Purpose Currently, coronary plaque changes are manually compared between a baseline and follow-up coronary computed tomography angiography (CCTA) images for long-term coronary plaque development... Show morePurpose Currently, coronary plaque changes are manually compared between a baseline and follow-up coronary computed tomography angiography (CCTA) images for long-term coronary plaque development investigation. We propose an automatic method to measure the plaque thickness change over time. Methods We model the lumen and vessel wall for both the baseline coronary artery tree (CAT-BL) and follow-up coronary artery tree (CAT-FU) as smooth three-dimensional (3D) surfaces using a subdivision fitting scheme with the same coarse meshes by which the correspondence among these surface points is generated. Specifically, a rigid point set registration is used to transform the coarse mesh from the CAT-FU to CAT-BL. The plaque thickness and the thickness difference is calculated as the distance between corresponding surface points. To evaluate the registration accuracy, the average distance between manually defined markers on clinical scans is calculated. Artificial CAT-BL and CAT-FU pairs were created to simulate the plaque decrease and increase over time. Results For 116 pairs of markers from nine clinical scans, the average marker distance after registration was 0.95 +/- 0.98 mm (two times the voxel size). On the 10 artificial pairs of datasets, the proposed method successfully located the plaque changes. The average of the calculated plaque thickness difference is the same as the corresponding created value (standard deviation +/- 0.1 mm). Conclusions The proposed method automatically calculates local coronary plaque thickness differences over time and can be used for 3D visualization of plaque differences. The analysis and reporting of coronary plaque progression and regression will benefit from an automatic plaque thickness comparison. Show less
From user-generated images of streets to professional architectural renderings, and from digital maps and drone footages to representations of invisible digital ecologies, this collection of essays... Show moreFrom user-generated images of streets to professional architectural renderings, and from digital maps and drone footages to representations of invisible digital ecologies, this collection of essays analyses the emergent practices of visualizing the street. Today, advancements in digital technologies of the image have given rise to the production and dissemination of imagery of streets and urban realities in multiple forms. The ubiquitous presence of digital visualizations has in turn created new forms of urban practice and modes of spatial encounter. Everyone who carries a smartphone not only plays an increasingly significant role in the production, editing and circulation of images of the street, but also relies on those images to experience urban worlds and to navigate in them. Such entangled forms of image-making and image-sharing have constructed new imaginaries of the street and have had a significant impact on the ways in which contemporary and future streets are understood, imagined, documented, navigated, mediated and visualized.Visualizing the Street investigates the social and cultural significance of these new developments at the intersection of visual culture and urban space. The interdisciplinary essays provide new concepts, theories and research methods that combine close analyses of street images and imaginaries with the study of the practices of their production and circulation. The book covers a wide range of visible and invisible geographies — From Hong Kong’s streets to Rio’s favelas, from Sydney’s suburbs to London’s street markets, and from Damascus’ war-torn streets to Istanbul’s sidewalks — and engages with multiple ways in which visualizations of the street function to document street protests and urban change, to build imaginaries of urban communities and alternate worlds, and to help navigate streetscapes. Show less
