25 Years of "Loop" Radiochemistry for PET Imaging

While conventional methods to ¹¹C- and ¹⁸F-labelled radiopharmaceuticals utilize a vial-based approach, in the past quarter-century, a modern, efficient, and cleaner "loop method" has been developed. This Perspective will shed light on the history behind the development of the loop radiochemistry method, the multifold advantages associated with the method over other approaches, its applications to the synthesis of ¹¹C- and ¹⁸F-labelled compounds and radiopharmaceuticals for preclinical and human PET imaging studies, its eventual expansion to diverse organic chemistry reactions and finally provide a future outlook for further developments in this field of radiochemistry.