Multiphoton Simultaneous Multislice Imaging with CAIPIRINHA Phase Encoding

Simultaneous multislice (SMS) imaging methods reduce scan time but increase specific absorption rate (SAR) because of additional radiofrequency (RF) pulses required for exciting multiple slices. Multiphoton excitation was recently proposed to significantly reduce SAR for SMS imaging. In this work, we further developed a phase-modulated multiphoton SMS excitation method that achieves CAIPIRINHA-type controlled aliasing, which improves image reconstruction quality significantly. Images obtained with our custom multiphoton CAIPIRINHA-SMS sequence have reduced aliasing artifacts and higher SNR compared to images obtained with a multiphoton SMS sequence without CAIPIRINHA. For a three-slice design, SAR is reduced by a factor of two.