Anatomical Imaging at 7 T Using 2D GRASE a Comparison with 2D TSE

Robert Trampel¹, Robin Martin Heidemann¹, Robert Turner¹

Specific absorption rate (SAR) is a serious problem at high field strengths, especially for sequences such as Turbo Spin-Echo (TSE). For a given desired tissue contrast, SAR reduction can provide either faster imaging or greater spatial coverage per unit time. By omitting most of the refocusing pulses of TSE, and replacing them with segmented EPI readouts, GRASE (Gradient-and-Spin-Echo) incurs much less SAR. Careful comparison of TSE and GRASE images at 7 T showed very similar SNR and contrast. The very slight decrease in GRASE image quality is balanced by a significant reduction in scan time (x 1/3) or increase in spatial coverage (x 3) as compared with TSE.