title: 188Re image performance assessment using small animal multi-pinhole SPECT/PET/CT system.
abstract: OBJECTIVE
  The goal of this study was to investigate the performance of a pre-clinical SPECT/PET/CT system for188Re imaging.
  
  
  METHODS
  Phantom experiments were performed aiming to assess the characteristics of two multi-pinhole collimators: ultra-high resolution collimator (UHRC) and high-energy ultra high resolution collimator (HE-URHC) for imaging188Re. The spatial resolution, image contrast and contrast-to-noise ratio (CNR) were investigated using micro-Jaszczak phantoms. Additionally, the quantification accuracy of188Re images was evaluated using two custom-designed phantoms. The188Re images were compared to those obtained with99mTc (gold standard); the acquired energy spectra were analyzed and Monte-Carlo simulations of the UHRC were performed. To verify our findings, a C57BL/6-mouse was injected with188Re-microspheres and scanned with both collimators.
  
  
  RESULTS
  The spatial resolution achieved in188Re images was comparable to that of99mTc. Acquisitions using HE-UHRC yielded188Re images with higher contrast and CNR than UHRC. Studies of quantitative accuracy of188Re images resulted in <10% errors for both collimators when the activity was calculated within a small VOI around the object of interest. Similar quantification accuracy was achieved for99mTc. However,188Re images showed much higher levels of noise in the background. Monte-Carlo simulations showed that188Re imaging with UHRC is severely affected by down-scattered photons from high-energy emissions. The mouse images showed similar biodistribution of188Re-microspheres for both collimators.
  
  
  CONCLUSIONS
  VECTor/CT provided188Re images quantitatively accurate and with quality comparable to99mTc. However, due to large penetration of UHRC by high-energy photons, the use of the HE-UHRC for imaging188Re in VECTor/CT is recommended.
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada. Electronic address: esquinas@phas.ubc.ca.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Esquinas
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Cristina
authors.initials: C
authors.lastname: Rodríguez-Rodríguez
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: José
authors.initials: J
authors.lastname: Carlos De La Vega
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Bokharaei
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Katayoun
authors.initials: K
authors.lastname: Saatchi
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
authors.forename: Maryam
authors.initials: M
authors.lastname: Shirmohammad
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Urs O
authors.initials: UO
authors.lastname: Häfeli
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
authors.forename: Vesna
authors.initials: V
authors.lastname: Sossi
authors.affiliation: Department of Radiology, University of British Columbia, Vancouver, BC V5Z 1M9, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Celler
mesh_terms: D000818:Animals; D007091:Image Processing, Computer-Assisted; D051379:Mice; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011868:Radioisotopes; D012211:Rhenium; D059629:Signal-To-Noise Ratio; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D011868:Radioisotopes; D012211:Rhenium
keywords: (188)Re; Image quality; Image quantification; Small-animal SPECT