Motion-tolerant diffusion mapping based on single-shot overlapping-echo detachment (OLED) planar imaging.

PURPOSE: A new diffusion-mapping method based on single-shot overlapping-echo detachment (DM-OLED) planar-imaging sequence, along with a corresponding separation algorithm, is proposed to achieve reliable quantitative diffusion mapping in a single shot. The method can resist the effects of motion and help in detecting the quick variation of diffusion under different physiological status. METHODS: The echo-planar imaging method is combined with two excitation pulses with small flip angle to gain overlapping-echo signal in a single shot. Then the overlapping signals are separated by a separation algorithm and used for diffusion computation. Numerical simulation, phantom, and in vivo rat experiments were performed to verify the efficiency, accuracy, and motion tolerance of DM-OLED. RESULTS: The DM-OLED sequence could obtain reliable diffusion maps within milliseconds in numerical simulation, phantom, and in vivo experiments. Compared with conventional diffusion mapping with spin-echo echo-planar imaging, DM-OLED has higher time resolution and fewer motion-incurred errors in the apparent diffusion coefficient maps. CONCLUSIONS: As a reliable fast diffusion measurement tool, DM-OLED shows promise for real-time dynamic diffusion mapping and functional magnetic resonance imaging. Magn Reson Med 80:200-210, 2018. © 2017 International Society for Magnetic Resonance in Medicine.