| Objective:The 3.0T magnetic resonance imaging MPI and LGE techniques were used to investigate the myocardial injury caused by COPD.Methods:12 healthy Bama mini pigs were divided into COPD model group(8 pigs)and normal control group(4 pigs).The model group was used to prepare COPD model with protease.CMR-MPI and CMR-LGE were used to examine the hearts of all Bama miniature pigs before and after modeling.The CMR-Cine,CMR-MPI and CMR-LGE images of the long axis two chamber,long axis four chamber and short axis two chamber hearts of the mini pigs were obtained.The differences of cardiac function between the model group and the normal group,before and after modeling were analyzed;CVI42 image post-processing software was used to observe and analyze CMR-MPI and CMR-LGE images for hypoperfusion and LGE(+),and their distribution areas and types were counted to discuss their differences and clinical significance.At the end of the examination,the experimental piglets were killed,the hearts were taken out,and the myocardial histochemical examination and routine pathological examination were performed.Results:(1)Six Bama minipigs in the model group completed the COPD model construction.Compared with the normal control group,the respiratory rate(67.67±3.45 vs 58.50±3.11,P=0.003)and heart rate(90.33±3.14 vs 80.25±4.03,P=0.002)of minipigs in the model group increased,while the body weight(24.62±0.64 vs 25.93 ± 0.35,P=0.008)was lower than that of the normal control group.In the model group,chest CT scan showed different degrees of emphysema and double lung infection.(2)The RVEF of model group was significantly lower than that of the control group(50.67±1.86 vs 54.25±1.26,P=0.001),but still slightly higher than the normal value 50%;in the model group,the RVEF after modelingwas significantly lower than before(50.67 ± 1.86 vs 54.38±1.41,P=0.001).There was no significant difference in LVEF between model group mini pigs and normal control group before(60.88±2.23 vs.60.75 ±1.50,P=0.992)and after(60.33 ± 1.63 vs.60.50±2.08,P=0.890)modeling.(3)There were 5 mini pigs in the model group(83.3%)with decreased myocardial perfusion,1 mini pig(16.7%)without decreased myocardial perfusion,and 4 mini pigs in the normal control group(100%)without decreased myocardial perfusion,the difference was statistically significant(P=0.010).There were 85 myocardial segments in 5 mini pigs with hypoperfusion,among which 21 segments showed hypoperfusion,while there was no hypoperfusion in all left ventriclesegments of mini pigs in the normal control group(P<0.001).The results of CMR-LGE showed that only 2(33.3%)minipigs in the model group had LGE(+),while 4(100%)Bama minipigs in the normal control group did not have LGE(+),the difference was not statistically significant(P=0.197).There were a total of 34 cardiac muscle segments in the 2 miniature pigs with myocardial LGE(+),of which 11 segments showed LGE(+),while none of the mini pigs in the normal control group showed LGE(+),with statistically significant differences(P=0.005).(4)In the model group mini pigs,there were 21 myocardial segments with decreased perfusion,including 10 in the base(33.3%),9 in the middle(30.0%),and only 2 in the apical and apical segments(8.0%).There was no significant difference in the distribution of myocardial segments with decreased perfusion(P=0.067).There were 11 segments of LGE(+),5(41.7%)in the basal and middle segments,1(10.0%)in the apical and apical cap segments,and there was no significant difference in the distribution of LGE(+)in each segment(P=0.198).The distribution of all types of decreased myocardial perfusion and LGE(+)in the middle of the base,apex of the heart and apex of the apex of the heart were not statistically significant.(5)Among the 21 segments with decreased perfusion in all model group mini pigs,there were 7 subendocardial(33.3%),12 intramural(57.1%),1 subepicardial(5.0%)and 1 transmural(5.0%),and the main type was intramural(P=0.001).Among the 11 LGE(+)segments,there were 4 subendocardial(36.4%),5 intramural(45.5%),1 subepicardial(9.1%)and 1 transmural(9.1%),Myocardial LGE(+)is also dominated by the intermural type,but there was no significant difference between the types of LGE(+)(P=0.169).Conclusion:(1)COPD can cause coronary artery microcirculation disturbance and myocardial injury.It can provide imaging evidence for the formulation of early intervention,diagnosis and treatment plan of COPD patients..(2)The 3.0t MRI MPI and LGE techniques can quantitatively display the coronary artery microcirculation disturbance and myocardial injury caused by COPD,which has a great clinical application prospect.(3)The coronary artery microcirculation disturbance and myocardial injury caused by COPD are mainly distributed in the anterior septum,posterior septum and inferior wall of the basal and middle parts.The common type is intramural type,and the second is subendocardial type,which can be regarded as the characteristic change of myocardial injury caused by COPD. |
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