Reproducibility of liver ADC measurements using first moment optimized diffusion imaging

Purpose: Cardiac-induced liver motion can bias liver ADC measurements and compromise reproducibility. The purpose of this work was to enable motion-robust DWI on multiple MR scanners and assess reproducibility of the resulting liver ADC measurements.

Methods: First moment-optimized diffusion imaging (MODI) was implemented on three MR scanners with various gradient performances and field strengths. MODI-DWI and conventional Stejskal-Tanner monopolar (MONO) DWI were acquired in eight (N = 8) healthy volunteers on each scanner, and DWI repetitions were combined using three different averaging methods. For each combination of scanner, acquisition, and averaging method, ADC measurements from each liver segment were collected. Systematic differences in ADC values between scanners and methods were assessed with linear mixed effects modeling, and reproducibility was quantified via reproducibility coefficients.

Results: MODI reduced left-right liver lobe ADC bias from 0.43 × 10^-3 mm²/s (MONO) to 0.19 × 10^-3 mm²/s (MODI) when simple (unweighted) repetition averaging was used. The bias was reduced from 0.23 × 10^-3 mm²/s to 0.06 × 10^-3 mm²/s using weighted averaging, and 0.14 × 10^-3 mm²/s to 0.01 × 10^-3 mm²/s using squared weighted averaging. There was no significant difference in ADC measurements between field strengths or scanner gradient performance. MODI improved reproducibility coefficients compared to MONO: 0.84 × 10^-3 mm²/s vs. 0.63 × 10^-3 mm²/s (MODI vs. MONO) for simple averaging, 0.66 × 10^-3 mm²/s vs. 0.50 × 10^-3 mm²/s for weighted averaging, and 0.61 × 10^-3 mm²/s vs. 0.47 × 10^-3 mm²/s for squared weighted averaging.

Conclusion: The feasibility of motion-robust liver DWI using MODI was demonstrated on multiple MR scanners. MODI improved interlobar agreement and reproducibility of ADC measurements in a healthy cohort.