MRI Findings Of Before And After Reperfusion Of Hibernating Myocardium Compare With Pathology

Objective:Establish rabbit hibernating myocardium model, to evaluate the value of CMRIfor demonstrating the hibernating myocardium and functional recovery of hibernatingmyocardium after reperfusion.Materials And Methods:Thirty rabbits were randomly divided into six groups. Group A was the normalcontrol group, the LAD of coronary artery of rabbits was not ligated during operation.Group B was the myocardium infarction groups, Group C was hibernatingmyocardium group and other reperfusion groups. Group C was devided to fivesubsections, CO group was hibernating myocardium group. The LAD wasobstructed by part-ligation of Group C. Group C1,C2,C3 who were gotreperfusional surgery after three days of first surgery. CMRI were performed 3 daysafter operation of group B and group CO, and pathological samples were collected forTTC staining and HE staining after CMRI. Group C1 were performed CMRI afterone day of reperfusion surgery and C2 were performed after three days and C3 wereperformed after seven days, and pathological samples were collected for TTC stainingand HE staining after CMRI. The appearances of CMRI compared with the results ofpathological examinations to analyses the appearances of CMRI comparatively.Results:Pathological appearances: Group A: All the five rabbits of group A werenormal on histopathologic examination. Group B: It was enlarged slightly of thechamber of left ventricle and slightly thinningz of focus segment. The focus segmentbecame white after TTC staining. HE staining showed that those cells of infarctedmyocardium obvious sharpen than normal,contour of cells still obstain though themembrans were splited. Group CO: It was showed that become crimson ofmyocardium of left ventricle. HE staining showed that feculence and swelling of cellsin focus segments,ambiguity of the structures of transverse striation. Group C1: It was showed that become crimson of myocardium of left ventricle. HE stainingshowed that feculence and swelling of cells in focus segments,ambiguity of thestructures of transverse striation. Group C2: It was showed that become crimson ofmyocardium of left ventricle. It was found punctiform infarcted myocardium in tworabbits. HE staining showed a few cells atrophy, solution, some fibrosis of interstitialsubstance and residual myocardium hypertrophy, disfiguration. Group C3: It wasshowed that become crimson of myocardium of left ventricle. It was foundpunctiform infarcted myocardium in one rabbits. HE staining showed a few cellsatrophy, solution, some fibrosis of interstitial substance and residual myocardiumhypertrophy and disfiguration.CMRI appearances: Group A: All rabbits were normal on CMRI. Group B: Itwas found that T₂WI signal intensity heighten of focus segments,slightly thinningz,thickening rate descend in end-systole and weaken of kinesis in focus segment.The first-pass perfusion imaging showed that hypo-enhancement in focus segments.It was found hyper-enhancement of focus segments on delayed enhancement image.Group CO: It was found that T₂WI signal intensity heighten,thickening rate descendin end-systole and weaken of kinesis of focus segments in four rabbits. The first-passperfusion imaging showed that hypo-enhancement of focus segments in four rabbits.C1: It was found that slightly thinningz of focus segment in one rabbit and threerabbits hypo-enhancement of focus segments in first-pass perfusion imaging. C2: Itwas found that thickening rate descend in end-systole in cine-MRI and slightlyweaken of kinesis of focus segments in one rabbits. The first-pass perfusion imagingshowed that hypo-enhancement in focus segments in two rabbits. C3: All rabbitswere not seen obvious abnormality on CMRI.Conclusion:1. The part-ligation approach to make rabbit hibernating myocardium modeland reperfusion model is not only easy for operation, but also economic and availably,and show good feasibility, should be worthy to be studied further.2. T₂WI signal intensity heighten of focus segments in infarctedmyocardium. HM can not find obvious signal intensity heighten in T₂WI just byeye, but showed signal intensity heighten by MR measurement. It might because thatslightly swelling of cells and interstitial.3. It was found hyper-enhancement on delayed enhancement image both ininfarcted and hibernating myocardium. Normal and other reperfusional myocardiumnot found hyper-enhancement on delayed enhancement image, so delayed enhancement image could help to the differential diagnosis between hibernatingmyocardium with reperfusional myocardium.4. Infarcted, hibernating and other reperfusional myocardium was graduallyrecovery in Tmax, S and SI of first-pass perfusion image. First-pass perfusionimage's value should be studied further.5. It might be help to discriminate infarcted myocardium from hibernatingmyocardium through thickening rate descend in end-systole in cine-MRI.6. It was found that T₂WI signal intensity was not heighten significantly,thickening rate descend in end-systole, without thinningz of focus segments inhibernating myocardium.It was found that T₂WI signal intensity was not heightensignificantly, thickening rate descend in end-systole and thinningz of focus segmentsin infarcted myocardium.7. The main CMRI appearances of hibernating myocardium were thickeningrate descend in end-systole, weaken of kinesis of focus segments, no obviousheper-enhancement in delayed enhancement image, hypo-enhancement of focussegments in first-pass perfusion imaging, and could be partial recover of functionafter reperfusion.