TKT and myocardial infarction: Additionally, immunohistochemistry revealed that HSV-tk-labelled BMSCs-derived cells were positive for cardiac troponin I. Multimodal imaging systems combining an α-MHC-HSV1-tk/18F-FHBG reporter gene and 18F-FDG metabolism imaging could be used to track differentiation of transplanted BMSCs and recovery of cardiac function in MI.