Figure 3. Image integration: the segmentation process. (A) For the segmentation process, a standard multislice CT scan is imported into the image integration system. Note the good contrast timing during the scan: it allows easy differentiation between the endocardium and the blood pool, and between the left-sided structures (left atrium, left ventricle) and right-sided structures (right atrium, right ventricle). (B) This image shows the setting of the intensity threshold (based on HU). (C) Subsequently, automatic competitive region-growing algorithms create the volume-rendered reconstruction of the left atrium, left ventricle, and aorta.