Quantitative assessment of iron load in myocardial overload rabbit model: preliminary study of MRI T2* map / 中华放射学杂志

ABSTRACT

Objective To preliminarily investigate the feasibility of MRI-T2* map in evaluating myocardial iron load of myocardial iron overload rabbit models.Methods Eleven rabbits were included in this study and divided into two groups,myocardial iron overload group (n =10) and the control group (n =1).Iron dextrin (dose of 50 mg/kg) was injected in muscles of thigh once a week,totally 12 weeks.Serum iron test and MRI examination were performed before iron injection,and 1 week to 12 weeks after iron injection.MRI scan protocol included short axial T2* map of the left ventricle and cross-section T2* map of the liver.T2* and R2* of the heart and the liver were measured.One rabbit was killed after MRI examination at pre-iron injection,1 week to 8 weeks,11 weeks and 12 weeks after iron injection,respectively.Heart and liver were avulsed to undergo in vitro MRI scan and then paraffin embedded for pathological slices.MRI scan protocol and measurements of the heart and the liver samples were the same to that of in vivo ones.Pearson correlation was used to calculate the relationships between the parameters.Results Myocardial T2* [(32.5 ± 8.3 ms)] and R2* values [(38.4 ± 7.9) Hz] had significant correlation with injecting iron content(1 033.2 ± 673.4 mg),the Pearson coefficients were-0.799 (P =0.001) and 0.770 (P =0.002),respectively.Myocardial T2 had no significant correlation with liver T2* values (r =0.556,P =0.070).T2* values of heart and liver in vivo [(32.5 ± 8.3) ms and (8.8 ± 5.4) ms],respectively had strong correlation with those in vitro [(19.4 ± 6.5) ms and (9.8 ± 5.0) ms],respectively (r =0.757,P =0.007 and r=0.861,P=0.001).T2* and R2* values of the heart and the liver in vivo and in vitro had no significant correlations with serum iron (P ＞ 0.05).On Prussian blue staining slices,blue particles of myocardium,sinus hepaticus and hepatocyte increased with injecting iron content.Conclusions It is feasible for MRI-T2* map to evaluate the myocardial iron load noninvasively.It may provide reliable information for detecting myocardial iron overload in patients with iron overload at an early stage.