Hybrid Light Imaging Using Cerenkov Luminescence and Liquid Scintillation for Preclinical Optical Imaging In Vivo

Purpose Cerenkov luminescence imaging (CLI) has recently emerged as a molecular imaging modality for radionuclides emitting β-particles. The aim of this study was to develop a hybrid light imaging (HLI) technique using a liquid scintillator to assist CLI by increasing the optical signal intensity from both β-particle and γ-ray emitting radionuclides located at deep regions in vivo . Procedures A commercial optical imaging system was employed to collect all images by HLI and CLI. To investigate the performance characteristics of HLI with a commercially available liquid scintillator (Emulsifier-safe), phantom experiments were conducted for two typical β-particle and γ-ray emitters, sodium iodide (Na[ 131 I]I) and 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG), respectively. To evaluate the feasibility of HLI for in vivo imaging, HLI was applied to a Na[ 131 I]I injected nu/nu mouse and an [ 18 F]FDG injected Balb-c mouse and compared with CLI alone. Results Measured HLI wavelength spectra with Emulsifier-safe showed higher signal intensities than for CLI at 500–600 nm. For material preventing light transmission of 12-mm thickness, CLI imaging provided quite low intensity and obscure signals of the source. However, despite degraded spatial resolution, HLI imaging provided sustained visualization of the source shape, with signal intensities 10–14 times higher than for CLI at 10-mm thickness. Furthermore, at 0, 4, and 8-mm material thicknesses, HLI showed a strong correlation between Na[ 131 I]I or [ 18 F]FDG radioactivity and signal intensity, as for CLI. In vivo studies also demonstrated that HLI could successfully visualize Na[ 131 I]I uptake in the mouse thyroid gland in the prone position and [ 18 F]FDG accumulation in the heart in the supine position, which were not observed with CLI. Conclusion Our preliminary studies suggest that HLI can provide enhanced imaging of a β-particle probe emitting together with γ-rays at deep tissue locations. HLI may be a promising imaging technique to assist with preclinical in vivo imaging using CLI.