title: Visual estimation of coronary calcium on computed tomography for attenuation correction.
abstract: BACKGROUND
  The coronary calcium score (CCS) provides independent diagnostic and prognostic information on top of myocardial perfusion imaging (MPI) in patients suspected for coronary artery disease, but requires an additional computed tomography (CT) scan.
  
  
  OBJECTIVE
  We investigated the accuracy and inter-reader reproducibility of visual estimation of the CCS on the CT used for attenuation correction.
  
  
  METHODS
  250 patients undergoing single photon emission computed tomography MPI and Agatston CCS were included. The CCS was also visually estimated on the CT for attenuation correction by two separate readers blinded to the Agatston CCS, and was categorized into a six-point scale (0, 1-10, 11-100, 101-400, 401-1000 and > 1000).
  
  
  RESULTS
  The median Agatston CCS was 82 [25th-75th percentile: 0-562], with a range from 0 to 7287. Of the visually estimated CCS, 60% (reader 1) and 65% (reader 2) were classified correctly into the 6 categories. 93% (reader 1) and 88% (reader 2) of the visually estimated CCS did not vary by more than one category from the Agatston CCS. The intraclass correlation coefficient for agreement between the Agatston CCS and the visually estimated CCS was 0.95 for reader 1 and 0.94 for reader 2. The intraclass correlation coefficient for inter-reader reproducibility of the visually estimated CCS was 0.96.
  
  
  CONCLUSIONS
  The CCS can be accurately estimated on the CT for attenuation correction, as high agreement is demonstrated with the Agatston CCS and inter-reader reproducibility is excellent. If no traditional Agatston CCS is performed, the degree of atherosclerosis should be assessed by means of estimating CCS on the CT for attenuation correction.
authors.affiliation: Departments of Cardiology, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: e.engbers@isala.nl.
authors.forename: E M
authors.initials: EM
authors.lastname: Engbers
authors.affiliation: Departments of Cardiology, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: v.r.c.derks@isala.nl.
authors.forename: J R
authors.initials: JR
authors.lastname: Timmer
authors.affiliation: Departments of Cardiology, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: m.mouden@isala.nl.
authors.forename: M
authors.initials: M
authors.lastname: Mouden
authors.affiliation: Nuclear Medicine, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: p.l.jager@isala.nl.
authors.forename: P L
authors.initials: PL
authors.lastname: Jager
authors.affiliation: Nuclear Medicine, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: s.knollema@isala.nl.
authors.forename: S
authors.initials: S
authors.lastname: Knollema
authors.affiliation: Nuclear Medicine, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: a.h.j.oostdijk@isala.nl.
authors.forename: A H J
authors.initials: AH
authors.lastname: Oostdijk
authors.affiliation: Departments of Cardiology, Isala, Dokter van Heesweg 2, 8025 AB Zwolle, The Netherlands. Electronic address: j.p.ottervanger@isala.nl.
authors.forename: J P
authors.initials: JP
authors.lastname: Ottervanger
mesh_terms: D000368:Aged; D000072226:Computed Tomography Angiography; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D000072098:Single Photon Emission Computed Tomography Computed Tomography; D061205:Vascular Calcification / Q000000981:diagnostic imaging* / Q000503:physiopathology
keywords: Attenuation correction; Coronary artery calcium; Visual estimation