title: Flexible radioluminescence imaging for FDG-guided surgery.
abstract: OBJECTIVE
  Flexible radioluminescence imaging (Flex-RLI) is an optical method for imaging18F-fluorodeoxyglucose (FDG)-avid tumors. The authors hypothesize that a gadolinium oxysulfide: terbium (GOS:Tb) flexible scintillator, which loosely conforms to the body contour, can enhance tumor signal-to-background ratio (SBR) compared with RLI, which utilizes a flat scintillator. The purpose of this paper is to characterize flex-RLI with respect to alternative modalities including RLI, beta-RLI (RLI with gamma rejection), and Cerenkov luminescence imaging (CLI).
  
  
  METHODS
  The photon sensitivity, spatial resolution, and signal linearity of flex-RLI were characterized with in vitro phantoms. In vivo experiments utilizing 13 nude mice inoculated with the head and neck (UMSCC1-Luc) cell line were then conducted in accordance with the institutional Administrative Panel on Laboratory Animal Care. After intravenous injection of18F-FDG, the tumor SBR values for flex-RLI were compared to those for RLI, beta-RLI, and CLI using the Wilcoxon signed rank test.
  
  
  RESULTS
  With respect to photon sensitivity, RLI, beta-RLI, and flex-RLI produced 1216.2, 407.0, and 98.6 times more radiance per second than CLI. Respective full-width half maximum values across a 0.5 mm capillary tube were 6.9, 6.4, 2.2, and 1.5 mm, respectively. Flex-RLI demonstrated a near perfect correlation with18F activity (r = 0.99). Signal uniformity for flex-RLI improved after more aggressive homogenization of the GOS powder with the silicone elastomer during formulation. In vivo, the SBR value for flex-RLI (median 1.29; interquartile range 1.18-1.36) was statistically greater than that for RLI (1.08; 1.02-1.14; p < 0.01) by 26%. However, there was no statistically significant difference in SBR values between flex-RLI and beta-RLI (p = 0.92). Furthermore, there was no statistically significant difference in SBR values between flex-RLI and CLI (p = 0.11) in a more limited dataset.
  
  
  CONCLUSIONS
  Flex-RLI provides high quality images with SBRs comparable to those from CLI and beta-RLI in a single 10 s acquisition.
authors: Department of Radiation Oncology, Stanford University, Stanford, California 94305.
authors: Martin T
authors: MT
authors: King
authors: Department of Radiation Oncology, Stanford University, Stanford, California 94305.
authors: Cesare H
authors: CH
authors: Jenkins
authors: College of Pharmacy, Oregon State University, Corvallis, Oregon 97331.
authors: Conroy
authors: C
authors: Sun
authors: Siris Medical, Mountain View, California 94043.
authors: Colin M
authors: CM
authors: Carpenter
authors: Department of Radiology, Stanford University, Stanford, California 94305 and Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors: Xiaowei
authors: X
authors: Ma
authors: Department of Radiation Oncology, Stanford University, Stanford, California 94305.
authors: Kai
authors: K
authors: Cheng
authors: Department of Radiation Oncology, Stanford University, Stanford, California 94305.
authors: Quynh-Thu
authors: QT
authors: Le
authors: Department of Otolaryngology, Stanford University, Stanford, California 94305.
authors: John B
authors: JB
authors: Sunwoo
authors: Department of Radiology, Stanford University, Stanford, California 94305.
authors: Zhen
authors: Z
authors: Cheng
authors: Department of Radiation Oncology, Stanford University, Stanford, California 94305.
authors: Guillem
authors: G
authors: Pratx
authors: Department of Radiation Oncology, Stanford University, Stanford, California 94305.
authors: Lei
authors: L
authors: Xing
mesh_terms: D000818:Animals; D005260:Female; D019788:Fluorodeoxyglucose F18; D049449:Luminescence; D051379:Mice; D061848:Optical Imaging; D025321:Surgery, Computer-Assisted / Q000379:methods*
chemical_list: D019788:Fluorodeoxyglucose F18