Longitudinal Assessment of Cardiac Native T1 in Transfusion-Dependent Thalassemia

Cardiovascular magnetic resonance (CMR) T2* is the reference standard for assessing myocardial iron overload (MIO). Native T1 mapping has emerged as a complementary technique and may be more sensitive for detecting mild or early myocardial iron deposition. We evaluated longitudinal changes in native left ventricular (LV) T1 values over 18 months in patients with transfusion-dependent thalassemia (TDT).

A total of 64 TDT patients consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia (E-MIOT) project underwent two CMR examinations at 1.5T. Native T1 mapping and T2* relaxometry were performed using standardized protocols. LV T1 and T2* values were calculated from 16 myocardial segments. LV ejection fraction was assessed by cine imaging.

At baseline, mean LV T1 was 959.51 ± 101.46 ms and mean LV T2* was 37.17 ± 9.44 ms, with a significant correlation between the two parameters (R = 0.533; p < 0.0001). Both LV T1 and T2* were reduced in 9 (14.1%) patients. Meanwhile, 17 (26.6%) patients exhibited reduced LV T1 despite normal LV T2*, whereas only one (1.6%) patient had normal LV T1 in the presence of pathological T2*. Increased LV T1 was observed in two (3.1%) patients. During follow-up, global LV T1 did not change significantly (mean change 1.99 ± 63.57 ms; p = 0.841), whereas LV T2* increased significantly (mean change 1.61 ± 4.52 ms; p = 0.001). Individual T1 trajectories varied: 22.2% of patients with normal baseline T1 developed reduced T1, while 26.9% of those with reduced baseline T1 normalized at follow-up. Changes in LV T1 were inversely associated with baseline T1 values (R = -0.406, p = 0.001) and correlated with changes in T2* (R = 0.311, p = 0.012), but not with age, ferritin, hemoglobin levels, or LV ejection fraction.

In well-managed TDT patients, native myocardial T1 values remain overall stable over mid-term follow-up despite marked interindividual variability. Baseline T1 values and parallel changes in T2* influence longitudinal changes in T1, supporting native T1 mapping as a complementary, but not interchangeable, tool to T2* for the assessment and longitudinal monitoring of MIO.