Quick Reduction of Specific Absorption Rate Constraints in Parallel RF Excitation Pulse Design by Maximum Volume Inscribed Ellipsoids

Table 3

Optimization of AFA and STA objective functions for the excitation and inversion examples without and with proposed MVIE SAR reduction.

MVIE SAR reduction	no	yes
Number of SAR constraints	491	1
Average power constraints	8	8
30-degree excitation with 5 points
Number of RF constraints	40	40
Arbitrary flip angle optimization (AFA)
Computation time [s]	2.63	1.24
Iteration count	41	38
Root mean square error [deg]	1.63	1.87
Small tip angle approximation (STA)
Computation time [s]	1.87	0.89
Iteration count	38	41
Root mean square error [deg]	1.64	1.90
180-degree inversion with 7 points
Number of RF constraints	56	56
Arbitrary flip angle optimization (AFA)
Computation time [s]	8.52	2.87
Iteration count	84	55
Root mean square error [deg]	15.44	15.44
Small tip angle approximation (STA)
Computation time [s]	4.84	1.44
Iteration count	65	52
Root mean square error [deg]	10.38	10.38