Noninvasive MRE accurately stages liver fibrosis in NAFLD

Magnetic resonance elastography demonstrates high accuracy in the noninvasive staging of liver fibrosis in patients with nonalcoholic fatty liver disease (NAFLD), reports a study.

In addition, elevated inflammatory activity and gamma-glutamyl transferase (GGT) level contribute to the overestimation of early liver fibrosis, but anthropometric measures such as body mass index (BMI) or the degree of steatosis do not.

“[W]e observed that MRE is a highly accurate, noninvasive technique for staging liver fibrosis in patients with NAFLD and nonalcoholic steatohepatitis (NASH), where we have established cut-offs of 2.65, 3.14, 3.53, and 4.45 kPa for mild (≥F1), significant (≥F2), and advanced (≥F3) fibrosis, and cirrhosis (F4), respectively,” the investigators said.

A systematic literature review was conducted to identify studies reporting MRE data in NAFLD patients. The investigators obtained data from the corresponding authors. They then performed a two-stage meta-analysis to determine the pooled diagnostic cut-off value for the various fibrosis stages. Finally, potential confounding factors that could influence the diagnostic accuracy of MRE in staging liver fibrosis were analysed using multilevel modeling methods.

Cut-off values

The meta-analysis included eight independent cohorts comprising 798 patients. In detecting significant fibrosis, MRE had an area under the receiver operating characteristic curve (AUROC) of 0.92, with a sensitivity of 79 percent and specificity of 89 percent. In advanced fibrosis, the AUROC for MRE was 0.92, with 87-percent sensitivity and 88-percent specificity, while that in cirrhosis was 0.94, with 88-percent sensitivity and 89-percent specificity. [J Hepatol 2023;79:592-604]

The investigators also defined the following cut-off to explore concordance between MRE and histopathology: ≥F2, 3.14 kPa (pretest probability, 39.4 percent); ≥F3, 3.53 kPa (pretest probability, 24.1 percent); and F4, 4.45 kPa (pretest probability, 8.7 percent).

Generalized linear mixed model analyses further revealed that histological steatohepatitis with higher inflammatory activity (odds ratio [OR], 2.448, 95 percent confidence interval [CI], 1.180‒5.079; p<0.05) and high GGT concentration (>120 U/L; OR, 3.388, 95 percent CI, 1.577‒7.278; p<0.01) significantly correlated with elevated liver stiffness, which could affect the accuracy in staging early fibrosis (F0‒F1).

On the other hand, BMI and steatosis, as measured by magnetic resonance imaging proton density fat fraction, were not confounders.

“[C]linical information and the possible presence of severe inflammation activity should be considered for early-stage fibrosis cohorts to optimize the diagnostic accuracy of MRE in staging liver fibrosis,” the investigators said.

Potential confounder

Additionally, subgroup and univariate analyses of the generalized linear mixed model showed that the presence of type 2 diabetes mellitus (T2DM) could potentially affect the diagnostic performance of MRE.

An earlier study observed a robust association between increased liver stiffness measurement by transient elastography and the presence of diabetes or greater insulin resistance in the whole population, as well as in a subgroup of participants with NAFLD. [Hepatology 2016;63:138-147]

“This may apparently induce patients with NAFLD with T2DM, which positively affects liver stiffness measurement in NAFLD,” the investigators said.