Measurement of Liver Iron Concentration by MRI Is Reproducible

Figure 1

Test of 12 different FeCl₃ solutions, ranging from 0.05 to 4 mg Fe/mL, to identify signal intensity ratios (SIR) close matches to average liver-to-muscle ratios of patients with moderate or high iron overload. Relationship between the iron concentration and the corresponding SIR in the two sequences of the method. (a) IW sequence (TR/TE/Flip 120/4/20°); (b) T2 sequence (TR/TE/Flip 120/14/20°). SIR was calculated between the signal intensities from each FeCl₃ solution and that from distilled water, without any iron. In both sequences SIR decreases with increasing iron concentration and it falls more steeply in T2 sequence, as occurs in clinical measurements. It is necessary to have one solution with specific concentration of FeCl₃ for each sequence and for each level of iron overload. For intermediate iron overload, the solution containing 0.5 mg Fe/mL (A1) gave the required IW signal intensity ratio (0.95) and the one with 0.3 mg Fe/mL (B1) gave the required T2 signal intensity ratio (0.47). For the high iron overload, 1.2 mg Fe/mL (A2) and 0.6 mg Fe/mL (B2) were necessary to obtain the desired IW and T2 ratios (0.35 and 0.6, resp.).

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(b)