the non-human primate brain using magnetization-prepared rapid gradient-echo (MPRAGE) sequence

The use of quantitative T-1 mapping in neuroscience and neurology has raised strong interest in the development of T-1-mapping techniques that can measure T-1 in the whole brain, with high accuracy and precision and within short imaging and computation times. Here, we present a new inversion-recovery (IR) based T-1-mapping method using a standard 3D magnetization-prepared rapid gradient-echo (MPRAGE) sequence. By varying only the inversion time (TI), but keeping other parameters constant. MPRAGE image signals become linear to exp( -TI/T-1), allowing for accurate T-1 estimation without flip angle correction. We also show that acquiring data at just 3 TIs, with the three different TI values optimized, gives maximum T-1 precision per unit time, allowing for new efficient approaches to measure and compute T-1. We demonstrate the use of our method at 7 T to obtain 3D T-1 maps of the whole brain in common marmosets at 0.60 mm resolution and within 11 min. T-1 maps from the same individuals were highly reproducible across different days. Across subjects, the peak of cerebral gray matter T-1 distribution was 1735 +/- 52 ms, and the lower edge of cerebral white matter T-1 distribution was 1270 +/- 43 ms. We found a significant decrease of T-1 in both gray and white matter of the marmoset brain with age over a span of 14 years, in agreement with previous human studies. This application illustrates that MPRAGE-based 3D T-1 mapping is rapid, accurate and precise, and can facilitate high-resolution anatomical studies in neuroscience and neurological diseases. Published by Elsevier Inc.