Comparison of hepatic iron quantification by MRI between 1.5 and 3 T, using different methods and conversion formulas

Area of Science:

• Radiology
• Medical Imaging
• Biophysics

Background:

• Accurate liver iron concentration (LIC) measurement is crucial for managing iron overload disorders.
• Magnetic Resonance Imaging (MRI) offers non-invasive LIC quantification, but estimates can vary with field strength and methodology.

Purpose of the Study:

• To compare liver iron concentration (LIC) estimates derived from 1.5-T and 3-T MRI systems.
• To evaluate the impact of different quantification methods and calibration groups on LIC accuracy and reproducibility.

Main Methods:

• Prospective study of 78 participants undergoing 1.5-T and 3-T liver MRI.
• Quantification of liver fat (PDFF) and iron (R2*) using multi-echo gradient recalled echo (ME-GRE) sequences.
• LIC calculation from R2* using European/American calibrations and signal intensity ratio (SIR) at 1.5-T.

Main Results:

• Strong correlation between 1.5-T and 3-T R2*-based LIC estimates (R=0.84-0.99).
• Low bias (±7%) when using identical calibration groups across field strengths.
• Significant bias (26%) observed when comparing American and European calibration groups.

Conclusions:

• LIC estimates are highly reproducible between 1.5-T and 3-T MRI when consistent calibration methods are employed.
• Differences in calibration groups introduce notable bias, affecting clinical comparability.
• Simple estimation formulas (R2*/2 at 1.5-T, R2*/4 at 3-T) offer clinical convenience but require alignment with established references.