兔活体主动脉脂质斑块的腔内超声显像和病理的对照研究

１１条新西兰兔进行血管腔内超声（ＩＶＵＳ）研究。其中８条经高胆固醇饲养６个月；另３条予正常饮食对照。采用６．２Ｆ，频率２０ＭＨｚ腔内超声导管。由腹主动脉下端水平插入超声导管至升主动脉，然后逐步退出，观察主动脉内膜、中膜和外膜的形态特征。结果发现，正常兔主动脉在腔内超声观察下均无内、中和外膜三层结构之分。３９个切面管壁弥漫性增厚，其形态看似管壁的三层结构，病理证实３４个切面有脂质斑块。平滑肌增生的脂质斑块，回声影低于血管壁。部份脂质斑块存在弥漫性纤维化、胆固醇结晶和少量镜下可见的钙化灶，回声影致密，与血管壁的回声相同，但其后无声影。腔内超声测定的斑块面积和厚度与病理结果比较，差别无显著意义（Ｐ＞０．０５），两者高度相关（分别为ｒ＝０．９７，Ｐ＜０．０００５和ｒ＝０．９６，Ｐ＜０．０００５）。

In-vivo Intravascular Ultrasound Study on Lipid Depositions of Rabbit Aorta

Consecutive in-vitro intravascular ultrasound(EVUS)studies of atherosclerotic plaque nature described the distinctive echogenic property of lipid despitions. The purposes of our study were to evaluate findings of the acoustic property of lipid deceptions in-vivo and assess the accuracy of IVUS on measurement of the size of plaque. Eleven anestheticed New Zealand rabbits, weighed 2. 5ic 3. 5kg, were studied by IVUS in-vivo. Eight of them were high cholesterol fed for 6 months. Three of them were normal fed for control. IVUS catheter was introduced from the abdominal aorta and analysis was made for the existence of plaque and its acoustic property. Plaque area and thickness were measured and results were compared with those of the histology analysis at same section. Results Showed that the intima, media and edventitia of arterial wall could not be identified by IVUS in vivo in all of normal rabbit aortas. Dissenminated thickening of aortic wall was detected in 39 segments by IVUS that append as three layered feature under IVUS study. Lipid deposition was comfirmed in histology in 34 of them. Most of the smooth muscle cell poliferations and lipid depositions were hypoechoic in nature.Some of the lipid depositions with disseminated lesions of fibrosis cholesterol crystals and calcification flecks, approved by histology,werer bright echoes without acoustic shadow, the echogenic property was similar as the vascular wall. Plaque areas measured byIVUS and histology was excellently correlated (r=0.969, Y=0.109 0. 93X, P<0.0005 ), and the same for Plaque thickness measurements (r= 0. 955, Y = 0. 05 0. 92X, P< 0. 0005).