PRIME: Phase reversed interleaved multi-Echo acquisition enables highly accelerated distortion-corrected diffusion...

High-resolution diffusion MRI (dMRI) is often constrained by the fundamental trade-off between geometric distortion, signal-to-noise ratio (SNR), and scan efficiency. The purpose of this study is to develop and evaluate a new pulse sequence for highly accelerated distortion-corrected dMRI by inserting additional echoes without prolonging TR, when generalized slice dithered enhanced resolution (gSlider) radiofrequency encoding is used for volumetric acquisition. A phase-reversed interleaved multi-echo acquisition (PRIME) was developed for rapid, high-resolution, and distortion-corrected dMRI, which includes multiple echoes where the first echo is for target diffusion-weighted imaging (DWI) acquisition with high-resolution and additional echoes are acquired with either lower resolution for 1) high-fidelity field map estimation, 2) phase navigation for shot-to-shot phase correction, 3) motion navigation across diffusion directions, or with high resolution to enable 4) high-fidelity diffusion relaxometry acquisitions. The sequence was evaluated on in vivo data acquired from healthy volunteers on clinical and Connectome 2.0 scanners. In vivo experiments demonstrated that 1) high in-plane acceleration was achieved using the high-fidelity field maps estimated from the second echo, which was made at a lower resolution/acceleration to increase its SNR while matching the effective echo spacing of the first readout, 2) high-resolution diffusion relaxometry parameters were estimated from triple-echo PRIME data using a white matter model of multi-TE spherical mean technique (MTE-SMT), and 3) high-fidelity mesoscale DWI at 490 µm isotropic resolution was obtained in vivo by capitalizing on the high-performance gradients of the Connectome 2.0 scanner. The proposed PRIME sequence enabled highly accelerated, high-resolution, and distortion-corrected dMRI using additional echoes without prolonging scan time when gSlider encoding is utilized.