Template-based balloon-marker and guidewire detection for coronary stents in cardiac fluoroscopy

The placement and visualization of coronary stents during fluoroscopy depends mainly on the detection of balloon markers and their connecting guidewires. In this paper, a novel template-based approach is proposed to detect balloon markers and guidewires in cardiac fluoroscopic images. In particular, guidewires are detected based on balloon markers only, without prior knowledge of the background or guidewire elements. Also, while earlier techniques used circular models of balloon markers, we propose a more realistic elliptical model. Training and the testing datasets for balloon marker and guidewire detection were collected from different Cathlab systems and annotated by an application specialist with 10 years of experience in this field. The balloon-marker detector achieved a precision of 98.5%. Within 3-pixel tolerance, the guidewire detector achieved a matching percentage of 99.5% with the true guidewire using a customized evaluation method. Moreover, the guidewire detector achieved a mean Hausdorff distance of 3.3 pixels (0.6 mm) and a longest-common-substring (LCS) distance with a mean matching percentage of 87% within 1-pixel tolerance. Clinical Relevance- The proposed novel technique of detecting the guidewire offers a constant computational time and insensitivity to the body structures or the guidewire-like elements (such as the surgical wires). This leads to improved stent visualization and reasonable processing times.