Intertumoral Differences in Hypoxia Selectivity of the PET Imaging Agent 64Cu(II)-Diacetyl-Bis(N4-Methylthiosemicarbazone)

Journal of Nuclear Medicine

Thies Schroeder¹  Hong Yuan¹  James E. Bowsher¹  Mark W. Dewhirst¹  Laurence W. Hedlund¹  Terence Wong¹ 

关键词: tumor hypoxia;    PET;    Cu-ATSM;   

DOI  :  

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Cu-Diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) is a recently developed PET imaging agent for tumor hypoxia. However, its accuracy and reliability for measuring hypoxia have not been fully characterized in vivo. The aim of this study was to evaluate 64Cu-ATSM as a hypoxia PET marker by comparing autoradiographic distributions of 64Cu-ATSM with a well-established hypoxia marker drug, EF5. Methods: R3230 mammary adenocarcinomas (R3230Ac), fibrosarcomas (FSA), and 9L gliomas (9L) were used in the study. EF5 and Hoechst 33342, a vascular perfusion marker, were administered to the animal for immunohistochemical analysis. 64Cu-ATSM microPET and autoradiography were performed on the same animal. The tumor-to-muscle ratio (T/M ratio) and standardized uptake values (SUVs) were characterized for these 3 different types of tumors. Five types of imagesmicroPET, autoradiography, EF5 immunostaining, Hoechst fluorescence vascular imaging, and hematoxylin-and-eosin histologywere superimposed, evaluated, and compared. Results: A significantly higher T/M ratio and SUV were seen for FSA compared with R3230Ac and 9L. Spatial correlation analysis between 64Cu-ATSM autoradiography and EF5 immunostained images varied between the 3 tumor types. There was close correlation of 64Cu-ATSM uptake and hypoxia in R3230Ac and 9L tumors but not in FSA tumors. Interestingly, elevated 64Cu-ATSM uptake was observed in well-perfused areas in FSA, indicating a correlation between 64Cu-ATSM uptake and vascular perfusion as opposed to hypoxia. The same relationship was observed with 2 other hypoxia markers, pimonidazole and carbonic anhydrase IX, in FSA tumors. Breathing carbogen gas significantly decreased the hypoxia level measured by EF5 staining in FSA-bearing rats but not the uptake of 64Cu-ATSM. These results indicate that some other 64Cu-ATSM retention mechanisms, as opposed to hypoxia, are involved in this type of tumor. Conclusion: To our knowledge, this study is the first comparison between 64Cu-ATSM uptake and immunohistochemistry in these 3 tumors. Although we have shown that 64Cu-ATSM is a valid PET hypoxia marker in some tumor types, but not for all, this tumor type–dependent hypoxia selectivity of 64Cu-ATSM challenges the use of 64Cu-ATSM as a universal PET hypoxia marker. Further studies are needed to define retention mechanisms for this PET marker.

【 授权许可】

Unknown