Data-Driven Optimized Flip Angle Selection for T-1 Estimation from Spoiled Gradient Echo Acquisitions

作者：Lewis Christina M^*; Hurley Samuel A; Meyerand M Elizabeth; Koay Cheng Guan

来源：Magnetic Resonance in Medicine, 2016, 76(3): 792-802.

DOI：10.1002/mrm.25920

• T-1 mapping
• flip angle selection
• error propagation
• SPGR

Purpose: Define criteria for selection of optimal flip angle sets for T-1 estimation and evaluate effects on T-1 mapping.
Theory and Methods: Flip angle sets for spoiled gradient echo-based T-1 mapping were selected by minimizing T-1 estimate variance weighted by the joint density of M-0 and T-1 in an initial acquisition. The effect of optimized flip angle selection on T-1 estimate error was measured using simulations and experimental data in the human and rat brain.
Results: For two-point acquisitions, optimized angle sets were similar to those proposed by other groups and, therefore, performed similarly. For multipoint acquisitions, optimal angle sets for T-1 mapping in the brain consisted of a repetition of two angles. Implementation of optimal angles reduced T-1 estimate variance by 30-40% compared with a multipoint acquisition using a range of angles. Performance of the optimal angle set was equivalent to that of a repetition of the two-angle set selected using criteria proposed by other researchers.
Conclusion: Repetition of two carefully selected flip angles notably improves the precision of resulting T-1 estimates compared with acquisitions using a range of flip angles. This work provides a flexible and widely applicable optimization method of particular use for those who repeatedly perform T-1 estimation.

• 出版日期2016-9
• 单位河北医科大学