mahsa paknezhad - Academia.edu (original) (raw)

Papers by mahsa paknezhad

Motivation: High resolution 2D whole slide imaging provides rich information about the tissue str... more Motivation: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions that each individual tissue slice experiences while cutting and mounting the tissue on the glass slide. Performing registration for the whole tissue slices may be adversely affected by the deformed tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose an accurate and robust regional registration algorithm for whole slide images which incrementally focuses registration on the area around the region of interest. Results: Using mean similarity index as the metric, the proposed algorithm (mean pm\pmpm std: 0.84pm0.110.84 \pm 0.110.84pm0.11) followed by a fine registration algorithm ($0.86 \pm 0.08$) outperf...

Biomedical Optics Express

Background: High resolution 2D whole slide imaging provides rich information about the tissue str... more Background: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions such as tissue tearing, folding and missing at each slide. Performing registration for the whole tissue slices may be adversely affected by distorted tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose a new approach to an accurate and robust registration of regions of interest for whole slide images. We introduce the idea of multi-scale attention for registration. Results: Using mean similarity index as the metric, the proposed algorithm (mean +- std: 0.84 +- 0.11) followed by a fine registration algorithm (0.86 +- 0.08) outperformed the state-of-the-art linear whole tissue regist...

Background: High resolution 2D whole slide imaging provides rich information about the tissue str... more Background: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions that each individual tissue slice experiences while cutting and mounting the tissue on the glass slide. Performing registration for the whole tissue slices may be adversely affected by the deformed tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose an accurate and robust regional registration algorithm for whole slide images which incrementally focuses registration on the area around the region of interest. Results: Using mean similarity index as the metric, the proposed algorithm (mean +- std: 0.84 +- 0.11) followed by a fine registration algorithm (0.86 +- 0.08) outperformed the...

Motivation High resolution 2D whole slide imaging provides rich information about the tissue stru... more Motivation High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions that each individual tissue slice experiences while cutting and mounting the tissue on the glass slide. Performing registration for the whole tissue slices may be adversely affected by the deformed tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose an accurate and robust regional registration algorithm for whole slide images which incrementally focuses registration on the area around the region of interest. Results Using mean similarity index as the metric, the proposed algorithm (mean ± std: 0.84 ± 0.11) followed by a fine registration algorithm (0.86 ± 0.08) outperformed the state-of-the-art linear whole tissue registration algorithm (0.74±0.19) and the regional version of this algorithm (0.81±0.15). The proposed algorithm also outperforms the state-of-the-art nonlinear registration algorithm (original: 0.82 ± 0.12, regional: 0.77 ± 0.22) for whole slide images and a recently proposed patch-based registration algorithm (patch size 256: 0.79 ± 0.16 , patch size 512: 0.77 ± 0.16) for medical images.

Medical Image Computing and Computer-Assisted Intervention - MICCAI 2016, 2016

Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases i... more Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases is important in diagnosing cardio-vascular diseases. Proper estimation of the volume requires knowledge of which MRI slice contains the topmost basal region of the LV. Automatic basal slice detection has proved challenging; as a result, basal slice detection remains a manual task which is prone to inter-observer variability. This paper presents a novel method that is able to track the basal slice over the whole cardiac cycle. The method was tested on 56 healthy and pathological cases and was able to identify the basal slices similar to experts' selection for 80 % and 85 % of the cases for end-diastole and end-systole, respectively. This provides a significant improvement over the leading state-of-the-art approach that obtained 59 % and 44 % agreement with experts on the same input.

Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trac... more Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trackers have become increasingly popular today, such as the Fitbit. This study aimed to compare the average number of steps per day using the wrist-worn Fitbit Flex and waist-worn Acti-Graph (wGT3X-BT) in free-living conditions. Methods 104 adult participants (n = 35 males; n = 69 females) were asked to wear a Fitbit Flex and an ActiGraph concurrently for 7 days. Daily step counts were used to classify inactive (<10,000 steps) and active (!10,000 steps) days, which is one of the commonly used physical activity guidelines to maintain health. Proportion of agreement between physical activity categorizations from ActiGraph and Fitbit Flex was assessed. Statistical analyses included Spearman's rho, intraclass correlation (ICC), median absolute percentage error (MAPE), Kappa statistics, and Bland-Altman plots. Analyses were performed among all participants, by each step-defined daily physical activity category and gender. Results The median average steps/day recorded by Fitbit Flex and ActiGraph were 10193 and 8812, respectively. Strong positive correlations and agreement were found for all participants, both genders, as well as daily physical activity categories (Spearman's rho: 0.76-0.91; ICC: 0.73-0.87). The MAPE was: 15.5% (95% confidence interval [CI]: 5.8-28.1%) for overall steps, 16.9% (6.8-30.3%) vs. 15.1% (4.5-27.3%) in males and females, and 20.4% (8.7-35.9%) vs. 9.6% (1.0-18.4%) during inactive days and active days. Bland-Altman plot indicated a median overestimation of 1300 steps/day by the Fitbit Flex in all participants.

Computer Methods and Programs in Biomedicine

BACKGROUND AND OBJECTIVES Tagged MR images provide an effective way for regional analysis of the ... more BACKGROUND AND OBJECTIVES Tagged MR images provide an effective way for regional analysis of the myocardium strain. A reliable myocardium strain analysis requires both correct segmentation and accurate motion tracking of the myocardium during the cardiac cycle. While many algorithms have been proposed for accurate tracking of the myocardium in tagged MR images, little focus has been placed on ensuring correct segmentation of the tagged myocardium during the cardiac cycle. Myocardial strain analysis is usually done by segmenting the myocardium in end-diastole, generating a mesh from the segmentation, propagating the mesh through the cardiac cycle using the output deformation field from motion tracking, and measuring strain on the deforming mesh. Due to the imposed tag strips on the anatomy, identification of the myocardium boundaries is challenging in tagged MR images. As a result, there is no guarantee that the propagated mesh is annotating the myocardium accurately through the cardiac cycle. Moreover, clinical studies indicate that incorrect myocardium annotation can result in overestimation of myocardial strains. METHODS We introduce a method to improve reliability of strain analysis by proposing a mesh which correctly segments the myocardium in tagged MRI by leveraging the available cine MRI segmentation. In particular, we generate a series of mesh proposals using the cine MRI segmentation and find the propagated mesh proposal which gives the most accurate full-cycle myocardium segmentation. RESULTS The mesh selection algorithm was tested on 22 2D MRI scans of diseased and healthy hearts. The proposed algorithm provided more accurate whole-cycle myocardium segmentation compared to the propagated end-diastolic mesh. Regional myocardium strain was measured for 10 3D MRI scans of healthy volunteers using the proposed mesh and the end-diastolic mesh. The measured strain using the proposed mesh was more similar to the expected myocardium strain for a healthy heart than the measured strain using the end-diastolic mesh. CONCLUSION The proposed approach provides accurate whole-cycle tagged myocardium segmentation and more reliable myocardium strain analysis.

PLOS ONE, 2017

Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trac... more Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trackers have become increasingly popular today, such as the Fitbit. This study aimed to compare the average number of steps per day using the wrist-worn Fitbit Flex and waist-worn Acti-Graph (wGT3X-BT) in free-living conditions. Methods 104 adult participants (n = 35 males; n = 69 females) were asked to wear a Fitbit Flex and an ActiGraph concurrently for 7 days. Daily step counts were used to classify inactive (<10,000 steps) and active (!10,000 steps) days, which is one of the commonly used physical activity guidelines to maintain health. Proportion of agreement between physical activity categorizations from ActiGraph and Fitbit Flex was assessed. Statistical analyses included Spearman's rho, intraclass correlation (ICC), median absolute percentage error (MAPE), Kappa statistics, and Bland-Altman plots. Analyses were performed among all participants, by each step-defined daily physical activity category and gender. Results The median average steps/day recorded by Fitbit Flex and ActiGraph were 10193 and 8812, respectively. Strong positive correlations and agreement were found for all participants, both genders, as well as daily physical activity categories (Spearman's rho: 0.76-0.91; ICC: 0.73-0.87). The MAPE was: 15.5% (95% confidence interval [CI]: 5.8-28.1%) for overall steps, 16.9% (6.8-30.3%) vs. 15.1% (4.5-27.3%) in males and females, and 20.4% (8.7-35.9%) vs. 9.6% (1.0-18.4%) during inactive days and active days. Bland-Altman plot indicated a median overestimation of 1300 steps/day by the Fitbit Flex in all participants.

Lecture Notes in Computer Science, 2016

Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases i... more Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases is important in diagnosing cardio-vascular diseases. Proper estimation of the volume requires knowledge of which MRI slice contains the topmost basal region of the LV. Automatic basal slice detection has proved challenging; as a result, basal slice detection remains a manual task which is prone to inter-observer variability. This paper presents a novel method that is able to track the basal slice over the whole cardiac cycle. The method was tested on 56 healthy and pathological cases and was able to identify the basal slices similar to experts&#39; selection for 80 % and 85 % of the cases for end-diastole and end-systole, respectively. This provides a significant improvement over the leading state-of-the-art approach that obtained 59 % and 44 % agreement with experts on the same input.

Journal of medical imaging (Bellingham, Wash.), 2016

Identification of the basal slice in cardiac imaging is a key step to measuring the ejection frac... more Identification of the basal slice in cardiac imaging is a key step to measuring the ejection fraction of the left ventricle. Despite all the effort placed on automatic cardiac segmentation, basal slice identification is routinely performed manually. Manual identification, however, suffers from high interobserver variability. As a result, an automatic algorithm for basal slice identification is required. Guidelines published in 2013 identify the basal slice based on the percentage of myocardium surrounding the blood cavity in the short-axis view. Existing methods, however, assume that the basal slice is the first short-axis view slice below the mitral valve and are consequently at times identifying the incorrect short-axis slice. Correct identification of the basal slice under the Society for Cardiovascular Magnetic Resonance guidelines is challenging due to the poor image quality and blood movement during image acquisition. This paper proposes an automatic tool that utilizes the two...

Medical Imaging 2016: Image Processing, 2016

Identification of the basal slice in cardiac imaging is a key step to measuring the ejection frac... more Identification of the basal slice in cardiac imaging is a key step to measuring the ejection fraction of the left ventricle. Despite all the effort placed on automatic cardiac segmentation, basal slice identification is routinely performed manually. Manual identification, however, suffers from high interobserver variability. As a result, an automatic algorithm for basal slice identification is required. Guidelines published in 2013 identify the basal slice based on the percentage of myocardium surrounding the blood cavity in the short-axis view. Existing methods, however, assume that the basal slice is the first short-axis view slice below the mitral valve and are consequently at times identifying the incorrect short-axis slice. Correct identification of the basal slice under the Society for Cardiovascular Magnetic Resonance guidelines is challenging due to the poor image quality and blood movement during image acquisition. This paper proposes an automatic tool that utilizes the two-chamber view to determine the basal slice while following the guidelines. To this end, an active shape model is trained to segment the two-chamber view and create temporal binary profiles from which the basal slice is identified. From the 51 tested cases, our method obtains 92% and 84% accurate basal slice detection for the end-systole and the end-diastole, respectively.

It has not been a long time since cloud computing was introduced to many organizations and busine... more It has not been a long time since cloud computing was introduced to many organizations and businesses. Over this relatively short period of time, many companies have deployed this new technology for their business and many others are planning to move to cloud computing in the foreseeable future. On the other hand, currently we are witnessing a wide range of issues and concerns around cloud services making companies not confident about moving into the cloud. In this paper, the authors have tried to give an overall image of different aspects of cloud computing by using fifteen different metrics. It includes both the advantages and the disadvantages to give companies and businesses a deep insight into the factors they should consider for identification of their application's suitability for the adoption of cloud computing.

International Journal of Computer Applications, 2013

Because of their good support and easy deployment, wireless ad-hoc networks are currently widely ... more Because of their good support and easy deployment, wireless ad-hoc networks are currently widely being used for many industrial or military applications. Like other communication networks, environmental conditions can have considerable impact on the performance of wireless ad-hoc networks. Temperature is a good example which results in thermal agitation of the charge carriers. Consequently, we should be able to precisely estimate the performance of these networks in various environmental conditions to see whether they satisfy our expectations or not before any deployment. Investigating the effect of Thermal noise on the routing performance of Wireless Ad-hoc Networks is something never done before. This paper evaluates the impact of Thermal noise on the routing capability of Mobile Ad-hoc Networks (MANETs); which are a kind of Wireless ad-hoc Networks; in existence of thermal noise. The results can be a useful guidance for outdoor implementation of MANETs for industrial process automation and control applications.

Because of their good support and easy deployment, wireless ad-hoc networks are currently widely ... more Because of their good support and easy deployment, wireless ad-hoc networks are currently widely being used for many industrial or military applications. Like other communication networks, environmental conditions can have considerable impact on the performance of wireless ad-hoc networks. Temperature is a good example which results in thermal agitation of the charge carriers. Consequently, we should be able to precisely estimate the performance of these networks in various environmental conditions to see whether they satisfy our expectations or not before any deployment. Investigating the effect of Thermal noise on the routing performance of Wireless Ad-hoc Networks is something never done before. This paper evaluates the impact of Thermal noise on the routing capability of Mobile Ad-hoc Networks (MANETs); which are a kind of Wireless ad-hoc Networks; in existence of thermal noise. The results can be a useful guidance for outdoor implementation of MANETs for industrial process automation and control applications.

Proceedings of the 9th Nordic Conference on Human-Computer Interaction - NordiCHI '16, 2016

Interactive tabletops allow direct touch manipulation and recognizing simultaneous touch events. ... more Interactive tabletops allow direct touch manipulation and recognizing simultaneous touch events. Users sometimes lean on the touch surface creating unintended touch input. Our work demonstrates how this unintended input can be employed to enhance interaction. In a study we develop a posture set organized into four classes. We present a vision-based machine-learning algorithm using an active shape model to recognize the classes. The algorithm categorizes lean gestures into one of the classes for interaction purposes. In a second study, we evaluate the model and propose interaction scenarios that use lean detection.

Motivation: High resolution 2D whole slide imaging provides rich information about the tissue str... more Motivation: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions that each individual tissue slice experiences while cutting and mounting the tissue on the glass slide. Performing registration for the whole tissue slices may be adversely affected by the deformed tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose an accurate and robust regional registration algorithm for whole slide images which incrementally focuses registration on the area around the region of interest. Results: Using mean similarity index as the metric, the proposed algorithm (mean pm\pmpm std: 0.84pm0.110.84 \pm 0.110.84pm0.11) followed by a fine registration algorithm ($0.86 \pm 0.08$) outperf...

Biomedical Optics Express

Background: High resolution 2D whole slide imaging provides rich information about the tissue str... more Background: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions such as tissue tearing, folding and missing at each slide. Performing registration for the whole tissue slices may be adversely affected by distorted tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose a new approach to an accurate and robust registration of regions of interest for whole slide images. We introduce the idea of multi-scale attention for registration. Results: Using mean similarity index as the metric, the proposed algorithm (mean +- std: 0.84 +- 0.11) followed by a fine registration algorithm (0.86 +- 0.08) outperformed the state-of-the-art linear whole tissue regist...

Background: High resolution 2D whole slide imaging provides rich information about the tissue str... more Background: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions that each individual tissue slice experiences while cutting and mounting the tissue on the glass slide. Performing registration for the whole tissue slices may be adversely affected by the deformed tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose an accurate and robust regional registration algorithm for whole slide images which incrementally focuses registration on the area around the region of interest. Results: Using mean similarity index as the metric, the proposed algorithm (mean +- std: 0.84 +- 0.11) followed by a fine registration algorithm (0.86 +- 0.08) outperformed the...

Motivation High resolution 2D whole slide imaging provides rich information about the tissue stru... more Motivation High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions that each individual tissue slice experiences while cutting and mounting the tissue on the glass slide. Performing registration for the whole tissue slices may be adversely affected by the deformed tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose an accurate and robust regional registration algorithm for whole slide images which incrementally focuses registration on the area around the region of interest. Results Using mean similarity index as the metric, the proposed algorithm (mean ± std: 0.84 ± 0.11) followed by a fine registration algorithm (0.86 ± 0.08) outperformed the state-of-the-art linear whole tissue registration algorithm (0.74±0.19) and the regional version of this algorithm (0.81±0.15). The proposed algorithm also outperforms the state-of-the-art nonlinear registration algorithm (original: 0.82 ± 0.12, regional: 0.77 ± 0.22) for whole slide images and a recently proposed patch-based registration algorithm (patch size 256: 0.79 ± 0.16 , patch size 512: 0.77 ± 0.16) for medical images.

Medical Image Computing and Computer-Assisted Intervention - MICCAI 2016, 2016

Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases i... more Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases is important in diagnosing cardio-vascular diseases. Proper estimation of the volume requires knowledge of which MRI slice contains the topmost basal region of the LV. Automatic basal slice detection has proved challenging; as a result, basal slice detection remains a manual task which is prone to inter-observer variability. This paper presents a novel method that is able to track the basal slice over the whole cardiac cycle. The method was tested on 56 healthy and pathological cases and was able to identify the basal slices similar to experts&#39; selection for 80 % and 85 % of the cases for end-diastole and end-systole, respectively. This provides a significant improvement over the leading state-of-the-art approach that obtained 59 % and 44 % agreement with experts on the same input.

Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trac... more Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trackers have become increasingly popular today, such as the Fitbit. This study aimed to compare the average number of steps per day using the wrist-worn Fitbit Flex and waist-worn Acti-Graph (wGT3X-BT) in free-living conditions. Methods 104 adult participants (n = 35 males; n = 69 females) were asked to wear a Fitbit Flex and an ActiGraph concurrently for 7 days. Daily step counts were used to classify inactive (<10,000 steps) and active (!10,000 steps) days, which is one of the commonly used physical activity guidelines to maintain health. Proportion of agreement between physical activity categorizations from ActiGraph and Fitbit Flex was assessed. Statistical analyses included Spearman's rho, intraclass correlation (ICC), median absolute percentage error (MAPE), Kappa statistics, and Bland-Altman plots. Analyses were performed among all participants, by each step-defined daily physical activity category and gender. Results The median average steps/day recorded by Fitbit Flex and ActiGraph were 10193 and 8812, respectively. Strong positive correlations and agreement were found for all participants, both genders, as well as daily physical activity categories (Spearman's rho: 0.76-0.91; ICC: 0.73-0.87). The MAPE was: 15.5% (95% confidence interval [CI]: 5.8-28.1%) for overall steps, 16.9% (6.8-30.3%) vs. 15.1% (4.5-27.3%) in males and females, and 20.4% (8.7-35.9%) vs. 9.6% (1.0-18.4%) during inactive days and active days. Bland-Altman plot indicated a median overestimation of 1300 steps/day by the Fitbit Flex in all participants.

Computer Methods and Programs in Biomedicine

BACKGROUND AND OBJECTIVES Tagged MR images provide an effective way for regional analysis of the ... more BACKGROUND AND OBJECTIVES Tagged MR images provide an effective way for regional analysis of the myocardium strain. A reliable myocardium strain analysis requires both correct segmentation and accurate motion tracking of the myocardium during the cardiac cycle. While many algorithms have been proposed for accurate tracking of the myocardium in tagged MR images, little focus has been placed on ensuring correct segmentation of the tagged myocardium during the cardiac cycle. Myocardial strain analysis is usually done by segmenting the myocardium in end-diastole, generating a mesh from the segmentation, propagating the mesh through the cardiac cycle using the output deformation field from motion tracking, and measuring strain on the deforming mesh. Due to the imposed tag strips on the anatomy, identification of the myocardium boundaries is challenging in tagged MR images. As a result, there is no guarantee that the propagated mesh is annotating the myocardium accurately through the cardiac cycle. Moreover, clinical studies indicate that incorrect myocardium annotation can result in overestimation of myocardial strains. METHODS We introduce a method to improve reliability of strain analysis by proposing a mesh which correctly segments the myocardium in tagged MRI by leveraging the available cine MRI segmentation. In particular, we generate a series of mesh proposals using the cine MRI segmentation and find the propagated mesh proposal which gives the most accurate full-cycle myocardium segmentation. RESULTS The mesh selection algorithm was tested on 22 2D MRI scans of diseased and healthy hearts. The proposed algorithm provided more accurate whole-cycle myocardium segmentation compared to the propagated end-diastolic mesh. Regional myocardium strain was measured for 10 3D MRI scans of healthy volunteers using the proposed mesh and the end-diastolic mesh. The measured strain using the proposed mesh was more similar to the expected myocardium strain for a healthy heart than the measured strain using the end-diastolic mesh. CONCLUSION The proposed approach provides accurate whole-cycle tagged myocardium segmentation and more reliable myocardium strain analysis.

PLOS ONE, 2017

Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trac... more Introduction Accelerometers are commonly used to assess physical activity. Consumer activity trackers have become increasingly popular today, such as the Fitbit. This study aimed to compare the average number of steps per day using the wrist-worn Fitbit Flex and waist-worn Acti-Graph (wGT3X-BT) in free-living conditions. Methods 104 adult participants (n = 35 males; n = 69 females) were asked to wear a Fitbit Flex and an ActiGraph concurrently for 7 days. Daily step counts were used to classify inactive (<10,000 steps) and active (!10,000 steps) days, which is one of the commonly used physical activity guidelines to maintain health. Proportion of agreement between physical activity categorizations from ActiGraph and Fitbit Flex was assessed. Statistical analyses included Spearman's rho, intraclass correlation (ICC), median absolute percentage error (MAPE), Kappa statistics, and Bland-Altman plots. Analyses were performed among all participants, by each step-defined daily physical activity category and gender. Results The median average steps/day recorded by Fitbit Flex and ActiGraph were 10193 and 8812, respectively. Strong positive correlations and agreement were found for all participants, both genders, as well as daily physical activity categories (Spearman's rho: 0.76-0.91; ICC: 0.73-0.87). The MAPE was: 15.5% (95% confidence interval [CI]: 5.8-28.1%) for overall steps, 16.9% (6.8-30.3%) vs. 15.1% (4.5-27.3%) in males and females, and 20.4% (8.7-35.9%) vs. 9.6% (1.0-18.4%) during inactive days and active days. Bland-Altman plot indicated a median overestimation of 1300 steps/day by the Fitbit Flex in all participants.

Lecture Notes in Computer Science, 2016

Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases i... more Estimating blood volume of the left ventricle (LV) in the end-diastolic and end-systolic phases is important in diagnosing cardio-vascular diseases. Proper estimation of the volume requires knowledge of which MRI slice contains the topmost basal region of the LV. Automatic basal slice detection has proved challenging; as a result, basal slice detection remains a manual task which is prone to inter-observer variability. This paper presents a novel method that is able to track the basal slice over the whole cardiac cycle. The method was tested on 56 healthy and pathological cases and was able to identify the basal slices similar to experts&#39; selection for 80 % and 85 % of the cases for end-diastole and end-systole, respectively. This provides a significant improvement over the leading state-of-the-art approach that obtained 59 % and 44 % agreement with experts on the same input.

Journal of medical imaging (Bellingham, Wash.), 2016

Identification of the basal slice in cardiac imaging is a key step to measuring the ejection frac... more Identification of the basal slice in cardiac imaging is a key step to measuring the ejection fraction of the left ventricle. Despite all the effort placed on automatic cardiac segmentation, basal slice identification is routinely performed manually. Manual identification, however, suffers from high interobserver variability. As a result, an automatic algorithm for basal slice identification is required. Guidelines published in 2013 identify the basal slice based on the percentage of myocardium surrounding the blood cavity in the short-axis view. Existing methods, however, assume that the basal slice is the first short-axis view slice below the mitral valve and are consequently at times identifying the incorrect short-axis slice. Correct identification of the basal slice under the Society for Cardiovascular Magnetic Resonance guidelines is challenging due to the poor image quality and blood movement during image acquisition. This paper proposes an automatic tool that utilizes the two...

Medical Imaging 2016: Image Processing, 2016

Identification of the basal slice in cardiac imaging is a key step to measuring the ejection frac... more Identification of the basal slice in cardiac imaging is a key step to measuring the ejection fraction of the left ventricle. Despite all the effort placed on automatic cardiac segmentation, basal slice identification is routinely performed manually. Manual identification, however, suffers from high interobserver variability. As a result, an automatic algorithm for basal slice identification is required. Guidelines published in 2013 identify the basal slice based on the percentage of myocardium surrounding the blood cavity in the short-axis view. Existing methods, however, assume that the basal slice is the first short-axis view slice below the mitral valve and are consequently at times identifying the incorrect short-axis slice. Correct identification of the basal slice under the Society for Cardiovascular Magnetic Resonance guidelines is challenging due to the poor image quality and blood movement during image acquisition. This paper proposes an automatic tool that utilizes the two-chamber view to determine the basal slice while following the guidelines. To this end, an active shape model is trained to segment the two-chamber view and create temporal binary profiles from which the basal slice is identified. From the 51 tested cases, our method obtains 92% and 84% accurate basal slice detection for the end-systole and the end-diastole, respectively.

It has not been a long time since cloud computing was introduced to many organizations and busine... more It has not been a long time since cloud computing was introduced to many organizations and businesses. Over this relatively short period of time, many companies have deployed this new technology for their business and many others are planning to move to cloud computing in the foreseeable future. On the other hand, currently we are witnessing a wide range of issues and concerns around cloud services making companies not confident about moving into the cloud. In this paper, the authors have tried to give an overall image of different aspects of cloud computing by using fifteen different metrics. It includes both the advantages and the disadvantages to give companies and businesses a deep insight into the factors they should consider for identification of their application's suitability for the adoption of cloud computing.

International Journal of Computer Applications, 2013

Because of their good support and easy deployment, wireless ad-hoc networks are currently widely ... more Because of their good support and easy deployment, wireless ad-hoc networks are currently widely being used for many industrial or military applications. Like other communication networks, environmental conditions can have considerable impact on the performance of wireless ad-hoc networks. Temperature is a good example which results in thermal agitation of the charge carriers. Consequently, we should be able to precisely estimate the performance of these networks in various environmental conditions to see whether they satisfy our expectations or not before any deployment. Investigating the effect of Thermal noise on the routing performance of Wireless Ad-hoc Networks is something never done before. This paper evaluates the impact of Thermal noise on the routing capability of Mobile Ad-hoc Networks (MANETs); which are a kind of Wireless ad-hoc Networks; in existence of thermal noise. The results can be a useful guidance for outdoor implementation of MANETs for industrial process automation and control applications.

Because of their good support and easy deployment, wireless ad-hoc networks are currently widely ... more Because of their good support and easy deployment, wireless ad-hoc networks are currently widely being used for many industrial or military applications. Like other communication networks, environmental conditions can have considerable impact on the performance of wireless ad-hoc networks. Temperature is a good example which results in thermal agitation of the charge carriers. Consequently, we should be able to precisely estimate the performance of these networks in various environmental conditions to see whether they satisfy our expectations or not before any deployment. Investigating the effect of Thermal noise on the routing performance of Wireless Ad-hoc Networks is something never done before. This paper evaluates the impact of Thermal noise on the routing capability of Mobile Ad-hoc Networks (MANETs); which are a kind of Wireless ad-hoc Networks; in existence of thermal noise. The results can be a useful guidance for outdoor implementation of MANETs for industrial process automation and control applications.

Proceedings of the 9th Nordic Conference on Human-Computer Interaction - NordiCHI '16, 2016

Interactive tabletops allow direct touch manipulation and recognizing simultaneous touch events. ... more Interactive tabletops allow direct touch manipulation and recognizing simultaneous touch events. Users sometimes lean on the touch surface creating unintended touch input. Our work demonstrates how this unintended input can be employed to enhance interaction. In a study we develop a posture set organized into four classes. We present a vision-based machine-learning algorithm using an active shape model to recognize the classes. The algorithm categorizes lean gestures into one of the classes for interaction purposes. In a second study, we evaluate the model and propose interaction scenarios that use lean detection.