Proceedings Article | 27 February 2010
Proc. SPIE. 7625, Medical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling
KEYWORDS: Chest, Visualization, Image segmentation, Heart, Image acquisition, Image registration, Transducers, Computed tomography, Electrocardiography, Process modeling
Image-guided interventions rely on the common assumption that pre-operative information can depict intraoperative
morphology with sufficient accuracy. Nevertheless, in the context of minimally invasive cardiac therapy
delivery, this assumption loses ground; the heart is a soft-tissue organ prone to changes induced during access to
the heart and especially intracardiac targets. In addition to its clinical value for cardiac interventional guidance
and assistance with the image- and model-to-patient registration, here we show how ultrasound imaging may be
used to estimate changes in the heart position and morphology of structures of interest at different stages in the
procedure. Using a magnetically tracked 2D transesophageal echocardiography transducer, we acquired in vivo
images of the heart at different stages during the procedural workflow of common minimally invasive cardiac
procedures, including robot-assisted coronary artery bypass grafting, mitral valve replacement/repair, or modelenhanced
US-guided intracardiac interventions, all in the coordinate system of the tracking system. Anatomical
features of interest (mitral and aortic valves) used to register the pre-operative anatomical models to the intraoperative
coordinate frame were identified from each dataset. This information allowed us to identify the global
position of the heart and also characterize the valvular structures at various peri-operative stages, in terms of
their orientation, size, and geometry. Based on these results, we can estimate the differences between the preand
intra-operative anatomical features, their effect on the model-to-subject registration, and also identify the
need to update or optimize any pre-operative surgical plan to better suit the intra-operative procedure workflow.
