Image guidance during minimally invasive cardiovascular interventions is primarily achieved based on X-ray fluoroscopy, which has several limitations including limited 3D imaging, significant doses of radiation to operators, and lack of contact force measurement between the cardiovascular anatomy and interventional tools. Ultrasound imaging may complement or possibly replace 2D fluoroscopy for intravascular interventions due to its portability, safety, and the ability of providing depth information. However, it is a challenging work to perfectly visualize catheters and guidewires in the ultrasound images. In this paper, we developed a novel method to locate the position and orientation of the catheter tip in 2D ultrasound images in real time by detecting and tracking a passive marker attached to the catheter tip. Moreover, the contact force can also be measured due to the length variation of the marker in real time. An active geometrical structure model based method was proposed to detect the initial position of the marker, and a KLT (Kanade-Lucas-Tomasi) based algorithm was developed to track the position, orientation, and the length of the marker. The ex vivo experimental results indicate that the proposed method is able to automatically locate the catheter tip in the ultrasound images and sense the contact force, so as to facilitate the operators’ work during intravascular interventions.
Research Fellow: Jin Guo
Project Investigator: Hongliang Ren