Multiband Low Field Diffusion Weighted Imaging

A DWI sequence using Le Roux's non-CPMG quadratic phase increment FSE that also builds on some of my older work. It turns out that the quadratic phase increment FSE is especially well suited for low-field systems, and that the issues (namely higher SAR + desire for fast encoding) that I faced on conventional systems are not present with portable MRI.

In this paper, I show how to account for additional phase sources arising from system imperfections that are prominent on portable systems. I also improved on the multiband RF-encoding schemes used for self-navigated DWI which I think was a bit of a low-hanging fruit that nobody noticed for 10 years.

I truly believe that if portable MRI takes off then this will be THE core approach for DWI. Compared to the previous papers describing DWI acquisitions on portable MRI systems, I estimate my approach gets the same image quality 5-10 times faster.

MATLAB code that implements the reconstruction and calibration steps, and some sample datasets are available here.

Lee PK, Qiu Y, Chen S, Wang C, Zhiyong Z. “Diffusion Weighted Fast Spin Echo with RF-Encoded Slabs for Portable Low-Field MRI Systems,” Magnetic Resonance in Medicine. 2026. DOI SOON