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Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The main indication for MRA is the assessment of intracranial aneurysm, but also assessment of vascular malformations. MRI of the intracranial vessels is most commonly performed using a 3D time of flight (TOF) technique, which provides imaging of the blood vessels without the use of IV contrast media by using specialised pulse sequences that are designed to distinguish between the movement of fluids within vessels and that of surrounding structures where no flow is present. TOF imaging uses a gradient echo sequence where blood flowing into an imaging slice is fully magnetised and appears brighter than the partially saturated stationary tissues that appear much lower in signal intensity. (Further technical description of the MRA techniques are described in Chapter 1.) This sequence is typically performed in combination with an MRI study of the brain with a minimum of T2-weighted transverse imaging.
Nanotechnology in Preventive and Emergency Healthcare
Published in Bhaskar Mazumder, Subhabrata Ray, Paulami Pal, Yashwant Pathak, Nanotechnology, 2019
Nilutpal Sharma Bora, Bhaskar Mazumder, Manash Pratim Pathak, Kumud Joshi, Pronobesh Chattopadhyay
Although nanorobots, or little robots, travel throughout the circulatory system, this technology is still in the nascent stage and needs further research and development. Fabricated nanorobots are injected into the systemic circulation of the patient for therapeutic or diagnostic purposes at the nanoscale level. Recently, a team of researchers developed nanorobots that were employed to deliver drugs in the form of MNPs into the CNS, which disrupted the BBB hypothermically by introducing the MNPs within an air-conditioned field in an experimental mouse model (Aguilar, 2012; Sheikh, 2014; Tabatabaei et al., 2012). In another study, a prototype of a nanorobot was developed, embedded with biosensors to give telemetric control, to transport data for cerebral aneurysm by detecting the overexpression of nitric oxide synthase (NOS). This nanorobot acts through detecting changes in the chemical gradient in the bloodstream and this information is relayed back to detect its position inside the blood vessel and ultimately detect the intracranial aneurysm (Cavalcanti et al., 2009).
CHEM for Endovascular Interventions
Published in Witold M. Sokolowski, Cold Hibernated Elastic Memory Structure, 2018
Witold M. Sokolowski, Naziha Chirani, L’Hocine Yahia
Limits of the detachable balloons system led to use of a new embolization material: micro-coils. The technique currently used is occlusion of aneurysms with coils made of platinum, a biocompatible material. The platinum coils can be deposited via a microcatheter in an intracranial aneurysm where it promotes thrombosis and, consequently, prevents a new bleeding. The microcatheter with coil are inserted and displaced through the femoral artery that can be followed by angiography. The platinum coil is detached from the stainless-steel guidewire by an electrical current that induces an electrolysis reaction on the ferric fixation and allows for the detachment of the coil. The platinum coils, despite their relatively inert nature, can be an ongoing source of inflammation within the aneurysm after implantation [5]. Szikora et al. reported that after multiple years, bare platinum coils are still not completely endothelialized at the aneurysm and parent artery interface, and therefore, the aneurysm is not optimally stabilized [6]. Coils have a tendency to have low filling volume as compared to total aneurysm volume [7,8] and may compact over time, allowing for aneurysm recanalization [9,10]. This results in re-exposure of the aneurysm wall and subsequent rupture or re-rupture, or can potentially result in the formation of aneurysms adjacent to the original aneurysm [11]. Recanalization may require additional treatment, thus adding to the overall cost of treatment and increasing risk to the patient. Therefore, the search for new and more effective occlusive materials has been continued and shape memory materials (SMMs) appear to be interesting candidates to this medical application.
A comparative study on computational fluid dynamic, fluid-structure interaction and static structural analyses of cerebral aneurysm
Published in Engineering Applications of Computational Fluid Mechanics, 2022
Hong Tao Sun, Kam Yim Sze, Kwok Wing Chow, Anderson Chun On Tsang
Cerebral aneurysm (CA), also known as intracranial aneurysm, is a localized dilation of the blood vessel. Previous autopsy studies reported that CA occurrence ranges from 0.2–9.9% (Vega et al., 2002; Wiebers et al., 2004). The rupture of CAs can lead to subarachnoid haemorrhage (SAH) in which blood enters the space surrounding the brain. About 50% of the SAH cases are fatal (Broderick et al., 1994; Kaminogo et al., 2003; Winn et al., 2002). In general, a clinician would formulate the treatment of a pre-rupture CA based on the following factors of the patient: age, overall health, medical history, signs and symptoms, tolerance for specific medications, the morphology of the CA, etc.