| PartⅠCorrelation of enhanced intensity of atherosclerotic plaque at contrast-enhanced ultrasonography with histological findingsObjectives:To evaluate the relationship between plaque neovascularization and plaque enhanced intensity by contrast-enhanced ultrasonography.Methods:25New Zealand white rabbits were fed with high fat diet to16weeks. CEU was performed to observe plaque echogenicity. Time-intensity curve was used to quantify the El of plaques. After harvesting the aorta, CD31stain was performed for calculating the density of neovascularization.Results:The echolucent plaques had higher E during CEU and higher neovascularization density at pathological stain than the echogenic plaques.The atherosclerotic plaque El and its ratio to luminal El were well related with neovascularization density (R=0.75, P<0.001; R=0.68, P<0.001) respectively.Conclusions:The atherosclerotic plaque enhanced intensity during CEU was well correlated to neovascularization density.CEU can assess the enhanced intensity of atherosclerotic plaque quantitatively, thus providing us a reliable way for evaluating the neovascularization of atherosclerotic plaque. Part ⅡThe Evaluation of Effects of Vasoactive Substances on Plaque Enhanced Intensity during Contrast-Enhanced UltrasonographyObjects:To evaluate the effects of vasoactive substances on plaque enhanced intensity during contrast-enhanced ultrasonography.Method:25New Zealand white rabbits were fed with a high fat and cholesterol diet for16weeks following balloon injury. Routine ultrasonic examinations were performed to classify the plaques into echolucent or echogenic according to their echogenicities. Rabbits were intravenously administered a0.4mL Sonovue bolus to perform the contrast examination. The images were stored in EchoPAC work station. Enhanced intensity in each frame was measured in the plaque drawn as a region of interest. Curve fitting was done with the formula Y(t)=A(1-e-kt)+B to get the enhanced intensity of the plaques and the lumen by computing the variation of plateau intensity and initial intensity. The enhanced intensity was then compared between the echolucent and the echogenic plaques. The rabbits were later injected with noradrenalin (NA), triphosadenine(ATP) respectively after the heart rate and blood pressure recovered, and repeat examination was done with contrast agent and enhanced intensity of the plaque was quantified again. SPSS15.0software was used to calculate the statistical characteristics of the data. All the measured data were displayed as mean±standard deviation. P<0.05was defined as having statistical significant difference. Independent sample T test was applied to analyze the variation between echolucent and echogenic plaques. The variation of enhanced intensity at baseline and after injecting NA or ATP was analyzed by paired T test.Results:The echolucent plaques expressed higher enhanced intensity than echogenic plaques (7.97±2.63dB vs.5.76±2.31dB, P=0.008). After administration of NA, plaque enhanced intensity and its ratio to lumen were lower than the base values (6.41±2.90vs7.51±3.81, P<0.001;0.38±0.17vs0.45±0.16,P=0.002) whereas the intensity and its ration to lumen after injecting ATP were higher than baseline(9.78±3.54vs7.49±2.72, P<0.001;0.59±0.23vs0.46±0.17, P<0.001).Conclusion:The enhanced intensity of the plaque can be affected by vasoactive substances. CEU may be useful to quantify the enhanced intensity of the plaque and the degree by which it is affected by vasoactive substances. It would then play an important role in evaluating the stability of atherosclerotic plaque. Part IIIThe Evaluation of effects of Endothelial Active Substances on Plaque Enhanced Intensity during Contrast-Enhanced UltrasonographyObjects:To evaluate the effects of endothelial active substances on plaque enhanced intensity during contrast-enhanced ultrasonography.Method:25New Zealand white rabbits were fed with a high fat and cholesterol diet for16weeks following balloon injury. Routine ultrasonic examination was performed to classify the plaques into echolucent or echogenic according to their echogenicities. Rabbits were intravenously administered a0.4mL Sonovue bolus to perform the contrast examination. The images were stored in EchoPAC work station. Enhanced intensity in each frame was measured in the plaque drawn as a region of interest. Curve fitting was done with the formula Y(t)=A(1-e-kt)+B to get the enhanced intensity of the plaques and the lumen by computing the variation of plateau intensity and initial intensity. The enhanced intensity was then compared between the echolucent and the echogenic plaques. The rabbits were later injected with Methyl Arginine (LNMMA) and endothelial blockers (PD142893) respectively when the heart rate and blood pressure recovered, and repeat examination was done with contrast agent and enhanced intensity of the plaque was quantified again. SPSS15.0software was used to calculate the statistical characteristics of the data. All the measured data were displayed as mean±standard deviation. P<0.05was defined as having statistical significant difference. Independent sample T test was applied to analyze the variation between echolucent and echogenic plaques. The variation of enhanced intensity at baseline and after injecting LNMMA or PD142893was analyzed by paired T test.Results:The echolucent plaques expressed higher enhanced intensity than echogenic plaques (7.97±2.63dB vs.5.76±2.31dB,P=0.008). After administration of LNMMA, plaque enhanced intensity and its ratio to lumen were lower than the base values (5.48±1.57dB vs7.04±2.26dB,P<0.001;0.40±0.13vs0.46±0.17, P=0.003) whereas the intensity and its ratio to lumen was higher after injecting PD142893(8.31±3.29dB vs7.41±2.85dB, P=0.018;0.51±0.22vs0.45±0.17, P=0.012).Conclusion:The enhanced intensity of the plaque can be affected by endothelial active substances. CEU may be useful to quantify the enhanced intensity of the plaque and the degree by which it is affected by endothelial active substances. It would then play an important role in evaluating the stability of atherosclerotic plaque. |
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