^99Tc^m-DTPA-DG显像对乳腺癌荷瘤裸鼠化疗疗效的评价

The relationship between chemotherapeutic response and ^99Tc^m-DTPA-DG uptake in breast cancer model

目的探讨^99Tc^m-DTPA-脱氧葡萄糖（DG）对乳腺癌荷瘤裸鼠化疗疗效的评价。方法建立乳腺癌荷瘤裸鼠模型。取裸鼠25只，体质量20～25g，分为5组，接种乳腺癌MCF-7细胞9d后进行化疗。对照组：注射0．1ml生理盐水；联合化疗1组：分别按体质量注射紫杉醇11mg／kg和阿霉素4．7mg／kg；联合化疗2组：分别按体质量注射紫杉醇5mg／kg和阿霉素2．3mg／kg；顺铂1组：按体质量注射顺铂8mg／kg；顺铂2组：按体质量注射顺铂4mg／kg。裸鼠化疗后分别于即刻和第7，14，21及28天注射^99Tc^m-DTPA-DG3．7MBq/只，0．5h后显像，勾画感兴趣区（ROI），计算肿瘤／健侧对应部位放射性（T／NT）比值，并测量肿瘤体积。第28天完成显像后，处死裸鼠，测量肿瘤／血液及肿瘤／肌肉放射性比值，计算抑瘤率。结果肿瘤组织吸收^99Tc^m-DTPA-DG较多，肿瘤／肌肉放射性比值对照组为5．65，高于联合化疗1组（0．98，t=8．735，P〈0．01）、联合化疗2组（1．13，t=4．826，P〈0．01）和顺铂1组（0．84，t=3．198，P〈0．05）。肿瘤／血液放射性比值对照组为3．1，高于联合化疗1组（0．83，t=7．652，P〈0．01）、联合化疗2组（1．29，t=3．976，P〈0．05）和顺铂1组（0．96，t=3．945，P〈0．05）；顺铂2组因不完全缓解，肿瘤／血液放射性比值为2．66，与对照组差异无统计学意义（t=2．496，P〉0．05）。^99Tc^m-DTPA-DG可使肿瘤组织清晰显像，联合化疗1组肿瘤体积400．0mm^3，与对照组（1132．8mm^3）差异有统计学意义（t=3．952，P〈0．01）；联合化疗2组肿瘤体积633．9mm^3（t=4．592，P〈0．05），顺铂1组肿瘤体积699．4mm^3（t=4．837，P〈0．05），这2组与对照组差异有统计学意义。除顺铂2组外，余各化疗组与对照组间T／NT比值差异有统计学意义（F=1018．165，P〈0．01）。结论化疗效果好的肿瘤，^99Tc^m-DTPA-DG显像示肿瘤体积较小，瘤体内放射性分布较少；而化疗效果差的肿瘤体积逐渐增大，瘤体内放射性分布较多。^99Tc^m-DTPA-DG显像可用于指导荷瘤裸鼠的化疗。

Objective It has been reported that ^99Tc^m-DTPA-deoxyglucose （DG） may be uptaken by tumor cells. This study was to evaluate the feasibility of using ^99Tc^m-DTPA-DG to assess ehemotherapeutic response of tumor. Methods Twenty-five female nude rats inoculated with MCF=7 cells for 9 d were randomly divided into five groups. The control group was treated with 0. 1 ml/kg of saline. The combined chemotherapy group Ⅰ was administered with 11 mg/kg of Taxol and 4.7 mg/kg of Doxorubicin. The cornbined chemotherapy group Ⅱ was injected with 5 mg/kg of Taxol and 2.3 mg/kg of Doxorubiein. The eisplatin group Ⅰ and Ⅱ were injected with 8 and 4 mg/kg of eisplatin, respectively. Scintigraphie studies were conducted at 0, 7, 14, 21 and 28 d after the treatments. The radioactivity ratio of tumor to non-tumor （ T/ NT） was calculated with region of interest （ROI） technique. After the last imaging the rats were sacrificed. The radioactivity ratios of tumor/bloed and tumor/muscle were measured. Tumor volume and thereby the inhibition rate in each group were calculated. Results Tumors were .clearly visualized on the ^99Tc^m-DTPA-DG images. The distribution of ^99Tc^m-DTPA-DG demonstrated that chemotherapeutic groups had lower tumor/muscle ratios （t=8. 735, 4. 826, 3. 198） and mmor/bloed ratios （t =7. 652, 3. 976, 3. 945 ） than control group （ all P 〈 0.05 ）. The T/NT ratios were significantly lower in the three chemotherapy groups than in control group （F = 1018. 165, P 〈0.01 ）, while there was no significant difference of T/NT ratios between cisplatin group Ⅱ and control group. The T/NT ratio changes were in agreement with the results of tumor volume measurements, except for cisplatin group Ⅱ. Conclusions There may be a correlation be： tween ^99Tc^m-DTPA-DG uptake and therapeutic effects after chemotherapy in tumor tissue. ^99Tc^m-DTPA-DG might be used to evaluate the therapeutic response of tumor.