Saunders AB, Gordon SG.
Procedural planning has classically relied on echocardiography and angiography to evaluate cardiac anatomy.1 A detailed knowledge of the anatomy is critical to procedural success. Computed tomography (CT) angiography provides high-resolution images of the cardiac structures, and reconstructed models can be rendered using a variety of software applications to produce three-dimensional (3D) images. From image processing applications, the images are flattened into a 2D image that represents a 3D structure. Applying color, for example, to a tissue density or Hounsfield unit creates a medical illustration of 3D. From CT studies, the images can be manipulated to position the structures in a specific orientation that highlights the area of interest (i.e., oblique view) and the model rendered and viewed in a controlled manner. The authors will present a virtual reality system where a CT study can be imported minutes after it is acquired to view an interactive true 3D representation. A clipping plane is applied to view and measure internal structures such as patent ductus arteriosus pulmonary ostia or septal defects.
Advanced medical imaging software (Mimics®, Materialise, Belgium) allows users to develop wire mesh and 3D anatomic models from CT data sets.2 Polygonal modeling of structures creates a 3D model from specific points called
vertices that define a shape. These wireframe models approximate the surface of a structure and allow inner structures to be viewed and measured in cross section or volume estimated. The data sets are loaded and density thresholds applied to the tissues of interest to create and export a 3D model as an STL file that can be 3D printed. Standard threshold definition values are applied then customized depending on the scan.
These models have applications for surgical procedural planning3,4, for the engineering of new devices, to enhance visuospatial understanding of anatomy at all levels of training, and can be utilized to educate owners. This session will emphasize practical application of this technology in a variety of clinical cases.
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4. Saunders AB, Birch SA. Three-dimensional modeling of a patent ductus arteriosus in a cat. J Vet Cardiol. 2015;17:S349–S353.