# Comparison of Manual Multi-ROI, Single-Location, and Volumetric Fat Fraction Measurements for Hepatic Steatosis Using MRI

## TL;DR

This study compares different MRI methods for measuring liver fat and finds that automated single-location MRI and MRS are reliable and efficient, while volumetric MRI tends to overestimate fat.

## Contribution

The study introduces a comparative evaluation of automated MRI methods against manual multi-ROI as a reference for hepatic steatosis.

## Key findings

- Single-location MRI-PDFF and MRS showed high agreement with manual measurements in steatosis grading.
- Volumetric MRI-PDFF had lower agreement and tended to overestimate fat levels.
- Manual multi-ROI MRI-PDFF showed excellent observer reliability.

## Abstract

Background/Objectives: To comparatively evaluate the clinical reliability of automated single-location MRI–proton density fat fraction (PDFF), single-voxel magnetic resonance spectroscopy (MRS), and volumetric MRI-PDFF measurements for quantitative assessment of hepatic steatosis, using manual multi-regions of interest (ROI) MRI-PDFF as the reference standard. Methods: In this retrospective single-center study, adult patients who underwent liver MRI with both MRI-PDFF and MRS between December 2024 and January 2026 were included. Manual multi-ROI MRI-PDFF measurements were obtained from eight Couinaud segments and served as the reference standard. Automated single-location MRI-PDFF, single-voxel MRS, and volumetric MRI-PDFF measurements were extracted from system-generated reports. Fat fraction values and steatosis grades were compared using non-parametric tests, Spearman correlation coefficients, exact agreement rates, weighted Cohen’s kappa statistics, and Bland–Altman analysis. Intra- and inter-observer reliability of manual multi-ROI measurements was assessed using intraclass correlation coefficients (ICC). Results: A total of 490 patients were included. Single-location MRI-PDFF and single-voxel MRS demonstrated high exact agreement with manual multi-ROI MRI-PDFF in steatosis grading (86.9% and 87.4%, respectively), with near-perfect agreement (weighted κ = 0.82–0.83). Volumetric MRI-PDFF showed lower exact agreement (76.1%) and a systematic tendency toward overestimation, with more frequent upward shifts in steatosis grade. All techniques showed strong correlations with manual measurements (ρ = 0.72–0.75). Manual multi-ROI MRI-PDFF demonstrated excellent inter- and intra-observer reliability (ICC > 0.97). Conclusions: Automated single-ROI MRI-PDFF and single-voxel MRS provide clinically reliable and time-efficient alternatives for hepatic steatosis assessment, while automated volumetric MRI-PDFF may introduce systematic bias toward overestimation.