Dependence of Magnetic Resonance Elastography-Derived Stiffness Values on Selected Imaging Parameters

To evaluate the influence of driver power and slice thickness on magnetic resonance elastography (MRE)-derived liver stiffness in human subjects and a tissue-mimicking phantom.

A prospective single-center observational study was performed involving 34 adult participants (20 males; median age: 29.0 ± 29.3 years) and a standard phantom. MRE was conducted on a 1.5T scanner using a 2D gradient-recalled echo-based sequence. Human data were acquired at driver powers of 25%-100% and slice thicknesses of 5 and 10 mm. The phantom was scanned with driver powers of 10%-100% and slice thicknesses from 2 to 10 mm. Two region-of-interest (ROI) approaches were applied: (A) fixed-location ROIs and (B) largest measurable ROIs. Stiffness maps were generated using the MMDI inversion algorithm. Statistical analysis included repeated measures ANOVA, paired t-tests or Wilcoxon signed-rank tests, and intraclass correlation coefficients (ICCs).

Measured whole-liver stiffness varied modestly over the driver power range, with the effect reaching statistical significance in Method B analysis (p = 0.037). Measurements of individual slices varied more significantly with driver power (Method A: p = 0.031; Method B: p < 0.001). Slice thickness had a significant effect on individual slice measurements (Method B: p = 0.007) but not on whole-liver measurements. In phantom studies, both parameters significantly influenced stiffness (p < 0.001 to p = 0.017). ICCs indicated good to excellent repeatability in vivo (0.79-0.96) and moderate to good repeatability in the phantom (0.62-0.89).

The results demonstrate that measured MRE-derived liver stiffness can be influenced by driver power and slice thickness, underscoring the need for standardization of these parameters in both clinical practice and research.