Incidental Magnetization Transfer Contrast by Fat Saturation Preparation Pulses in Multi-Slice MR Imaging: An Illustration of Look-Locker EPI Sequences

Wanyong Shin¹, Hong Gu¹, Yihong Yang¹

It is demonstrated that the frequency selective fat saturation preparation pulses generate incidental magnetization transfer contrast (MTC) effects in multi-slice imaging. Simulation reveals that the fractional signal loss by these MTC effects are severer when smaller flip angle, shorter TR, and larger slice number are applied. Incidental MTC effects induce a signal attenuation (up to 30%) and bias on T1 measurement (up to 20%) when inversion recovery Look-Locker EPI sequences are used. Furthermore, it is shown that water-only excitation pulses have the potential to minimize the signal attenuation and provide unbiased T1 measurement without fat artifacts in MR images.