Quantitative MRI of fatty liver disease in a large pediatric cohort: correlation between liver fat fraction, stiffness, volume, and patient-specific factors

Purpose Magnetic resonance imaging (MRI) techniques are increasingly used to quantify and monitor liver tissue characteristics including fat fraction, stiffness, and liver volume. The purpose of this study was to assess the inter-relationships between multiple quantitative liver metrics and patient-specific factors in a large pediatric cohort with known or suspected fatty liver disease. Materials and methods In this IRB-approved, HIPAA-compliant study, we retrospectively reviewed patient data and quantitative liver MRI results in children with known/suspected fatty liver disease. Relationships between liver MRI tissue characteristics and patient variables [sex, age, body mass index (BMI), diabetic status (no diabetes mellitus, insulin resistance/“prediabetes” diagnosis, or confirmed diabetes mellitus), and serum alanine transaminase (ALT)] were assessed using linear mixed models. Results 294 quantitative liver MRI examinations were performed in 202 patients [128/202 (63.4%) boys], with a mean age of 13.4 ± 2.9 years. Based on linear mixed models, liver fat fraction was influenced by age (−0.71%/+1 year, p = 0.0002), liver volume (+0.006%/+1 mL, p < 0.0001), liver stiffness (−2.80%/+1 kPa, p = 0.0006), and serum ALT (+0.02%/+1 U/L, p = 0.0019). Liver stiffness was influenced by liver volume (+0.0003 kPa/+1 mL, p = 0.001), fat fraction (−0.02 kPa/+1% fat, p = 0.0006), and ALT (0.002 kPa/+1 U/L, p = 0.0002). Liver volume was influenced by sex (−262.1 mL for girls, p = 0.0003), age (+51.8 mL/+1 year, p = 0.0001), BMI (+49.1 mL/+1 kg/m 2 , p < 0.0001), fat fraction (+30.5 mL/+1% fat, p < 0.0001), stiffness (+192.6 mL/+1 kPa, p = 0.001), and diabetic status (+518.94 mL for diabetics, p = 0.0009). Conclusions Liver volume, fat fraction, and stiffness are inter-related and associated with multiple patient-specific factors. These relationships warrant further study as MRI is increasingly used as a non-invasive biomarker for fatty liver disease diagnosis and monitoring.