  Purpose: This study aims to develop a high-resolution whole-brain
multi-parametric quantitative MRI approach for simultaneous mapping of
myelin-water fraction (MWF), T1, T2, and proton-density (PD), all within a
clinically feasible scan time.
  Methods: We developed 3D ViSTa-MRF, which combined Visualization of Short
Transverse relaxation time component (ViSTa) technique with MR Fingerprinting
(MRF), to achieve high-fidelity whole-brain MWF and T1/T2/PD mapping on a
clinical 3T scanner. To achieve fast acquisition and memory-efficient
reconstruction, the ViSTa-MRF sequence leverages an optimized 3D
tiny-golden-angle-shuffling spiral-projection acquisition and joint
spatial-temporal subspace reconstruction with optimized preconditioning
algorithm. With the proposed ViSTa-MRF approach, high-fidelity direct MWF
mapping was achieved without a need for multi-compartment fitting that could
introduce bias and/or noise from additional assumptions or priors.
  Results: The in-vivo results demonstrate the effectiveness of the proposed
acquisition and reconstruction framework to provide fast multi-parametric
mapping with high SNR and good quality. The in-vivo results of 1mm- and
0.66mm-iso datasets indicate that the MWF values measured by the proposed
method are consistent with standard ViSTa results that are 30x slower with
lower SNR. Furthermore, we applied the proposed method to enable 5-minute
whole-brain 1mm-iso assessment of MWF and T1/T2/PD mappings for infant brain
development and for post-mortem brain samples.
  Conclusions: In this work, we have developed a 3D ViSTa-MRF technique that
enables the acquisition of whole-brain MWF, quantitative T1, T2, and PD maps at
1mm and 0.66mm isotropic resolution in 5 and 15 minutes, respectively. This
advancement allows for quantitative investigations of myelination changes in
the brain.
