血管生成是许多生理过程和病理状况的共同特征。含RGD的肽能与新生血管内皮细胞和几种肿瘤细胞上表达的整合素αvβ3强结合,具有高特异性,使它们成为成像血管生成的有前途的分子试剂。尽管研究了含RGD的肽与放射性核素的结合,即,18F,64Cu,和68Ga的正电子发射断层扫描(PET)成像已显示出高空间分辨率和示踪剂摄取的准确量化,这些放射性示踪剂中只有少数已成功转化为临床应用.这篇综述总结了基于RGD的示踪剂在肿瘤和邻近组织中的积累,并与传统的18F-脱氧葡萄糖(FDG)成像进行比较。基于RGD的示踪剂的诊断价值,鉴别诊断,肿瘤亚体积描绘,主要讨论了治疗反应预测。非常低的RGD积累,与高FDG代谢相反,在正常脑组织中发现,这表明基于RGD的成像为改善脑肿瘤成像提供了优异的肿瘤背景比。然而,在正常肝组织中,基于RGD的示踪剂的强度远高于FDG,这可能导致低估肝脏的原发性或转移性病变。在多项研究中,基于RGD的影像学检查成功地实现了实体肿瘤的诊断和鉴别诊断以及放化疗反应的预测,提供相对于FDG成像的互补而非相似信息。最感兴趣的是,基线RGD摄取值不仅可用于预测抗血管生成治疗的肿瘤疗效,还要监测正常器官不良事件的发生。在抗血管生成治疗中这种独特的双重预测价值可能比基于FDG的成像更好。
Angiogenesis is a common feature of many physiological processes and pathological conditions. RGD-containing peptides can strongly bind to integrin αvβ3 expressed on endothelial cells in neovessels and several tumor cells with high specificity, making them promising molecular agents for imaging angiogenesis. Although studies of RGD-containing peptides combined with radionuclides, namely, 18F, 64Cu, and 68Ga for positron emission tomography (PET) imaging have shown high spatial resolution and accurate quantification of tracer uptake, only a few of these radiotracers have been successfully translated into clinical use. This review summarizes the RGD-based tracers in terms of accumulation in tumors and adjacent tissues, and comparison with traditional 18F-fluorodeoxyglucose (FDG) imaging. The value of RGD-based tracers for diagnosis, differential diagnosis, tumor subvolume delineation, and therapeutic response prediction is mainly discussed. Very low RGD accumulation, in contrast to high FDG metabolism, was found in normal brain tissue, indicating that RGD-based imaging provides an excellent tumor-to-background ratio for improved brain tumor imaging. However, the intensity of the RGD-based tracers is much higher than FDG in normal liver tissue, which could lead to underestimation of primary or metastatic lesions in liver. In multiple studies, RGD-based imaging successfully realized the diagnosis and differential diagnosis of solid tumors and also the prediction of chemoradiotherapy response, providing complementary rather than similar information relative to FDG imaging. Of most interest, baseline RGD uptake values can not only be used to predict the tumor efficacy of antiangiogenic therapy, but also to monitor the occurrence of adverse events in normal organs. This unique dual predictive value in antiangiogenic therapy may be better than that of FDG-based imaging.