Assessment of Imaging Modalities Against Liver Biopsy in Nonalcoholic Fatty Liver Disease: The Amsterdam NAFLD-NASH Cohort

Background: Noninvasive diagnostic methods are urgently required in disease stratification and monitoring in nonalcoholic fatty liver disease (NAFLD). Multiparametric magnetic resonance imaging (MRI) is a promising technique to assess hepatic steatosis, inflammation, and fibrosis, potentially enabling noninvasive identification of individuals with active and advanced stages of NAFLD.

Purpose: To examine the diagnostic performance of multiparametric MRI for the assessment of disease severity along the NAFLD disease spectrum with comparison to histological scores.

Study type: Prospective, cohort.

Population: Thirty-seven patients with NAFLD.

Field strength/sequence: Multiparametric MRI at 3.0 T consisted of magnetic resonance (MR) spectroscopy (MRS) with multi-echo stimulated-echo acquisition mode, magnitude-based and three-point Dixon using a two-dimensional multi-echo gradient echo, MR elastography (MRE) using a generalized multishot gradient-recalled echo sequence and intravoxel incoherent motion (IVIM) using a multislice diffusion weighted single-shot echo-planar sequence.

Assessment: Histological steatosis grades were compared to proton density fat fraction measured by MRS (PDFF_MRS ), magnitude-based MRI (PDFF_MRI-M ), and three-point Dixon (PDFF_Dixon ), as well as FibroScan® controlled attenuation parameter (CAP). Fibrosis and disease activity were compared to IVIM and MRE. FibroScan® liver stiffness measurements were compared to fibrosis levels. Diagnostic performance of all imaging parameters was determined for distinction between simple steatosis and nonalcoholic steatohepatitis (NASH).

Statistical tests: Spearman's rank test, Kruskal-Wallis test, Dunn's post-hoc test with Holm-Bonferroni P-value adjustment, receiver operating characteristic curve analysis. A P-value <0.05 was considered statistically significant.

Results: Histological steatosis grade correlated significantly with PDFF_MRS (r_s = 0.66, P < 0.001), PDFF_MRI-M (r_s = 0.68, P < 0.001), and PDFF_Dixon (r_s = 0.67, P < 0.001), whereas no correlation was found with CAP. MRE and IVIM diffusion and perfusion significantly correlated with disease activity (r_s = 0.55, P < 0.001, r_s = -0.40, P = 0.016, r_s = -0.37, P = 0.027, respectively) and fibrosis (r_s = 0.55, P < 0.001, r_s = -0.46, P = 0.0051; r_s = -0.53, P < 0.001, respectively). MRE and IVIM diffusion had the highest area-under-the-curve for distinction between simple steatosis and NASH (0.79 and 0.73, respectively).

Data conclusion: Multiparametric MRI is a promising method for noninvasive, accurate, and sensitive distinction between simple hepatic steatosis and NASH, as well as for the assessment of steatosis and fibrosis severity.

Level of evidence: 2 TECHNICAL EFFICACY: 2.