动态对比增强磁共振成像在^(125)I粒子治疗胰腺癌疗效评估中的实验研究

Use of DCE-MRI for evaluating the efficacy of ^(125)I seed interstitial brachytherapy for pancreatic carcinoma

目的:探讨采用动态对比增强磁共振成像(dynamic contrast-enhanced magnetic resonance imaging,DCE-MRI)评估125I粒子组织间植入治疗人胰腺癌裸鼠移植瘤疗效的价值。方法:将人胰腺癌SW1990细胞株接种于BABL/c裸鼠右下肢旁腹股沟区偏背侧皮下,当瘤体直径长至8～10 mm时进行干预,共16只成瘤大小合适的裸鼠用于实验,分别植入125I粒子(8只,实验组)和空载粒子(8只,对照组),在粒子植入前及治疗后2周及2个月行MRI常规扫描及DCE-MRI成像,并对肿瘤标本行组织病理学检查。结果:实验组肿瘤细胞坏死明显,而对照组肿瘤细胞无明显或有少量坏死。所有裸鼠的心、肝、肺、肾及脾脏等组织均无明显放射炎症表现。常规MRI评价125I粒子治疗胰腺癌疗效的价值有限。实验组肿瘤实质与坏死交界区的Ktrans值最高,其次为整个肿瘤组织的Ktrans值,再次为肿瘤实质,最后是肿瘤坏死区。实验组治疗后2周及2个月裸鼠的整个肿瘤组织Ktrans值均较治疗前降低,且整个肿瘤组织的Ktrans与肿瘤坏死率有间一定的相关性(r=-0.518,P=0.01);而肿瘤坏死率与肿瘤体积间有一定相关性,坏死随着肿瘤体积增加而增加(r=0.641,P=0.001)。结论:125I粒子治疗人胰腺癌裸鼠可导致移植瘤内坏死,且对周围脏器较安全。用常规MRI及DCE-MRI对裸鼠皮下移植瘤成像是可行的。常规MRI对治疗疗效的评估作用有限,而DCE-MRI则可定量分析125Ⅰ粒子治疗后肿瘤血管灌注特性的改变,对疗效的评估有重要价值。

Objective To evaluate the efficacy of 125I interstitial brachytherapy for human pancreatic cancer xenograft in nude mice by dynamic contrast-enhanced magnetic response imaging（DCE-MRI）.Methods Human pancreatic cancer cell line SW1990 cells were injected subcutaneously into the dorsal area of right lower limb next to groin of BABL/c nude mice.Therapeutic intervention was performed when the tumor size reached 8-10 mm.A total of 16 nude mice were studied,in which 8 nude mice were implanted interstitially with 125I seeds and 8 were implanted with blank seeds.Conventional MRI scans and DCE-MRI were performed before and 2 weeks,2 months after seeds implantation.Tumor samples were studied by histopathological examination.Results Obvious tumor necrosis could be seen in 125I seeds implantation group,while no obvious necrosis was seen in control group.Heart,liver,lung,kidney and spleen of nude mice showed no significant radiological inflammation.Conventional MRI imaging had limited value for evaluating the efficacy of 125I seeds brachytherapy for pancreatic cancer.The Ktrans value of the boundary zone between tumor parenchyma and necrosis area was the highest,followed by Ktrans values of the entire tumor tissue,the tumor parenchyma,and finally the tumor necrosis.The Ktrans values of entire tumor 2 weeks and 2 months after 125I seeds implantation were lower than that before implantation.The Ktrans of entire tumor had some negative correlation with tumor necrosis（r =-0.518,P = 0.01）,and tumor necrosis had some positive correlation with tumor volume（r = 0.641,P = 0.001）.Conclusions 125I interstitial brachytherapy is effective for treating human pancreatic cancer xenografts in nude mice.125I seeds implantation is safe for nearby organs.Conventional MRI imaging has limited value for evaluating the efficacy of 125I seeds brachytherapy for human pancreatic cancer xenograft,while DCE-MRI imaging could quantitatively analyze the vascular perfusion changes of tumor after 125I seeds brachytherapy and had substantial value for the evaluation of its efficacy.