The role of ECG-gated MDCT in the evaluation of aortic and mitral mechanical valves: Initial experience

OBJECTIVE. The objective of our study was to evaluate the role of ECG-gated MDCT in the functional evaluation of mechanical prosthetic aortic and mitral valves. MATERIALS AND METHODS. Twenty sequential patients with 23 mechanical prosthetic valves were evaluated with an ECG-gated 40- or 64-MDCT scanner. Multiplanar reformation, maximal-intensity-projection, volume-rendering, and volume-averaging techniques were used for visualization of valve leaflets in systole and diastole. The visibility of each mechanical valve was evaluated by consensus of a radiologist and a cardiologist using a subjective 5-point scale (0-4). MDCT findings were correlated with fluoroscopic opening and closing angle measurements and echocardiographic pressure gradient measurements in 11 and 19 valves, respectively. RESULTS. The series included 18 bileaflet and five single-leaflet mechanical valves. The visibility score for the bileaflet mechanical valves was excellent ( score of 4) in all 18 cases, but it was lower for single-leaflet valves ( mean score, 2.8; range, 1-4) ( p = 0.04). Bland-Altman plots showed high agreement between MDCT and fluoroscopy for measurements of opening and closing angles of bileaflet mechanical valves. In four patients, a stuck valve was seen on MDCT and was confirmed by fluoroscopy. Doppler echocardiography showed increased transvalvular pressure in two of the four patients with a stuck mitral valve and increased transaortic pressure in four patients with normal prosthetic aortic valve motion. CONCLUSION. Our preliminary results suggest that MDCT is a promising technique for functional evaluation of bileaflet mechanical valves, allowing reliable measurements of opening and closing leaflet angles. However, the role of MDCT in the evaluation of single-leaflet valves might be limited.