title: Single low-dose CT scan optimized for rest-stress PET attenuation correction and quantification of coronary artery calcium.
abstract: BACKGROUND
  Coronary artery calcium is an important marker of coronary artery disease. Myocardial perfusion imaging (MPI) using PET-CT technology requires a CT scan for attenuation correction (CTAC) but is not used routinely to measure coronary calcium burden. This study aimed to determine if a low-dose CTAC scan can also accurately quantify coronary artery calcium.
  
  
  METHODS
  Twenty-three patients underwent both a traditional coronary artery calcium scan on a dedicated cardiac CT scanner (CAC-CT) and a myocardial perfusion scan on a hybrid PET-CT scanner. The standard MPI protocol includes rest and stress-matched PET and CTAC scans. The post-stress CTAC scan was modified to approximate the CAC-CT scan protocol while maintaining ~0.5 mSv dose. Coronary artery calcium scores were compared between the Ca-CTAC and CAC-CT scans.
  
  
  RESULTS
  The modified Ca-CTAC scan showed a trend toward slight decreases in segmental stress perfusion of 2-3.5% in the anterior wall segments (P < 0.05). Correlation and agreement between the proposed Ca-CTAC and standard CAC-CT calcium scores at the optimal threshold of 110 HU were also excellent (r (2) = 0.99, κ = 1.0). There was a small difference in the regression slope vs unity: Ca-CTAC = 0.96 × CAC (P < 0.05), but the categorical classification of calcium was accurate in all twenty-three patients (κ = 1.0).
  
  
  CONCLUSIONS
  A single low-dose rest CTAC scan can be used for accurate attenuation correction of rest and stress PET perfusion images, thus allowing a post-stress CTAC scan to be optimized for improved quantification of coronary artery calcium without increasing radiation dose vs standard protocols.
authors.affiliation: The National Cardiac PET Centre, Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON, K1Y 4W7, Canada.
authors.forename: Tyler S
authors.initials: TS
authors.lastname: Kaster
authors.forename: Girish
authors.initials: G
authors.lastname: Dwivedi
authors.forename: Leah
authors.initials: L
authors.lastname: Susser
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Renaud
authors.forename: Rob S B
authors.initials: RS
authors.lastname: Beanlands
authors.forename: Benjamin J W
authors.initials: BJ
authors.lastname: Chow
authors.forename: Robert A
authors.initials: RA
authors.lastname: deKemp
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging*; D002118:Calcium / Q000032:analysis; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging; D010477:Perfusion; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium