title: Clinical interpretation standards and quality assurance for the multicenter PET/CT trial rubidium-ARMI.
abstract: Rubidium-ARMI ((82)Rb as an Alternative Radiopharmaceutical for Myocardial Imaging) is a multicenter trial to evaluate the accuracy, outcomes, and cost-effectiveness of low-dose (82)Rb perfusion imaging using 3-dimensional (3D) PET/CT technology. Standardized imaging protocols are essential to ensure consistent interpretation.
  
  
  METHODS
  Cardiac phantom qualifying scans were obtained at 7 recruiting centers. Low-dose (10 MBq/kg) rest and pharmacologic stress (82)Rb PET scans were obtained in 25 patients at each site. Summed stress scores, summed rest scores, and summed difference scores (SSS, SRS, and SDS [respectively] = SSS-SRS) were evaluated using 17-segment visual interpretation with a discretized color map. All scans were coread at the core lab (University of Ottawa Heart Institute) to assess agreement of scoring, clinical diagnosis, and image quality. Scoring differences greater than 3 underwent a third review to improve consensus. Scoring agreement was evaluated with intraclass correlation coefficient (ICC-r), concordance of clinical interpretation, and image quality using κ coefficient and percentage agreement. Patient (99m)Tc and (201)Tl SPECT scans (n = 25) from 2 centers were analyzed similarly for comparison to (82)Rb.
  
  
  RESULTS
  Qualifying scores of SSS = 2, SDS = 2, were achieved uniformly at all imaging sites on 9 different 3D PET/CT scanners. Patient scores showed good agreement between core and recruiting sites: ICC-r = 0.92, 0.77 for SSS, SDS. Eighty-five and eighty-seven percent of SSS and SDS scores, respectively, had site-core differences of 3 or less. After consensus review, scoring agreement improved to ICC-r = 0.97, 0.96 for SSS, SDS (P < 0.05). The agreement of normal versus abnormal (SSS ≥ 4) and nonischemic versus ischemic (SDS ≥ 2) studies was excellent: ICC-r = 0.90 and 0.88. Overall interpretation showed excellent agreement, with a κ = 0.94. Image quality was perceived differently by the site versus core reviewers (90% vs. 76% good or better; P < 0.05). By comparison, scoring agreement of the SPECT scans was ICC-r = 0.82, 0.72 for SSS, SDS. Seventy-six and eighty-eight percent of SSS and SDS scores, respectively, had site-core differences of 3 or less. Consensus review again improved scoring agreement to ICC-r = 0.97, 0.90 for SSS, SDS (P < 0.05).
  
  
  CONCLUSIONS
  (82)Rb myocardial perfusion imaging protocols were implemented with highly repeatable interpretation in centers using 3D PET/CT technology, through an effective standardization and quality assurance program. Site scoring of (82)Rb PET myocardial perfusion imaging scans was found to be in good agreement with core lab standards, suggesting that the data from these centers may be combined for analysis of the rubidium-ARMI endpoints.
authors.affiliation: University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Renaud
authors.forename: Ilias
authors.initials: I
authors.lastname: Mylonas
authors.forename: Brian
authors.initials: B
authors.lastname: McArdle
authors.forename: Taylor
authors.initials: T
authors.lastname: Dowsley
authors.forename: Kathy
authors.initials: K
authors.lastname: Yip
authors.forename: Eric
authors.initials: E
authors.lastname: Turcotte
authors.forename: Jean
authors.initials: J
authors.lastname: Guimond
authors.forename: Mikael
authors.initials: M
authors.lastname: Trottier
authors.forename: Philipe
authors.initials: P
authors.lastname: Pibarot
authors.forename: Conor
authors.initials: C
authors.lastname: Maguire
authors.forename: Lucille
authors.initials: L
authors.lastname: Lalonde
authors.forename: Karen
authors.initials: K
authors.lastname: Gulenchyn
authors.forename: Gerald
authors.initials: G
authors.lastname: Wisenberg
authors.forename: R Glenn
authors.initials: RG
authors.lastname: Wells
authors.forename: Terrence
authors.initials: T
authors.lastname: Ruddy
authors.forename: Benjamin
authors.initials: B
authors.lastname: Chow
authors.forename: Rob S B
authors.initials: RS
authors.lastname: Beanlands
authors.forename: Robert A
authors.initials: RA
authors.lastname: deKemp
mesh_terms: D000368:Aged; D002170:Canada; D003362:Cost-Benefit Analysis; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods* / Q000592:standards*; D015588:Observer Variation; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D011785:Quality Assurance, Health Care; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012414:Rubidium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*; D057170:Translational Research, Biomedical; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D012414:Rubidium Radioisotopes
keywords: 82Rb; myocardial perfusion imaging; positron emission tomography