Quantification of cardiac iron in patients with thalassemia with 3-T MRI calibrated by 1.5-T MRI.

Background: Due to the small sample size of many studies, it remained unclear what standardized reference range the T2* cutoff at 3 T would be used to assess the severity of cardiac iron load. In addition, the number of patients with moderate to severe cardiac iron load was small in some studies, especially the sample of patients with severe cardiac iron load.

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

Material And Methods: A total of 122 patients with thalassemia underwent cardiac T2* imaging at both 1.5 T and 3 T. Cardiac R2* (1000/T2*) values of the 100 patients at 3 T were fitted against the values at 1.5 T using linear regression and the prediction equation was derived. The remaining 22 cases were used to test the prediction accuracy of the equation.

Results: The combined R2* values exhibited a strong linear relationship between 1.5 T and 3 T (= 0.830，<0.001). At the center, it had a slope of 1.348 and an intercept of 37.279. According to the equation, the truncated T2* values of cardiac iron overload and cardiac heavy iron overload at 3 T were <10 ms and <6 ms, respectively. The two truncated T2* values were used to diagnose different levels of cardiac iron overloaded of 22 patients at 3 T; the accuracy rates were 95.5% and 100.0%, respectively.

Conclusion: T2* quantification of cardiac iron load at 3 T MRI resulted to be feasible, reproducible, and reliable.