Simultaneous multi-segment (SMSeg) EPI over multiple focal regions

作者：Kaibao Sun, Zheng Zhong, Guangyu Dan, Kezhou Wang, Muge Karaman, Qingfei Luo, Xiaohong Joe Zhou · 发表于：Physics in Medicine and Biology · 年份：2023 · DOI：10.1088/1361-6560/acb2a9 · 被引用次数：3 · 研究领域：Advanced MRI Techniques and Applications、Atomic and Subatomic Physics Research、Advanced Neuroimaging Techniques and Applications

Abstract Objective. This study aimed at developing a simultaneous multi-segment (SMSeg) imaging technique using a two-dimensional (2D) RF pulse in conjunction with echo planar imaging (EPI) to image multiple focal regions. Approach. The SMSeg technique leveraged periodic replicates of the excitation profile of a 2D RF pulse to simultaneously excite multiple focal regions at different locations. These locations were controlled by rotating and scaling transmit k-space trajectories. The resulting multiple isolated focal regions were projected into a composite ‘slice’ for display. GRAPPA-based parallel imaging was incorporated into SMSeg by taking advantage of coil sensitivity variations in both the phase-encoded and slice-selection directions. The SMSeg technique was implemented at 3 T in a single-shot gradient-echo EPI sequence and demonstrated in a phantom and human brains for both anatomic imaging and functional imaging. Main results. In both the phantom and the human brain, SMSeg images from three focal regions were simultaneously acquired. SMSeg imaging enabled up to a six-fold acceleration in parallel imaging without causing appreciable residual aliasing artifacts when compared with a conventional gradient-echo EPI sequence with the same acceleration factor. In the functional imaging experiment, BOLD activations associated with a visuomotor task were simultaneously detected in two non-coplanar segments (each with a size of 240 × 30 mm 2 ), corresponding to visual and motor...