Pulse sequence diagram of the optimized cardiac CEST imaging technique. (a) ECG trigger delay is set so that the readout is in the quiescent phase of the cardiac cycle. TR is set to be 4000 ms so that another data acquisition won't start until magnetization is almost back to equilibrium. 33 images were collected at different saturation frequency offsets ranging from -4.8 ppm to 4.8 ppm with a step size of 0.3 ppm. (b) CEST preparation module consists of five Gaussian pulses of flip angle 2700° and duration of 30 ms at duty cycle of 50% (B1rms is 3.76uT). There is a spoiler gradient after each Gaussian pulse to crush the residual transverse magnetization.