In vivo molecular imaging of apoptosisand necrosis in atherosclerotic plaquesusing MicroSPECT-CT and MicroPET-CT Imaging

Purpose: 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). Procedures: Collar-induced carotid atherosclerosis ApoE knockout mice were imaged with ^99mTc-AnxAF568 SPECT-CT to study apoptosis and sequentially with PET-CT following ¹²⁴I-Hypericin ( ¹²⁴I-Hyp) injection to visualize necrosis. Results: SPECT depicted increased ^99mTc-AnxAF568 uptake in both atherosclerotic carotid arteries, whereas our data suggest that this uptake is not merely apoptosis related. Although PET of ¹²⁴I-Hyp was hampered by the slow blood clearance in atherosclerotic mice, ¹²⁴I-Hyp was able to target necrosis in the atherosclerotic plaque. Conclusion: Both ^99mTc- AnxAF568 and ¹²⁴I-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.