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Endoscopic Optical Coherence Tomography: Technologies and Applications
Published in Margarida M. Barroso, Xavier Intes, In Vivo, 2020
Dawei Li, Hyeon-Cheol Park, Wu Yuan, Xinwen Yao, Xingde Li
OCT provides enough resolution for accurate detection of neointimal hyperplasia (NIH) observed after a drug-eluting stent, which usually exceeds the capabilities of intravascular ultrasound (IVUS). Similarly, fibrous cap thickness can only be assessed in vivo by OCT. The disadvantage of the current OCT systems lies in the optical penetration depth, which is typically less than 2 mm in tissue. Therefore, a multimodality IVUS/OCT catheter has been invented to exploit the synergistic advantages of IVUS and OCT [Bourantas et al., 2013; Feldchtein et al., 1998). The prototypes for such a hybrid catheter have already been tested in vitro (see Figure 4.14). However, technical limitations must be addressed before it can be used in clinical practice, including size, coregistration of the IVUS and OCT images, image quality, and the image acquisition rate.
Spectral CT Imaging Using MARS Scanners
Published in Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski, Spectral, Photon Counting Computed Tomography, 2020
Aamir Y. Raja, Steven P. Gieseg, Sikiru A. Adebileje, Steven D. Alexander, Maya R. Amma, Fatemeh Asghariomabad, Ali Atharifard, Benjamin Bamford, Stephen T. Bell, Srinidhi Bheesette, Anthony P. H. Butler, Philip H. Butler, Pierre Carbonez, Alexander I. Chernoglazov, Shishir Dahal, Jérôme Damet, Niels J. A. de Ruiter, Robert M. N. Doesburg, Brian P. Goulter, Joseph L. Healy, Praveen K. Kanithi, Stuart P. Lansley, Chiara Lowe, V. B. H. Mandalika, Emmanuel Marfo, Aysouda Matanaghi, Mahdieh Moghiseh, Raj K. Panta, Hannah M. Prebble, Nanette Schleich, Emily Searle, Jereena S. Sheeja, Rayhan Uddin, Lieza Vanden Broeke, V. S. Vivek, E. Peter Walker, Michael F. Walsh, Manoj Wijesooriya
Cardiovascular disease is very much an inflammatory disease that is aggravated by elevated levels of cholesterol ester-carrying low-density lipoproteins (LDLs) in the blood [81]. The LDLs passing through the artery wall appear to become altered, either through oxidation or aggregation to become a form of “high-uptake LDL” that is rapidly taken up by inflammatory macrophage cells recruited into the plaques [82, 83]. These cholesterol-filled macrophages make up a significant part of the atheroma mass, along with T-cells and cholesterol-filled smooth muscle cells. As part of the inflammatory response, these cells release additional oxidants, so exacerbating the process by making more oxidized LDL. In advanced plaques, which typically start forming in late to middle aged patients, the cholesterol filled macrophages start to die through a necrotic process. The dying cells lyse open releasing the cellular contents into the extracellular space of the plaque. The resulting necrotic core region is rich in cholesterol esters and is usually covered by covered by a fibrous cap of proteins and connective tissue cells. If this complex structure is ruptured, usually due to thinning of the fibrous cap, the exposed plaque contents cause blood clotting within the artery.
Spectral Molecular CT with Photon-Counting Detectors
Published in Salah Awadalla, Krzysztof Iniewski, Solid-State Radiation Detectors, 2017
Cardiovascular disease (CVD) is one of the leading causes of death and a major cause of hospitalization in the Western world [66–68]. Fatal events such as myocardial infarctions (heart attacks) and strokes are typically caused by the rupture of vulnerable or unstable atherosclerotic plaques and consequent vascular blockage [69]. Unstable plaques consist of a soft lipid pool covered by a thin layer of fibrous cap, whereas stable plaques typically have a thick fibrous cap [70]. Early detection of plaque vulnerability is critical for preventing the severe downstream effects of heart disease. Atherosclerotic plaques can rupture as a result of the breakdown of the fibrous cap that covers the lipid core. The unstable plaque is prone to inflammatory changes near this thin fibrous cap, which can weaken the fibrous cap and lead to rupturing. Atherosclerosis accounts for ~70% of fatal acute myocardial infarctions or sudden coronary deaths [71].
Advances in the application of computational fluid dynamics in cardiovascular flow
Published in Cogent Engineering, 2023
Nitesh Kumar, Ganesha A, Girish H, Shiva Kumar, Gowrava Shenoy B
When an artery has stenosis, it works in the opposite way of a healthy one, causing low and fluctuating WSS during cardiac cycles as well as high shear stress at the throat. The WSS development was predicted using both transient numerical modelling and Ultrasound Doppler experimental approaches, which were both validated (Lopes et al., 2020). Atherosclerosis-prone location is mainly the carotid bulb and the phenomenon is clearly explained which will serve to show its focal nature where it localize in the region of low shear stress in arterial tree (Ooij & Van, Markl, 2020). The application of realistic models in studies gained from medical imaging equipment such as CT and MRI in combination with deep learning and artificial intelligence techniques is a recent trend in computational hemodynamics. Local hemodynamics, particularly shear rate, are the primary cause of thrombus development and plaque rupture, according to advances in stroke research (Kim et al., 2019; Sorin et al., 2020). The presence of high shear rate at partially occluded arteries initiates platelet activation and platelet binding takes place which plays an important role in thrombosis. When there is high speed flow through the stenosis the fibrous cap is subjected to high shear stress which results in plaque rupture (Scharf, 2018).