Purpose: To assess regional iron distribution by magnetic resonance imaging (MRI)-R 2 * within the heart of patients with b-thalassemia major (TM) and other iron overload diseases.
Materials and Methods: Breathhold electrocardiogram (ECG)-gated MRI (1.5 T) of the heart was used for the measurement of transverse relaxation rates R 2 * in 32 patients (11-79 years). In a mid-papillary short-axis slice divided into septal, anterior, lateral, and posterior quadrants, R 2 * was analyzed from region of interest (ROI)-based signal intensities from 12 echo times (TE ΒΌ 1.3-26 msec). Typical boundary effects were evaluated in detail.
Results:
The segmentation of the cardiac wall resulted in highly significant correlations of R 2 * between septal and all other quadrants. In the patient group with R 2 * < 50 s Γ1 (normal), all quadrants show higher normalized median rates (126%-174%) than the septum (P < 10 Γ4 ), while this was relatively smaller in the group with septal R 2 * > 50 s Γ1 . Typical boundary effects on segmental R 2 * from blood, lung tissue, epicardial fat, and hepatic iron could not be easily separated from segmental iron distribution.
Conclusion:
The measurement of MRI-R2* in the interventricular septum is the least affected method by boundary effects to detect patients with iron overload at risk of developing heart failure.