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Hemochromatosis: diagnosis and quantification of liver iron with gradient-echo MR imaging
Y Gandon1, D Guyader, J F Heautot
1Department of Medical Imaging, Pontchaillou Hospital, Rennes, France.
Purpose:
To assess the role of magnetic resonance (MR) imaging in detection and quantification of liver iron overload.
Materials And Methods:
MR imaging at 0.5 T was prospectively performed on 77 patients (67 with liver iron overload and 10 without) who underwent a liver biopsy with biochemical determination of the liver iron concentration (LIC) (normal, < 36 mumol per gram of liver tissue [dry weight]). Ratios of signal intensities and liver T2 relaxation time were calculated from images obtained with spin-echo and breath-hold gradient-echo (GRE) sequences.
Results:
Liver-to-tissue signal intensity ratios were better correlated with LIC than T2 relaxation time. Long-echo-time GRE sequences were the most sensitive for detection of slight overload. Thus, high sensitivity (94%) and specificity (90%) were obtained with a liver-to-fat ratio threshold of 1. The quantification of iron with MR imaging was accurate when the LIC was 80-300 mumol/g. For heavy overload, above 300 mumol/g, quantification was impossible owing to complete signal loss. Pancreatic and splenic signal intensity were unchanged in most cases.
Conclusion:
This method, which can be improved by using more sensitive sequences with a high-field-strength system, should be competitive with biopsy for the diagnosis of substantial liver iron overload.
Insights
Magnetic resonance (MR) imaging effectively detects and quantifies liver iron overload. This non-invasive method shows high sensitivity and specificity, offering a competitive alternative to liver biopsy for substantial iron overload.
Area of Science:
- Radiology
- Medical Imaging
- Hepatology
Background:
- Liver iron overload is a condition requiring accurate assessment.
- Liver biopsy, while definitive, is invasive.
- Non-invasive imaging techniques are sought for diagnosis.
Purpose of the Study:
- To evaluate magnetic resonance (MR) imaging for detecting and quantifying liver iron overload.
- To compare MR imaging performance against liver biopsy standards.
Main Methods:
- Prospective MR imaging at 0.5 T in 77 patients.
- Comparison with liver biopsy and biochemical liver iron concentration (LIC) measurements.
- Analysis of signal intensity ratios and T2 relaxation times using spin-echo and gradient-echo (GRE) sequences.
Main Results:
- Signal intensity ratios correlated better with LIC than T2 relaxation time.
- Long-echo-time GRE sequences demonstrated high sensitivity (94%) and specificity (90%) for detecting overload.
- Accurate quantification was achieved for LIC between 80-300 mumol/g; heavy overload (>300 mumol/g) resulted in signal loss.
Conclusions:
- MR imaging is a sensitive and specific tool for diagnosing substantial liver iron overload.
- The technique shows promise as a non-invasive alternative to biopsy.
- Improvements with high-field-strength systems and advanced sequences are anticipated.