Feasibility, reproducibility, and reliability for cardiac iron quantification at 3T in comparison with 1.5T
Long Li Ling1, peng peng1, and Huang Zhong Kui1

1The First Affiliated Hospital of Guangxi Medical University, Nanning, China, People's Republic of

Synopsis

To demonstrate that assessment of cardiac iron burden by T2* imaging is feasible, reproducible, and reliable at 3T. With 3T MRI scanners increasingly used in clinical settings, this study may lay a foundation for further MRI development of quantitative markers for noninvasive cardiac iron overloaded assessment at higher fields. Though cardiac T2* measurement at 3T seemed not to offer any greater advantages than 1.5T at present, it is more useful for some hospitals having only 3T scanner.

Objectives

To explore the feasibility，reproducibility, and reliability of using T2* values in quantifying cardiac iron burden in thalassemia patients at 3T.

Methods

A total of 87 transfusion-dependent thalassemia patients with varying levels of iron overload were enrolled in the study，including 85 thalassemia major and 2 thalassemia intermedia cases. Seventy patients were selected randomly as the first group for using to determine the regression fit between 1.5T and 3T. And the 17 patients left as the second group used to determine the range of errors in T2* estimates from the linear regression model.Patients were scanned with Siemens systems (Avanto 1.5T and Verio 3T). For cardiac iron load assessment, a single mid-ventricular short axis slice was obtained by a T2* multiple-slice gradient-echo sequence with a electrocardiographic (ECG) gated and a single end-expiratory breath-hold. The combined T2* values exhibited a strong linear relationship between 1.5T and 3T (r=0.935，P=0.000). The T2* values of the two repeated measurements were nonsignificantly different (z=﹣0.072, P=0.943), and ICC was 0.990. In the heart, it had a slope of 0.477 and an intercept of 0.965. Through the equation, the cut-off T2* values of cardiac iron overload and heavy cardiac iron overload at 3T was ＜10.5 ms and ＜5.7 ms, respectively. Using the two cut-off T2* values to diagnose different levels of cardiac iron overloaded at 3T, the accuracy was 96.5% and 94.3%, respectively.

Results

The combined T2* values exhibited a strong linear relationship between 1.5T and 3T (r=0.935，P=0.000). The T2* values of the two repeated measurements were nonsignificantly different (z=﹣0.072, P=0.943), and ICC was 0.990. In the heart, it had a slope of 0.477 and an intercept of 0.965. Through the equation, the cut-off T2* values of cardiac iron overload and heavy cardiac iron overload at 3T was ＜10.5 ms and ＜5.7 ms, respectively. Using the two cut-off T2* values to diagnose different levels of cardiac iron overloaded at 3T, the accuracy was 96.5% and 94.3%, respectively.

Conclusions

T2* quantification of iron burden in the heart resulted to be feasible, reproducible, and reliable at 3T.

Acknowledgements

This work was supported by research grants from National Natural Science Foundations of China (Grant No.81460260, Grant No.81160175,Grant No.81360221 and Grant No.30960361) and Natural Science Foundation of Guangxi (2011GXNSFA018226).

References

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Figures

Fig.1 Left of figure shows typical cardiac images at 1.5T and 3T from a patient with thalassemia major with different TEs(1.5T: TE=2.97–21.68ms, increasing in 2.69ms increments; 3T: TE=2.68–18.85ms, increasing in 2.31ms increments). Note that the signal in the heart decays more rapidly at 3T than at 1.5T, indicating a lower T2* value(T2*=6.3 ms,at 1.5T;T2*=3.7 ms,at 3T). Right of figure shows the corresponding decay curves at 1.5T and 3T in the same patient as in left MR images

Fig.2 The 3T values of T2* plotted against the corresponding 1.5T values for the first group patients. The line of best fit(R2=0.875) and the curves indicating 95% CI are indicated

Fig.3 a The predicted values of T2* by Eq.2 and the original values at 3T. The line of best fit and the curves indicating 95% CI are indicated b Bland-Altman plots shows the differences between the predicted values of T2* by Eq.2 and the original values at 3T. The solid line shows the mean difference between the 2 measurements, whereas the dashed lines indicate 95% CIs

Fig.3 a The predicted values of T2* by Eq.2 and the original values at 3T. The line of best fit and the curves indicating 95% CI are indicated b Bland-Altman plots shows the differences between the predicted values of T2* by Eq.2 and the original values at 3T. The solid line shows the mean difference between the 2 measurements, whereas the dashed lines indicate 95% CIs



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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