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Abstract Introduction Quantitative MRI is important for non-invasive tissue characterisation. In previous work we developed a clinically feasible multi-contrast protocol for T 1 -weighted imaging based on the MP2RAGE sequence that was optimised for both children and adults. It was demonstrated that a range of Fluid And White Matter Suppression (FLAWS) related contrasts could be produced while maintaining T 1 -weighted uniform image (UNI) quality, a challenge at higher field strengths. Here we introduce an approach to use these images to calculate effective proton density (PD*) and quantitative T 1 relaxation maps especially for shorter repetition times (TR MP2RAGE ) than those typically used previously. Methods T 1 and PD* were estimated from the analytical equations of the MP2RAGE signal derived for partial Fourier acquisitions. The sensitivity of the fitting results was evaluated with respect to the TR MP2RAGE and B 1 + effects on both excitation flip angles and inversion efficiency and compared to vendor T 1 maps which do not use B 1 + information. Data acquired for a range of individuals (aged 10-54 years) at the shortest TR MP2RAGE (4000ms) were compared across white matter (WM), cortical grey matter, and deep grey matter regions. Results The T 1 values were insensitive to the choice of different TR MP2RAGE . The results were similar to the vendor T 1 maps if the B 1 + effects on the excitation flip angle and inversion efficiency were not included in the fits. T 1 values varied over development into adulthood, especially for the deep grey matter regions whereas only a very small difference was observed for WM T 1 . Effective PD maps were produced which did not show a significant difference between children and adults for the age range included. Conclusion We produced PD* maps and improved the accuracy of T 1 maps from an MP2RAGE protocol that is optimised for UNI and FLAWS-related contrasts in a single scan at 7T by incorporating the excitation flip angle and inversion efficiency related effects of B 1 + in the fitting. This multi-parametric protocol made it possible to acquire high resolution images (0.65mm iso) in children and adults within a clinically feasible duration (7:18 min:s). The combination of analytical equations utilizing B 1 + maps led to T 1 fits that were consistent at different TR MP2RAGE values. Average WM T 1 values of adults and children were very similar (1092ms vs 1117ms) while expected reductions in T 1 with age were found for GM especially for deep GM.
Dokumacı et al. (Mon,) studied this question.