Objectives: To determine the feasibility of a multi-step magnetic resonance imaging (MRI) approach for comprehensive assessment of hepatic steatosis defined as liver fat content of ≥5 % in an asymptomatic population.
Methods: The study was approved by the institutional review board and written informed consent of all participants was obtained. Participants of a population-based study cohort underwent a three-step 3-T MRI-based assessment of liver fat. A dual-echo Dixon sequence was performed to identify subjects with hepatic steatosis, followed by a multi-echo Dixon sequence with proton density fat fraction estimation. Finally, single-voxel T2-corrected multi-echo spectroscopy was performed.
Results: A total of 215 participants completed the MRI protocol (56.3 % male, average age 57.2 ± 9.4 years). The prevalence of hepatic steatosis was 55 %. Mean liver proton density fat fraction was 9.2 ± 8.5 % by multi-echo Dixon and 9.3 ± 8.6 % by multi-echo spectroscopy (p = 0.51). Dual-echo Dixon overestimated liver fat fraction by 1.4 ± 2.0 % (p < 0.0001). All measurements showed excellent correlations (r ≥ 0.9, p < 0.001). Dual-echo Dixon was highly sensitive for the detection of hepatic steatosis (sensitivity 0.97, NPV 0.96) with good specificity and PPV (0.75 and 0.81, respectively).
Conclusions: A multi-step MRI approach may enable rapid and accurate identification of subjects with hepatic steatosis in an asymptomatic population.
Key points: • Dual-echo Dixon can rapidly and reliably exclude hepatic steatosis without complex post-processing. • Multi-echo Dixon and multi-echo spectroscopy yield similar results regarding hepatic fat quantification. • Each sequence can be performed in one breath-hold. • These sequences can be implemented in routine abdominal MRI protocols. • Thus hepatic fat can be evaluated without relevant increase in scan time.
Keywords: Dual-echo Dixon; Magnetic resonance imaging; Magnetic resonance spectroscopy; Multi-echo Dixon; Non-alcoholic fatty liver disease.