3.0T磁共振钆延迟强化技术评价小型猪慢性阻塞性肺病模型心肌纤维化的实验研究

Evaluation of myocardial fibrosis in miniature pig model of COPD by the 3.0T magnetic resonance LGE techniques:An experimental study

目的利用3.0 T心脏磁共振(cardiovascular magnetic resonance,CMR)钆延迟强化(late gadolinium enhancement,LGE)技术评估巴马小型猪慢性阻塞性肺病(chronic obstructive pulmonary disease,COPD)模型左心室(left ventricle,LV)心肌纤维化,为评估COPD心肌组织学损伤提供影像学依据。材料与方法选用20头健康巴马小型猪,随机分成COPD模型组(16头,蛋白酶制备COPD模型)及正常对照组(4头)。分别于造模前及造模不同阶段(4周、8周及20周)行多模态CMR扫描。对比各组小型猪之间常规心脏参数的差异;分析各组LV心肌LGE发生率、分布及类型。结果模型组共有14头小型猪COPD模型构建成功。造模早期及中期(4周、8周)模型组与对照组的基线资料差异均无统计学意义(P>0.05);而造模后期(20周)呼吸频率及心率均明显加快(P分别为0.003、0.002);体质量降低(P=0.007)。造模早、中期各组小型猪心功能参数之间差异无统计学意义(P>0.05)。与造模前及对照组比较,造模后期右心室前壁(right ventricular anterior wall,RVAW)(P均<0.001)均有所增厚,右心室舒张末横径(right ventricular end diastolic diameter,RVDd)(P<0.001)及左心室后壁(left ventricular posterior wall,LVPW)(P=0.018)较造模前有所增厚,左心室舒张末横径(left ventricular end diastolic diameter,LVDd)(P=0.05)及左心室舒张末容积(left ventricular end diastolic volume,LVEDV)(P=0.005)较造模前有所减低。右心室射血分数(right ventricular ejection fraction,RVEF)较造模前及对照组均降低(P<0.001及为0.001);左心室射血分数(left ventricular ejection fraction,LVEF)差异无统计学意义(P均>0.05)。造模后模型组有5头小型猪共23个心肌节段(23/85)发生LGE,与对照组及造模前比较均出现显著差异(P均<0.01)。LGE主要位于左室基底部及中间部,其分布差异有统计学意义(P<0.05),且LGE以肌壁间型最为多见。结论COPD早期即可出现RVEF降低,但仍在正常范围内;少部分LV心肌可出现心肌纤维化,但LVEF未见明确改变。基于CMR的LGE技术可为COPD患者早期干预、诊疗计划的制定以及预后的评估提供影像学依据。

Objective:To explore the feasibility of 3.0 T cardiovascular magnetic resonance(CMR)late gadolinium enhancement(LGE)techniques in assessing early left ventricular(LV)myocardial fibrosis in miniature pig COPD model,so as to provide imaging basis for detecting early myocardial injury in COPD.Materials and Methods:Twenty healthy Bama miniature pigs were divided into COPD model group(16 pigs,COPD model was prepared by protease)and normal control group(4 pigs).Before modeling and at different stages of modeling(4 weeks,8 weeks and 20 weeks),multimodal CMR scanning was performed.The differences of conventional cardiac parameters among the groups were compared,and the incidence,distribution and types of LV myocardial LGE were analyzed.Results:The COPD model of 14 miniature pigs in the model group was successfully constructed.There was no significant difference in baseline data between the model group and the control group in the early and middle stage of modeling(4 weeks and 8 weeks)(P>0.05);however,in the late stage of modeling(20 weeks),respiratory rate and heart rate were significantly increased(P=0.003 and 0.002 respectively);body weight was decreased(P=0.007).There was no significant difference in heart function parameters between groups in the early and middle stages of modeling(P>0.05).The right ventricular anterior wall(RVAW)(all P<0.001)was thickened,while the right ventricular end diastolic diameter(RVDd)(P<0.001)and left ventricular posterior wall(LVPW)(P=0.018)was only thicker than before modeling,left ventricular end diastolic diameter(LVDD)(P=0.05)and left ventricular end diastolic volume(LVEDV)(P=0.005)were decreased than before modeling.The right ventricular ejection fraction(RVEF)was lower than that before modeling and in the control group(P<0.001 and 0.001);the left ventricular ejection fraction(LVEF)had no statistical difference(P>0.05).LGE was found in 23 myocardial segments(23/85)of 5 minipigs in the model group after modeling,which was significantly different from that in the control group and before modeling(all P<0.01).LGE was mainly located in the basal and middle slices of left ventricle,and the distribution was statistically significant(P<0.05),and the most common type of LGE was intramural type.Conclusions:In the early stage of COPD,decreased RVEF,but still in the normal range could be observed.Myocardial fibrosis occurred in a small part of LV myocardium,accompanied with normal LVEF.LGE technology based on CMR could provide imaging basis for early intervention,diagnosis and treatment planning and prognosis evaluation of COPD patients.