— The paper describes the computation of motion trajectories in ultrasound videos of atherosclero... more — The paper describes the computation of motion trajectories in ultrasound videos of atherosclerotic plaques. Preliminary results indicate that motion trajectories follow the cardiac cycles, forcing motions from different parts of the plaque and arterial walls to appear in phase. Based on the periodicity of the motion, we found that a Fourier series, using a small number of harmonics, can approximate the periodic motion due to the cardiac motion cycle. Furthermore, plaque motion exhibited larger deviations and more abrupt changes than arterial wall motion. Index Terms — Atherosclerosis, motion estimation, ultrasound,
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Speech signals may provide important information for measuring and modelling human behaviour, esp... more Speech signals may provide important information for measuring and modelling human behaviour, especially for assessing mental health as well as estimating the emotional state of a person. Speaker’s physiological and/or physical state may be thus identified by detecting the cognitive decline (CD) or stress levels using signal analysis of voice. This preliminary study presents a survey on methods introduced for CD and stress voice detection in humans. It is shown that increase in signal’s fundamental frequency (f0) as well as its frequency formants, are the most common effects of CD and stress. Additional voice parameters could be used to identify normal from CD and normal from stressed voice as well as the cognitive state of the elderly. The present study poses the initiation of a project for the development of a mobile application for the automated voice detection and analysis on the fly, which will aid in the detection of early signs of CD and stress. Further investigation with app...
Abstract—It is well-known that speckle is a multiplica-tive noise that degrades the visual evalua... more Abstract—It is well-known that speckle is a multiplica-tive noise that degrades the visual evaluation in ultrasound imaging. The recent advancements in ultrasound instru-mentation and portable ultrasound devices necessitate the need of more robust despeckling techniques for enhanced ultrasound medical imaging for both routine clinical prac-tice and teleconsultation. The objective of this work was to carry out a comparative evaluation of despeckle filtering based on texture analysis, image quality evaluation met-rics, and visual evaluation by medical experts in the as-sessment of 440 (220 asymptomatic and 220 symptomatic) ultrasound images of the carotid artery bifurcation. In this paper a total of 10 despeckle filters were evaluated based on local statistics, median filtering, pixel homogeneity, ge-ometric filtering, homomorphic filtering, anisotropic diffu-
High-resolution vascular B-mode and Doppler ultrasound provide information not only on the degree... more High-resolution vascular B-mode and Doppler ultrasound provide information not only on the degree of carotid artery stenosis but also on the characteristics of the arterial wall including the size and consistency of atherosclerotic plaques [1]. Carotid stenosis alone has limitations in predicting risk and does not show plaque vulnerability and instability, thus other ultrasonographic plaque morphologic characteristics have been studied for better prediction of the risk stroke. Plaque echogenicity as assessed by B-mode ultrasound has been found to reliably predict the content of soft tissue and the amount of calcification in carotid plaques. Additionally, it has been reported that subjects with echolucent atherosclerotic plaques have increased risk of ischemic cerebrovascular events [2]. More recent studies by Nicolaides et al. [3] Topakian et al. [4] and Kyriacou et al. [5], showed that plaque echolucency and plaque morphology can be used to predict stroke. Other studies have report...
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2021
Recent studies have suggested that textural characteristics of the intima-media complex (IMC) may... more Recent studies have suggested that textural characteristics of the intima-media complex (IMC) may be more useful than the intima-media thickness (IMT) in evaluating cardiovascular risk. The primary aim of our study was to investigate the association between texture features of the common carotid IMC and prevalent clinical cardiovascular disease (CVD). The secondary aim was to determine whether IMT and IMC texture features vary between the left and right carotid arteries. The study was performed on 2208 longitudinal-section ultrasound images of the left (L) and right (R) common carotid artery (CCA), acquired from 569 men and 535 women out of which 125 had clinical CVD. L and R sides of the IMC were intensity normalized and despeckled. The IMC was semiautomatically delineated for all images using a semiautomated segmentation system, and 61 different texture features were extracted. The corresponding IMT semiautomated measurements (mean±SD) of the L and R sides were 0.73±0.21 mm/0.69±0...
Stroke is one of the most important causes of death in the world and the leading cause of serious... more Stroke is one of the most important causes of death in the world and the leading cause of serious, long-term disability. There is an urgent need for better techniques to diagnose patients at risk of stroke based on the measurements of the intima media thickness (IMT) and the segmentation of the atherosclerotic carotid plaque. The objective of this work was to carry out a comparative evaluation of despeckle filtering on ultrasound images of the carotid artery, and develop a new segmentation system, for detecting the IMT of the common carotid artery and the borders of the athrerosclerotic carotid plaque in longitudinal ultrasound images of the carotid artery. To the, best of our knowledge no similar system has been developed for segmenting the atherosclerotic carotid plaque, although a number of techniques have been proposed for IMT segmentation. A total of 11 despeckle filtering methods were evaluated based on texture analysis, image quality evaluation metrics, and visual evaluation ...
The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early in... more The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early indicator of the development of cardiovascular disease (CVD). It was proposed but not thoroughly investigated that the media thickness (MT), its composition and texture may be indicative for identifying the risk of stroke and differentiating between patients with high and low risk. In this study we present an automated method for segmentation of the media layer and measurement of its thickness in ultrasound images of the CCA.
In this paper we discuss the use of clinical quality criteria in the assessment and design of ult... more In this paper we discuss the use of clinical quality criteria in the assessment and design of ultrasound video compression systems. Our goal is to design efficient systems that can be used to transmit quality ultrasound videos at the lowest possible bitrates. This led us to the development of a spatially- varying encoding scheme, where quantization levels are spatially varying as a function of the diagnostic significance of the video. Diagnostic Regions of Interest (ROIs) for carotid ultrasound medical video are defined, which are then used as input for Flexible Macroblock Ordering (FMO) slice encoding. Diagnostically relevant FMO slice encoding is attained by enabling variable quality slice encoding, tightly coupled by each region's diagnostic importance. Redundant Slices (RS) utilization increases compressed video's resilience over error prone transmission mediums. We present preliminary findings on three carotid ultrasound videos at CIF resolution, for packet loss rates u...
The carotid artery wall motion characteristics from ultrasound videos may provide useful informat... more The carotid artery wall motion characteristics from ultrasound videos may provide useful information regarding healthy, asymptomatic or symptomatic subjects as well as aid in the development and validation of motion analysis algorithms. This still remains a challenging task, as actual motion characteristics and indices are not directly available. In the present work we propose a methodology for generating simulated common carotid artery (CCA) ultrasound videos, which consists of the following steps: i) Generate the first frame of the CCA video using an artificial carotid image, ii) Generate the consecutive video frames by applying motion in the axial and radial directions, iii) Apply random speckle noise in each consecutive video frame, iv) Generate the systolic and diastolic frames of the entire cardiac cycle and v) Extract measurements for evaluating the CCA motion characteristics. A total of 120 frames were generated for each simulated video covering three cardiac cycles. Error measurements are presented for evaluating the simulation result. The proposed simulation procedure is simple and not computationally efficient and can thus be used widely in assessing the performance of different motion estimation and analysis algorithms.
The objective of this study was to investigate differences in intima-media thickness (IMT) and di... more The objective of this study was to investigate differences in intima-media thickness (IMT) and diameter (D) measurements of the common carotid artery (CCA) in ultrasound imaging in normal subjects and renal failure disease (RFD) patients. Manual measurements by two experts and automated segmentation measurements (based on snakes and active contour models (ACM)) were carried out on 73 normal subjects, and 80 RFD patients. Statistical analysis was carried out using the Wilcoxon rank-sum test at p<0.05. Results demonstrated that the mean IMT and D measurements were significantly higher for the RFD group versus the normal group. Moreover, there was no significant difference between the manual and automated measurements. The ACM segmentation was slightly more accurate than segmentation based on snakes. Further work is needed to validate these findings on a larger group of subjects.
IEEE Int. Special Topic Conf. on Inform. Technology in Biomedicine, Oct 26, 2006
Abstract—The paper describes the computation of motion trajectories in ultrasound videos of ather... more Abstract—The paper describes the computation of motion trajectories in ultrasound videos of atherosclerotic plaques. Preliminary results indicate that motion trajectories follow the cardiac cycles, forcing motions from different parts of the plaque and arterial walls to appear in phase. Based on the periodicity of the motion, we found that a Fourier series, using a small number of harmonics, can approximate the periodic motion due to the cardiac motion cycle.
IEEE journal of translational engineering in health and medicine, 2017
The objective of this paper was to investigate texture feature variability in ultrasound video of... more The objective of this paper was to investigate texture feature variability in ultrasound video of the carotid artery during the cardiac cycle in an attempt to define new discriminatory biomarkers of the vulnerable plaque. More specifically, in this paper, 120 longitudinal ultrasound videos, acquired from 40 normal (N) subjects from the common carotid artery and 40 asymptomatic (A) and 40 symptomatic (S) subjects from the proximal internal carotid artery were investigated. The videos were intensity normalized and despeckled, and the intima-media complex (IMC) (from the N subjects) and the atherosclerotic carotid plaques (from the A and S subjects) were segmented from each video, in order to extract the M-mode image, and the texture features associated with cardiac states of systole and diastole. The main results of this paper can be summarized as follows: 1) texture features varied significantly throughout the cardiac cycle with significant differences identified between the cardiac ...
— The paper describes the computation of motion trajectories in ultrasound videos of atherosclero... more — The paper describes the computation of motion trajectories in ultrasound videos of atherosclerotic plaques. Preliminary results indicate that motion trajectories follow the cardiac cycles, forcing motions from different parts of the plaque and arterial walls to appear in phase. Based on the periodicity of the motion, we found that a Fourier series, using a small number of harmonics, can approximate the periodic motion due to the cardiac motion cycle. Furthermore, plaque motion exhibited larger deviations and more abrupt changes than arterial wall motion. Index Terms — Atherosclerosis, motion estimation, ultrasound,
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Speech signals may provide important information for measuring and modelling human behaviour, esp... more Speech signals may provide important information for measuring and modelling human behaviour, especially for assessing mental health as well as estimating the emotional state of a person. Speaker’s physiological and/or physical state may be thus identified by detecting the cognitive decline (CD) or stress levels using signal analysis of voice. This preliminary study presents a survey on methods introduced for CD and stress voice detection in humans. It is shown that increase in signal’s fundamental frequency (f0) as well as its frequency formants, are the most common effects of CD and stress. Additional voice parameters could be used to identify normal from CD and normal from stressed voice as well as the cognitive state of the elderly. The present study poses the initiation of a project for the development of a mobile application for the automated voice detection and analysis on the fly, which will aid in the detection of early signs of CD and stress. Further investigation with app...
Abstract—It is well-known that speckle is a multiplica-tive noise that degrades the visual evalua... more Abstract—It is well-known that speckle is a multiplica-tive noise that degrades the visual evaluation in ultrasound imaging. The recent advancements in ultrasound instru-mentation and portable ultrasound devices necessitate the need of more robust despeckling techniques for enhanced ultrasound medical imaging for both routine clinical prac-tice and teleconsultation. The objective of this work was to carry out a comparative evaluation of despeckle filtering based on texture analysis, image quality evaluation met-rics, and visual evaluation by medical experts in the as-sessment of 440 (220 asymptomatic and 220 symptomatic) ultrasound images of the carotid artery bifurcation. In this paper a total of 10 despeckle filters were evaluated based on local statistics, median filtering, pixel homogeneity, ge-ometric filtering, homomorphic filtering, anisotropic diffu-
High-resolution vascular B-mode and Doppler ultrasound provide information not only on the degree... more High-resolution vascular B-mode and Doppler ultrasound provide information not only on the degree of carotid artery stenosis but also on the characteristics of the arterial wall including the size and consistency of atherosclerotic plaques [1]. Carotid stenosis alone has limitations in predicting risk and does not show plaque vulnerability and instability, thus other ultrasonographic plaque morphologic characteristics have been studied for better prediction of the risk stroke. Plaque echogenicity as assessed by B-mode ultrasound has been found to reliably predict the content of soft tissue and the amount of calcification in carotid plaques. Additionally, it has been reported that subjects with echolucent atherosclerotic plaques have increased risk of ischemic cerebrovascular events [2]. More recent studies by Nicolaides et al. [3] Topakian et al. [4] and Kyriacou et al. [5], showed that plaque echolucency and plaque morphology can be used to predict stroke. Other studies have report...
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2021
Recent studies have suggested that textural characteristics of the intima-media complex (IMC) may... more Recent studies have suggested that textural characteristics of the intima-media complex (IMC) may be more useful than the intima-media thickness (IMT) in evaluating cardiovascular risk. The primary aim of our study was to investigate the association between texture features of the common carotid IMC and prevalent clinical cardiovascular disease (CVD). The secondary aim was to determine whether IMT and IMC texture features vary between the left and right carotid arteries. The study was performed on 2208 longitudinal-section ultrasound images of the left (L) and right (R) common carotid artery (CCA), acquired from 569 men and 535 women out of which 125 had clinical CVD. L and R sides of the IMC were intensity normalized and despeckled. The IMC was semiautomatically delineated for all images using a semiautomated segmentation system, and 61 different texture features were extracted. The corresponding IMT semiautomated measurements (mean±SD) of the L and R sides were 0.73±0.21 mm/0.69±0...
Stroke is one of the most important causes of death in the world and the leading cause of serious... more Stroke is one of the most important causes of death in the world and the leading cause of serious, long-term disability. There is an urgent need for better techniques to diagnose patients at risk of stroke based on the measurements of the intima media thickness (IMT) and the segmentation of the atherosclerotic carotid plaque. The objective of this work was to carry out a comparative evaluation of despeckle filtering on ultrasound images of the carotid artery, and develop a new segmentation system, for detecting the IMT of the common carotid artery and the borders of the athrerosclerotic carotid plaque in longitudinal ultrasound images of the carotid artery. To the, best of our knowledge no similar system has been developed for segmenting the atherosclerotic carotid plaque, although a number of techniques have been proposed for IMT segmentation. A total of 11 despeckle filtering methods were evaluated based on texture analysis, image quality evaluation metrics, and visual evaluation ...
The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early in... more The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early indicator of the development of cardiovascular disease (CVD). It was proposed but not thoroughly investigated that the media thickness (MT), its composition and texture may be indicative for identifying the risk of stroke and differentiating between patients with high and low risk. In this study we present an automated method for segmentation of the media layer and measurement of its thickness in ultrasound images of the CCA.
In this paper we discuss the use of clinical quality criteria in the assessment and design of ult... more In this paper we discuss the use of clinical quality criteria in the assessment and design of ultrasound video compression systems. Our goal is to design efficient systems that can be used to transmit quality ultrasound videos at the lowest possible bitrates. This led us to the development of a spatially- varying encoding scheme, where quantization levels are spatially varying as a function of the diagnostic significance of the video. Diagnostic Regions of Interest (ROIs) for carotid ultrasound medical video are defined, which are then used as input for Flexible Macroblock Ordering (FMO) slice encoding. Diagnostically relevant FMO slice encoding is attained by enabling variable quality slice encoding, tightly coupled by each region's diagnostic importance. Redundant Slices (RS) utilization increases compressed video's resilience over error prone transmission mediums. We present preliminary findings on three carotid ultrasound videos at CIF resolution, for packet loss rates u...
The carotid artery wall motion characteristics from ultrasound videos may provide useful informat... more The carotid artery wall motion characteristics from ultrasound videos may provide useful information regarding healthy, asymptomatic or symptomatic subjects as well as aid in the development and validation of motion analysis algorithms. This still remains a challenging task, as actual motion characteristics and indices are not directly available. In the present work we propose a methodology for generating simulated common carotid artery (CCA) ultrasound videos, which consists of the following steps: i) Generate the first frame of the CCA video using an artificial carotid image, ii) Generate the consecutive video frames by applying motion in the axial and radial directions, iii) Apply random speckle noise in each consecutive video frame, iv) Generate the systolic and diastolic frames of the entire cardiac cycle and v) Extract measurements for evaluating the CCA motion characteristics. A total of 120 frames were generated for each simulated video covering three cardiac cycles. Error measurements are presented for evaluating the simulation result. The proposed simulation procedure is simple and not computationally efficient and can thus be used widely in assessing the performance of different motion estimation and analysis algorithms.
The objective of this study was to investigate differences in intima-media thickness (IMT) and di... more The objective of this study was to investigate differences in intima-media thickness (IMT) and diameter (D) measurements of the common carotid artery (CCA) in ultrasound imaging in normal subjects and renal failure disease (RFD) patients. Manual measurements by two experts and automated segmentation measurements (based on snakes and active contour models (ACM)) were carried out on 73 normal subjects, and 80 RFD patients. Statistical analysis was carried out using the Wilcoxon rank-sum test at p<0.05. Results demonstrated that the mean IMT and D measurements were significantly higher for the RFD group versus the normal group. Moreover, there was no significant difference between the manual and automated measurements. The ACM segmentation was slightly more accurate than segmentation based on snakes. Further work is needed to validate these findings on a larger group of subjects.
IEEE Int. Special Topic Conf. on Inform. Technology in Biomedicine, Oct 26, 2006
Abstract—The paper describes the computation of motion trajectories in ultrasound videos of ather... more Abstract—The paper describes the computation of motion trajectories in ultrasound videos of atherosclerotic plaques. Preliminary results indicate that motion trajectories follow the cardiac cycles, forcing motions from different parts of the plaque and arterial walls to appear in phase. Based on the periodicity of the motion, we found that a Fourier series, using a small number of harmonics, can approximate the periodic motion due to the cardiac motion cycle.
IEEE journal of translational engineering in health and medicine, 2017
The objective of this paper was to investigate texture feature variability in ultrasound video of... more The objective of this paper was to investigate texture feature variability in ultrasound video of the carotid artery during the cardiac cycle in an attempt to define new discriminatory biomarkers of the vulnerable plaque. More specifically, in this paper, 120 longitudinal ultrasound videos, acquired from 40 normal (N) subjects from the common carotid artery and 40 asymptomatic (A) and 40 symptomatic (S) subjects from the proximal internal carotid artery were investigated. The videos were intensity normalized and despeckled, and the intima-media complex (IMC) (from the N subjects) and the atherosclerotic carotid plaques (from the A and S subjects) were segmented from each video, in order to extract the M-mode image, and the texture features associated with cardiac states of systole and diastole. The main results of this paper can be summarized as follows: 1) texture features varied significantly throughout the cardiac cycle with significant differences identified between the cardiac ...
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Papers by Christos P Loizou