title: Hybrid Light Imaging Using Cerenkov Luminescence and Liquid Scintillation for Preclinical Optical Imaging In Vivo.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Department of Radioisotope Science, Graduate School of Medical Sciences, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Shimamoto
authors.affiliation: Department of Radioisotope Science, Institute of Resource Development and Analysis, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Gotoh
authors.affiliation: Department of Pathology and Experimental Medicine, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Hasegawa
authors.affiliation: Department of Radioisotope Science, Institute of Resource Development and Analysis, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811, Japan. akojima@kumamoto-u.ac.jp.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kojima
mesh_terms: D000818:Animals; D001610:Beta Particles; D005720:Gamma Rays; D021621:Imaging, Three-Dimensional; D049449:Luminescence; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D061848:Optical Imaging / Q000379:methods*; D012815:Signal Processing, Computer-Assisted
keywords: Cerenkov luminescence imaging; Liquid scintillation imaging; Na[131I]I; Preclinical mouse in vivo imaging; [18F]FDG; β-particle and γ-ray emitting radionuclides
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