Evaluation of aortic valve stenosis using cardiovascular magnetic resonance: comparison of an original semiautomated analysis of phase-contrast cardiovascular magnetic resonance with Doppler echocardiography.
BACKGROUND
Accurate quantification of aortic valve stenosis (AVS) is needed for relevant management decisions. However, transthoracic Doppler echocardiography (TTE) remains inconclusive in a significant number of patients. Previous studies demonstrated the usefulness of phase-contrast cardiovascular magnetic resonance (PC-CMR) in noninvasive AVS evaluation. We hypothesized that semiautomated analysis of aortic hemodynamics from PC-CMR might provide reproducible and accurate evaluation of aortic valve area (AVA), aortic velocities, and gradients in agreement with TTE.


RESULTS
We studied 53 AVS patients (AVA(TTE)=0.87±0.44 cm(2)) and 21 controls (AVA(TTE)=2.96±0.59 cm(2)) who had TTE and PC-CMR of aortic valve and left ventricular outflow tract on the same day. PC-CMR data analysis included left ventricular outflow tract and aortic valve segmentation, and extraction of velocities, gradients, and flow rates. Three AVA measures were performed: AVA(CMR1) based on Hakki formula, AVA(CMR2) based on continuity equation, AVA(CMR3) simplified continuity equation=left ventricular outflow tract peak flow rate/aortic peak velocity. Our analysis was reproducible, as reflected by low interoperator variability (<4.56±4.40%). Comparison of PC-CMR and TTE aortic peak velocities and mean gradients resulted in good agreement (r=0.92 with mean bias=-29±62 cm/s and r=0.86 with mean bias=-12±15 mm Hg, respectively). Although good agreement was found between TTE and continuity equation-based CMR-AVA (r>0.94 and mean bias=-0.01±0.38 cm(2) for AVA(CMR2), -0.09±0.28 cm(2) for AVA(CMR3)), AVA(CMR1) values were lower than AVA(TTE) especially for higher AVA (mean bias=-0.45±0.52 cm(2)). Besides, ability of PC-CMR to detect severe AVS, defined by TTE, provided the best results for continuity equation-based methods (accuracy >94%).


CONCLUSIONS
Our PC-CMR semiautomated AVS evaluation provided reproducible measurements that accurately detected severe AVS and were in good agreement with TTE.
INSERM U678/UPMC Universite Paris 6, Hôpital Européen Georges Pompidou, 20 Rue Leblanc, Paris, France.
Carine
C
Defrance
Emilie
E
Bollache
Nadjia
N
Kachenoura
Ludivine
L
Perdrix
Nataliya
N
Hrynchyshyn
Eric
E
Bruguière
Alban
A
Redheuil
Benoit
B
Diebold
Elie
E
Mousseaux
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D057205:Automation, Laboratory; D001783:Blood Flow Velocity; D016022:Case-Control Studies; D015150:Echocardiography, Doppler; D005260:Female; D006439:Hemodynamics; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010297:Paris; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D016277:Ventricular Function, Left; D055815:Young Adult