A 2D spiral turbo-spin-echo technique

Purpose: 2D turbo-spin-echo (TSE) is widely used in the clinic for neuroimaging. However, the long refocusing radiofrequency pulse train leads to high specific absorption rate (SAR) and alters the contrast compared to conventional spin-echo. The purpose of this work is to develop a robust 2D spiral TSE technique for fast T-2-weighted imaging with low SAR and improved contrast. Methods: A spiral-in/out readout is incorporated into 2D TSE to fully take advantage of the acquisition efficiency of spiral sampling while avoiding potential off-resonance-related artifacts compared to a typical spiral- out readout. A double encoding strategy and a signal demodulation method are proposed to mitigate the artifacts because of the T-2-decay-induced signal variation. An adapted prescan phase correction as well as a concomitant phase compensation technique are implemented to minimize the phase errors. Results: Phantom data demonstrate the efficacy of the proposed double encoding/signal demodulation, as well as the prescan phase correction and concomitant phase compensation. Volunteer data show that the proposed 2D spiral TSE achieves fast scan speed with high SNR, low SAR, and improved contrast compared to conventional Cartesian TSE. Conclusion: A robust 2D spiral TSE technique is feasible and provides a potential alternative to conventional 2D Cartesian TSE for T-2-weighted neuroimaging.