Background: Accurate hepatic iron overload assessment in thalassemia major patients is critical for optimal clinical management. While T_2^* based MRI relaxometry is the standard noninvasive reference for tissue iron quantification, T_2^* values vary with scanner, imaging protocol, and analysis method, potentially causing clinical misclassification. This study evaluated the necessity of quality control and site-specific correction coefficients.
Methods: In this retrospective, observational, two-center study, hepatic iron concentration was quantified in 79 patients with β-thalassemia major from Mashhad and Zahedan using MRI relaxometry. Initially, images were analyzed without applying correction coefficients (non-modified) and patients were classified into five clinical severity groups based on T_2^* values. For quantitative validation, a phantom containing defined iron concentrations was imaged at both centers, and site-specific correction coefficients were derived from the relationship between phantom T_2^* values and actual iron concentration. Patient datasets were then reanalyzed by applying these coefficients (QC-modified), and classifications were updated accordingly.
Findings: Applying the center-specific correction coefficients significantly altered clinical iron-overload categorization in 31.6% of patients. Without corrections, iron levels tended to be overestimated in the Zahedan center and underestimated in the Mashhad center. The phantom study confirmed a very strong correlation between T_2^* values and true iron concentration (R2 ≈ 0.98), confirming the accuracy of the calibration method.
Conclusion: The findings highlight that phantom-based calibration and scanner-specific analysis play a pivotal role in enhancing the quantitative accuracy of MRI relaxometry and preventing diagnostic errors in thalassemia patients. Implementing scanner-specific analysis improves iron burden estimation and facilitates more precise clinical decisions regarding transfusion and chelation therapy.