Cross-Vendor Validation of Proton Density Fat Fraction and T₁ Mapping Using a Combined Proton Density Fat Fraction-T1...

In chronic liver disease, fat and fibroinflammatory changes often coexist. However, their biomarkers, proton density fat fraction (PDFF) and T₁, are typically assessed separately. Their reproducibility under mutual confounding remains unclear.

To assess multicenter, multi-vendor reproducibility of confounder-corrected chemical shift-encoded (CSE)-MRI-based PDFF mapping and MOLLI-based T₁ mapping using a combined PDFF-T₁ phantom.

Prospective phantom study.

Commercial PDFF-T₁ Phantom (Model 725) with varying PDFF (0%-30%) and T₁ (200-1400 ms) values.

1.5 T and 3 T multi-echo, three-dimensional spoiled-gradient-echo (SGRE) sequence for PDFF mapping, and MOLLI sequence (5(3)3 acquisition scheme) using two-dimensional SGRE readouts for T₁ mapping across four centers and vendors.

PDFF and T₁ maps were acquired using standardized protocols. PDFF maps were reconstructed locally, while T₁ maps were generated using a centralized algorithm. All maps were quantitatively analyzed by a single radiologist using standardized region-of-interest placement. Phantom temporal stability was assessed at one center across five sessions over 9 months (baseline, retest, 1 week, 6 and 9 months).

Intraclass correlation coefficients (ICC), reproducibility coefficients (RDC), and linear regression analysis were used. A p value < 0.05 was considered statistically significant.

PDFF showed overall excellent reproducibility (ICC = 0.987, RDC = 3.7%), with increased variability at higher T₁ values (RDC up to 7.9% at T₁ = 1400 ms). T₁ mapping showed good reproducibility in the absence of fat (RDC 16-161 ms at PDFF = 0%), but moderate to poor reproducibility in the presence of fat, with RDC increasing up to 1553 ms at PDFF 30%. Temporal stability was excellent ICC ≥ 0.998 for both PDFF and T₁, and RDC of 1.1%-1.3% for PDFF and 52-57 ms for T₁.

This phantom study demonstrated high reproducibility of PDFF, whereas T₁ reproducibility deteriorated at higher fat and T₁ levels, underscoring the need for fat-corrected T₁ mapping for reliable assessment of fibroinflammatory changes.

N/A.

Stage 1.