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.