title: Performance assessment of a preclinical PET scanner with pinhole collimation by comparison to a coincidence-based small-animal PET scanner.
abstract: PET imaging of rodents is increasingly used in preclinical research, but its utility is limited by spatial resolution and signal-to-noise ratio of the images. A recently developed preclinical PET system uses a clustered-pinhole collimator, enabling high-resolution, simultaneous imaging of PET and SPECT tracers. Pinhole collimation strongly departs from traditional electronic collimation achieved via coincidence detection in PET. We investigated the potential of such a design by direct comparison to a traditional PET scanner.
  
  
  METHODS
  Two small-animal PET scanners, 1 with electronic collimation and 1 with physical collimation using clustered pinholes, were used to acquire data from Jaszczak (hot rod) and uniform phantoms. Mouse brain imaging using (18)F-FDG PET was performed on each system and compared with quantitative ex vivo autoradiography as a gold standard. Bone imaging using (18)F-NaF allowed comparison of imaging in the mouse body. Images were visually and quantitatively compared using measures of contrast and noise.
  
  
  RESULTS
  Pinhole PET resolved the smallest rods (diameter, 0.85 mm) in the Jaszczak phantom, whereas the coincidence system resolved 1.1-mm-diameter rods. Contrast-to-noise ratios were better for pinhole PET when imaging small rods (<1.1 mm) for a wide range of activity levels, but this reversed for larger rods. Image uniformity on the coincidence system (<3%) was superior to that on the pinhole system (5%). The high (18)F-FDG uptake in the striatum of the mouse brain was fully resolved using the pinhole system, with contrast to nearby regions equaling that from autoradiography; a lower contrast was found using the coincidence PET system. For short-duration images (low-count), the coincidence system was superior.
  
  
  CONCLUSIONS
  In the cases for which small regions need to be resolved in scans with reasonably high activity or reasonably long scan times, a first-generation clustered-pinhole system can provide image quality in terms of resolution, contrast, and the contrast-to-noise ratio superior to a traditional PET system.
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada mwalker@physics.ubc.ca.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Walker
authors.affiliation: Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands.
authors.forename: Marlies C
authors.initials: MC
authors.lastname: Goorden
authors.affiliation: Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Dinelle
authors.affiliation: Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands MILabs, Utrecht, The Netherlands; and Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Ruud M
authors.initials: RM
authors.lastname: Ramakers
authors.affiliation: Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Stephan
authors.initials: S
authors.lastname: Blinder
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Maryam
authors.initials: M
authors.lastname: Shirmohammad
authors.affiliation: Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands MILabs, Utrecht, The Netherlands; and.
authors.forename: Frans
authors.initials: F
authors.lastname: van der Have
authors.affiliation: Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands MILabs, Utrecht, The Netherlands; and Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Freek J
authors.initials: FJ
authors.lastname: Beekman
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Vesna
authors.initials: V
authors.lastname: Sossi
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging; D051379:Mice; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D059629:Signal-To-Noise Ratio
keywords: VECTor; pinhole PET; preclinical PET; small-animal PET