Wyniki wyszukiwania - BazTech

1

The effect of stenosis rate and Reynolds number on local flow characteristics and plaque formation around the atherosclerotic stenosis

Chen Xueping, Zhan Yiyi, Fu Yi, Lin Jiangguo, Ji Yanru, Zhao Chengbi, Fang Ying, Wu Jianhua

Acta of Bioengineering and Biomechanics

|

2021

|

Vol. 23, no. 1

135--147

EN

Purpose: Atherosclerosis causes plaque to build-up in arteries. Effect of the specific local hemodynamic environment around an atherosclerotic plaque on the thrombosis formation does not remain quite clear but is believed to be crucial. The aim of this study is to uncover the flow effects on plaques formation. Methods: To study the mechanically regulated plaque formation, the flow fields in artery blood vessels with different stenosis rates at various Reynolds numbers were simulated numerically with the two-dimensional axisymmetric models, and the hemodynamic characteristics around the plaque were scaled with stenosis rate and Reynolds number. Results: The results showed that increases of both Reynolds number and stenosis rate facilitated the occurrence of flow separation phenomenon, extended recirculation zone, and upregulated the maximum normalized wall shear stress near the plaque throat section while downregulated the minimal normalized wall shear stress at the front shoulder of plaque, as it should be; in the atherosclerotic plaque leeside of the recirculation zone, an obvious catch bond region of wall shear stress might exist especially under low Reynolds number with stenosis rate smaller than 30%. This catch bond region in the plaque leeside might be responsible for the LBF (low blood flow)-enhanced formation of the atherosclerotic plaque. Conclusions: This work may provide a novel insight into understanding the biomechanical effects behind the formation and damage of atherosclerotic plaques and propose a new strategy for preventing atherosclerotic diseases.

2

Automated characterization and classification of coronary atherosclerotic plaques for intravascular optical coherence tomography

Yang Jianli, Zhang Bo, Wang Hongrui, Lin Feng, Han Yechen, Liu Xiuling

Biocybernetics and Biomedical Engineering

|

2019

|

Vol. 39, no. 3

719--727

EN

Identification of coronary atherosclerotic plaques and vulnerable plaques is of great clinical significance in the diagnosis and treatment of coronary artery diseases, such as myocardial infarction and sudden death. Optical coherence tomography (OCT) is a catheter-based intracoronary imaging technique with high resolution (<20 μm) adopted to study the morphology of atherosclerotic plaques and identification of the composition of plaques. Nevertheless, manual characterization and quantification of plaques by clinicians is a labor-intensive and subjective procedure. This study aimed to propose a novel plaque characterization algorithm to automatically characterize and classify the atherosclerotic plaques (fibrous, calcific, and lipid-rich). First, nongeometric features such as Fisher vector, principal component analysis, histogram of the oriented gradient, and local binary pattern were investigated and adapted to two geometric features (basic feature and texture feature) to characterize the plaques. Second, for automated classification of the plaques, a hard example mining strategy was introduced to train support vector machine classifier and improve the effectiveness of training data. Third, to demonstrate the relationship between the selected features and the plaque classification accuracy, different feature compositions and comparisons were presented. The contribution of key features to the final classification was revealed. Datasets from 20 OCT pullbacks of 9 patients were used in the training and testing using the proposed algorithm. The overall classification accuracy reached 96.8%, and that of fibrous, calcific, and lipid-rich plaques was 94%, 97.2%, and 99.2%, respectively.

3

Recognition of atherosclerotic plaques and their extended dimensioning with computerized tomography angiography imaging

Markiewicz T., Dziekiewicz M., Maruszyński M., Bogusławska-Walecka R., Kozłowski W.

International Journal of Applied Mathematics and Computer Science

|

2014

|

Vol. 24, no. 1

33--47

EN

In this paper the authors raise the issue of automatic discrimination of atherosclerotic plaques within an artery lumen based on numerical and statistical thresholding of Computerized Tomography Angiographic (CTA) images and their advanced dimensioning as a support for preoperative vessel assessment. For the study, a set of tomograms of the aorta, as well as the ilio-femoral and femoral arteries were examined. In each case a sequence of about 130–480 images of the artery cutoff planes were analyzed prior to their segmentation based on morphological image transformation. A crucial step in the staging of atherosclerotic alteration is recognition of the plaque in the CTA image. To solve this problem, statistical and linear fitting methods, including the least-squares approximation by polynomial and spline polynomial functions, as well as the error fitting function were used. Also, new descriptors of atherosclerotic changes, such as the lumen decrease factor, the circumference occupancy factor, and the convex plaque area factor, are proposed as a means of facilitating preoperative vessel examination. Finally, ways to reduce the computational time are discussed. The proposed methods can be very useful for automatic quantification of atherosclerotic changes visualized by CTA imaging.

4

Możliwości zastosowania terapii fotodynamicznej w leczeniu chorób naczyń krwionośnych

Derkacz A., Biały D., Wawrzyńska M.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

|

2003

|

Vol. 9, nr 1-2

83-91

PL

Terapia fotodynamiczna (PDT) jest nową, obiecującą metodą wprowadzaną do leczenia chorób naczyń krwionośnych. Zastosowanie PDT daje możliwość bezpiecznego i selektywnego zniszczenia struktur blaszki miażdżycowej oraz powstrzymania ewentualnego procesu nawrotu zwężenia po zabiegach konwencjonalnej angioplastyki wewnątrznaczyniowej. W poniższym opracowaniu przedstawiono wyniki przeprowadzonych do tej pory doświadczeń na eksperymentalnych modelach zwierzęcych oraz pierwszych prób klinicznych z zastosowaniem PDT.

EN

Photodynamic therapy (PDT) is a new promising method applied to cardiovascular diseases. The potential of PDT for atraumatic and effective debulking of atheromatous plaque and postulated capability to inhibit or reduce restenosis are being studied. This review presents recent results of experimental animal studies and first clinical trials of the presented method.

5

Diagnostyka fotodynamiczna in vitro zmian miażdżycowych w naczyniach krwionośnych z użyciem mono-l-aspartyl chlorinu e6. Doniesienie wstępne

Biały D., Derkacz A., Wawrzyńska M., Smereka A., Bednarkiewicz A., Stręk W., Ziółkowski P.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

|

2003

|

Vol. 9, nr 3-4

141-146

PL

Diagnostyka (PDD) i terapia (PDT) fotodynamiczna jest jedną z nowych metod wykorzystywanych do tej pory w rozpoznawaniu i leczeniu zmian nowotworowych. Celem poniższej pracy była ocena in vitro skuteczności PDD z użyciem mono-L-aspartyl chlorinu e6 jako fotouczulacza w diagnostyce poszczególnych stadiów zaawansowania blaszki miażdżycowej. Uzyskane wyniki świadcząo tym, że spektroskopowa ocena fluorescencji indukowanej może być wiarygodną metodą detekcji zmian miażdżycowych.

EN

Photodynamic diagnosis (PDD) and therapy (PDT) is a new method used in clinical practice for diagnosing and treating neoplasms. The purpose of the following study was to asses in vitro the capability of PDD with use of mono-L-aspartyl chlorin e6 to recognize atherosclerotic plaque. The results of the study confirm that PDD may be a useful diagnostic tool for identifying atherosclerotic artery wall changes.