能谱CT早期评价^125Ⅰ粒子植入治疗胰腺癌效果实验研究

Application of spectral CT imaging in making early evaluation of the effect of ^(125)Ⅰ particle interstitialbrachytherapy for pancreatic carcinoma: an experimental study

目的探讨能谱CT成像早期评价^(125)Ⅰ粒子组织间植入治疗胰腺癌效果的应用价值。方法人原位胰腺癌Bx PC-3细胞株接种于16只BABL/c裸鼠四肢偏背侧皮下,成瘤1~1.5 cm;分别植入^(125)Ⅰ粒子(实验组,n=8)和空载粒子(对照组,n=8),2周后行能谱CT平扫及多期相(10 s、25 s、60 s)增强扫描,获取多期相系列图像。测量瘤体对比噪声比(CNR)和碘浓度(IC),得出瘤体标准化碘浓度(n IC)。瘤体免疫组化染色后,分析瘤体组织内微血管密度(MVD),n IC与MVD相关性。结果实验组各期相(10 s、25 s、60 s)瘤体n IC值均低于对照组,差异有统计学意义(P<0.05);实验组MVD计数低于对照组,差异有统计学意义(t=5.957,P<0.01);各期相n IC与MVD均存在正线性相关(分别为r=0.63,P<0.0001;r=0.51,P=0.002;r=0.48,P=0.0017)。结论能谱CT是监测^(125)Ⅰ粒子组织间植入治疗胰腺癌效果的有效方法 。

Objective To discuss the application of spectral CT imaging in evaluating the early therapeutic response of ^125Ⅰseed interstitial brachytherapy for pancreatic carcinoma in experimental nude mice.Methods Bx PC- 3 human pancreatic cancer cell xenografts were subcutaneously inoculated at the dorsal part of the limbs in 16 BABL/c nude mice. When the tumor developed to the size of 1-1.5 cm, the tumor- bearing mice were randomly divided into the study group（n=8,receiving implantation of^125Ⅰseeds of 1.0 m Ci） and the control group（n=8,receiving implantation of ghost shell particles of 0 m Ci）. Two weeks after the procedure,plain spectral CT scan as well as enhanced multiphase（10 s, 25 s and 60 s） spectral CT scan were performed to obtain multi- phasic image series. The contrast- to- noise ratio（CNR） and iodine concentration（IC） inside the lesions were determined, and the normalized iodine concentrations（n IC） of tumor were thus obtained.Immunohistochemical staining of tumor was used to measure microvessel density（MVD） within the tumor;the correlation between n IC and MVD was analyzed. Results The lesion＇s n ICs measured on each of three phases（10 s,25 s and 60 s） in the study group were lower than those in the control group, the differences were statistically significant（P〈0.05）. MVD count in the study group was lower than that in the control group,the difference was statistically significant（t=5.957,P〈0.01）. A parallel linear correlation existed between n IC obtained from each phase of three phases and MVD count（r=0.63,P〈0.000 1;r=0.51,P=0.002;and r=0.48,P =0.001 7 for 10 s, 25 s and 60 s phases respectively）. Conclusion Spectral CT imaging is an effective method for evaluating the therapeutic effect of ^125Ⅰseed interstitial brachytherapy for pancreatic carcinoma of experimental mice.