Slice-selective adiabatic magnetization T -preparation (SAMPA) for efficient T -weighted imaging at ultrahigh field strengths.

Purpose: At high field, T -weighted (T w) imaging is limited by transmit field inhomogeneity and increased radiofrequency power deposition. In this work, we introduce SAMPA (Slice-selective Adiabatic Magnetization T PrepAration) and demonstrate its use for efficient brain T w imaging at 7 Tesla (T).

Methods: SAMPA was designed by subsampling an optimized B insensitive rotation (BIR4) waveform with small tip angle linear subpulses. To perform T w imaging, SAMPA was inserted before a fast gradient echo acquisition. The off-resonance behavior, B robustness, and slice selectivity of the novel T preparation module were analyzed using Bloch simulations. The performance of SAMPA for T w imaging was demonstrated in phantom experiments as well as in the brains of healthy volunteers at 7T.

Results: Based on simulations, the proposed design operates at peak B of 15 μT and higher, within a 400 Hz bandwidth. T values were in strong agreement with spin echo-based T mapping in phantom experiments. Whole brain, interleaved multislab three-dimensional imaging could be acquired with 0.8 mm isotropic resolution in 5:36 min per T weighting.

Conclusion: Compared with previous adiabatic T preparation techniques, SAMPA allows for slice-selectivity, which can lead to efficient and robust acquisitions for T w imaging at high field. Magn Reson Med 76:1741-1749, 2016. © 2015 International Society for Magnetic Resonance in Medicine.