摘要
目的观察兔急性心肌梗死（AMI）后心功能随时间演变的规律，探讨MRI影像特征及心功能指标的变化与左心室重塑的关系。方法日本长耳白兔45只，采用开胸结扎法建立心肌梗死模型。分别于术后即刻（0周）和术后1、2、4、6、8周共6个时间点行在体MR检查，测定各项心功能指标，包括：左心室舒张末期容积（EDV）、每搏输出量（SV）、射血分数（EF）、射血率峰值（PER）、充盈率峰值（PFR）。比较心肌梗死后心功能参数随时间变化的规律。在每个时间点随机取5只动物的心脏离体标本，行MR扩散张量成像（DTI），测量ADC值、各向异性分数（FA）值。不同时间点的心功能参数组间比较采用重复测量方差分析，各时间点梗死区心肌及不同区域心肌的FA值与ADC值的比较采用单因素方差分析，相邻2组均数的比较采用LSD-t检验。结果随着梗死时间的延长，左心室EDV呈现增加趋势，由术前的（2．21±0．35）ml增加到术后8周时的（3．15±0．57）ml，但差异无统计学意义（F=1．384，P=0．220）。EF则由（57．31±11．11）％下降至（34．71±8．72）％，呈明显下降趋势，差异有统计学意义（F=27．134，P=0．001）。EF随着EDV增加呈现下降趋势，线性回归分析得出一次方程：y=-5．58x＋57．7（F=8．855，P=0．005）。随梗死时间的延长，PER由（27．31±13．06）ml／s下降至（17．31±6．41）ml／s（F=2．105，P=0．037），而PFR则由（23．79±14．15）ml／s下降至（12．07±6．91）ml／s（F=2．366，P=0．011）。梗死区FA值随着梗死时间的延长而下降，由0．442±0．093下降至0．107±0．037（F=12．61，P=0．001），而ADC值则由（5．07±1．15）×10^-4mm^2／s上升至（6．39±0．78）×10^-4mm^2／s（F=4．166，P=0．022），差异均有统计学意义。梗死区、边缘区和外围区的FA值分别为0．201±0．049、0．316±0．127、0．323±0．117，ADC值分别为（6．19±1．78）×10^-4、（5．44±2．63）×10^-4、（5．29±2．02）×10^-4mm^2／s，差异均有统计学意义（F=3．896，P=0．004；F=3．248，P=0．018）。FA、ADC值在梗死区与边缘区比较差异均有统计学意义（t=7．327，P=0．001；t=3．292，P=0．005），而边缘区和外围区的FA值、ADC值的差异无统计学意义（t=1．024，P=0．129；t=1．467，P=0．164）。结论MR心功能测定可以动态监测AMI后心室功能性重塑过程，通过DTI可以反映心室结构性重塑过程的心肌微观察结构的改变。MRI可以作为心肌梗死后左心室重塑的一种可行性的评价方法。
Objective To observe the change of cardiac function after acute myocardial infarction （AMI） in rabbit model, and to study MRI characteristics of left ventricular remodeling （LVR）. Methods Forty-five Japanese white rabbits underwent chest-opening coronary artery ligation surgery to obtain rabbit myocardial infarction model. The animals were scanned on a 1.5 T MR scanner （ GE Healthcare, Chalfont St. Giles, UK） at six time-points as surgery, 1, 2, 4, 6, 8 weeks after surgery. Cardiac function parameters were measured, including left ventricular end diastolic volume （ EDV ） , stroke volume （ SV ） , ejection fraction （EF）, peak ejection rate （PER） and peak filling rate （PFR）. At each time point,5 rabbits were randomly selected and performed re-thoracotomy to obtain heart specimen. Each specimen was examined by MRI with the diffusion tensor imaging （DTI）. The value of ADC and fractional anisotrnpy （FA） were collected. Cardiac function data sets of different time points were analyzed using repeated measures data of ANOVA. The FA and ADC values of infarction myocardium set of different time points or different parts of the myocardium were analyzed using one-way ANOVA. The average was compared statistically between two adjacent groups using LSD-t test. Results Left ventricular EDV increased in progress with the time. It was increased from （2. 21±0. 35 ） ml preoperatively to （3.15±0. 57）ml 8-week postoperatively. But the difference was not statistical significant （ F = 1. 384, P = 0. 220）. EF was decreased from（57.31±11.11 ）% to （34. 71±8.72）% . It dropped significantly and the difference was statistically significant （F = 27. 134, P = O. 001 ）. EF showed a downward trend with the increase of EDV. By linear regression analysis, an equation was set up with y = - 5.58x ＋ 57.7 （ F = 8. 855 ,P = 0. 005）. On the other hand, PER showed a progressive decline from （27.31±13.06） ml/s to （ 17.31±6. 41 ） ml/s （ F = 2. 105, P = 0. 037）, and PFR decreased from （ 23.79±14. 15 ） ml/s to （ 12.07±6. 91 ） ml/s （ F = 2. 366, P = 0. 011 ）. FA value decreased from 0. 442±0. 093 to 0. 107 ±0. 037（F = 12. 61 ,P =0. 001 ） ,and ADC value showed upward trend from （5.07±1.15）×10-4 mm2/s to（6. 39±0.78 ）×10-4 mm2/s （F = 4. 166,P = 0. 022 ）. FA values of infarct, adjacent and remote region were 0. 201±0. 049, 0. 316 ＋ 0. 127 and 0. 323×0. 117 respectively（ F = 3. 896, P = 0. 004 ）, and the ADC values in these regions were （ 6. 19±1.78 ）×10 -4, （ 5.44±2. 63 ）×10 -4, （ 5.29± 2. 02 ）×10 -4 mm：/s respectively （ F = 3. 248, P = 0. 018 ）. FA and ADC values were significantly different between the infarct region and adjacent region （ t = 7. 327, P = 0. 001 ;t = 3. 292, P = 0. 005, respectively）, but there was no significantly different between adjacent region and remote region （ t = 1. 024, P = 0. 129 ; t = 1. 467, P = 0. 164, respectively ）. Conclusions MRI measurement of parameters of cardiac function can be used to monitor the process of left ventricular function remodeling after AMI. The process of micro-structural remodeling of myocardium can he reflected by DTI. MRI provides a feasible imaging modality for LVR after AMI.
出处
《中华放射学杂志》
CAS
CSCD
北大核心
2012年第7期645-649,共5页
Chinese Journal of Radiology
基金
国家“十一五”科技支撑计划资助项目（2007BAl05801）
关键词
心肌梗死
心室重构
磁共振成像
扩散
Myocardial infarction
Ventricular remodeling
Diffusion magnetic resonanceimaging
