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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.
