Abstract 16168: Nuclear Molecular Imaging of Apoptosis in Heart Transplant Rejection

IntroductionTransplant rejection is a significant concern post-heart transplant. Currently, endomyocardial biopsies are used for rejection assessment, but can be susceptible to interpretation bias and procedural complications. A hallmark of transplant rejection is apoptosis. We propose to noninvasively target apoptosis with the novel SPECT/CT imaging agent, Tc-duramycin.HypothesisTargeting cell-mediated apoptotic rejection in heart-transplanted mice with Tc-duramycin (Tc-D) will be able to delineate rejection severity.Methods19 B6 mice received abdominal heterotopic cardiac allografts. Group organization and imaging timeline shown in Fig 1. ALO served as an acute rejection model, CON served as control, IMS served as acute rejection with treatment, and CHR served as chronic rejection. We calculated mean ROI and percent injected dose per gram (%ID/g) difference between the heterotopic and native hearts. Rejection was graded via ISHLT rubric.ResultsIn vivo and ex vivo imaging are shown in Fig 2 and 3 respectively. Mean ROI and %ID/g were significantly different in all groups (P=0.0025 and P=0.0035 respectively). Mean ROI and %ID/g was greater in ALO animals as compared to that in CON animals (P=0.012, and P=0.005 respectively). Mean ROI difference was significantly greater in ALO animals as compared to IMS animals (P=0.021). Uptake was significantly correlated with ISHLT-graded severity of rejection (Rho=0.0677, P=0.002).ConclusionsTc-D is a feasible tracer to delineate heart transplant rejection noninvasively.