title: A hybrid approach for quantification of aortic valve stenosis using cardiac magnetic resonance imaging and echocardiography.
abstract: BACKGROUND
  Doppler-derived calculation of aortic valve area (AVA) using the continuity equation can be difficult at times, e.g. due to poor acoustic windows, heavy calcification of the aortic valve, or significant flow acceleration in the left ventricular outflow tract. The aim of this study was to compare AVA as assessed by means of transthoracic echocardiography (TTE) with a hybrid approach, where the Doppler-derived numerator in the continuity equation was replaced by cardiovascular magnetic resonance (CMR) determination of stroke volume.
  
  
  METHODS
  Twenty consecutive patients admitted for evaluation of aortic stenosis underwent transthoracic echocardiography and CMR determination of stroke volume within a time period of 3 weeks. Additionally, continuous-wave Doppler spectra of the aortic valve were acquired immediately after the CMR examination.
  
  
  RESULTS
  There was no statistically significant difference for mean AVA between the two methods (0.88 +/- 0.23 cm2 by the standard continuity equation versus 0.86 +/- 0.23 cm2 by the hybrid approach, p = 0.55; r = 0.73, p < 0.01). The mean difference was 0.02 cm2 and the limits of agreement were -0.32 to 0.36. Only 2 patients were classified differently by the two methods. Intraobserver and interobserver variability and reproducibility were superior for the hybrid approach.
  
  
  CONCLUSIONS
  The hybrid method for determination of AVA is an excellent alternative to the standard approach by TTE.
authors.affiliation: Medical Department, University Hospital Mannheim, Mannheim, Germany. dariush.haghi@med.ma.uni-heidelberg.de
authors.forename: Dariusch
authors.initials: D
authors.lastname: Haghi
authors.forename: Theano
authors.initials: T
authors.lastname: Papavassiliu
authors.forename: Gabor
authors.initials: G
authors.lastname: Kalmar
authors.forename: Meike
authors.initials: M
authors.lastname: Schroder
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Neff
authors.forename: Jens J
authors.initials: JJ
authors.lastname: Kaden
authors.forename: Ute
authors.initials: U
authors.lastname: Muller
authors.forename: Karl K
authors.initials: KK
authors.lastname: Haase
authors.forename: Martin
authors.initials: M
authors.lastname: Borggrefe
authors.forename: Tim
authors.initials: T
authors.lastname: Suselbeck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000473:pathology*; D004452:Echocardiography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D013318:Stroke Volume