Indirect evidence for the potential ability of magnetic resonance imaging to evaluate the myocardial iron content in patients with transfusional ironoverload

The purpose of this study was to evaluate the potential ability of magnetic resonance imaging (MRI) for evaluation of myocardial iron deposits. The ap plied MRI technique has earlier been validated for quantitative determinati on of the liver iron concentration. The method involves cardiac gating and may, therefore, also be used for simultaneous evaluation of myocardial iron . The tissue signal intensities were measured from spin echo images and the myocardium/muscle signal intensity ratio was determined. The SI ratio was converted to tissue iron concentration values based on a modified calibrati on curve from the liver model. The crucial steps of the method were optimiz ed; i.e. recognition and selection of the myocardial slice for analysis and positioning of the regions of interest (ROIs) within the myocardium and th e skeletal muscle. This made the myocardial MRI measurements sufficiently r eproducible. We applied this method in 41 multiply transfused patients. Our data demonstrate significant positive linear relationships between differe nt iron store parameters and the MRI-derived myocardial iron concentration, which was significantly related to the serum ferritin concentration (rho = 0.62, P < 0.0001) and to the MRI-determined liver iron concentration (rho = 0.36, P = 0.02). The myocardial MRI iron concentrations demonstrated also a significant positive correlation with the number of blood units given (r ho = 0.45, P = 0.005) and the aminotransferase serum concentration (rho = 0 .54, P = 0.0008). Our data represents indirect evidence for the ability of MRI techniques based on myocardium/muscle signal intensity ratio measuremen ts to evaluate myocardial iron overload. (C) 2001 Elsevier Science B.V. All rights reserved.