Advances in radiotracer development for molecular imaging

Molecular imaging is currently defined by the society of nuclear medicine as the visualization, characterization and measurement of biological processes at the molecular and cellular levels in humans and other living systems [1]. Historically, molecular imaging can be traced back to France in 1896, when Henri Becquerel discovered that certain materials emitted energetic rays, a physical process that called radioactive decay later [2]. In 1950s, Michel Ter-Pogossian and his colleagues conducted some pioneering molecular imaging studies in the determination of oxygen content in malignant neoplasms by using ¹⁵O-labeled gas mixture. Later, based on ¹⁵O-labeled radiopharmaceuticals, Ter-Pogossian et al developed quantitative in vivo tracer techniques and carried out a series of brain imaging studies such as the first quantitative measurements of regional brain oxygen consumption in human etc [3, 4].