R2* imaging of transfusional iron burden at 3T and comparison with 1.5T

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Abstract
Purpose: To determine normative R2* values in the liver and heart at 3T, and establish the relationship between R2* at 3T and 1.5T over a range of tissue iron concentrations.Materials and Methods: A total of 20 healthy control subjects and 14 transfusion‐dependent patients were scanned at 1.5T and 3T. At each field strength R2* imaging was performed in the liver and heart.Results: Normative R2* values in the liver were estimated from the control group to be 39.2 ± 9.0 second−1 at 1.5T and 69.1 ± 21.9 second−1 at 3T. Normative cardiac values were estimated as 23.4 ± 2.2 second−1 at 1.5T and 30.0 ± 3.7 second−1 at 3T. The combined R2* data from patients and control subjects exhibited a linear relationship between 3T and 1.5T. In the liver, the line of best fit to the 3T vs. 1.5T data had a slope of 2.00 ± 0.06 and an intercept of −11 ± 4 second−1. In the heart, it had a slope of 1.88 ± 0.14 and an intercept of −15 ± 4 second−1.Conclusion: These preliminary data suggest that the iron‐dependent component of R2* scales linearly with field strength over a wide range of tissue iron concentrations. The incidence of susceptibility artifacts may, however, also increase with field strength. J. Magn. Reson. Imaging 2007;25:540–547.