Single-Shot ${\text{T}}_{{2}}$ Mapping Through OverLapping-Echo Detachment (OLED) Planar Imaging.

Abstract

Develop a reliable single-shot T₂ mapping method with extra robustness to motion and the potential for real-time dynamic and quantitative MR imaging. A single-shot T₂ mapping sequence was proposed based on spin-echo planar imaging acquisition scheme. Two overlapped echo signals with different T₂ weighting were obtained simultaneously by using two small flip-angle excitation pulses and corresponding echo-shifting gradients. A detachment algorithm based on structure similarity constraint was proposed to separate the two echo signals. T₂ mapping was obtained from the two separated echo signals. The robustness and efficiency of the method were demonstrated through simulation, phantom experiments, and human brain measurements. Reliable T₂ mapping can be obtained within milliseconds even under continuous head motion. Reliable T₂ mapping was achieved with a single shot for the first time. The proposed method will facilitate real-time dynamic and quantitative MR imaging.