| Part One Study on Optimized Sequences and Main Measurement Indexes of Cardiac MRI Scanning for Chinese Miniature PigsPurpose:The optimized sequences and main measurement indexes of cardiac scanning magnetic resonance imaging(CMR)T1 mapping scans for Chinese mini-pigs were investigated.Methods: Ten healthy Chinese miniature pigs underwent CMR scan with T1-mapping technique based on modified Look-Locker acquisition with saturation recovery(MLLSR)MLLSR.Images were analyzed using CVI 42v5.5 post-processing software for image postprocessing analysis.The region of interest was delineated according to the 17-segment analysis proposed by the American Heart Association,and the initial T1 values of the myocardium in the apical,middle and basal regions of the left ventricle were measured.The initial T1 Value of the similarities and differences,the diagnostic significance,at the same time proposed to explore and solve the experimental scan encountered problems affecting the scanning and image quality,and to further find solutions to optimize the program,and finally get the optimization of CMRI T1-mapping scan optimization sequence technology and Determine the main measurement indicators.Results:(1)A total of 9 healthy Chinese miniature pigs underwent cardiac magnetic resonance scanning.Through several improvements and optimization of the sequence and related parameters in the scanning process,the experimental scanning time was significantly shortened and the quality of the collected images was improved.The results showed that T1 mapping based on MLLSR sequence can quantify the myocardial T1 value.There are some experimental bases and high usability in the study of clinical myocardial disease.(2)The average initial T1 value of myocardium at all levels was(1110.8±13.5)ms.The mean T1 value of the central apex was(1050.5±17.8)ms,the mean T1 value of the middle myocardium was(1107.9±55.2)ms,and the average of the basal myocardial T1.The value was(1026.7±36.2)ms.The difference was statistically significant(P<0.05).There was no statistical difference in the initial T1 value between the apical and basal myocardium.There was a statistically significant difference between the initial T1 values at the apex and the middle.Conclusion:(1)Optimization of optimized sequences for cardiac magnetic resonance imaging(CMR)scanning in Chinese miniature pigs has ignificantly improved experimental scanning rates and image quality.(2)T1mapping technology in clinical aspects of myocardial disease has good experimental basis and availability,and provides methodological basis for further research.Part Two Evaluation of T1 mapping in evaluating the changes of myocardium induced by early COPD modelingPurpose:To investigate the use of T1 mapping quantitative assessment of early COPD caused by secondary changes of early myocardial injury and increase T1 value before and after the change.Methods: A COPD model was prepared using 10 healthy Chinese miniature pigs,and a combination of trypsin solution and papain solution was used to create an early COPD experimental pig model.The experimental pigs were normal(week 0)to cardiac magnetic resonance CMR scans at 3 weeks,6 weeks,9 weeks,and 4 weeks and 8 weeks after the start of modeling.Long-axis,left-ventricular,four-chamber position,and short-axis front and back of the enhanced four-chamber position of the apical film and plain scan short axial apex-the middle-the image of the base,two-chamber heart and four-chamber T1-mapping image.The images were analyzed by the CVI 42v5.5 post-processing software to measure the plain scan T1 values before and after the enhancement of the myocardial segments in the apex,middle and bottom of the heart.The left and right ventricle were analyzed before and after the enhancement of different myocardial segments in the left ventricle.Changes in T1 values before and after different myocardial segmentation and n different phases of modeling,discuss differences and diagnostic significance.Results:(1)Experiments A total of 6 Chinese miniature pigs were successfully modeled and completed cardiac magnetic resonance CMR scans.At the 4th week after model establishment,the mean initial T1 values of left ventricular apex,medial and basal myocardium were(1066.2±57.8)ms,(1125.3±45.1)ms,(1065.4±86.7)ms,respectively.Slightly increased,the difference was not statistically significant(all P>0.05).(2)The average initial T1 value of the left ventricular apex was(1176.8±88.4)ms after the 8th week of modeling,which was higher than before modeling.The difference was statistically significant(P<0.05).The average initial T1 value of the middle myocardium was(1246.7±60.2)ms.There was no statistically significant difference from the pre-model(P>0.05);the average initial T1 value of the basal myocardium was(1204.5±75.3)ms.There was no significant difference between the two groups before modeling(P>0.05)(3)At the 4th week after modeling,the average initial T1 values of the left ventricular apex,the middle and the basal myocardium were(1066.2±57.8)ms,(1125.3±45.1)ms,(1065.4±86.7)ms respectively;the left ventricular apex,the middle part and the 8th week.The average initial T1 value of the basal myocardium was(1176.8±88.4)ms,(1246.7±60.2)ms,(1204.5±75.3)ms.There was no ignificant difference between the apex and the basement in the two stages.Statistically significant(P<0.05).(4)Before and after modeling,there was a significant difference in T1 between the apex of the left ventricle,the anterior wall of the middle part,the anterior wall and the inferior wall(all P <0.05),and the T1 mapping technique could be used to quantitatively assess the early secondary Myocardial function changes.Conclusion:(1)The T1 mapping technique can quantitatively assess the changes of early secondary myocardial damage caused by early COPD,and provide some imaging evidence.(2)Before and after modeling,there was a significant difference in the plain T1 value between the initial and enhanced anterior and inferior myocardium of the left ventricular apex,the anterior middle wall,the anteroseptal wall,and the inferior wall of the experimental pigs.Can be considered as a clinically significant indicator of early myocardial injury caused by COPD. |
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