心肌铁过载兔模型心功能的MR评价

Assessment of Cardiac Function of Rabbit Models of Myocardial Iron Overload:An MR Study

目的应用心脏磁共振(CMR)探讨兔心肌铁过载模型的心功能与心肌铁负荷程度之间的关系。方法日本长耳兔11只,按照每只50mg/kg的剂量,于大腿深部肌肉注射含铁量为50mg/mL的右旋糖酐铁,每周注射1次,共注射12周。在注射右旋糖酐铁前全部行心脏MR检查,作为正常对照,每次注射完右旋糖酐铁1周后复查MR。扫描序列包括左心室连续短轴位电影(cine)、有效横向弛豫时间成像(T_2~*map)序列。定量分析左、右心室功能参数和心肌T_2~*、R2*值。相应时间点处死动物后取心脏,固定标本后取部分心肌组织进行病理切片及普鲁士蓝染色。所有实验兔在行MRI检查前1d,抽取3mL静脉血查血清铁。左、右心室功能参数与注入铁含量、血清铁、T_2~*map测量值的相关关系采用Pearson相关分析。结果左心室心功能参数中左心室舒张末期直径(LVEDD)、左心室舒张末期容积(LVEDV)、左心室收缩末期容积(LVESV)和左心室射血分数(LVEF)与注入铁含量呈显著线性相关(均P<0.05),右心室心功能参数中右心室舒张末期容积(RVEDV)、右心室收缩末期容积(RVESV)和右心室射血分数(RVEF)与注入铁含量具有线性相关性(均P<0.05)。左心室心功能参数中左心室每搏输出量(LVSV)和左心室心输出量(LVCO)与血清铁浓度具有中等线性相关性,而右心室心功能参数中RVEDV和RVESV与血清铁浓度具有显著线性相关关系(均P<0.05)。左心室收缩末期直径(LVESD)、LVEDV、LVESV和LVEF与心肌T_2~*值呈显著线性相关关系,LVEDD、LVESD、LVEDV、LVESV和LVSV与心肌R2*值具有线性相关性(均P<0.05)。右心室心功能参数中,RVEDV和RVESV与心肌T_2~*呈中等负相关性(均P<0.05),而与心肌R2*呈正性线性相关(均P<0.05)。结论心脏磁共振能同时评价心功能和心肌铁负荷程度,LVESV较LVEF能更好地反映心肌铁过载时的心功能情况。

TO investigate the relationship between cardiac function and myocardial iron load in the iron-overload rabbit model by cardiac magnetic resonancc(CMR).Methods Iron dextrin at a concentration of 50 mg/mL was injected in the muscle of the thighs of rabbits(n=1 Donee a week for a total of 12 week..MR was performed in the 11 rabbits before and one week after iron dextrin injection.MR scanning protocol included a left ventricular continuous short-axis cine?effective transverse relaxation time imaging sequence(TV'map).T'he left and right ventricular function parameters and myocardial TV and R2'"'values were quantitatively analyzed.T'he animal models at the indicated time points were sacrificed toharvest thehcarts.After the specimens were fixed)some myocardial tissues were taken for pathological sectioning and Prussian blue staining.T'hrce mL of venous blood were sampled for detection of scrum iron one day before the MRI examination.T'he correlation between left and right ventricular function parameters and iron content,scrum iron,or T?'map measurements was analyzed by Pearson correlation.Results"The left ventricular cardiac function parameters such as left ventricular end-diastolic diameterC LVEDD),left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),and left ventricular ejection fraction(LVEF)wcre significantly linearly correlated with iron dextrin contcntCall P〈0.05)/The right ventricular cardiac function pa rameters such as right ventricular end-diastolic volumc(RVEDV)?right ventricular end-systolic volumc(RVESV)and right ventricular ejection fractionCR VEF.)were linearly correlated with iron dextrin content(P〈0.05 for all).Left ventricular cardiac output(LVSV)and left ventricular cardiac output(LVCO)had a moderate linear correlation with scrum iron concentrations,LVE:SV,and LVEF were signiicantlycorrclatcd with myocardialTYsvalucs.LVE:DD,LVE:SD,LVE:DV,LVE:SV,and LVSV were linearly correlated with myocardial R2X values(both F<0.05).In the right ventricular cardiac function paramictcrs?RV-EDV and RVESV were miodcratcly negatively correlated with miyocardiai TV'(F<0.05)?but positively correlated with miyocar-dial R2"(F<0.05).Conclusion CMR can evaluate cardiac function and miyocardial iron load at the samic timic.LVESV could be better than LVEF"to predict cardiac function of miyocardial iron overload.