Therefore, thrombus perviousness was introduced as a derivative measure of permeability.
|
|
The value of thrombus perviousness in acute ischemic stroke treatment is currently being researched.
|
|
Therefore, it has been suggested to only use thin-slice CT images (≤2.5 mm) to measure thrombus perviousness.
|
|
A number of studies has been conducted on the effects of thrombus perviousness on NCCT and CTA.Borst J, Berkhemer OA, Santos EMM, et al. Value of thrombus CT characteristics in patients with acute ischemic stroke. AJNR 2017.
|
|
Thrombus perviousness is an imaging biomarker which is used to estimate clot permeability from CT imaging. It reflects the ability of artery-occluding thrombi to let fluid seep into and through them. The more pervious a thrombus, the more fluid it lets through. Thrombus perviousness can be measured using radiological imaging routinely performed in the clinical management of acute ischemic stroke: CT scans without intravenous contrast (also called non- contrast CT, in short NCCT) combined with CT scans after intravenously administered contrast fluid (CT-angiography, in short CTA).
|
|
Emilie Santos et al. introduced the term thrombus perviousness in 2016 to estimate thrombus permeability in ischemic stroke patients. Before, Mishra et al. used ‘residual flow within the clot’, and Frölich et al. used ‘antegrade flow across incomplete vessel occlusions’ to describe an estimate of thrombus permeability.
|
|
The amount of contrast that seeps into a thrombus can be quantified by the density difference of thrombi between non- contrast computed tomography (NCCT) and CT angiography (CTA) images. Two measures for thrombus perviousness have been introduced: (1) the void fraction and (2) thrombus attenuation increase (TAI).
|
|
Furthermore, level of perviousness may reflect histopathological composition of clots or size of contact surface for thrombolytic medication, thereby influencing effectiveness of thrombolysis.Bembenek JP, Niewada M, Siudut J, et al. Fibrin clot characteristics in acute ischaemic stroke patients treated with thrombolysis: the impact on clinical outcome. Thrombosis and Haemostasis 2017.
|
|
TAI measurements performed on CT scans with thicker slices will be less accurate, because volume averaging results in a reduction of thrombus density on NCCT.Tolhuisen ML, Enthoven J, Santos EMM, et al. The effect of non-contrast CT slice thickness on thrombus density and perviousness assessment. CMMI/RAMBO/SWITCH, oral presentation at MICCAI 2017.
|
|
In addition, dynamic imaging modalities have been used to investigate thrombus perviousness/permeability in animal and laboratory studies Voronov RS, Stalker TJ, Brass LF, Diamond SL. Simulation of Intrathrombus Fluid and Solute Transport Using In Vivo Clot Structures with Single Platelet Resolution. Annals of Biomedical Engineering 2013Laurens N, Koolwijk P, de Maat MPM. Fibrin structure and wound healing. J Thromb Haemost 2006.
|
|
In the manual thrombus perviousness assessment, spherical ROIs with a diameter of 2 mm are manually placed in the thrombus, both on NCCT and CTA. To improve reflection of possible thrombus heterogeneity, three ROIs are placed per imaging modality rather than one.Santos EMM, Yoo AJ, Beenen LF, Berkhemer OA, den Blanken MD, Wismans C, et al. Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke.
|
|
Currently, treatment for acute ischemic stroke due to an occlusion of one of the arteries of the proximal anterior intracranial circulation consists of intravenous thrombolysis followed by endovascular thrombectomy for patients that arrive at the hospital within 4.5 hours of stroke onset. Patients that arrive later than 4.5 hours after onset, or have contra-indications for intravenous thrombolysis can still be eligible for endovascular thrombectomy only. Even with treatment, not all patients recover after their stroke; many are left with permanent brain damage. Increased thrombus perviousness may decrease brain damage during stroke by allowing more blood to reach the ischemic tissue.
|
|
In her art works, Oksana elaborates an aesthetic perception of a human being in times of drastic social and geo-political change that is experienced by every generation, irrespective of the era or geographical placement. Oksana’s academic knowledge in such fields as science, the philosophy of digital technologies, the history of religions and art history and her multiculturalism have created the foundation of her artistic identity and enabled her to create timeless and versatile artworks with the aim of searching for this generation's new cultural code and facilitating a creative dialogue between different religions and social groups. The artist manages to combine a vivid figurativeness of visually and formally unique works with perviousness of interpretations, based on eternal values. The symbolic images in her paintings are always both focused and ambiguous.
|
|