Abstract #0072

Improvement in B1+ Homogeneity of 3T Cardiac MRI in Swine with Dual-Source Parallel RF Excitation

Daniel A. Herzka¹, Haiyan Ding²,³, Michael Schar⁴,⁵

¹Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States; ²Biomedical Engineering, Tsinghua University, Beijing, China; ³Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, United States; ⁴Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, MD, United States; ⁵Clinical Science, Philips Healthcare, Cleveland, OH, United States

MRI scanners use an integrated birdcage coil to generate radio frequency (RF) excitation fields (B1+). It has been reported that at 3T variations in flip angle can range from 31 to 66% (B1+ inhomogeneities) over the left ventricle and average flip angles can be reduced by ~20% (RF power). Multi-channel transmit systems allow RF-shimming to locally improve the B1+ field. We quantify improvements in B1+ field homogeneity and average RF power resulting from dual-source parallel RF excitation in cardiac swine imaging. Correlation with animal size demonstrates that larger subjects suffer more B1+ field inhomogeneity and benefit more from RF shimming.