This talk will focus on aspects of fluorescence lifetime imaging ranging from preclinical to clinical applications. He will discuss the challenges facing the measurement of fluorescence lifetimes in thick biological tissue, and the tools he has developed to address these challenges. The unique features and limitations of whole-body fluorescence lifetime tomography will be discussed along with preclinical applications for cardiac imaging, cancer, and neuropathology. He will also present recent translational applications of fluorescence lifetime in the clinical setting and discuss the results of their recent clinical trials for cancer imaging.