Reproducibility of hepatic MR elastography across field strengths, pulse sequences, scan intervals, and readers

Abstract

Purpose: To evaluate the reproducibility of hepatic MRE under various combinations of settings of field strength, pulse sequence, scan interval, and reader in non-alcoholic fatty liver disease (NAFLD) patients. Methods: Adult NAFLD patients were prospectively enrolled for serial hepatic MRE with 1.5 T using 2D GRE sequence and 3.0 T using 2D SE-EPI sequence on the same day and after 2 weeks, resulting a total of four MRE examinations per patient. Three readers with various levels of background knowledge in MRE technique and liver anatomy measured liver stiffness after a training session. Linear regression, Bland–Altman analysis, within-subject coefficient of variation, and reproducibility coefficient (RDC) were used to determine reproducibility of hepatic MRE measurement. Results: Twenty patients completed the MRE sessions. Liver stiffness through MRE showed pooled RDC of 26% (upper 95% CI 30.6%) and corresponding limits of agreement (LOA) within 0.55 kPa across field strengths, MRE sequences, and 2-week interscan interval in three readers. Small mean biases and narrow LOA were observed among readers (0.05–0.19 kPa ± 0.53). Conclusion: The magnitude of change across combinations of scan parameters is within acceptable clinical range, rendering liver stiffness through MRE a reproducible quantitative imaging biomarker. A lower reproducibility was observed for measurements under different field strengths/MRE sequences at a longer (2 weeks) interscan interval. Operators should be trained to acquire region of interest consistently in repeat examinations.