Flexible reduced field of view magnetic resonance imaging based on single-shot spatiotemporally encoded technique
Li Jinga), Cai Cong-Bob), Chen Lina), Chen Yingc), Qu Xiao-Boa), Cai Shu-Hui†a)
       
2D SPEN sequence with flexible rFOV scheme used in this study. The 180° pulse is used for slice selection and refocusing. G exc is the encoding/exciting gradient, T exc is the encoding time, G acq is the decoding/sampling gradient, G pos is the positioning gradient transferring the current decoding location to the start location of next ROI, T pre is the pre-acquisition delay, and T acq is the decoding time ( T acq = N echo · T blip, where N echo is the number of sampling points along the SPEN dimension, T blip is the duration of one blip gradient along the SPEN dimension). Notice that G pos is applied only when the decoding position needs to be transferred to the next ROI. In other cases, it is replaced by the decoding gradient G acq. Abbreviations: exc: spatiotemporal-encoding excitation, ro: readout direction, acq: acquisition, echo: sampled echoes, blip: blip gradient, pos: position, pre: pre-acquisition, and ror: rephased gradient.