Simultaneous T 1 and T 2 Mapping in the Brain With QuantoRAGE : An MP2RAGE Variant Using T 2 ‐Prepared Inversion

Abstract

ABSTRACT Purpose To develop and validate a repeatable and reproducible approach, QuantoRAGE, for simultaneous whole‐brain T 1 and T 2 mapping using adiabatic magnetization preparation. Methods QuantoRAGE is a 3D FLASH‐based sequence using an adiabatic T 2 ‐prepared inversion followed by two readout blocks. Sequence repetitions with different preparation durations and inversion times provide T 1 ‐ and T 2 ‐weighted images. Quantitative parameters are voxel‐wise estimated by matching signal evolutions to a dictionary generated from extended phase graph simulations. To accelerate the method, the protocol was optimized using Cramér‐Rao lower bound analysis, and a neural‐network was trained on sequence‐specific dictionaries for fast matching. The optimized protocol was evaluated in phantom and healthy volunteers at 3 T and compared against reference MP2RAGE T 1 and multi‐echo spin‐echo T 2 measurements. In vivo repeatability and reproducibility were quantified using scan‐rescan experiments. Feasibility of QuantoRAGE at 7 T was tested in vivo. Results At 3 T, T 1 and T 2 phantom quantification agreed with nominal values (T 1 : r = 0.98, T 2 : r = 0.99). In eight healthy volunteers, high repeatability (bias ± SD, T 1 : 14.1 ± 30.2 ms, T 2 : 1.2 ± 1.7 ms) and reproducibility (T 1 : 18.9 ± 32.6 ms, T 2 : 1.1 ± 2.1 ms) were observed across brain regions, with T 1 estimates comparable to reference methods ( r = 0.96, slope = 0.74), and T 2 underestimated ( r = 0.79, slope = 0.44). Fast matching produced results consistent with dictionary‐matching and significantly reduced parameter estimation time. At 7 T, the adiabatic preparation resulted in homogeneous T 1 and T 2 maps at 0.8‐mm isotropic resolution. Conclusion QuantoRAGE enabled reproducible simultaneous T 1 and T 2 mapping at 3 T, providing an efficient framework for longitudinal and cross‐sectional quantitative MRI studies and showed feasibility at 7 T.