The impact of shimming strategies and scan regions on RF-induced heating near a bone screw under 3T MRI

This paper investigates the impact of shimming strategies and scan regions on the radiofrequency (RF) induced heating near a bone screw in the ASTM phantom under 3T magnetic resonance imaging (MRI). Three shimming strategies, i.e. B1 homogeneity, focusing performance, and power efficiency, and two scan regions, head and chest, were studied. The peak RF-induced heating in terms of local specific absorption rate (SAR) is compared among quadrature source excitation and the three shimmed source excitations obtained by using a particle swarm optimization method. For the scan region of the head, all three shimming strategies can reduce the RF-induced heating. For the scan region of the chest, the shimming strategies of B1 homogeneity and focusing performance can reduce the peak SAR while the shimming strategy of power efficiency increases the peak SAR.