Distribution of cardiac iron measured by magnetic resonance imaging (MRI)‐R*2

Abstract

To assess regional iron distribution by magnetic resonance imaging (MRI)-R(2)* within the heart of patients with β-thalassemia major (TM) and other iron overload diseases. 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 = 1.3-26 msec). Typical boundary effects were evaluated in detail. 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(-1) (normal), all quadrants show higher normalized median rates (126%-174%) than the septum (P < 10(-4)), while this was relatively smaller in the group with septal R(2)* > 50 s(-1). 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. 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.