title: Quantifying Aortic Valve Calcification using Coronary Computed Tomography Angiography.
abstract: BACKGROUND
  Aortic valve calcification (AVC) has been associated with major adverse cardiovascular events and all-cause mortality. We sought to develop and validate a method to quantify AVC using coronary CT angiography (CTA).
  
  
  METHODS
  Of 59 patients who underwent both non-contrast and contrast enhanced coronary CTA, 25 patients served as the derivation cohort and 34 patients served as the validation cohort. For non-contrast enhanced CT, quantification of AVC was performed using the Agatston method for coronary artery calcification (CAC). For contrast enhanced coronary CTA, a region of interest (ROI) was placed in the ascending aorta and the mean aortic attenuation value (HUAorta) and standard deviation (SD) were measured. Using a calcium threshold of mean HUAorta+ 2SD, the AVCCTAwas calculated. All other Agatston score parameters (weighting factors and area calculations) remained unchanged.
  
  
  RESULTS
  In the derivation cohort, the correlation between AVCCACand AVCCTAwas excellent (r = 0.982). Using the line of best fit, a correction factor was calculated enabling the conversion of AVCCTAresults to a AVCCACequivalent (AVCCorrected= 1.868 × AVCCTA). Using this correction in the validation cohort, the correlation and agreement between AVCCACand AVCCorrectedwere good (ICC = 0.939; 95% CI: 0.881-0.969; kappa = 0.700; 95% CI: 0.469-0.931).
  
  
  CONCLUSIONS
  The quantification of AVCCorrectedusing contrast enhanced CTA is feasible using a systematic approach with very good reliability and good agreement with AVCCAC. Larger-scale validation studies are needed to determine whether the use of AVCCACcan be eliminated in favour of AVCCorrected.
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Canada; King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Abdulrahman M
authors.initials: AM
authors.lastname: Alqahtani
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Canada.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Boczar
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Canada.
authors.forename: Vinay
authors.initials: V
authors.lastname: Kansal
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Canada.
authors.forename: Kwan
authors.initials: K
authors.lastname: Chan
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Canada.
authors.forename: Girish
authors.initials: G
authors.lastname: Dwivedi
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Canada; Department of Radiology, University of Ottawa, Canada. Electronic address: bchow@ottawaheart.ca.
authors.forename: Benjamin J W
authors.initials: BJ
authors.lastname: Chow
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging*; D002114:Calcinosis / Q000000981:diagnostic imaging*; D055424:Cardiac-Gated Imaging Techniques; D016022:Case-Control Studies; D000072226:Computed Tomography Angiography; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014283:Triiodobenzoic Acids / Q000008:administration & dosage
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol
keywords: Aortic stenosis; Aortic valve calcification; Cardiac CT angiography