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摘要
Purpose: To develop an analytically based algorithm for rapid optimization of the local radiofrequency magnetic (B-1(+)) field intensity for a given radiofrequency power through a transmit array. The analytical nature of the method will yield insight to optimization requirements and provides a valuable reference for numerically based searches. Methods: With the knowledge of the B-1(+) field distribution generated by each single coil of the array, both the phases and the amplitudes of each coil current are optimized to maximize the magnitude of the B-1(+) field in a specific location of the body per unit of power transmitted through the array and, consequently, minimizing the whole body specific absorption rate for a given pulse sequence. Results: Simulations considering the human body show that the proposed method can reduce the whole-body specific absorption rate for a given B-1(+) magnitude at the location of interest by a factor of about 6.3 compared to the classic birdcage current configuration, and by a factor of 3.2 compared to phase-only shimming in a case with significant coupling between the elements of the array. Conclusion: The proposed method can rapidly provide valuable information pertinent to the optimization of field distributions from transmit arrays. Magn Reson Med 71:432-439, 2014.
- 出版日期2014-1
