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Rapid Fire Abstracts

Rapid Fire 06- Tissue Characterization II

Magnetic resonance evaluation of tissue iron deposition in adult regularly transfused thalassemia intermedia compared to thalassemia major patients (RF_FR_349)

Friday, January 31, 2025
11:00 AM – 11:10 AM East Coast USA Time
Location: Blue Room PreFunction
Background:

The R2* Magnetic Resonance Imaging (MRI) technique is the non-invasive reference standard for the detection and regular monitoring of organ-specific iron deposition. Data about distribution, clinical correlates, and outcomes of iron overload in regularly transfused patients with thalassemia intermedia (TI) remain limited.
This multicenter study aimed to assess if, due to the different rate of blood transfusions, regularly transfused TI patients can be differentiated from the thalassemia major (TM) population based on hepatic, pancreatic, and cardiac iron levels.

Methods:

We considered 135 adult regularly transfused thalassemia intermedia (TI) patients (44.73±12.16 years, 77 females) and 135 age- and sex-matched thalassemia major (TM) patients (43.35±9.83 years, 77 females), enrolled in the Extension-Myocardial Iron Overload in Thalassemia Network.
Hepatic, pancreatic and cardiac R2* values were measured. Hepatic R2* values were converted into liver iron concentration (LIC) values.

Results:

Age, sex, frequency of splenectomy and chelation, and serum ferritin levels were comparable between the two groups, but TI patients started regular transfusions significantly later and showed significantly lower pre-transfusion hemoglobin levels (Table 1).

Table 2 shows the comparison of tissue iron levels between TI and TM patients. No difference was found in hepatic iron levels. The TI group was characterized by significantly lower global pancreas R2* values and frequency of pancreatic iron overload (R2* >38 Hz). The duration of regular transfusions, significantly correlated with global pancreas R2* values and different between the two disease groups, was used as covariate in the ANCOVA and the difference in pancreatic R2* values between TI and TM remained significant (p=0.020).

TI patients exhibited significantly lower global heart R2* values and number of segments with R2* >50Hz than TM patients. The prevalence of a significant myocardial iron overload was comparable between the two groups, but the presence of at least one myocardial segment with R2* >50 Hz was significantly reduced in TI patients.

Figure 1 shows the ROC curves and the best-cut-offs of MRI iron overload parameters for discriminating between regularly transfused TI and TM patients. The MRI LIC was not a discriminator (AUC=0.51 p=0.853). Both global pancreas R2* values and global heart R2* values were able to differentiate between TI and TM (AUC=0.73 p< 0.00001 and AUC=0.63 p=0.0001, respectively). The Delong’s test showed a significant difference among the AUCs (p=0.015), with pancreatic iron levels having a stronger discriminatory ability.

Conclusion:

Besides the comparable hepatic iron levels, TI patients were characterized by lower pancreatic and cardiac siderosis than TM patients. These differences could not be explained by the different duration of the transfusional regimen. Pancreatic iron levels demonstrated better discriminative ability between TI and TM compared to cardiac iron levels, likely because pancreatic iron deposition precedes cardiac siderosis. Our findings may provide a foundation to evaluate the early initiation of treatments such as red blood cell transfusions and chelation therapy in TI patients.