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OBJECTIVE: The objective of this study was to evaluate the validity of “four-dimensional” computed tomography (4D-CT) in the morphological and functional evaluation of mechanical prosthetic valves.
METHODS: Thirty-seven patients with forty-five implanted mechanical valves were studied with electrocardiogram gated multi-detector (16 or 256 rows) computed tomography (MDCT). Volume-rendering three-dimensional and multiplanar reformation were obtained. Valve leaflet movement was evaluated using reformatted images in a cine mode (Four-dimensional images). Patient age was 65.1 ± 10.1 (0.5-85) years old. The series included 18 aortic and 27 mitral mechanical valves and 36 bileaflet valves and nine mono-leaflet valves. Fifteen patients had atrial fibrillation. Seven patients had permanent pacemaker implantation. The quality of mechanical valve leaflet visualization was scored on a four-grade scale (leaflet index). The level of artifact was also scored (artifact index).
RESULTS: There were two stuck valve patients who required emergency surgery. Stuck mechanical leaflet could be visualized by 4D-CT. With all bileaflet mechanical valve, valve leaflet motions were visualized with four-dimensional images. On the contrary, in four out of nine valves with mono-leaflet valves, opening and closing angle could not be visualized, because of radiopacity of the leaflet. Leaflet index and artifact index were significantly lower in monoleaflet valve (p<0.0001, p=0.0037). By 256-row MD-CT, artifact index was better than by 16-row without statistical difference (p=0.0654).
CONCLUSIONS: Functional and morphological evaluation of mechanical valve with four-dimensional multi-detector computed tomography is promising in patients with bileaflet mechanical valve. However, the evaluation of mono-leaflet valve is limited.