Evaluation of the usefulness of ^<99m>Tc-MIBI scintigraphy and positron emission tomography to analyze the radiotherapeutic effects in breast cancer models

放射治疗是原发性和转移性乳腺癌的主要治疗手段。本研究旨在探讨~（13）<99m>Tc-MIBI和脱氧葡萄糖（DG）在乳腺癌模型照射前后分布的差异。我们还研究了微血管密度和13 Tc-MIBI摄取之间的相关性<99m>。【材料与方法】采用<99m><14>小鼠乳腺癌细胞系FM 3A、MM 48和埃利希，用~（13）Tc-MIBI和~（13）C-DG制备小鼠乳腺癌移植模型的双示踪剂宏观放射自显影（ARG）图像。放射治疗效果通过测量肿瘤负荷、摄取和使用^ Tc-MIBI和^ F-FDG的ARG发现来监测<99m><18>，微血管密度通过免疫组织化学染色CD 34来定量，并与使用^ Tc-MIBI的ARG进行比较<99m>。[结果] 3种肿瘤的生长速度和放射敏感性不同，但~（13）<99m>Tc-MIBI摄取量与肿瘤生长速度无明显相关性。在<14><99m>所有肿瘤模型中，与^ C-DG相比，^ Tc-MIBI在癌细胞中积累更多，而在浸润的成纤维细胞和巨噬细胞中积累更少。肿瘤组织中的微血管密度与<99m>ARG上的13 Tc-MIBI摄取显著相关。[结论]<99m>~（13）Tc-MIBI在肿瘤细胞中有明显的蓄积作用，可作为评价放疗疗效的敏感指标。血管生成似乎增强了肿瘤中13 Tc-MIBI的积累<99m>。这些特征可能有利于使用13 Tc-MIBI进行肿瘤成像<99m>。

【Introduction】 Radiotherapy is a principal treatment in primary and metastatic breast cancer. The aim of this study was to investigate the difference of distribution of ^<99m>Tc-MIBI and deoxyglucose (DG) before and after irradiation in breast cancer models. We also investigated the correlation between microvessel density and ^<99m>Tc-MIBI uptake.【Materials and Methods】 Double-tracer macroautoradiography (ARG) images were prepared with ^<99m>Tc-MIBI and ^<14>C-DG in transplanted models using 3 mouse breast cancer cell lines (FM3A, MM48 and Ehrlich). The radiotherapeutic effects were monitored by measuring tumor burden, uptake and ARG finding using ^<99m>Tc-MIBI and ^<18>F-FDG.Microvessel density was quantified by immunohistochemical staining for CD34 and compared with ARG using ^<99m>Tc-MIBI.【Results】 Three tumors showed different growth rates and radiosensitivities, but ^<99m>Tc-MIBI uptake did not correlate significantly with the growth rates. Compared with ^<14>C-DG, ^<99m>Tc-MIBI accumulated more in cancer cells and less in infiltrating fibroblasts and macrophages in all tumor models. Microvessel density in tumor tissue correlated significantly with ^<99m>Tc-MIBI uptake on ARG.【Conclusion】 Accumulation of ^<99m>Tc-MIBI in cancer cells is preferential and can be used as a sensitive marker to examine the response of radiotherapy. Angiogenesis seems to enhance accumulation of ^<99m>Tc-MIBI in tumors. These characteristics may be favorable for tumor imaging using ^<99m>Tc-MIBI.