Fast, Robust T2-IVIM Quantitative MRI With Distortion and Motion-Corrected Multi-Echo EPI

To enable robust, motion- and distortion-corrected T2-IVIM parameter estimation within clinically feasible scan times.

A single-shot, multi-echo spin-echo EPI sequence was used to acquire abdominal diffusion-weighted MRI with time-efficient sampling of b-value and TE pairs. The multi-echo acquisition enabled distortion correction using reverse phase-encoding between echoes. Motion and distortion correction were applied before fitting a joint T2-IVIM model across the b-value and TE dimensions to obtain TE-independent IVIM parameters and compartment-specific T2 estimates. For comparison, a previously established single-echo T2-IVIM protocol with longer scan times and a single-echo protocol matched to the multi-echo parameters were acquired. Uncertainty was evaluated with wild bootstrap error analysis.

The multi-echo approach enabled motion- and distortion-corrected T2-IVIM mapping in under 5 min, compared with 11-13 min for the prior minimal single-echo protocol or nearly 19 min when acquired as separate shots. The liver was selected as the target organ due to its marked sensitivity to $T_2$ effects in standard IVIM. Error analysis showed comparable per-voxel uncertainty between the multi-echo method and the minimal single-echo protocol.

The combination of multi-echo sequence design and artifact correction enabled stable fitting of the extended T2-IVIM model with improved liver coverage and less than half the scan time of prior protocols. These advances support broader clinical applicability of T2-IVIM imaging by reducing acquisition burden while enhancing artifact correction and parameter robustness.