^(99)Tc^m-HL91显像评估放疗疗效动物实验研究

Experimental research for the evaluation of radiotherapeutic response with 99Tcm-HL91 hypoxia imaging

目的:探讨99Tcm-HL91显像评估肝癌放疗疗效的可行性。方法:20只荷瘤小鼠随机分成放疗组和对照组。放疗组小鼠采用6MeV电子线,单次剂量15Gy进行放疗,对照组小鼠不进行放疗。两组小鼠均于放疗前、放疗后3天及放疗后5天经鼠尾静脉注射37MBq(0.1ml)99Tcm-HL91,4小时后SPECT采集小鼠前位平面图像,计算肿瘤与对侧相应部位放射性计数比值(T/NT)。显像当日游标卡尺测量肿瘤最大长径(A)和最大垂直横径(B),计算肿瘤体积。最后一次显像结束后处死全部模型小鼠,取肿瘤称重并制成病理切片,HE染色计算肿瘤切片坏死面积百分比(PNA)。结果:肿瘤99Tcm-HL91显像良好,肿瘤部位与对侧相应部位有较高的放射性计数比。放疗组小鼠放疗后T/NT、Rv3、Rv5、肿瘤体积和重量均明显低于对照组,PNA明显高于对照组(P<0.05)。放疗前T/NT与Rv5及PNA均不相关(P>0.05)。放疗3天时T/NT增加量与Rv5成正相关,与PNA成负相关。放疗3天时T/NT摄取增加组的Rv5大于摄取减少组,PNA低于摄取减少组(P<0.05)。结论:放疗后99Tcm-HL91乏氧显像可用于监测放疗效果。

Objective： The aim of this study was to evaluate the radiotherapeutic response with ^99Tc^m-HL91 hypoxia imaging in mice bearing Hca-F25 tumor cells. Methods： All the mice bearing Hca-F25 tumor cells were divided into the irradiation group and the control group. The irradiation group were irradiated at a dose rate of 300MU/min with 6MeV linear accelerator; each irradiation dose was 15Gy. The control group weren＇t irradiated. All the mice were injected intravenously with 0.1ml（37MBq） of ^99Tc^m-HL91 before radiotherapy, 3d and 5d after radiotherapy. Imaging was carried out 4 hours later and the tumor-to-normal ratio （T/NT） was calculated. Tumor length （A） and maximum vertical diameter （B） were measured before each imaging and caculated tumor volumes （mm^3）. At the end of the study, the weight and radioactivity of the tumors were measured. Percent of necrotic area （PNA） was calculated through hematoxylin-eosin （HE） staining of the tumor sections. Results： Tumors had good images. T/NT, Rv3, Rv5, tumor volumes and weights in the irradiation group were all obviously lower after irradiation than that in the control group（P〈0.05）, but PNA was on the opposition（P〈0.05）. T/NT before treatment was not correlated with Rv5 and PNA （P〉0.05）. Increased T/NT 3d after irradiation bad positive correlation with R,5, and negative correlation with PNA（P〈0.05）. Irradiation 3d later, the average Rv5 of uptake in the increased subgroup was more than that of uptake in the decreased subgroup, but the PNA was quite the reverse, there were significant differences （P〈0.05）. Conclusions： ^99Tc^m- HL91 image after irradiation was able to evaluate the radiotherapeutic response.