2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2013
Low density lipoprotein (LDL) has a significant role on the atherosclerotic plaque development, w... more Low density lipoprotein (LDL) has a significant role on the atherosclerotic plaque development, while the concentration of high density lipoproteins (HDL) is considered to play an atheroprotective role according to several biochemical mechanisms. In this work, it is the first time that both LDL and HDL concentrations are taken into account in order to predict the regions prone for plaque development. Our modeling approach is based on the use of a realistic three-dimensional reconstructed pig coronary artery in two time points. Biochemical data measured in the pig were also included in order to develop a more customized model. We modeled coronary blood flow by solving the Navier-Stokes equations in the arterial lumen and plasma filtration in the arterial wall using Darcy's Law. HDL transport was modeled only in the arterial lumen using the convection-diffusion equation, while LDL transport was modeled both in the lumen and the arterial wall. An additional novelty of this work is that we model the oxidation of LDL taking into account the atheroprotective role of HDL. The results of our model were in good agreement with histological findings demonstrating that increased oxidized LDL is found near regions of advanced plaques, while non-oxidized LDL is found in regions of early plaque types.
European heart journal cardiovascular Imaging, Jan 17, 2018
To examine the efficacy of angiography derived endothelial shear stress (ESS) in predicting ather... more To examine the efficacy of angiography derived endothelial shear stress (ESS) in predicting atherosclerotic disease progression. Thirty-five patients admitted with ST-elevation myocardial infarction that had three-vessel intravascular ultrasound (IVUS) immediately after revascularization and at 13 months follow-up were included. Three dimensional (3D) reconstruction of the non-culprit vessels were performed using (i) quantitative coronary angiography (QCA) and (ii) methodology involving fusion of IVUS and biplane angiography. In both models, blood flow simulation was performed and the minimum predominant ESS was estimated in 3 mm segments. Baseline plaque characteristics and ESS were used to identify predictors of atherosclerotic disease progression defied as plaque area increase and lumen reduction at follow-up. Fifty-four vessels were included in the final analysis. A moderate correlation was noted between ESS estimated in the 3D QCA and the IVUS-derived models (r = 0.588, P < ...
Purpose: To study the dose and time effect of external beam irradiation on the morphometry of bot... more Purpose: To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. Methods and materials: Eight groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy 6 MV X-ray dose, (c) with a 18-Gy, (d) treated with balloon angioplasty,
Heart failure (HF) is a chronic disease associated with significant prevalence, mortality, and he... more Heart failure (HF) is a chronic disease associated with significant prevalence, mortality, and health care expenditure. The aim of the present study was to explore the factors associated with anxiety and depression experienced by patients hospitalized with HF. We evaluated 190 hospitalized HF patients in four public hospitals. The data were collected using a specific questionnaire, which, apart from demographic and clinical variables, included the Hospital Anxiety and Depression Scale (HADS). In the total sample, 24.7% and 32.6% of patients were found to have moderate or high levels of anxiety, respectively. Simple multinomial logistic regression showed that no characteristic was significantly associated with anxiety. It also appeared that 17.4% of patients had minor and 24.2% major depression. Among the factors examined, longer disease duration was associated with a higher probability of being depressed (p=0.041). Moreover, single/divorced and widowed patients were more likely to have major depression compared to married patients (35.6% vs. 19.2%, p=0.046). Simple multinomial logistic regression revealed that married patients were 59% less likely to have major depression compared to their unmarried counterparts (OR: 0.41). Moreover, patients with short (&amp;amp;amp;amp;amp;amp;amp;amp;lt;1 year) and moderate (2-5 years) disease duration were 69% (OR: 0.31) and 61% (OR: 0.39) less likely to have major depression compared to those with a long disease duration. Multiple multinomial logistic regression showed that only the disease duration remained statistically significantly associated with depression after controlling for the rest of factors found to be significant at a univariate level. Nurses and physicians must take measures for the identification, assessment and management of anxiety and depression in this clinical population.
Advanced Topics in Scattering Theory and Biomedical Engineering - 9th International Workshop on Mathematical Methods in Scattering Theory and Biomedical Engineering, 2010
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2012
The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of co... more The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of coronary arteries using Frequency Domain Optical Coherence Tomography (FD-OCT) images. The rationale is to fuse the information about the curvature of the artery, derived from biplane angiographies, with the information regarding the lumen wall, which is produced from the FD-OCT examination. The method is based on a three step approach. In the first step the lumen borders in FD-OCT images are detected. In the second step a 3D curve is produced using the center line of the vessel from the two biplane projections. Finally in the third step the detected lumen borders are placed perpendicularly onto the path based on the centroid of each lumen border. The result is a 3D reconstructed artery produced by all the lumen borders of the FD-OCT pullback representing the 3D arterial geometry of the vessel.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolut... more Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolution tomographic images of the coronary lumen and outer vessel wall. While OCT images present morphological information in highly resolved detail, the characterization of the various plaque components relies on trained readers. The aim of this study is to extract a set of features in grayscale OCT images and to use them in order to classify the atherosclerotic plaque. Intensity and texture based features we used in order to classify the plaque in four plaque types: Calcium (C), Lipid Pool (LP), Fibrous Tissue (FT) and Mixed Plaque (MP). 50 OCT annotated images from 3 patients were used to train and test the proposed plaque characterization method. Using a Random Forests classifier overall classification accuracy 80.41% is reported.
2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2013
Low density lipoprotein (LDL) has a significant role on the atherosclerotic plaque development, w... more Low density lipoprotein (LDL) has a significant role on the atherosclerotic plaque development, while the concentration of high density lipoproteins (HDL) is considered to play an atheroprotective role according to several biochemical mechanisms. In this work, it is the first time that both LDL and HDL concentrations are taken into account in order to predict the regions prone for plaque development. Our modeling approach is based on the use of a realistic three-dimensional reconstructed pig coronary artery in two time points. Biochemical data measured in the pig were also included in order to develop a more customized model. We modeled coronary blood flow by solving the Navier-Stokes equations in the arterial lumen and plasma filtration in the arterial wall using Darcy&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s Law. HDL transport was modeled only in the arterial lumen using the convection-diffusion equation, while LDL transport was modeled both in the lumen and the arterial wall. An additional novelty of this work is that we model the oxidation of LDL taking into account the atheroprotective role of HDL. The results of our model were in good agreement with histological findings demonstrating that increased oxidized LDL is found near regions of advanced plaques, while non-oxidized LDL is found in regions of early plaque types.
European heart journal cardiovascular Imaging, Jan 17, 2018
To examine the efficacy of angiography derived endothelial shear stress (ESS) in predicting ather... more To examine the efficacy of angiography derived endothelial shear stress (ESS) in predicting atherosclerotic disease progression. Thirty-five patients admitted with ST-elevation myocardial infarction that had three-vessel intravascular ultrasound (IVUS) immediately after revascularization and at 13 months follow-up were included. Three dimensional (3D) reconstruction of the non-culprit vessels were performed using (i) quantitative coronary angiography (QCA) and (ii) methodology involving fusion of IVUS and biplane angiography. In both models, blood flow simulation was performed and the minimum predominant ESS was estimated in 3 mm segments. Baseline plaque characteristics and ESS were used to identify predictors of atherosclerotic disease progression defied as plaque area increase and lumen reduction at follow-up. Fifty-four vessels were included in the final analysis. A moderate correlation was noted between ESS estimated in the 3D QCA and the IVUS-derived models (r = 0.588, P < ...
Purpose: To study the dose and time effect of external beam irradiation on the morphometry of bot... more Purpose: To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. Methods and materials: Eight groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy 6 MV X-ray dose, (c) with a 18-Gy, (d) treated with balloon angioplasty,
Heart failure (HF) is a chronic disease associated with significant prevalence, mortality, and he... more Heart failure (HF) is a chronic disease associated with significant prevalence, mortality, and health care expenditure. The aim of the present study was to explore the factors associated with anxiety and depression experienced by patients hospitalized with HF. We evaluated 190 hospitalized HF patients in four public hospitals. The data were collected using a specific questionnaire, which, apart from demographic and clinical variables, included the Hospital Anxiety and Depression Scale (HADS). In the total sample, 24.7% and 32.6% of patients were found to have moderate or high levels of anxiety, respectively. Simple multinomial logistic regression showed that no characteristic was significantly associated with anxiety. It also appeared that 17.4% of patients had minor and 24.2% major depression. Among the factors examined, longer disease duration was associated with a higher probability of being depressed (p=0.041). Moreover, single/divorced and widowed patients were more likely to have major depression compared to married patients (35.6% vs. 19.2%, p=0.046). Simple multinomial logistic regression revealed that married patients were 59% less likely to have major depression compared to their unmarried counterparts (OR: 0.41). Moreover, patients with short (&amp;amp;amp;amp;amp;amp;amp;amp;lt;1 year) and moderate (2-5 years) disease duration were 69% (OR: 0.31) and 61% (OR: 0.39) less likely to have major depression compared to those with a long disease duration. Multiple multinomial logistic regression showed that only the disease duration remained statistically significantly associated with depression after controlling for the rest of factors found to be significant at a univariate level. Nurses and physicians must take measures for the identification, assessment and management of anxiety and depression in this clinical population.
Advanced Topics in Scattering Theory and Biomedical Engineering - 9th International Workshop on Mathematical Methods in Scattering Theory and Biomedical Engineering, 2010
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2012
The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of co... more The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of coronary arteries using Frequency Domain Optical Coherence Tomography (FD-OCT) images. The rationale is to fuse the information about the curvature of the artery, derived from biplane angiographies, with the information regarding the lumen wall, which is produced from the FD-OCT examination. The method is based on a three step approach. In the first step the lumen borders in FD-OCT images are detected. In the second step a 3D curve is produced using the center line of the vessel from the two biplane projections. Finally in the third step the detected lumen borders are placed perpendicularly onto the path based on the centroid of each lumen border. The result is a 3D reconstructed artery produced by all the lumen borders of the FD-OCT pullback representing the 3D arterial geometry of the vessel.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolut... more Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolution tomographic images of the coronary lumen and outer vessel wall. While OCT images present morphological information in highly resolved detail, the characterization of the various plaque components relies on trained readers. The aim of this study is to extract a set of features in grayscale OCT images and to use them in order to classify the atherosclerotic plaque. Intensity and texture based features we used in order to classify the plaque in four plaque types: Calcium (C), Lipid Pool (LP), Fibrous Tissue (FT) and Mixed Plaque (MP). 50 OCT annotated images from 3 patients were used to train and test the proposed plaque characterization method. Using a Random Forests classifier overall classification accuracy 80.41% is reported.
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Papers by Lampros Michalis