Assessment of Nonalcoholic Fatty Liver Disease Progression in Children Using Magnetic Resonance Imaging

Abstract

Objective: To assess liver disease progression using paired magnetic resonance imaging (MRI) measurements of liver fat fraction (FF) and stiffness.

Study design: Retrospective cohort study including patients with nonalcoholic fatty liver disease who had undergone repeat MRI studies. Descriptive statistics were used, as well as Pearson or Spearman correlation when appropriate. Mixed model analyses were used to determine relationships between liver FF/stiffness and predictor variables.

Results: Sixty-five patients (80% non-Hispanic, mean age 14 ± 3 years) were included. Time from first to last MRI was 27 ± 14 months. Over time, body mass index z score remained stable, and there were no significant differences in mean serum aminotransferases, insulin, glucose, triglycerides, low-density lipoprotein, and high-density lipoprotein (HDL) levels. However, the proportion of patients with alanine aminotransferase (ALT) < 50 U/L increased. MRI FF and stiffness decreased in 29% and 20% of patients, respectively, and increased in 25% and 22% of patients, respectively. There was a weak positive correlation between FF change and ALT change (r = 0.41, P = .053) and a moderate negative correlation between change in FF and change in serum HDL levels (r = -0.58, P = .004). After adjusting for HDL, increase in serum insulin was the only variable predictive of increase in FF (P = .061). There was no correlation between change in liver stiffness and change in ALT (r = .02, P = .910).

Conclusions: MRI-determined hepatic FF and stiffness improved in a minority of patients overtime. ALT levels were not reflective of the change in FF or stiffness. MRI-based imaging is complementary in the assessment of NAFLD progression.

Keywords: MR elastography; Proton density fat fraction; hepatic fibrosis liver stiffness; hepatic steatosis; pediatric NAFLD; progression.

Figure 1.

Change over time in MRI/MRE findings.

Figure 2.

Axial T2-weighted, A, fat saturated image, B, color wave image, and C, elastogram at diagnosis show mild hepatomegaly with normal liver stiffness manifest as purples, blues, and greens in the elastogram (mean = 2.2 kPa). Axial T2-weighted, D, fat saturated image, B, color wave image, and C, elastogram 4 years later show further enlargement of the liver with subtly increased T2-weighted signal. Waves in the liver are appreciably longer, reflective of elevated liver stiffness and faster wave travel. Liver stiffness is markedly increased (reds and yellows in the elastogram) with mean liver stiffness of 5.5 kPa.