Purpose:To assess the tissue iron concentration of the left ventricle (LV) using a multislice, multiecho T2* MR technique and a segmental analysis.Materials and Methods: T2* multiecho MRI was performed in 53 thalassemia major patients. Three short-axis views of the LV were obtained and analyzed with custom-written software. The myocardium was automatically segmented into 12 segments. The T2* value on each segment as well as the global T2* value were calculated. Cine dynamic images were also obtained to evaluate biventricular function parameters by quantitative analysis.Results: For the T2* global value, the coefficient of variation (CoV) for intra-/interobserver and interstudy reproducibility was 3.9% (r ϭ 0.98), 5.5% (r ϭ 0.98), and 4.7% (r ϭ 0.99) respectively. Three groups were identified based on analysis of myocardial T2*: homogeneous (21%), heterogeneous (38%), and no myocardial iron overload (41%). The mean serum ferritin, liver iron concentration, and urinary iron excretion were significantly different among the groups. We did not find significant differences among groups in biventricular function. There was a correlation between the global T2* value and the T2* value in the mid-ventricular septum (r ϭ 0.95, P Ͻ 0.0001). Conclusion:Multislice multiecho T2* MRI provides a noninvasive, fast, reproducible means of assessing myocardial iron distribution. The single measurement of mid-septal T2* correlated well with the global T2* value.

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A segmental, multislice, multi-echo T 2 Ã MRI approach could be useful in heart iron-overloaded patients to account for heterogeneous iron distribution, demonstrated by histological studies. However, segmental T 2 Ã assessment in heart can be affected by the presence of geometrical and susceptibility artefacts, which can act on different segments in different ways. The aim of this study was to assess T 2 Ã value distribution in the left ventricle and to develop a correction procedure to compensate for artefactual variations in segmental analysis. MRI was performed in four groups of 22 subjects each: healthy subjects (I), controls (II) (thalassemia intermedia patients without iron overload), thalassemia major patients with mild (III) and heavy (IV) iron overload. Three short-axis views (basal, median, and apical) of the left ventricle were obtained and analyzed using custom-written, previously validated software. The myocardium was automatically segmented into a 16-segment standardized heart model, and the mean T 2 Ã value for each segment was calculated. Punctual distribution of T 2 Ã over the myocardium was assessed, and T 2 Ã inhomogeneity maps for the three slices were obtained. In group I, no significant variation in the mean T 2 Ã among slices was found. T 2 Ã showed a characteristic circumferential variation in all three slices. The effect of susceptibility differences induced by cardiac veins was evident, together with low-scale variations induced by geometrical artefacts. Using the mean segmental deviations as correction factors, an artefact correction map was developed and used to normalize segmental data. The correction procedure was validated on group II. Group IV showed no significant presence of segmental artefacts, confirming the hypothesis that susceptibility artefacts are additive in nature and become negligible for high levels of iron overload. Group III showed a greater variability with respect to normal subjects. The correction map failed to compensate for these variations if both additive and percentage-based corrections were applied. This may reinforce the hypothesis that true inhomogeneity in iron deposition exists.

CMR guided the change of chelation therapy in nearly 70% of patients, leading to a lower risk of iron-mediated HF and of arrhythmias than previously reported. Homogeneous MIO remained a risk factor for HF but also myocardial fibrosis and ventricular dysfunction identified patients at high risk. Arrhythmias were independent of MIO but increased with atrial dilatation. CMR by a multi-parametric approach dramatically improves cardiac outcomes and provides prognostic information beyond cardiac iron estimation.