Concepts in Magnetic Resonance Part A, Bridging Education and Research / 2019 / Article / Tab 3

Research Article

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 noyes

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

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