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Evaluation of hepatic iron concentration heterogeneities using the MRI R2* mapping method
Jean Mazé1, Guillaume Vesselle1, Guillaume Herpe1
1Imaging Department, CHU de Poitiers, 2 Rue de la milétrie, 86000 CHU de Poitiers, France.
European Journal of Radiology
|June 3, 2019
Summary
Magnetic resonance R2* mapping can measure hepatic iron concentration (HIC) heterogeneities. This method reveals variations in iron levels across the liver, particularly in patients with high iron overload.
Area of Science:
- Medical Imaging
- Hepatology
- Quantitative MRI
Background:
- Hepatic iron concentration (HIC) is crucial for diagnosing and managing iron overload disorders.
- Accurate assessment of HIC distribution within the liver is essential for understanding disease progression and treatment efficacy.
- Current methods may not fully capture the spatial variability of iron in the liver.
Purpose of the Study:
- To evaluate the utility of magnetic resonance (MR) R2* mapping for quantifying hepatic iron concentration (HIC) heterogeneities.
- To compare different R2* post-processing methods against a reference standard for HIC measurement.
- To assess the variability of HIC within the liver in healthy volunteers and patients with suspected iron overload.
Main Methods:
- A prospective study included 94 patients with suspected hepatic iron overload and 10 volunteers.
- A multi-echo R2* MR sequence was employed with fat saturation.
- Three post-processing fitting methods (SED, SEDt, COS) were compared to the signal intensity ratio (SIR) method.
- Hepatic iron concentration heterogeneity was assessed using R2* mapping with region of interest (ROI) placement in each liver segment.
Main Results:
- Strong linear correlations (r=0.973 for SEDt, r=0.955 for COS) were found between R2* mapping methods and the SIR reference.
- Mean intra-liver standard deviation (SD) for HIC heterogeneity was 1.58 μmol/g in volunteers and 4.73 μmol/g in patients.
- Increased HIC heterogeneity was observed in patients with HIC > 60 μmol/g (mean intra-liver SD = 13.90 μmol/g).
- The IVth liver segment showed the highest HIC in the patient group.
Conclusions:
- This study demonstrates, for the first time, in vivo hepatic iron concentration heterogeneities using whole-liver R2* mapping.
- The R2* mapping technique shows promise for assessing HIC distribution.
- Further studies are needed to confirm these findings, which may aid in single ROI analysis limitations.
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