Table 2.

Comparison of multiplexed vector field shaping (MVFS) to focused constrained power optimization (FOCO) for the single tumor model using 40 channels and single frequency fields at 600 MHz. Results are separated into SAR statistics, tumor coverage, and solution details. FOCO was performed using a rank-1 approximation of the central tumor SAR matrix and compared to six different MVFS application scenarios. “Center” uses the full-rank central SAR matrix, “Averaged” utilizes a single target matrix built from averaging over the whole tumor volume. The remaining four examples used all 257 tumor SAR matrices to derive a field shaping (“S”) result. Here, the subscript defines the target norm used (either 2 or ∞) and the following number stands for the target SAR in W/kg (either 75 or 150 W/kg). The “Rank” row describes how many time-interleaved solutions were identified for the respective solution. As expected, the FOCO solution was of rank 1 while MVFS provided multiple excitations to better cover the target volume. The results for S₂150 are visualized in Figure 6a–f.

Performance		MVFS
Metrics		FOCO	Center	Averaged	S2 150	S2 75	S∞ 150	S∞ 75
Local 10 g-SAR [W/kg]	Mean	69	75	76	76	68	69	68
	Max	107	120	123	122	95	103	99
	Min	33	41	43	43	45	51	51
	SD	15	17	17	17	11	12	12
Coverage	TC25	1.00	1.00	1.00	1.00	1.00	1.00	1.00
	TC50	0.87	0.80	0.77	0.79	0.99	0.95	1.00
	TC80	0.13	0.14	0.12	0.12	0.23	0.16	0.18
Solution	Time [s]	16.5	14	22.2	22.8	21.7	24	26
	Rank	1	2	2	2	3	3	3