IVIM diffusion-weighted imaging of the liver at 3.0 T: Comparison with 1.5 T

Abstract

PurposeTo compare intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) of the liver between 1.5T and 3.0T in terms of parameter quantification and inter-platform reproducibility. Materials and methodsIn 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 800s/mm2. A single observer measured IVIM parameters for each platform and estimated signal to noise ratio (eSNR) at b0, 200, 400 and 800s/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. ResultsThe 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*). ConclusionLiver 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.