Snapshot whole-brain T1 relaxometry using steady-state prepared spiral multislice variable flip angle imaging

Abstract

Purpose: Variable flip angle (VFA) imaging is widely used for whole-brain T1 quantification. Because of the requirement to acquire at least two sets of MR images at different flip angles, VFA relaxometry is relatively slow. Here, whole-brain VFA T1 mapping at 1.5 T is accelerated by using efficient spiral non-Cartesian imaging. Methods: To quantify T1 in the human brain, radiofrequency spoiled gradient-echo imaging is performed at two optimized flip angles using an interleaved 2D multislice sequence with high spoiling efficiency. The acquisitions are accelerated by using a spiral trajectory with 10 interleaves combined with a dedicated magnetization preparation to ensure steady-state conditions in minimal time. Results: The investigated MR scan protocol allowed the acquisition of whole-brain T1 maps at a clinically relevant resolution in only 40 s (0.7 s per slice) with high reproducibility. White and gray matter T1 peaks clearly could be delineated by calculation of whole-brain T1 histograms, and the delivered T1 values showed good agreement with the reference method in selected regions of interest. Conclusion: Due to the use of a fast spiral k-space trajectory, whole-brain VFA T1 mapping could be accelerated by an order of magnitude compared to conventional Cartesian sampling. Magn Reson Med 79:856–866, 2018. © 2017 International Society for Magnetic Resonance in Medicine.