Effects of tuning condition, head size and position on the SAR of MRI dual-row transmit arrays

We have developed a workflow for numerical investigation of magnetic resonance imaging RF coil arrays. Use of fully parameterized 3-D and RF circuit models, and customized scripts for several time-consuming post-processing steps resulted in fast and continuous (24/7) generation of useful and important results. The high simulation speed allowed sensitivity analysis to be conducted for the most important dependencies - array diameter, human model position and tuning condition. For a dual-row array of 280 mm in diameter, as compared with a dual-row array of 250 or 230 mm in diameter, the safety excitation efficiency is higher and a lower margin of error is needed to maintain safety in operation. The impact of the tuning conditions and head position on the spatial-average 10-gram SAR significantly increases when the distance between the human model and the array decreases.