title: Clinical feasibility of90Y digital PET/CT for imaging microsphere biodistribution following radioembolization.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the clinical feasibility of next generation solid-state digital photon counting PET/CT (dPET/CT) technology and imaging findings in patients following90Y microsphere radioembolization in comparison with standard of care (SOC) bremsstrahlung SPECT/CT (bSPECT/CT).
  
  
  METHODS
  Five patients underwent SOC90Y bremsstrahlung imaging immediately following routine radioembolization with 3.5 ± 1.7 GBq of90Y-labeled glass microspheres. All patients also underwent dPET/CT imaging at 29 ± 11 h following radioembolization. Matched pairs comparison was used to compare image quality, image contrast and90Y biodistribution between dPET/CT and bSPECT/CT images. Volumetric assessments of90Y activity using different isocontour thresholds on dPET/CT and bSPECT/CT images were also compared.
  
  
  RESULTS
  Digital PET/CT consistently provided better visual image quality and90Y-to-background image contrast while depicting90Y biodistribution than bSPECT/CT. Isocontour volumetric assessment using a 1% threshold precisely outlined90Y activity and the treatment volume on dPET/CT images, whereas a more restrictive 20% threshold on bSPECT/CT images was needed to obtain comparable treatment volumes. The use of a less restrictive 10% threshold isocontour on bSPECT/CT images grossly overestimated the treatment volume when compared with the 1% threshold on dPET/CT images.
  
  
  CONCLUSIONS
  Digital PET/CT is clinically feasible for the assessment of90Y microsphere biodistribution following radioembolization, and provides better visual image quality and image contrast than routine bSPECT/CT with comparable acquisition times. With further optimization and clinical validation, dPET technology may allow faster and more accurate imaging-based assessment of90Y microsphere biodistribution.
authors.affiliation: Wright Center of Innovation in Biomedical Imaging, Department of Radiology, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Room 430, 4th Floor, Columbus, OH, 43210, USA.
authors.forename: Chadwick L
authors.initials: CL
authors.lastname: Wright
authors.affiliation: Wright Center of Innovation in Biomedical Imaging, Department of Radiology, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Room 430, 4th Floor, Columbus, OH, 43210, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Binzel
authors.affiliation: Wright Center of Innovation in Biomedical Imaging, Department of Radiology, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Room 430, 4th Floor, Columbus, OH, 43210, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
authors.forename: Evan J
authors.initials: EJ
authors.lastname: Wuthrick
authors.affiliation: Wright Center of Innovation in Biomedical Imaging, Department of Radiology, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Room 430, 4th Floor, Columbus, OH, 43210, USA. Knopp.16@osu.edu.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Knopp
mesh_terms: D004621:Embolization, Therapeutic; D005240:Feasibility Studies; D006801:Humans; D008863:Microspheres; D000072078:Positron Emission Tomography Computed Tomography; D014018:Tissue Distribution; D015021:Yttrium Radioisotopes / Q000737:chemistry* / Q000627:therapeutic use*
chemical_list: D015021:Yttrium Radioisotopes
keywords: 90Y microsphere radioembolization; Assessment of biodistribution; Digital PET/CT