IVIM Diffusion-weighted Imaging of the Liver at 3.0T: Comparison with 1.5T

Purpose: To compare intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) of the liver between 1.5T and 3.0 T in terms of parameter quantification and inter-platform reproducibility.

Materials and methods: In this IRB approved prospective study, 19 subjects (17 patients with chronic liver disease and 2 healthy volunteers) underwent two repeat scans at 1.5T and 3.0T. Each scan included IVIM DWI using 16 b values from 0 to 800 s/mm². A single observer measured IVIM parameters for each platform and estimated signal to noise ratio (eSNR) at b0, 200, 400 and 800 s/mm². Wilcoxon paired tests were used to compare liver eSNR and IVIM parameters. Inter-platform reproducibility was assessed by calculating within-subject coefficient of variation (CV) and Bland-Altman limits of agreement. An ice water phantom was used to test ADC variability between the two MRI systems.

Results: The mean invitro difference in ADC between the two platforms was 6.8%. eSNR was significantly higher at 3.0T for all selected b values (p=0.006-0.020), except for b0 (p=0.239). Liver IVIM parameters were significantly different between 1.5T and 3.0T (p=0.005-0.044), except for ADC (p=0.748). The inter-platform reproducibility of true diffusion coefficient (D) and ADC were good, with mean CV of 10.9% and 11.1%, respectively. Perfusion fraction (PF) and pseudodiffusion coefficient (D*) showed more limited inter-platform reproducibility (mean CV of 22.6% for PF and 46.9% for D*).

Conclusion: Liver D and ADC values showed good reproducibility between 1.5T and 3.0T platforms; while there was more variability in PF, and large variability in D* parameters between the two platforms. These findings may have implications for drug trials assessing the role of IVIM DWI in tumor response and liver fibrosis.