In Vivo Molecular Imaging of Apoptosisand Necrosis in Atherosclerotic PlaquesUsing MicroSPECT-CT and MicroPET-CT Imaging

The purpose of this paper is to study molecular imaging of apoptosis and necrosis, two key players in atherosclerosis instability, using a multimodal imaging approach combining single photon emission computed tomography (SPECT), positron emission tomography (PET), and computed tomography (CT). Collar-induced carotid atherosclerosis ApoE knockout mice were imaged with Tc-99m-AnxAF568 SPECT-CT to study apoptosis and sequentially with PET-CT following I-124-Hypericin (I-124-Hyp) injection to visualize necrosis. SPECT depicted increased Tc-99m-AnxAF568 uptake in both atherosclerotic carotid arteries, whereas our data suggest that this uptake is not merely apoptosis related. Although PET of I-124-Hyp was hampered by the slow blood clearance in atherosclerotic mice, I-124-Hyp was able to target necrosis in the atherosclerotic plaque. Both Tc-99m-AnxAF568 and I-124-Hyp uptake are increased in atherosclerotic carotid vasculature compared to control arteries. While apoptosis imaging remains challenging, necrosis imaging can be feasible after improving the biodistribution characteristics of the probe.