A SEmi-Adiabatic matched-phase spin echo (SEAMS) PINS pulse-pair for B1-insensitive simultaneous multislice imaging.

Purpose Simultaneous multislice (SMS) imaging is a powerful technique that can reduce image acquisition time for anatomical, functional, and diffusion weighted magnetic resonance imaging. At higher magnetic fields, such as 7 Tesla, increased radiofrequency (RF) field inhomogeneity, power deposition, and changes in relaxation parameters make SMS spin echo imaging challenging. We designed an adiabatic 180° Power Independent of Number of Slices (PINS) pulse and a matched-phase 90° PINS pulse to generate a SEmi-Adiabatic Matched-phase Spin echo (SEAMS) PINS sequence to address these issues. Methods We used the adiabatic Shinnar Le-Roux (SLR) algorithm to generate a 180° pulse. The SLR polynomials for the 180° pulse were then used to create a matched-phase 90° pulse. The pulses were sub-sampled to produce a SEAMS PINS pulse-pair and the performance of this pulse-pair was validated in phantoms and in vivo. Results Simulations as well as phantom and in vivo results, demonstrate multislice capability and improved B₁-insensitivity of the SEAMS PINS pulse-pair when operating at RF amplitudes of up to 40% above adiabatic threshold. Conclusion The SEAMS PINS approach presented here achieves multislice spin echo profiles with improved B₁-insensitivity when compared with a conventional spin echo. Magn Reson Med 75:709-717, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]