Automatic Pre-estimating of Optimal Imaging Frequency in bSSFP-based Cardiac Imaging

In cardiac magnetic resonance imaging (CMRI), balanced steady-state free precession (bSSFP) is a widely used technique. However, this technique is susceptible to resonance frequency shift artifacts, which can severely affect image quality and limit the clinical application of CMRI. Achieving a homogeneous field through gasket adjustment and high-order shimming is particularly challenging in the bSSFP technique for cardiac applications due to cardiac and respiratory movements. Additionally, the current measurement of the optimal imaging frequency with frequency scouting sequence still requires additional imaging and can produce deviations due to visual inspection errors. To address these issues, we proposed an effective automatic method to estimate the optimal imaging frequency in the region of interest by combining echo peak characteristics with a frequency scouting sequence. The frequency shift is simulated by changing the phase of the transmitting pulse, and the optimal imaging frequency is then calculated according to the echo peak characteristics. Experimental results demonstrated that our method achieves superior results compared to traditional methods and the frequency scouting method. Furthermore, our approach remarkably reduces calibration time and facilitates the clinical cardiac application of bSSFP technique.