For the fibrotic heart, development of this technology is lagging behind and until now it has been used to demonstrate focal scarring after myocardial infarction in pre-clinical (217–220) and preliminary clinical studies (221) by tracing myofibroblasts, or collagen type I. Recent advances demonstrated feasibility of detecting diffuse interstitial myocardial fibrosis using specific collagen probes in the β2-AR (β-2-adrenergic receptor) overexpressing mouse model in vivo, and in ischemic human heart specimens (222). The gene discussed is ADRB2; the disease is myocardial infarction.