Robert Trampel1, Robin Martin Heidemann1, Robert Turner1
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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.