The adventitia and outer media of large blood vessels are supplied with nutrients by microscopic blood vessels called vasa vasorum. While vasa vasorum have been implicated in a number of diseases including atherosclerosis, knowledge of their functional anatomy and specific role in these diseases has been hindered due to the small size of the vasa vasorum, and difficulty in accessing them. Micro-CT and histological methods have been used in ex-vivo animal studies of the vasa vasorum, but these techniques are limited by their inability to be used for in-vivo investigation. As such, there is very little in-vivo human data available. Intra-vascular ultrasound can acquire high-resolution anatomic images of coronary vessels. ChromaFlo IVUS has been used to identify blood flow in vessel lumens and has exciting prospect for in-vivo studies of vasa vasorum functional anatomy. In this study, ChromaFlo IVUS images of the human mid-left anterior descending coronary artery (LAD) were segmented to analyze the distribution of adventitial vasa vasorum proximal to intimal plaque. Previous animal studies suggest that formation of intimal plaque is accompanied by increased density of adventitial vasa vasorum. The data collected with ChromaFlo ultrasound is inconsistent with the current literature. While IVUS has the fidelity to acquire high-resolution US images of the coronary arteries, ChromaFlo lacks the necessary resolving power to differentiate the vasa vasorum. Further study of IVUS and other imaging methods on a large cohort will provide the basis for future in-vivo analysis of coronary disease.
The incidence of certain types of cardiac arrhythmias is increasing. Effective, minimally invasive treatment has remained elusive. Pharmacologic treatment has been limited by drug intolerance and recurrence of disease. Catheter based ablation has been moderately successful in treating certain types of cardiac arrhythmias, including typical atrial flutter and fibrillation, but there remains a relatively high rate of recurrence. Additional side effects associated with cardiac ablation procedures include stroke, perivascular lung damage, and skin burns caused by x-ray fluoroscopy. Access to patient specific 3-D cardiac images has potential to significantly improve the process of cardiac ablation by providing the physician with a volume visualization of the heart. This would facilitate more effective guidance of the catheter, increase the accuracy of the ablative process, and eliminate or minimize the damage to surrounding tissue. In this study, a semiautomatic method for faithful cardiac segmentation was investigated using Analyze - a comprehensive processing software package developed at the Biomedical Imaging Resource, Mayo Clinic. This method included use of interactive segmentation based on math morphology and separation of the chambers based on morphological connections. The external surfaces of the hearts were readily segmented, while accurate separation of individual chambers was a challenge. Nonetheless, a skilled operator could manage the task in a few minutes. Useful improvements suggested in this paper would give this method a promising future.