INVITED COMMENTARY Combined 18F-FDG–FDOPA Tumor Imaging for Assessing Response to Therapy

dopa (FDOPA), and 15O-water, by Dimi-trakopoulou-Strauss et al. (1) in this is-sue of The Journal of Nuclear Medicine, raises several interesting issues likely to be important in the evolution of PET in oncology. These issues are the use of PET to monitor response to therapy, the impact of tumor uptake of alternative substrates on FDG imaging, and the combined use of multiple tracers to as-sess tumor metabolism. RESPONSE TO THERAPY FDG PET is now widely used in the diagnosis and staging of a broad vari-ety of malignancies. Metabolic imag