A confirmatory study of the calibration formula between liver iron concentration (LIC) and R2* values in thalassemia patients

Objective To explore the maximum LIC range applicable to LIC-R2* calibration formula of different studies. Methods The liver T2* images of 195 thalassemia patients were measured by CMRtools/Thalassemia Tools (CMRtools), and the calculated T2* values were converted into R2* values. The R2* data were calculated according to the calibration formula of different studies to calculate the corresponding liver iron concentration (LIC e ), and the relationship between LIC e and the liver iron concentration (LIC F ) provided by FerriScan was compared. Truncation method was adopted to reduce the range, and the maximum LIC F ranges corresponding to each formula with no statistical difference and high correlation and consistency were recorded. Clinical grading of LIC F and LIC e in different range was conducted to explore the relationship between the grading results. Results There was no significant difference ( P > 0.05) between the LIC e calculated by different calibration formulas and the corresponding LIC F within the applicable maximum LIC value range, and there was a high correlation ( r s > 0.75, P < 0.05) and consistency ( W > 0.75, P < 0.05) between them. There was no significant difference ( P > 0.05) and a high consistency (kappa > 0.75, P < 0.05) between the clinical grading results. Conclusion Different calibration curves have a specific maximum LIC range when calculating LIC. Different research centers should choose different calibration curves according to the LIC range of their own studies.