The effect of measurement area size on the reliability of myocardial iron load measurement in cardiac magnetic resonance imaging examinations of thalassemia patients

Background/aim The aim of this study was to evaluate the intraobserver and interobserver reliability of cardiac T2* MRI measurements in different region of interest (ROI) sizes. Materials and methods Cardiac T2* MRIs of 24 thalassemia major patients were evaluated. Two different ROI sizes were used for measurement. In the first measurement, an ROI approximately 5 mm in diameter was used in the interventricular septal myocardium. In the other method, the whole ventricular septal myocardium was used as the measurement. The intraobserver and interobserver variabilities were assessed with the intraclass correlation coefficient (ICC). Results The measurement of the first observer, the ICC of the small-sized ROI (ssROI), was 0.869, and the measurement for the second observer, the ICC of the ssROI, was 0.659. The ICC of the whole-septal ROI (wsROI) was 0.991 for the first observer and 0.980 for the second observer. Interobserver variability, for the mean measurement, was 0.442 for the ICC of ssROI and 0.883 for the ICC of wsROI. Conclusion For the evaluation of myocardial iron load with T2* MRI we suggest making measurements with ROI, including all of the interventricular septum, as a consequence of high intraobserver and interobserver consistency.