Cardiac and Coronary Artery Disease

There are significant evolving applications of 3D interactive visualization in the treatment of heart and coronary artery in the background. The accurate localization of the prostate tumor relative to critical anatomic structures, such as the urinary sphincter, seminal vesicles, and neurovascular bundles, improves physician navigation and performance in resection of pathology during the prostatectomy procedure.

FIGURE 25 Dynamic volume models of beating heart and coronary arteries at end-diastole and end-systole (left-right) seen from opposite (180°) viewpoints (top-bottom).

Percent Occlusion: 55% Minimum Diameter: 2.2mm Length ot Stenosis; 12mm Volume: 152mm 3

FIGURE 26 3D volume model of coronary artery reconstructed from IVUS scan through a segment showing plaque burden and regions of vessel narrowing. Individual IVUS sections can be precisely registered and localized relative to this vessel volume model. Quantitative analysis of coronary artery lumen and compositing plaque facilitates both accurate diagnosis and effective therapeutic decisions.

disease [14,22]. Figure 25 shows unique visualizations of rendered reconstructions from the Mayo Dynamic Spatial Reconstructor [52]. These volume models show the left ventricular chamber at end-diastole and end-systole with the associated coronary artery tree at the same two points in the cardiac cycle. The two views are 180° apart. Similar dynamic visualizations are possible using data from modern cine CT scanners, emerging cardiac MRI technology, and new 3D ultrasound devices, and permit quantitative assessment of cardiac function, including ejection fractions, coronary flow, and myocardial mechanics and perfusion.

Using intravascular ultrasound (IVUS) imaging catheters, the intraluminal space of the coronary arteries can be imaged and various segmentation and rendering algorithms applied to do quantitative analysis of plaques and narrowing of arteries [16,24,43]. The image also can be used to guide precise placement of stents in the coronary arteries to effectively recover normal functional flow and minimize restenosis. IVUS images can be submitted to multispectral analysis [39] for quantitative characterization of the lumen, including the atherosclerotic plaques. These spectral characteristics can be compared with histological analysis of the diseased arteries [43,69] to determine specific attributes of the plaques that are associated with the multispectral patterns in the images. This information can be used to quantitatively determine the disposition of the plaques to rupturing [14] and producing thrombi ("plaque vulnerability"), as well as their susceptibility to focused treatment by targeted local delivery of drugs or radiation. The reconstructed lumen and plaque burden can be accurately modeled and rendered in three dimensions and each IVUS cross-section registered to it for examination and precise determination of the stenosis, extent of plaquing, and localization of the stent, as illustrated in Fig. 26. Reexamination or review display of the pull-back sequence of images can be accomplished by pointing at locations on the 3D rendered lumen or running the sequence forward and backward while the cursor moves on the 3D model. The luminal surface may be color coded with local cross-sectional area, effective radius, and shortest distance to the centroid to draw specific attention to the stenoses. Local statistics about the lumen can be computed and reported as the reference images change, as also shown in Fig. 26.

Application of interactive volume modeling and visualization can also be used for image guidance of cardiac ablation procedures to treat chronic arrhythmias in the heart

FIGURE 27 Left panel shows close-up of endocardial surface with tissue target in line with ablation catheter, which has been placed in correct position using real-time visualization of anatomy (from ultrasound) accurately registered to and mapped with electrophysiologic myocardial activation times (from electrode array). Right panel shows activation map return to normal after ablation. See also Plate 124.

FIGURE 27 Left panel shows close-up of endocardial surface with tissue target in line with ablation catheter, which has been placed in correct position using real-time visualization of anatomy (from ultrasound) accurately registered to and mapped with electrophysiologic myocardial activation times (from electrode array). Right panel shows activation map return to normal after ablation. See also Plate 124.

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