表观扩散系数在肝癌动脉化疗栓塞后早期监测中的价值

Value of apparent diffusion coefficient in monitoring tumor response to TACE of hepatic carcinoma in rabbits

目的 评价表观扩散系数（apparent diffusion coefficient，ADC）在兔VX2肝癌动脉化疗栓塞（TACE）后监测肿瘤坏死中的作用。方法（1）选用30只成年雄性新西兰大白兔，其中6只为种兔，将VX2瘤组织碎块种植于肝包膜下，建立移植性肝癌模型。（2）2周后将接种成功的24只VX2兔行常规MRI及扩散加权成像（DWI）。常规MRI用FSE序列；DWI检查用SE-EPI序列（TR/TE=3000．4000ms／50．9-70．2ms；层厚为3mm；层距为0．5mm；FOV为12cm×12cm；b值为600s／mm^2）。（3）将24只兔平均分为A、B两组。A组动物MRI检查后用超液化碘油与阿霉素制成乳化栓塞剂行TACE治疗，B组不治疗。（4）治疗后3dA、B两组均行MRI检查，方法同（2）。在肿瘤内分散放置3个感兴趣区（ROI），分别测得3个ADC值，取平均数。（5）检查完毕后将所有动物处死取肝脏做病理，测量肿瘤坏死范围，以百分数表示。测量A、B两组的ADC值，研究其与肿瘤坏死百分数的相关性。结果24只（100％）动物接种成功，2周后肿瘤直径约l一2cm。治疗后A组平均ADC值为（1．92±0.19）×10～mm^2／s，B组平均ADC值为（1．634±0.12）×10^-3mm^2／s；A组肿瘤坏死率约为94％，B组为50％；A组平均坏死率为（89．1±0．4）％，B组平均坏死率为（46．6±0.5）％。A、B两组间ADC值差异有显著性（P〈0．05），与坏死率的相关系数分别为0．92和0．89。结论ADC值与肝癌TACE治疗后的肿瘤坏死密切相关，可用于早期监测TACE的疗效。

Objective To evaluate the usefulness of apparent diffusion coefficient （ADC） in estimating tumor necrosis after transarterial chemoembulization （TACE）.Methods （1）24 adult male New Zealand White rabbits were selected, the VX2 tumor cells were implanted into the left lobe of the liver, and established the implanted model of hepatic carcinoma. （2） 2 weeks later, 24 rabbits bearing VX2 tumors successfully underwent conventional MRI and DWI examination. Both conventional images and DWI were obtained with a 1 .5T MR imaging system（Signa Infinity Twinspeed Excite, GE, US） and a phased array knee coil. The DWI protocol was SE- EPI （TR/TE = 3000 - 4000 ms/50.9 - 70.2 ms; slice thickness, 3 mm; interslice gap , 0.5 mm; FOV ,12 × 12 cm; b-factors , 600 s/mm^2 ）. （3）All 24 rabbits beating VX2 tumors in the livers were divided randomly into two groups： A, TACE group and B,control group. A group underwent TACE using the mixture of ethiodized oil and Adriamycin; while B group was untreated. （4）3 days after treatment, beth A、B groups performed MRI study using the same ways as （2） .3 ROIs were placed diffusedly in the tumor and the mean ADC value was measured. （5）After MRI scan, all animals were sacrificed and the livers were dissected and sliced. The percentage of necrotic area in each rabbit was calculated, and the relationship between ADC of A、B groups and extent of necrosis was analyzed by a Pearson＇s correlation test. Results 24 rabbits （100%）were implanted successfully, and the tumors were 1 - 2 cm in diameter 2 weeks later. There was a significant difference in the ADCs between TACE group and control group by （ 1.92 ± 0.19 ） ×10^- 3 mm^2/s vs （ 1.63 ± 0.12） × 10^-3 mm^2/s; the tumor necrotic percentage was in 89.1 ± 0.4% in TACE group while 46.6 ± 0.5% in the control group. A significant positive correlation between ADC and tumor necrosis was noted. Conclusion The ADC value correlates well with tumor necrosis, it has potentiasl for detecting early response of tumor to TACE.