Research project for predictive diagnosis of cancer recurrence using positron emission tomography.

本研究是应用正电子发射断层扫描技术检测复发癌组织中代谢增加的基础研究项目，它可能早于复发癌组织中体积的增加。在肿瘤组织中，不仅在癌细胞中而且在非肿瘤组织（基质）中观察到FDG摄取。在活化的巨噬细胞和年轻的肉芽组织中观察到特别高的FDG摄取。这可能是治疗后炎症引起FDG摄取假阳性的原因。癌细胞和非肿瘤组织的FDG摄取可能有助于PET图像中看到的活性。比较快、慢生长肿瘤的FDG摄取率，快、慢生长肿瘤的FDG摄取率高于Met和TdR摄取率。FDG可能是一个很好的示踪剂，用于评估肿瘤之间的差异，即治疗前的诊断。肉芽组织和巨噬细胞对Met的摄取较低，且低于FDG的摄取，整个肿瘤对Met的摄取较早达到平台。它作为游离Met汇集在肿瘤组织内。然后，将继续将细胞汇集的游离Met与时间相关地掺入大分子、蛋白质、脂质、RNA和DNA中。肿瘤放疗后Met摄取的变化与增殖标志物胸苷摄取的变化接近。FDG摄取与体内活组织百分比呈线性相关。放疗后肿瘤的放射自显影研究显示，残留的活癌细胞中的甲硫氨酸和胸苷摄取最高，而FDG摄取在活癌细胞和巨噬细胞之间没有差异。Met是一种示踪剂，代表增殖的癌细胞的延伸，并且可能适用于使用正电子发射断层扫描来预测癌症复发的诊断。

This is a basic research project fot the detection of metabolic increase in recurrent cancer tissue using positron emission tomography that may be earlier than the volumetric increase in cancer tissue at the recurrence.We have performed autoradiographic studies to elucidate the intratumoral distribution of FDG and 14Cmethionine (Met). In a tumor tissue, FDG uptake was observed not only in cancer cells but also in non-neoplastic tissue (stroma). Especially high FDG uptake is seen in activated macrophages and young granlation tissue. That may be a cause of false positive FDG uptake by post-therapy inflammation. FDG uptake both by cancer cells and by non-neoplastic tissues may contribute to the activity seen in PET images. Comparison of rapid and slow growing tumors showed that FDG uptake ratio of the rapid to the slow was higher than the uptake ratio with Met and thymidine. FDG may be an excellent tracer for the evaluation of differences among tumors, that is pre-treatment siagnosis.While, tumor uptake of Met is largely achieved by viable cancer cells. Granulation tissue and macrophages showed low Met uptake and were lower than that of FDG.Met uptake by whole tumor will arrive at plateau early. It is pooled inside tumor tissue as free Met. Then, time related incorporation of cellularly pooled free Met into macromolecules, protein, lipids, RNA and DNA will be continued. Met uptake changes after tumor radiotherapy is close to the uptake changes of thymidine that is a marker of proliferation. FDG uptake showed a linear correlation to the percentage of viable tissue in vivo. Autoradiography study of post-radiotherapy tumor shows the highest methionine and thymidine uptake in residual viable cancer cells, whereas FDG uptake did not differ between viable cancer cells and macrophages. Met is a tracer that represents extension of proliferating cancer, cells, and may be suitable for predictive diagnosis of cancer recurrence using positron emission tomography.