Evaluation of iron overload: dual-energy computed tomography versus magnetic resonance imaging

Abstract

Figures 1 &2 show the phantoms, T2*-map, CT images, plots of R2* and HU versus iron-content, T2* curves fitting, and DECT iron-map. T2* ranged from 6 ms to 36 ms. There were strong correlations between iron-content and R2*, HU values and HU differences at different energy levels (r > 0.95 and P < 0.0001). There were moderate correlations between iron-content and HU ratios (except 80/140) with 0.42 < |r| < 0.76 and 0.02 < P < 0.2. The T2* relaxation curves of the 21 ms and 10 ms tubes were used to differentiate between normal, overloaded, and severely-overloaded iron (Figure 1d). The HU values of these two tubes showed perfect linear relationships with energy-level (E) over diagnostic levels 80-140 kVp: HU = -0.29E +56.3 and HU = -0.76E+151.8 for the 21 ms and 10 ms T2*-values. The resulting CT-map (Figure 2d) is used to identify three regions: normal, overloaded, and severely-overloaded iron. Conclusions DECT can be used for iron quantification with high accuracy similar to MRI, which might help in patient staging, independent of the energy level. New DECT scanners with low radiation-exposure, much shorter scan-time, and higher capability of measuring large iron-contents compared to MRI, may provide promising approach for evaluating myocardial iron overload.