Abstract 2230: Multidetector Computed Tomography Can Evaluate the Size and Function of Mechanical Valves
Introduction: Determination of mechanical valve function and size with multidetector computed tomography (MDCT) is feasible, but its accuracy is not established.
Hypothesis: MDCT can accurately assess the size and function of mechanical valves.
Methods: Retrospective evaluation of 62 consecutive patients with 64 mechanical valves (37 single-disc, 27 bi-leaflet; 59 aortic, 5 mitral) and both 64-slice ECG-gated MDCT and transthoracic echocardiography (TTE); a subset had fluoroscopy (n=10). Independent, blinded interpretations by 2 radiologists (MDCT) and 2 cardiologists (TTE and fluoroscopy) were performed. MDCT measured opening angles (OA), annulus diameter (AD), geometric orifice area (GOA), and evaluated complete closure. TTE measured mean pressure gradient (MPG), ejection fraction, and aortic insufficiency. Fluoroscopy measured OA.
Results: Mean ejection fraction was 62 ± 8%; it was <50% in 2 patients. Each MDCT variable could be measured in all cases. There was excellent correlation and low inter-observer variability between MDCT readers for OA (r=0.96, p<0.001; 76.7 ±9.0 vs. 76.8 ± 9.6°, p=0.73), AD (r=0.96, p<0.001; 25.9 ± 3.3 vs. 25.9 ± 3.2 mm, p=0.70), and GOA (r=0.98, p<0.001; 3.8 ± 0.9 vs. 3.6 ± 0.9 cm2, p<0.001). There was strong correlation and no difference in the OA between MDCT and fluoroscopy (n=10; r=0.77, p<0.001; 79.2 ± 9.8 vs. 77.2 ± 15.5°, p=0.44). In comparison to available manufacturer specifications, the OA with MDCT was lower with both single-disc (n=36, 67.4 ± 5.7 vs. 75°, p<0.001) and bi-leaflet (n=21, 83.8 ± 3.9 vs. 90°, p<0.001) valves. There was strong correlation and a small underestimation with MDCT compared to manufacturer specifications for the AD (n=42; r=0.75, p<0.001; 26.5 ± 3.0 vs. 27.6 ± 3.3 mm, p=0.005) and GOA (n=35; r=0.89, p<0.001; 3.8 ± 0.8 vs. 3.6 ± 0.7 cm2, p=0.006). Each disc closed fully on MDCT, with no more than mild aortic insufficiency in all cases. The MPG for aortic valves was inversely correlated to the AD (r=−0.65, p<0.001) and GOA (r=−0.63, p<0.001).
Conclusion: MDCT has high interobserver agreement in measuring the AD, GOA, and OA, with results similar to manufacturer specifications. The OA with MDCT strongly correlates to fluoroscopy. MDCT can evaluate the size and function of mechanical valves.