title: Improvements in PET Image Quality in Time of Flight (TOF) Simultaneous PET/MRI.
abstract: An integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanner with time of flight (TOF) technology is now available for clinical use. The aim of this study is to evaluate the potential of TOF PET in PET/MRI to reduce artifacts in PET images when compared to non-TOF PET/MRI, TOF PET/X-ray computed tomography (CT), and non-TOF PET/CT.
  
  
  
  All patients underwent a single 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) injection, followed first by PET/CT, and subsequently by PET/MRI. PET/CT exams were requested as standard-of-care for oncological indications. Using the PET acquisitions datasets, 4 series of images (TOF PET/CT, non-TOF PET/CT, TOF PET/MRI, and non-TOF PET/MRI) were reconstructed. These image series were visually evaluated for: (1) dental metal artifacts, (2) breathing artifacts, and (3) pelvic artifacts due to scatter correction errors from high bladder [(18)F]FDG concentration. PET image quality was assessed by a 3-point scale (1-clinically significant artifact, 2-non clinically significant artifact, and 3-no artifact).
  
  
  
  Twenty-five patients (mean ± SD age: 56 ± 13 years old; female: 10, male: 15) were enrolled. TOF PET/MRI, non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT scores 2.8, 2.5, 2.4, and 2.3, respectively for the presence of dental artifacts, 2.8, 2.5, 2.2, and 1.9, respectively, for the presence of breathing artifacts, and 2.7, 1.7, 2.0, and 1.3, respectively, for the presence of pelvic artifacts TOF PET/MRI images showed the highest image quality scores among the 4 datasets of PET images.
  
  
  
  The superior timing resolution and resulting TOF capability of the new PET/MRI scanner improved PET image quality in this cohort by reducing artifacts compared to non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT.
authors.affiliation: Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Stanford University, 300 Pasteur Drive, H2200, Stanford, CA, 94305-5281, USA.|Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, Stanford, CA, USA.
authors.forename: Ryogo
authors.initials: R
authors.lastname: Minamimoto
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, Stanford, CA, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Levin
authors.affiliation: Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Stanford University, 300 Pasteur Drive, H2200, Stanford, CA, 94305-5281, USA.|Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, Stanford, CA, USA.
authors.forename: Mehran
authors.initials: M
authors.lastname: Jamali
authors.affiliation: Department of Radiology, Stanford University, Stanford, CA, USA.
authors.forename: Dawn
authors.initials: D
authors.lastname: Holley
authors.affiliation: Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Stanford University, 300 Pasteur Drive, H2200, Stanford, CA, 94305-5281, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Barkhodari
authors.affiliation: Department of Radiology, Stanford University, Stanford, CA, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Zaharchuk
authors.affiliation: Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Stanford University, 300 Pasteur Drive, H2200, Stanford, CA, 94305-5281, USA. aiagaru@stanford.edu.
authors.forename: Andrei
authors.initials: A
authors.lastname: Iagaru
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000592:standards*; D008279:Magnetic Resonance Imaging / Q000592:standards*; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000592:standards; D049268:Positron-Emission Tomography / Q000592:standards*; D013997:Time Factors; D014057:Tomography, X-Ray Computed
keywords: Artifact; Image quality; PET/CT; PET/MRI; Time of flight