The transgene consists of a mouse insulin promoter, (MIP, Ins2) driving a trifusion imagining reporter consisting of a bioluminescent reporter from a modified firefly luciferase gene (luc) fused to a florescent reporter, enhanced green florescent protein (EGFP) derived from the jellyfish Aequorea Victoria, which is fused to a positron emission tomography reporter, herpes simplex virus 1 sr39 thymidine kinase (HSV-1 sr39-TK). (J:163151)