Purpose: To introduce a new approach called tailored variable flip-angle (VFA) scheduling for SNR-efficient 3D T1ρ mapping of the brain using a magnetization-prepared gradient-echo sequence. Methods: Simulations were used to assess the relative SNR efficiency, quantitative accuracy, and spatial blurring of tailored VFA scheduling for T1ρ mapping of brain tissue compared with magnetization-prepared angle-modulated partitioned k-space spoiled gradient-echo snapshots (MAPSS), a state-of-the-art technique for accurate 3D gradient-echo T1ρ mapping. Simulations were also used to calculate optimal imaging parameters for tailored VFA scheduling versus MAPSS, without and with nulling of CSF. Four participants were imaged at 3T MRI to demonstrate the feasibility of tailored VFA scheduling for T1ρ mapping of the brain. Using MAPSS as a reference standard, in vivo data were used to validate the relative SNR efficiency and quantitative accuracy of the new approach. Results: Tailored VFA scheduling can provide a 2-fold to 4-fold gain in the SNR of the resulting T1ρ map as compared with MAPSS when using identical sequence parameters while limiting T1ρ quantification errors to 2% or less. In vivo whole-brain 3D T1ρ maps acquired with tailored VFA scheduling had superior SNR efficiency than is achievable with MAPSS, and the SNR efficiency improved with a greater number of views per segment. Conclusions: Tailored VFA scheduling is an SNR-efficient GRE technique for 3D T1ρ mapping of the brain that provides increased flexibility in choice of imaging parameters compared with MAPSS, which may benefit a variety of applications.
Bibliographical noteFunding Information:
Brain & Behavior Research Foundation NARSAD Young Investigator Award; and National Institutes of Health (K01AR070894, P41EB027061, and R01EB022019) The authors thank Shalom Michaeli for providing the adiabatic excitation pulses used in the spin-lock preparation pulse and assisting with their implementation. This work was supported by a NARSAD Young Investigator Award from the Brain & Behavior Research Foundation and grants from the National Institutes of Health (K01AR070894, P41EB027061, and R01EB022019). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
- quantitative MRI
- tailored VFA scheduling