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Measurement of liver iron concentration by MRI is reproducible.

Alústiza JM, Emparanza JI, Castiella A, Casado A, Garrido A, Aldazábal P, San Vicente M, Garcia N, Asensio AB, Banales J, Salvador E, Moyua A, Arozena X, Zarco M, Jauregui L, Vicente O - Biomed Res Int (2015)

Bottom Line: The phantom was analysed in the same equipment and 14 times in the reference machine.FeCl3 solutions containing 0.3, 0.5, 0.6, and 1.2 mg Fe/mL were chosen to generate the phantom.The average of the intramachine variability for patients was 10% and for the intermachines 8%.

View Article: PubMed Central - PubMed

Affiliation: Osatek, Donostia Universitary Hospital, P. Dr. Beguiristain 109, 20014 Donostia/San Sebastián, Spain.

ABSTRACT

Purpose: The objectives were (i) construction of a phantom to reproduce the behavior of iron overload in the liver by MRI and (ii) assessment of the variability of a previously validated method to quantify liver iron concentration between different MRI devices using the phantom and patients.

Materials and methods: A phantom reproducing the liver/muscle ratios of two patients with intermediate and high iron overload. Nine patients with different levels of iron overload were studied in 4 multivendor devices and 8 of them were studied twice in the machine where the model was developed. The phantom was analysed in the same equipment and 14 times in the reference machine.

Results: FeCl3 solutions containing 0.3, 0.5, 0.6, and 1.2 mg Fe/mL were chosen to generate the phantom. The average of the intramachine variability for patients was 10% and for the intermachines 8%. For the phantom the intramachine coefficient of variation was always below 0.1 and the average of intermachine variability was 10% for moderate and 5% for high iron overload.

Conclusion: The phantom reproduces the behavior of patients with moderate or high iron overload. The proposed method of calculating liver iron concentration is reproducible in several different 1.5 T systems.

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Related in: MedlinePlus

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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fig1: 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.).

Mentions: Figure 1 illustrates the relationship between the signal intensity ratio in 12 tubes with different FeCl3 concentrations ranging from 0.05 to 4 mg Fe/mL for the two sequences. In both cases, signal intensity inversely correlates with the iron concentration, but the signal falls more steeply in the T2 sequence, as occurs in clinical measurements [11]. Two different tubes were necessary to obtain the SI ratios of 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 0.3 mg Fe/mL (B1) the required T2 signal intensity ratio (0.47). For 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 mg Fe/mL, resp.). Based on this data, the phantom was constructed using one tube without iron and each of the four different FeCl3 solutions (Figure 2).


Measurement of liver iron concentration by MRI is reproducible.

Alústiza JM, Emparanza JI, Castiella A, Casado A, Garrido A, Aldazábal P, San Vicente M, Garcia N, Asensio AB, Banales J, Salvador E, Moyua A, Arozena X, Zarco M, Jauregui L, Vicente O - Biomed Res Int (2015)

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.).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4385637&req=5

fig1: 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.).
Mentions: Figure 1 illustrates the relationship between the signal intensity ratio in 12 tubes with different FeCl3 concentrations ranging from 0.05 to 4 mg Fe/mL for the two sequences. In both cases, signal intensity inversely correlates with the iron concentration, but the signal falls more steeply in the T2 sequence, as occurs in clinical measurements [11]. Two different tubes were necessary to obtain the SI ratios of 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 0.3 mg Fe/mL (B1) the required T2 signal intensity ratio (0.47). For 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 mg Fe/mL, resp.). Based on this data, the phantom was constructed using one tube without iron and each of the four different FeCl3 solutions (Figure 2).

Bottom Line: The phantom was analysed in the same equipment and 14 times in the reference machine.FeCl3 solutions containing 0.3, 0.5, 0.6, and 1.2 mg Fe/mL were chosen to generate the phantom.The average of the intramachine variability for patients was 10% and for the intermachines 8%.

View Article: PubMed Central - PubMed

Affiliation: Osatek, Donostia Universitary Hospital, P. Dr. Beguiristain 109, 20014 Donostia/San Sebastián, Spain.

ABSTRACT

Purpose: The objectives were (i) construction of a phantom to reproduce the behavior of iron overload in the liver by MRI and (ii) assessment of the variability of a previously validated method to quantify liver iron concentration between different MRI devices using the phantom and patients.

Materials and methods: A phantom reproducing the liver/muscle ratios of two patients with intermediate and high iron overload. Nine patients with different levels of iron overload were studied in 4 multivendor devices and 8 of them were studied twice in the machine where the model was developed. The phantom was analysed in the same equipment and 14 times in the reference machine.

Results: FeCl3 solutions containing 0.3, 0.5, 0.6, and 1.2 mg Fe/mL were chosen to generate the phantom. The average of the intramachine variability for patients was 10% and for the intermachines 8%. For the phantom the intramachine coefficient of variation was always below 0.1 and the average of intermachine variability was 10% for moderate and 5% for high iron overload.

Conclusion: The phantom reproduces the behavior of patients with moderate or high iron overload. The proposed method of calculating liver iron concentration is reproducible in several different 1.5 T systems.

Show MeSH
Related in: MedlinePlus