Standardization of PET Imaging in Clinical Trials

A biomarker is a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. In vitro biomarkers include histopathologic and serologic correlates and the newer genomic and proteomic assays. In vivo biomarkers include evaluation of disease extent with CT and MR imaging and disease characterization using molecular and functional imaging with single-photon emission CT, PET, and optical agents. This article reviews the various roles a biomarker can play and the path of evaluation and development of these assays. The specifics of development of PET biomarkers and the role that standardization plays are highlighted.