Detecting Early-Stage Liver Fibrosis Using Macromolecular Proton Fraction Mapping Based on Spin-Lock MRI: Preliminary Observations

Background Liver fibrosis is characterized by macromolecule depositions. Recently, a novel technology termed macromolecular proton fraction quantification based on spin-lock magnetic resonance imaging (MPF-SL) is reported to measure macromolecule levels. Hypothesis MPF-SL can detect early-stage liver fibrosis by measuring macromolecule levels in the liver. Study Type Retrospective. Subjects Fifty-five participants, including 22 with no fibrosis (F0) and 33 with early-stage fibrosis (F1-2), were recruited. Field Strength/Sequence 3 T; two-dimensional (2D) MPF-SL turbo spin-echo sequence, 2D spin-lock T1rho turbo spin-echo sequence, and multi-slice 2D gradient echo sequence. Assessment Macromolecular proton fraction (MPF), T1rho, liver iron concentration (LIC), and fat fraction (FF) biomarkers were quantified within regions of interest. Statistical Tests Group comparison of the biomarkers using Mann-Whitney U tests; correlation between the biomarkers assessed using Spearman's rank correlation coefficient and linear regression with goodness-of-fit; fibrosis stage differentiation using receiver operating characteristic curve (ROC) analysis. P-value < 0.05 was considered statistically significant. Results Average T1rho was 41.76 +/- 2.94 msec for F0 and 41.15 +/- 3.73 msec for F1-2 (P = 0.60). T1rho showed nonsignificant correlation with either liver fibrosis (rho = -0.07; P = 0.61) or FF (rho = -0.14; P = 0.35) but indicated a negative correlation with LIC (rho = -0.66). MPF was 4.73 +/- 0.45% and 5.65 +/- 0.81% for F0 and F1-2 participants, respectively. MPF showed a positive correlation with liver fibrosis (rho = 0.59), and no significant correlations with LIC (rho = 0.02; P = 0.89) or FF (rho = 0.05; P = 0.72). The area under the ROC curve was 0.85 (95% confidence interval [CI] 0.75-0.95) and 0.55 (95% CI 0.39-0.71; P = 0.55) for MPF and T1rho to discriminate between F0 and F1-2 fibrosis, respectively. Data Conclusion MPF-SL has the potential to diagnose early-stage liver fibrosis and does not appear to be confounded by either LIC or FF. Level of Evidence 3 Technical Efficacy Stage 3

Automated summary

This study used MPF-SL technology to measure macromolecule levels in the liver and found that it can detect early-stage liver fibrosis, and is not confounded by liver iron concentration or fat fraction.