- Michael Speidel
3D echocardiography and x-ray fluoroscopy image fusion for real-time tracking
Structural Heart interventions in the cardiac catheterization lab (such as TAVR, or Transcatheter Aortic Valve Replacement) demand accurate, real-time imaging of both catheter devices and patient anatomy. Ultimately, the fusion of 3D Echocardiography with derived 3D models of catheter devices from X-ray Fluoroscopy is desired; with this visualization model, we hope to facilitate the success of such procedures. My research has investigated the possibility of using 3D transthoracic (TTE) echo in place of Transesophageal (TEE), to reduce patient risk and procedure times. Under IRB approval, we imaged a series of healthy volunteers in order to determine how image quality in 3D transthoracic echo was dependent on acoustic window and patient position. Patient supine (on back) is an atypical position for acquiring echocardiograms (typically the patient is lying on their left side); however, it the cardiac cath lab, this positioning is not feasible. Optical and electromagnetic tracking of the TTE probe was performed concurrently with subject scanning. Knowing the 3D position and orientation (e.g. pose estimation) of the probe in X-ray space is necessary to performing fusion between these two imaging modalities. Currently, an x-ray pose-estimation technique is being investigated, in which small, radio-opaque fiducials are attached to the TTE probe. With these uniquely-orientated fiducials in a 2D x-ray image, the 3D pose of the TTE probe can be estimated relative to the x-ray system.