Regional Analysis of Liver Surface Nodularity in a Single Axial MR Image for Staging Liver Fibrosis

Abstract

Background: The assessment of liver surface nodularity (LSN) for staging hepatic fibrosis is restricted in clinical practice because it requires customized software and time-consuming procedures. A simplified method to estimate LSN score may be useful in the clinic.

Purpose: To evaluate the regional analysis of LSN and processing time in a single axial liver MR image for staging liver fibrosis.

Study type: Retrospective.

Population: A total of 210 subjects, a multicenter study.

Field strength/sequence: A 3 T/noncontrast gradient echo T1WI.

Assessment: Subjects were divided into five fibrosis groups (F₀ = 29; F₁ = 20; F₂ = 32; F₃ = 50; F₄ = 79) based on the METAVIR fibrosis scoring system. The mean LSN (on three slices) and regional LSN (on one slice) measurements, and the processing times, are compared. The regional LSN scores in five regions-of-interests (ROI_1-5 ) were analyzed in a single axial MRI at the level of the hilum by two independent observers.

Statistical tests: Regional variations in LSN scores were compared using ANOVA with Tukey test. Agreement between the mean and regional LSN measurements was evaluated using Pearson correlation coefficients (r) and Bland-Altman plots. The diagnostic performance of mean and regional LSN scores according to fibrosis stage was evaluated with the AUROC. A P value < 0.05 was considered statistically significant.

Results: Total processing time for a regional LSN measurement (3.6 min) was 75.5% less than that for mean LSN measurement (14.7 min). Mean LSN scores and all five regional LSN scores showed significant differences between fibrosis groups. Among regional LSN scores, ROI₅ showed the highest AUROC (0.871 at cut-off 1.12) for discriminating F_0-2 vs. F_3-4 and the best correlation with mean LSN score (r = 0.800, -0.07 limit of agreement).

Conclusion: Quantitative regional LSN measurement in a single axial MR image reduces processing time. Regional ROI₅ LSN score might be useful for clinical decision-making and for distinguishing the difference between early fibrosis (F_0-2 ) and advanced fibrosis (F_3-4 ) in the liver.

Evidence level: 3 TECHNICAL EFFICACY: Stage 2.

Keywords: liver fibrosis; liver surface nodularity (LSN); regional analysis.