CT导引下 ^(125)Ⅰ粒子置入治疗兔VX_2肝转移癌

Experimental research on rabbits VX_2 malignant liver tumor treatment with ^(125)I seeds brachytherapy under CT guidance

目的探讨 CT 导引下瘤体内^(125)Ⅰ粒子置入治疗兔 VX_2肝转移癌的疗效及其病理改变,为^(125)Ⅰ粒子临床应用中合理化治疗方案的取得提供理论依据。方法新西兰兔32只制备成 VX_2肝转移癌模型,完全随机法分为4组,每组8只,依据术前治疗计划系统(TPS)设计在 CT 引导下置入不同活度粒子,分别为:37.0、25.9和14.8 m Bq,对照组置入粒子空壳。观察置入后1周、2周、1个月、2个月和3个月各组肿瘤的大小、活性、影像和病理组织形态学的变化。结果治疗组自然生存期(88±12)d 明显高于对照组(22±7)d。治疗3个月后,治疗组平均肿瘤体积分别为:37.0 mBq 组(0.06±0.02)cm^3、25.9 mBq 组(0.21±0.05)cm^3、14.8 mBq 组(1.74±1.22)cm^3,重复测量方差分析及 LSD 两两比较表明37.0 mBq 与25.9 mBq 组间差异无统计学意义(t=0.35,P>0.05),但均低于14.8 mBq组(t 值分别为2.59、2.24,P值均<0.05)。治疗后增强 MR 扫描显示37.0 mBq 组强化消失5例,25.9 mBq 组强化消失4例,而14.8 mBq 组强化消失仅1例。病理检查37.0 mBq 组及25.9 mBq 组大部分瘤巢缩小至消失,疗效优于14.8 mBq 组,但在放射粒子对正常肝组织影响方面37.0 mBq 组较其他治疗组严重。结论短期疗效证明,25.9 mBq 的^(125)Ⅰ粒子可对高增殖活性的肝恶性肿瘤起到良好的控制作用,并且对正常肝组织的损伤程度较小。

Objective To evaluate the therapeutic effects and pathological changes on rabbits with VX2 liver tumor treated with CT-guided ^125I seeds interstitial brachytherapy, and to investigate the criterion of ^125I seeds selection and optimized therapeutic regimen, so as to provide the theoretical basis for the clinical application of ^125I seeds treatment. Methods Thirty-two New Zealand rabbits with VX2 malignant liver tumor were randomly divided into 4 groups. According to the treatment planning system （TPS）, rabbits in group A, B and C were subject to different amounts of ^125I seeds with varying radiant activities, which were 37.0 mBq（n = 8）, 25.9 mBq（ n = 8）, and 14. 8 mBq（ n = 8 ）, respectively, and group D as the control group （ n = 8 ）. In order to investigate the changes of tumor sizes and its activity, rabbits in each group were observed under CT, MRI, and histopathological examinations after irradiated for 1 week, 2 weeks, 1 month, 2 months, and 3 months. Results During 3 months observation, animals in treatment group demonstrated significantly prolonged survival rate （88 ±12 d） as compared to control group （22 ±7 d）. General linear model repeated measures analysis and LSD showed tumor volumes reduced significantly, which were 37. 0 mBq（0. 06 ±0. 02 ） cm^3, 25.9 mBq（0.21 ±.05） cm^3 and 14.8 mBq（1.74 ±1.22） cm^3, respectively. There were no significant difference between 37.0 mBq and 25.9 mBq group （ t = 0. 35, P 〉 0.05） , but all lower than 14. 8 mBq group （t = 2. 59, 2. 24, P 〈 0. 05 ）. Three months after treatment, 5 cases in group A and 4 cases in group B showed no tumor enhancement on MR imaging. On the contrary, only 1 case in group C showed no tumor enhancement. At the end of observation, living tumor cells were hardly seen in group A and B when examined under microscope and electron microscope, and the tumor area was completely wrapped up by fibrous tissue, while small amount of tumor still remained alive in group C. However, more complications occurred in group A than in group B and C, such as fibroplasias and pseudo-lobulation in adjacent liver structure. Conclusion As far as the short-term therapeutic effects are concerned, 25.9 mBq ^125I seeds prove to be a best choice in treating high proliferation malignant liver tumors without severe injuries to the liver.