Work

Evaluation of 0.55T MRI for Simultaneous R2* and Fat Fraction Quantification in the Presence of Hepatic Iron Overload and Steatosis Using Simulations and Phantoms

Year: 2025

Type: article

Abstract: ABSTRACT Purpose To create virtual liver models simulating the concurrent presence of hepatic iron overload and steatosis based on human liver histology and to assess the accuracy and precision of R2* and fat fraction (FF) estimation at 0.55T compared to 1.5T. Methods Virtual liver models simulating the coexistence of iron overload and steatosis were created, encompassing clinical liver iron concentration (LIC) (0–20 mg/g) and FF (0%–30%) ranges, using morphological characteristics derived from human liver histology. MRI signals were synthesized via Monte Carlo simulations under varying SNR conditions (SNR original (SNR orig ) and SNR enhanced (SNR enh )) at 0.55T (SNR orig,0.55T = 20; SNR enh,0.55T = 50) and 1.5T (SNR orig,1.5T = 50). Simulation results were validated using iron‐fat phantoms (FF: 0%–40%; iron concentration: 0–8 μg/mL) scanned across varying SNRs using different signal averages (SNR orig,0.55T , SNR orig,1.5T = 1; SNR enh,0.55T = 4). Accuracy and precision of 0.55T for estimating R2* and FF compared to 1.5T were assessed using boxplots, heatmaps, and Kruskal–Wallis statistical tests. Results SNR orig,0.55T demonstrated reduced or comparable FF estimation bias relative to SNR orig,1.5T , with significantly lower bias for SNR enh,0.55T , especially for severe iron overload and FF ≤ 20%. LIC estimation for SNR orig,0.55T and SNR enh,0.55T demonstrated higher accuracy compared to SNR orig,1.5T with significant differences ( p < 0.028) for all combinations of LIC and FF except for severe iron overload with FF > 10% ( p > 0.183). Further, SNR enh,0.55T showed improved precision for FF and LIC estimation compared to SNR orig,1.5T . Phantom experiments showed reduced bias for both FF and LIC estimation for SNR enh,0.55T compared to SNR orig,1.5T . Conclusion 0.55T shows promising results for concurrent R2 * and FF estimation, enhancing accuracy and precision compared to 1. 5 T, especially with enhanced SNR.

Source: Magnetic Resonance in Medicine

DOI: 10.1002/mrm.70162

Authors: Utsav Shrestha, Mark Bolding, Teresa Santiago, Zachary Abramson, Cara E. Morin, Aaryani Tipirneni‐Sajja