Leaflet Free Edge Detection for the Automatic Analysis of Prosthetic Heart Valve Opening and Closing Motion Patterns from High Speed Video Recordings

摘要

Prosthetic heart valves (PHVs) are routinely used in clinical settings to replace defective native heart valves in patients suffering from valvular heart disease. Although PHV designs must be rigorously tested using cardiovascular testing equipment to ensure their optimal characteristics and safe operation, visual data obtained during simulations are typically assessed manually, a tedious and error-prone task. The valve orifice area over time, which informs on the opening and closing motion patterns, constitutes a key quality metric for PHV assessment. In addition to the very fast motion of the valve's leaflets, a major issue lies in the orifice being partly occluded by the leaflets' inner side or inaccurately depicted due to its transparency, which is not addressed in the literature. In this paper, we propose a novel orifice segmentation approach for automatic PHV quantitative performance analysis, based on the detection of the leaflet free edges to accurately extract the actual orifice area. Utilizing video frames recorded with a high speed digital camera during in vitro simulations, an initial estimation of the orifice area is first obtained via active contouring and then refined to capture the leaflet free edges via a curve extension scheme based on brightness and smoothness criteria. Evaluation on three different PHVs demonstrated the effectiveness of our approach to detect valve leaflet free edges and extract the actual orifice area, significantly outperforming a baseline algorithm both in terms of valve design evaluation metrics and computer vision evaluation metrics.