兔VX2肝癌高能聚焦超声治疗后灌注加权成像与微血管密度的比较研究

目的比较分析兔肝VX2瘤行高能聚焦超声(HIFU)治疗前后不同ROI的MR灌注加权成像(PWI)变化特点,并与微血管密度(MVD)进行比较,探讨两者的相关性。材料与方法新西兰大白兔42只,采用组织块种植的方法成功制成40只兔VX2肝癌模型,随机分为治疗组20只,对照组20只,治疗组行HIFU治疗。待肿瘤直径≥10 mm时,分别于治疗前、治疗后14 d对两组行常规MRI及PWI。MR扫描使用Philips 1.5 T MR成像仪,PWI采用SE-EPI序列,信号强度-时间曲线的最大信号下降斜率(SRSmax)作为定量指标,选取病灶与周围正常肝组织的ROI,分别测量治疗前、后不同ROI的血流灌注值。标本行免疫组化检测,并与PWI结果进行对照,分析不同ROI的SRSmax变化规律,进行统计学分析。结果 40只兔肝癌模型共发现48个瘤灶,其中33只瘤兔共36个瘤灶纳入最后数据分析。T2WI上,瘤灶信号呈不均匀高、低混杂信号;血流灌注图上不同ROI血流灌注程度及强度均有差异。治疗组治疗前后肿瘤中央区、周边区SRSmax值差异有统计学意义(P<0.05);对照组前、后两次PWI,肿瘤中央区SRSmax值两两比较差异有统计学意义(P<0.05);治疗后治疗组与对照组瘤周区的SRSmax值两两比较差异有统计学意义(P<0.05);治疗组肿瘤周边区的SRSmax值与MVD检测结果呈正相关(r=0.78,P=0.01)。结论兔肝VX2瘤各ROI的PWI表现与MVD表达程度、范围一致;PWI能反映VX2癌HIFU治疗前后肿瘤的血管生成、破坏状况。

Comparison of perfusion imaging and microvessel density in rabbit models of hepatic VX2 tumors after high intensity focused ultrasound

Objective： Compare perfusion-weighted imaging（PWI） characteristics and parameters changes with before and after high intensity focused ultrasound（HIFU）,supposed to discuss the correlation of Maximal signal reduction slope（SRSmax） and microvessel density（MVD）.Materials and Methods： Forty rabbit models of hepatic VX2 tumors were implated successfully,two weeks later,after routine scans were performed on 1.5 T MR scanner,using EPI-SE series,40 New Zealand white rabbits with VX2 carcinoma were divided randomly into treatment group 20,control group 20,HIFU with treatment group.Perfusion-weighted imaging and enhanced scan were performed 14 d before and after HIFU with both groups.Select the region of interest（ROI） of the central of tumor,surrounding of tumor and paratumor parenchyma.SRSmax of the signal intensity versus time curves were created as quantitative variable.Analyze the SRSmax change degrees and regularities of different ROI.specimens of MVD were examined and compared with PWI.Results： Forty-eight lesions were detected in 40 rabbit models,and 36 lesions in 33 rabbit models were statistical analysis finally.Tumor showed heterogeneous were mixed with high signal,normal signal and low signal,the degrees and intensity of blood perfusion in different ROI were different.After HIFU,the SRSmax value of central and surrounding of tumor were statistically decreased than that before HIFU（P0.05）.In control group,the SRSmax value of central of tumor with second were statistically decreased than the first（P0.05）.The SRSmax value of surrounding of tumor in HIFU group were statistically decreased than that of control group（P0.05）.The SRSmax and MVD correlation analysis showed that they were positively correlated with surrounding of tumor in HIFU group（r=0.78,P=0.01）.Conclusions： The degrees of blood perfusion of different ROI were consistented with the results of MVD.PWI on VX2 carcinomas are matched with the levels and scopes of necrosis,PWI can be used in evaluating the liver tumor angiogenesis and angioruin with the treatment of HIFU.