Subashini Srinivasan1, 2, Daniel B. Ennis, 12
1Department of Bioengineering, University of California, Los Angeles, CA, United States; 2Department of Radiological Sciences, University of California, Los Angeles, CA, United States
Cardiac structural and functional imaging is routinely performed using balanced steady-state free precession (bSSFP) due to its high contrast and high SNR efficiency. Higher flip angles generate higher blood-myocardial contrast, but can result in substantially increased SAR, which may result in exceeding SAR limitations or limit its applicability in patients with implanted devices. In our work, we describe novel variable flip angle (VFA) scheme coupled with a k-space acquisition strategy for low SAR bSSFP cardiac cine imaging. Our results show that VFA-bSSFP cardiac cine imaging can reduce the SAR by at least 45% compared to conventional bSSFP, while maintaining blood myocardial SNR and CNR. VFA-bSSFP can also increase the CNR by at least 29% with SAR matched to a conventional bSSFP scheme.