大鼠模型心肌纤维结构弥散张量成像的可行性研究

摘要

目的 探讨对大鼠离体心脏的心肌纤维结构进行弥散张量成像(DT-MRI)的可行性.方法 20只健康雄性大鼠心脏离体、固定后,使用DT-MRI技术采集图像,并利用Diffusion Toolkit、Track Vis、及Matlab软件处理分析图像,观察心肌纤维的走行、排布、平均螺旋角分布,测量左心室乳头肌层面前壁、后壁及侧壁ADC值、FA值,采用单因素方差分析比较其统计学差异.结果 SD大鼠扩散张量心肌纤维成像显示,正常大鼠心脏心肌纤维完整,排列连续、整齐,形态、走行与解剖结构大致相吻合.左心室短轴位乳头肌层面显示,左心室壁自内向外由三层心肌纤维结构构成,排列成均匀、致密的双螺旋结构.左心室乳头肌层面HA图显示,由心内膜向心外膜的平均螺旋角从90°向-90°逐渐过渡.左心室乳头肌层面前壁、后壁、侧壁ADC值分别为(9.56±1.29)×10-4 mm2/s,(9.49±1.15)×10-4mm2/s,(9.40±1.16) ×10-4mm2/s;FA值分别为0.81±0.02,0.81±0.02,0.80±0.03,前壁、后壁及侧壁间ADC值与FA值差异均无统计学意义(F分别为0.083,0.510,P＞0.05).结论 弥散张量成像(DT-MRI)技术可以三维显示离体心脏心肌纤维的走行、排布、环绕方向及其完整性,并能通过ADC值及FA值定量分析心肌纤维的弥散性质及各向异性,为后续研究梗死后心肌纤维结构重塑提供了前期实验基础及技术支持.%Objective To investigate the feasibility of ex-vivo diffusion tensor magnetic resonance imaging (DT-MRI) of the rat myocardial fiber architecture.Methods Fixed male rats heart (n =20) underwent DTI and the original images of myocardial fiber structures were processed by Diffusion Toolkit,Track Vis and Matlab.The characteristic of myocardial fibers arrangement,ADC map,FA map and HA map were observed.The ADC values and FA values of anterior wall,posterior all and lateral wall of myocardial fibers were calculated,and were compared by using one-way ANOVA.Results The SD rats' myocardial fibers appeared in compact and inerratic distribution,and the direction and arrangement were in agreement with the anatomical structure approximately.The regular direction and arrangement,double helix structure in fibers were shown in myocardial fibers tracer map and tensor map in papillary muscle plane,also trilaminar myocardial fiber structures of left ventricular wall were appeared.Myocardial fiber HA map showed mean helix angle of left ventricular endocardium to epicardium ranged from =90° to-90°.The ADC values of anterior wall,posterior all and lateral wall of myocardial fibers were (9.56 ± 1.29) × 10-4 mm2/s,(9.49 ± 1.15) × 10-4mm2/s,(9.40 ± 1.16) × 10-4 mm2/s respectively.The FA values of anterior wall,posterior all and lateral wall of myocardial fibers were 0.81 ± 0.02,0.81 ± 0.02,0.80 ± 0.03 respectively.There were no significant differences in ADC values and FA values of anterior wall,posterior all and lateral wall of myocardial fibers (F =0.083,0.510,P ＞ 0.05,respectively).Conclusion This study shows that DTI is an effective method to three-dimensionally observe and quantitatively measure the characteristics of myocardial fibers of isolated heart.This study provides experimental basis and technical support for further study of ventricular remodeling after myocardial infarction.