title: Scintillating balloon-enabled fiber-optic system for radionuclide imaging of atherosclerotic plaques.
abstract: Atherosclerosis underlies coronary artery disease, the leading cause of death in the United States and worldwide. Detection of coronary plaque inflammation remains challenging. In this study, we developed a scintillating balloon-enabled fiber-optic radionuclide imaging (SBRI) system to improve the sensitivity and resolution of plaque imaging using (18)F-FDG, a marker of vascular inflammation, and tested it in a murine model.
  
  
  METHODS
  The fiber-optic system uses a Complementary Metal-Oxide Silicon (CMOS) camera with a distal ferrule terminated with a wide-angle lens. The novelty of this system is a scintillating balloon in the front of the wide-angle lens to image light from the decay of (18)F-FDG emission signal. To identify the optimal scintillating materials with respect to resolution, we calculated the modulation transfer function of yttrium-aluminum-garnet doped with cerium, anthracene, and calcium fluoride doped with europium (CaF2:Eu) phosphors using an edge pattern and a thin-line optical phantom. The scintillating balloon was then fabricated from 10 mL of silicone RTV catalyst mixed with 1 mL of base and 50 mg of CaF2:Eu per mL. The addition of a lutetium oxyorthosilicate scintillating crystal (500 μm thick) to the balloon was also investigated. The SBRI system was tested in a murine atherosclerosis model: carotid-ligated mice (n = 5) were injected with (18)F-FDG, followed by ex vivo imaging of the macrophage-rich carotid plaques and nonligated controls. Confirmatory imaging of carotid plaques and controls was also performed by an external optical imaging system and autoradiography.
  
  
  RESULTS
  Analyses of the different phosphors showed that CaF2:Eu enabled the best resolution of 1.2 μm. The SBRI system detected almost a 4-fold-higher radioluminescence signal from the ligated left carotid artery than the nonligated right carotid: 1.63 × 10(2) ± 4.01 × 10(1) vs. 4.21 × 10(1) ± 2.09 × 10(0) (photon counts), P = 0.006. We found no significant benefit to adding a scintillating crystal to the balloon: 1.65 × 10(2) ± 4.07 × 10(1) vs. 4.44 × 10(1) ± 2.17 × 10(0) (photon counts), P = 0.005. Both external optical imaging and autoradiography confirmed the high signal from the (18)F-FDG in carotid plaques versus controls.
  
  
  CONCLUSIONS
  This SBRI system provides high-resolution and sensitive detection of (18)F-FDG uptake by murine atherosclerotic plaques.
authors: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California Division of Radiation Physics, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; and rtzaman@stanford.edu.
authors: Raiyan T
authors: RT
authors: Zaman
authors: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California.
authors: Hisanori
authors: H
authors: Kosuge
authors: Siris Medical, Mountain View, California.
authors: Colin
authors: C
authors: Carpenter
authors: Division of Radiation Physics, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; and.
authors: Conroy
authors: C
authors: Sun
authors: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California.
authors: Michael V
authors: MV
authors: McConnell
authors: Division of Radiation Physics, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; and.
authors: Lei
authors: L
authors: Xing
mesh_terms: D000818:Animals; D019788:Fluorodeoxyglucose F18; D008297:Male; D051379:Mice; D055100:Optical Fibers; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging / Q000295:instrumentation*
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG; atherosclerotic model; atherosclerotic plaque; radionuclide imaging; scintillating balloon