title: Aortic annulus diameter determination by multidetector computed tomography: reproducibility, applicability, and implications for transcatheter aortic valve implantation.
abstract: OBJECTIVE
  This study sought to determine the most reproducible multidetector computed tomography (MDCT) measurements of the aortic annulus and to determine methods to improve the applicability of these measurements for transcatheter aortic valve implantation.
  
  
  BACKGROUND
  The reproducibility and applicability of MDCT annular measurements to guide transcatheter aortic valve implantation remain unclear.
  
  
  METHODS
  Annular measurements were performed in 50 patients planed for transcatheter aortic valve implantation in multiple planes: basal ring (short- and long-axis, mean diameter, area-derived diameter), coronal, sagittal, and 3-chamber projections. A theoretical model was developed taking into account the differences between the most reproducible MDCT measurements and transesophageal echocardiography to guide valve size choice.
  
  
  RESULTS
  The most reproducible measurements were the area-derived diameter and basal ring average diameter (inter-reader intraclass correlation coefficient: 0.87 [95% confidence interval: 0.81 to 0.92] and 0.80 [95% confidence interval: 0.70 to 0.87]; respectively; intrareader >0.90 for all readers). These were generally larger than transesophageal echocardiography diameters (mean difference of 1.5 ± 1.6 mm and 1.1 ± 1.7 mm, respectively). When a strategy of valve-sizing is undertaken using these CT measurements using an echocardiographic sizing scale, a different THV size would be selected in 44% and 40% of cases, respectively. When adjusting the sizing cutoffs to account for the differences in observed diameters, this was reduced to 10% to 12% (p < 0.01 for both, respectively).
  
  
  CONCLUSIONS
  The most reproducible MDCT measurements of the annulus are the area-derived diameter and basal ring average diameter, with derived values generally larger than those obtained with echocardiography. If MDCT is used for valve sizing, a strategy incorporating these differences may be important. MDCT using these easily derived measurements may be ideally suited to sizing transcatheter aortic valves as they account for the eccentricity of the aortic annulus, are reproducible, and are noninvasive.
authors: St. Paul's Hospital, University of British Columbia, Vancouver, Canada.
authors: Ronen
authors: R
authors: Gurvitch
authors: John G
authors: JG
authors: Webb
authors: Ren
authors: R
authors: Yuan
authors: Mark
authors: M
authors: Johnson
authors: Cameron
authors: C
authors: Hague
authors: Alexander B
authors: AB
authors: Willson
authors: Stefan
authors: S
authors: Toggweiler
authors: David A
authors: DA
authors: Wood
authors: Jian
authors: J
authors: Ye
authors: Robert
authors: R
authors: Moss
authors: Christopher R
authors: CR
authors: Thompson
authors: Stephan
authors: S
authors: Achenbach
authors: James K
authors: JK
authors: Min
authors: Troy M
authors: TM
authors: Labounty
authors: Ricardo
authors: R
authors: Cury
authors: Jonathon
authors: J
authors: Leipsic
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D006328:Cardiac Catheterization / Q000295:instrumentation; D016009:Chi-Square Distribution; D017548:Echocardiography, Transesophageal; D005260:Female; D006349:Heart Valve Diseases / Q000000981:diagnostic imaging* / Q000628:therapy*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D018579:Patient Selection; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed