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4D X-ray Computed Tomography
Published in Paolo Russo, Handbook of X-ray Imaging, 2017
Amit Mehndiratta, Soenke H. Bartling, Rajiv Gupta
Traditionally, Digital Subtraction Angiography (DSA) has been the Gold Standard for acquiring dynamic imaging of blood vessels. DSA enables two-dimensional X-ray projections that can be acquired at a fast rate, usually, 30 frames per second (fps) or higher. As such, DSA enables dynamic imaging of the vasculature and other anatomy in the projection domain (i.e., 3D dynamic imaging using time-elapsed 2D projections). This chapter discusses technologies and methods required to add another dimension to this process, viz., 4D dynamic imaging using time-elapsed 3D tomographic views.
X-Ray-Based Imaging
Published in John G Webster, Minimally Invasive Medical Technology, 2016
Imaging of vessels is important both for diagnosis of vascular disease, as well as for assisting in interventional procedures such as stent placement, balloon angioplasty and thrombolysis (declotting). Fluoroscopy is commonly used for catheter guidance and interventional procedures. Digital subtraction angiography (DSA), developed in the 1970s, continues to be the most widely used method for obtaining vascular images. The principles of DSA are also being used in MR angiography.
Conebeam CT for Medical Imaging and Image-Guided Interventions
Published in Salim Reza, Krzysztof Iniewski, Semiconductor Radiation Detectors, 2017
Digital subtraction angiography (DSA) is a fluoroscopy technique to provide excellent blood vessel visualization in a dense soft tissue environment. DSA images are obtained using contrast medium images subtracting the “pre-contrast image” or the mask image after the contrast medium has been injected into the blood vessels.
A realistic way to investigate the design, and mechanical properties of flow diverter stents
Published in Expert Review of Medical Devices, 2021
Prasanth Velvaluri, Mariya S. Pravdivtseva, Johannes Hensler, Fritz Wodarg, Olav Jansen, Eckhard Quandt, Jan-Bernd Hövener
Other shortcomings of 4D flow MRI often include insufficient spatial resolution for small vessels and aneurysms, limited sensitivity to the low velocities, and non-repetitive flow patterns. Higher fields [30] and acceleration techniques [31] can overcome some of these issues; real-time MRI may be used to image non-repetitive flow [32]. The flow diversion can be investigated with higher accuracy by computational fluid dynamics (CFD) or particle-image velocimetry. However, the latter works exclusively in vitro. In contrast, the 4D flow MRI can be applied in vitro and in vivo and thus compared easily. Another method that can also be applied in vivo and in vitro, but not considered in this study, is digital subtraction angiography (DSA). DSA is based on X-ray exposure applied during the injection of contrast agents into the arteries, providing a 2D projection of vessels. The technique is often used to guide vascular interventions, e.g. during the stroke treatment [33]. The technique allows, for example, to access the flow diversion efficacy by measuring the time needed for the contrast agent to leave the aneurysm sac [34]. The change in the DSA-based 2D velocity field maps can estimate the treatment success [35,36].
A video processing pipeline for intraoperative analysis of cerebral blood flow
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2020
Sören Klemm, Robin Rexeisen, Walter Stummer, Xiaoyi Jiang, Markus Holling
The goal of all neurosurgical procedures is to exclude pathologies (e.g. tumours, vascular malformations) without compromising the patency of surrounding vessels. Digital subtraction angiography (DSA) remains gold standard for diagnostic and intraoperative assessment of vessel patency. While invasiveness and infrastructural challenges impede extensive intraoperative application, other types of blood flow measurements were developed. With micro-ultrasound probes (Siasios et al. 2012) the patency of vessels could be determined acoustically. Especially the perivascular-flow-ultrasound-probe (Charbel et al. 1998) can evaluate the blood flow quantitatively. Application of Indocyanine green (ICG) allows determination of vessel integrity and semi-quantitative blood flow calculation (Raabe et al. 2003, 2005; Holling et al. 2013; Nakagawa et al. 2017, Saito et al. 2018). Meanwhile, similar options are provided by fluorescein (Wrobel et al. 1994). Another well-known but technically complex method is laser speckle flow imaging which shares the drawback of the aforementioned techniques of showing only flow-changes on the brain surface (Nomura et al. 2014; Richards et al. 2017; Ito et al. 2018).