Practical value of cardiac magnetic resonance imaging for clinical quantification of aortic valve stenosis: comparison with echocardiography.
BACKGROUND
Valvular pathology can be analyzed quickly and accurately through the use of Doppler ultrasound. For aortic stenosis, the continuity equation approach with Doppler velocity-time integral (VTI) data is by far the most commonly used clinical method of quantification. In view of the emerging popularity of cardiac magnetic resonance (CMR) as a routine clinical imaging tool, the purposes of this study were to define the reliability of velocity-encoded CMR as a routine method for quantifying stenotic aortic valve area, to compare this method with the accepted standard, and to evaluate its reproducibility.


RESULTS
Patients (n=24) with aortic stenosis (ranging from 0.5 to 1.8 cm2) were imaged with CMR and echocardiography. Velocity-encoded CMR was used to obtain velocity information in the aorta and left ventricular outflow tract. From this flow data, pressure gradients were estimated by means of the modified Bernoulli equation, and VTIs were calculated to estimate aortic valve orifice dimensions by means of the continuity equation. The correlation coefficients between modalities for pressure gradients were r=0.83 for peak and r=0.87 for mean. The measurements of VTI correlated well, leading to an overall strong correlation between modalities for the estimation of valve dimension (r=0.83, by means of the identified best approach). For 5 patients, the CMR examination was repeated using the best approach. The repeat calculations of valve size correlated well (r=0.94).


CONCLUSIONS
Velocity-encoded CMR can be used as a reliable, user-friendly tool to evaluate stenotic aortic valves. The measurements of pressure gradients, VTIs, and the valve dimension correlate well with the accepted standard of Doppler ultrasound.
Caruthers
Shelton D
SD
Cardiovascular Magnetic Resonance Laboratories, Barnes-Jewish Hospital, Cardiovascular Division, Washington University School of Medicine, St Louis, MO 63110, USA. saw@howdy.wustl.edu
Lin
Shiow Jiuan
SJ
Brown
Peggy
P
Watkins
Mary P
MP
Williams
Todd A
TA
Lehr
Katherine A
KA
Wickline
Samuel A
SA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001022:Aortic Valve Insufficiency; D001024:Aortic Valve Stenosis / Q000175:diagnosis* / Q000473:pathology; D001783:Blood Flow Velocity; D004452:Echocardiography; D015150:Echocardiography, Doppler; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D015203:Reproducibility of Results; D014654:Vascular Patency; D016277:Ventricular Function, Left