MicroPET imaging interrogates a mouse carrying a tumor that expresses a dopamine type 2 receptor (D2R) reporter gene and a separate tumor that carries the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene. The mouse is imaged with F-18 fluoroethylspiperone, which homes in on the D2 receptor, and then again with F-18-penciclovir, which homes in on the cells expressing HSV1-tk.
(Provided by S. Gambhir; reproduced with permission of the Journal of Nuclear Medicine)