Three‐dimensional diffusion MRI using simultaneous multislab with blipped‐CAIPI in a 4D k‐space framework

Abstract

PurposeTo develop an efficient simultaneous multislab imaging method with blipped‐controlled aliasing in parallel imaging (blipped‐SMSlab) in a 4D k‐space framework, and to demonstrate its efficacy in high‐resolution diffusion MRI (dMRI).Theory and MethodsFirst, the SMSlab 4D k‐space signal expression is formulated, and the phase interferences from intraslab and interslab encodings on the same physical z‐axis are analyzed. Then, the blipped‐SMSlab dMRI sequence is designed, with blipped–controlled aliasing in parallel imaging (blipped‐CAIPI) gradients for interslab encoding, and a 2D multiband accelerated navigator for inter‐kz‐shot phase correction. Third, strategies are developed to remove the phase interferences, by RF phase modulation and/or phase correction during reconstruction, thus decoupling intraslab and interslab encodings that are otherwise entangled. In vivo experiments are performed to validate the blipped‐SMSlab method and preliminarily evaluate its performance in high‐resolution dMRI compared with traditional 2D imaging.ResultsIn the 4D k‐space framework, interslab and intraslab phase interferences of blipped‐SMSlab are successfully removed using the proposed strategies. Compared with non–CAIPI sampling, the blipped‐SMSlab acquisition reduces the g‐factor and g‐factor‐related SNR penalty by about 12%. In addition, in vivo experiments show the SNR advantage of blipped‐SMSlab dMRI over traditional 2D dMRI for 1.3‐mm and 1.0‐mm isotropic resolution imaging with matched acquisition time.ConclusionRemoving interslab and intraslab phase interferences enables SMSlab dMRI with blipped‐CAIPI in a 4D k‐space framework. The proposed blipped‐SMSlab dMRI is demonstrated to be more SNR‐efficient than 2D dMRI and thus capable of high‐quality, high‐resolution fiber orientation detection.