title: A Prototype High-Resolution Small-Animal PET Scanner Dedicated to Mouse Brain Imaging.
abstract: We developed a prototype small-animal PET scanner based on depth-encoding detectors using dual-ended readout of small scintillator elements to produce high and uniform spatial resolution suitable for imaging the mouse brain.
  
  
  
  The scanner consists of 16 tapered dual-ended-readout detectors arranged in a 61-mm-diameter ring. The axial field of view (FOV) is 7 mm, and the transaxial FOV is 30 mm. The scintillator arrays consist of 14 × 14 lutetium oxyorthosilicate elements, with a crystal size of 0.43 × 0.43 mm at the front end and 0.80 × 0.43 mm at the back end, and the crystal elements are 13 mm long. The arrays are read out by 8 × 8 mm and 13 × 8 mm position-sensitive avalanche photodiodes (PSAPDs) placed at opposite ends of the array. Standard nuclear-instrumentation-module electronics and a custom-designed multiplexer are used for signal processing.
  
  
  
  The detector performance was measured, and all but the crystals at the very edge could be clearly resolved. The average intrinsic spatial resolution in the axial direction was 0.61 mm. A depth-of-interaction resolution of 1.7 mm was achieved. The sensitivity of the scanner at the center of the FOV was 1.02% for a lower energy threshold of 150 keV and 0.68% for a lower energy threshold of 250 keV. The spatial resolution within a FOV that can accommodate the entire mouse brain was approximately 0.6 mm using a 3-dimensional maximum-likelihood expectation maximization reconstruction. Images of a hot-rod microphantom showed that rods with a diameter of as low as 0.5 mm could be resolved. The first in vivo studies were performed using (18)F-fluoride and confirmed that a 0.6-mm resolution can be achieved in the mouse head in vivo. Brain imaging studies with (18)F-FDG were also performed.
  
  
  
  We developed a prototype PET scanner that can achieve a spatial resolution approaching the physical limits of a small-bore PET scanner set by positron range and detector interaction. We plan to add more detector rings to extend the axial FOV of the scanner and increase sensitivity.
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China yf.yang@siat.ac.cn.
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Julien
authors.initials: J
authors.lastname: Bec
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Mengxi
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Judenhofer
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Bai
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Kun
authors.initials: K
authors.lastname: Di
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Yibao
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico; and.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Rodriguez
authors.affiliation: Radiation Monitoring Devices Inc., Watertown, Massachusetts.
authors.forename: Purushottam
authors.initials: P
authors.lastname: Dokhale
authors.affiliation: Radiation Monitoring Devices Inc., Watertown, Massachusetts.
authors.forename: Kanai S
authors.initials: KS
authors.lastname: Shah
authors.affiliation: Radiation Monitoring Devices Inc., Watertown, Massachusetts.
authors.forename: Richard
authors.initials: R
authors.lastname: Farrell
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Jinyi
authors.initials: J
authors.lastname: Qi
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, Davis, California.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Cherry
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging*; D004581:Electronics; D004867:Equipment Design; D019788:Fluorodeoxyglucose F18; D007091:Image Processing, Computer-Assisted; D008187:Lutetium; D051379:Mice; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D017640:Silicates
chemical_list: D019275:Radiopharmaceuticals; D017640:Silicates; C477682:lutetium orthosilicate; D019788:Fluorodeoxyglucose F18; D008187:Lutetium
keywords: brain imaging; high resolution; mouse; positron emission tomography; small animal PET