Diffusion-weighted MRI-based Virtual Elastography for the Assessment of Liver Fibrosis

Abstract

Background Diffusion-weighted (DW) MRI-based elastography has recently been proposed for noninvasive liver fibrosis staging but requires evaluation in a larger number of patients. Purpose To compare DW MRI and MR elastography for the assessment of liver fibrosis. Materials and Methods In this retrospective study, patients underwent MR elastography and DW MRI between November 2017 and April 2018. Shear modulus measured by MR elastography (μ MRE ) was obtained in each patient from regions of interest placed on liver stiffness maps by two independent readers. Shifted apparent diffusion coefficient (ADC) was calculated from DW MRI ( b = 200 and 1500 sec/mm 2 ) and converted to DW MRI-based virtual shear modulus (μ Diff ). MRI-based liver fibrosis stages were estimated from μ MRE and μ Diff values (F0-F4) and serum fibrosis markers were assessed. Statistical analyses included Bland-Altman plots, Bayesian prediction, and receiver operating characteristic analyses. Results Seventy-four patients (mean age, 68 years ± 9 [standard deviation]; 45 men) were evaluated. Interreader coefficient of reproducibility was 0.86 kPa for DW MRI and 1.2 kPa for MR elastography. Strong correlation between shifted ADC and μ MRE was observed ( r 2 = 0.81; P MRE and μ Diff values (mean difference, -0.02 kPa ± 0.88; P Diff showed better performance in discriminating fibrosis stages F0-F2 from F3-F4 (AUC, 0.79; 95% confidence interval: 0.69, 0.90), whereas serum markers showed slightly better results for…