Whole-organ and segmental stiffness measured with liver magnetic resonance elastography in healthy adults: significance of the region of interest

Abstract

PurposeMR elastography (MRE) is a recent non-invasive technique that provides in vivo data on the viscoelasticity of the liver. Since the method is not well established, several different protocols were proposed that differ in results. The aim of the study was to analyze the variability of stiffness measurements in different regions of the liver.MethodsTwenty healthy adults aged 24–45 years were recruited. The examination was performed using a mechanical excitation of 64 Hz. MRE images were fused with axial T2WI breath-hold images (thickness 10 mm, spacing 10 mm). Stiffness was measured as a mean value of each cross section of the whole liver, on a single largest cross section, in the right lobe, and in ROIs (50 pix.) placed in the center of the left lobe, segments 5/6, 7, 8, and the parahilar region.ResultsWhole-liver stiffness ranged from 1.56 to 2.75 kPa. Mean segmental stiffness differed significantly between the tested regions (range from 1.55 ± 0.28 to 2.37 ± 0.32 kPa; P < 0.0001, ANOVA). Within-method variability of measurements ranged from 14 % for whole liver and segment 8–26 % for segment 7. Within-subject variability ranged from 13 to 31 %. Results of measurement within segment 8 were closest to the whole-liver method (ICC, 0.84).ConclusionsStiffness of the liver presented significant variability depending on the region of measurement. The most reproducible method is averaging of cross sections of the whole liver. There was significant variability between stiffness in subjects considered healthy, which requires further investigation.

Comparison of technical failure of MR elastography for measuring liver stiffness between gradient‐recalled echo and spin‐echo echo‐planar imaging: A systematic review and meta‐analysis

“…Finally, 31 studies fulfilled the eligibility criteria for our analysis, including eight studies using both GRE and SE‐EPI sequences, 22 studies using only a GRE sequence, , , , , , , , and one study using only an SE‐EPI sequence . As one study using both GRE and SE‐EPI sequences potentially overlapped with a population in another GRE sequence outcome study, we did not include the outcomes of this study in the evaluation of the pooled proportion of technical failure of GRE sequences, but used it only for the head‐to‐head comparison between GRE and SE‐EPI sequences.…”

“…The demographic characteristics of the included studies are shown in Table . In brief, subjects were enrolled prospectively in 16 studies and retrospectively in 15 studies , , , , , , , . The mean patient ages in 14 studies , , , , , , , , ranged from 25 to 60.5 years, but we could not analyze patient age in the other studies, because they did not report demographic information on all subjects, but reported only those with successful examinations.…”

“…Nonetheless, as people tend to focus more on successful results rather than technical failure when presenting the results of studies, the failure rates of MRE have not been reported well. A limited number of studies have reported on the technical failure rate of MRE, and fewer studies have made comparisons regarding the failure rates between these two sequences. The results from the studies are also limited by their small sample sizes and the resulting low levels of evidence.…”

Liver Stiffness Measurements with MR Elastography: Agreement and Repeatability across Imaging Systems, Field Strengths, and Pulse Sequences

“…All liver stiffness measurements were made while remaining blinded to measurement values obtained with other sequences in the same patient. Liver stiffness values for each MR elastography examination were expressed as a mean of mean stiffness measurements (in kilopascals) from each of four axial sections through the mid liver, as this has previously been defined as a reproducible method of measuring liver stiffness (18).…”

Magnetic Resonance Elastography and Other Magnetic Resonance Imaging Techniques in Chronic Liver Disease: Current Status and Future Directions

“…Compared to the standard anatomic evaluation of liver morphology, MRE performs significantly better for both significant fibrosis (0.989 in MRE vs 0.71 to 0.82 in MRI) and cirrhosis (0.935 in MRE vs 0.61 to 0.80 in MRI) 16. Using a 3.7-kPa cutoff value, the study by Venkatesh et al 6. found that MRE yielded a sensitivity of 91% and specificity of 80% for differentiating F0–F2 from F3–F4 grades of fibrosis.…”