title: Development of a PET/Cerenkov-light hybrid imaging system.
abstract: OBJECTIVE
  Cerenkov-light imaging is a new molecular imaging technology that detects visible photons from high-speed electrons using a high sensitivity optical camera. However, the merit of Cerenkov-light imaging remains unclear. If a PET/Cerenkov-light hybrid imaging system were developed, the merit of Cerenkov-light imaging would be clarified by directly comparing these two imaging modalities.
  
  
  METHODS
  The authors developed and tested a PET/Cerenkov-light hybrid imaging system that consists of a dual-head PET system, a reflection mirror located above the subject, and a high sensitivity charge coupled device (CCD) camera. The authors installed these systems inside a black box for imaging the Cerenkov-light. The dual-head PET system employed a 1.2×1.2×10 mm3 GSO arranged in a 33 × 33 matrix that was optically coupled to a position sensitive photomultiplier tube to form a GSO block detector. The authors arranged two GSO block detectors 10 cm apart and positioned the subject between them. The Cerenkov-light above the subject is reflected by the mirror and changes its direction to the side of the PET system and is imaged by the high sensitivity CCD camera.
  
  
  RESULTS
  The dual-head PET system had a spatial resolution of ∼1.2 mm FWHM and sensitivity of ∼0.31% at the center of the FOV. The Cerenkov-light imaging system's spatial resolution was ∼275 μm for a 22Na point source. Using the combined PET/Cerenkov-light hybrid imaging system, the authors successfully obtained fused images from simultaneously acquired images. The image distributions are sometimes different due to the light transmission and absorption in the body of the subject in the Cerenkov-light images. In simultaneous imaging of rat, the authors found that 18F-FDG accumulation was observed mainly in the Harderian gland on the PET image, while the distribution of Cerenkov-light was observed in the eyes.
  
  
  CONCLUSIONS
  The authors conclude that their developed PET/Cerenkov-light hybrid imaging system is useful to evaluate the merits and the limitations of Cerenkov-light imaging in molecular imaging research.
authors.affiliation: Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.
authors.forename: Fuka
authors.initials: F
authors.lastname: Hamamura
authors.affiliation: Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Watabe
authors.affiliation: Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Kanai
authors.affiliation: CYRIC, Tohoku University, Miyagi 980-8578, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watabe
authors.affiliation: Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kato
authors.affiliation: Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.
authors.forename: Yoshimune
authors.initials: Y
authors.lastname: Ogata
authors.affiliation: Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
mesh_terms: D000818:Animals; D001921:Brain; D004867:Equipment Design; D005123:Eye / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D019788:Fluorodeoxyglucose F18; D006243:Harderian Gland / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008954:Models, Biological; D057054:Molecular Imaging / Q000295:instrumentation* / Q000379:methods; D061848:Optical Imaging / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods; D019275:Radiopharmaceuticals; D011923:Rats, Nude; D059629:Signal-To-Noise Ratio
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18