Visualizing Intersegmental Artery Ostium Location for Spinal Angiography
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Spinal digital subtraction angiography (SpDSA) is a diagnostic radiological procedure for evaluating vascular abnormalities of the spinal cord. During the procedure, a catheter is advanced to the aorta under fluoroscopic guidance, and up to 30 intersegmental arteries (ISAs) are visualized with radiopaque contrast medium. Although understanding the locations of the ISA ostia is essential knowledge for performing SpDSA, very little study has been dedicated to this topic, particularly with regard to radiological imaging. As a result, few visual resources exist for learning this anatomy in the context of SpDSA. As part of this thesis, a retrospective radiological study was conducted to measure the location of each ISA ostium using data collected at the Johns Hopkins Hospital. A protocol was developed to compile images of all catheterized ostia from a single spinal angiogram into a composite image. Data was collected from 40 patients, and analyzed for clinically relevant trends, including by sex and age. Analysis confirmed several prior anatomical assumptions regarding ostia location and identified a substantial leftward shift in ostia location with age that was most pronounced at vertebral level T5, the most common level of the principal thoracic anterior radiculomedullary artery, the artery of von Haller. The leftward shift could play a role in forming stenoses at level T5, which may increase the susceptibility of the spinal cord to ischemia at that level. The data was used to inform the creation of didactic visualizations, including illustrations and an animation that contextualized the data in the performance of SpDSA. Visuals were created for a physician audience to be used as educational resources. Beyond contributing the anatomical and educational literature, this project explored the use of medical visualization techniques in conducting original research, resulting in the development of a novel image analysis protocol.