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Fong S, Fortino G, Ghista D, Piccialli F. Special issue on deep learning and big data analytics for medical e-diagnosis/AI-based e-diagnosis. Neural Comput Appl 2023; 35:1-5. [PMID: 37362576 PMCID: PMC10224755 DOI: 10.1007/s00521-023-08689-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 05/16/2023] [Indexed: 06/28/2023]
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Wong KKL, Xu J, Chen C, Ghista D, Zhao H. Functional magnetic resonance imaging providing the brain effect mechanism of acupuncture and moxibustion treatment for depression. Front Neurol 2023; 14:1151421. [PMID: 37025199 PMCID: PMC10070747 DOI: 10.3389/fneur.2023.1151421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 02/22/2023] [Indexed: 04/08/2023] Open
Abstract
The efficacy of acupuncture and moxibustion in the treatment of depression has been fully recognized internationally. However, its central mechanism is still not developed into a unified standard, and it is generally believed that the central mechanism is regulation of the cortical striatum thalamic neural pathway of the limbic system. In recent years, some scholars have applied functional magnetic resonance imaging (fMRI) to study the central mechanism and the associated brain effects of acupuncture and moxibustion treatment for depression. This study reviews the acupuncture and moxibustion treatment of depression from two aspects: (1) fMRI study of the brain function related to the acupuncture treatment of depression: different acupuncture and moxibustion methods are summarized, the fMRI technique is elaborately explained, and the results of fMRI study of the effects of acupuncture are analyzed in detail, and (2) fMRI associated "brain functional network" effects of acupuncture and moxibustion on depression, including the effects on the hippocampus, the amygdala, the cingulate gyrus, the frontal lobe, the temporal lobe, and other brain regions. The study of the effects of acupuncture on brain imaging is not adequately developed and still needs further improvement and development. The brain function networks associated with the acupuncture treatment of depression have not yet been adequately developed to provide a scientific and standardized mechanism of the effects of acupuncture. For this purpose, this study analyzes in-depth the clinical studies on the treatment of anxiety and depression by acupuncture and moxibustion, by depicting how the employment of fMRI technology provides significant imaging changes in the brain regions. Therefore, the study also provides a reference for future clinical research on the treatment of anxiety and depression.
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Affiliation(s)
- Kelvin K. L. Wong
- The Research Center for Medical AI, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jinping Xu
- The Research Center for Medical AI, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Cang Chen
- The Research Center for Medical AI, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Dhanjoo Ghista
- The Research Center for Medical AI, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Hong Zhao
- Acupuncture and Moxibustion Department, Luohu District Hospital of Traditional Chinese Medicine, Shenzhen, China
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Hong Z, Liu X, Ding H, Zhao P, Gong S, Wang Z, Ghista D, Fan J. Flow patterns in the venous sinus of pulsatile tinnitus patients with transverse sinus stenosis and underlying vortical flow as a causative factor. Comput Methods Programs Biomed 2022; 227:107203. [PMID: 36370596 DOI: 10.1016/j.cmpb.2022.107203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/25/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Transverse sinus stenosis (TSS) is commonly found in Pulsatile Tinnitus (PT) patients. Vortex flow is prominent in venous sinus with stenosis, and so it is important to determine the distribution and strength of the vortical flow to understand its influence on the occurrence of PT. METHODS In this study, by using computational fluid dynamics for hemodynamic analysis in patient-specific geometries based on Magnetic Resonance Imaging (MRI), we have investigated the blood flow within the venous sinus of 16 subjects with PT. We have employed both laminar and turbulent flow models for simulations, to obtain (i) streamlines of velocity distribution in the venous sinus, and (ii) pressure distributions of flow patterns in the venous sinus. Then, hemodynamic analysis in the venous sinus recirculation zone was carried out, to determine the flow patterns at the junction of transverse sinuses and sigmoid sinuses. Finally, we have proposed a new model for turbulence evaluation based on the regression analysis of anatomic and hemodynamics parameters. RESULTS Correlation analysis between the anatomical parameters and the hemodynamic parameters has shown that stenosis at the transverse sinus was the main factor in the local hemodynamics variation in the venous sinus of patients; in this context, it is shown that vorticity can be used as a prime indicator of the severity of the stenosis function. Our results have shown a significant correlation between the vorticity and the stenotic maximum velocity (SMV) (r = 0.282, p = 0.004). Then, a parameterized prediction model is proposed to determine the vorticity in terms of flow and anatomic variables, termed as the turbulence eddy prediction model (TEP model). Our result have shown that the TEP model is sensitive to the dominant flow distribution, with a high correlation to the flow-based vorticity (r = 0.809, p = 0.009). CONCLUSIONS The quantification of the vorticity (as both vorticity and MVV) in the downstream of TSS could be a marker for indication of turbulent energy at the transverse-sigmoid sinus, which could potentially serve as a hemodynamic marker for the functional assessment of the PT-related TSS.
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Affiliation(s)
- Zhenxin Hong
- Foshan University, #18 Jiangwan 1st Road Foshan, Guangdong 528000, China
| | - Xin Liu
- Foshan University, #18 Jiangwan 1st Road Foshan, Guangdong 528000, China; Guangdong Academy Research on VR Industry, Foshan University, #18 Jiangwan 1st Road Foshan, Guangdong 528000, China
| | - Heyu Ding
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yongan Road, Xicheng District, Beijing 100050, China
| | - Pengfei Zhao
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yongan Road, Xicheng District, Beijing 100050, China
| | - Shusheng Gong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, No. 95, Yongan Road, Xicheng District, Beijing 100050, China
| | - Zhenchang Wang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yongan Road, Xicheng District, Beijing 100050, China.
| | | | - Jinsong Fan
- Foshan University, #18 Jiangwan 1st Road Foshan, Guangdong 528000, China.
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Liu X, Xu C, Rao S, Zhang Y, Ghista D, Gao Z, Yang G. Physiologically personalized coronary blood flow model to improve the estimation of noninvasive fractional flow reserve. Med Phys 2022; 49:583-597. [PMID: 34792807 DOI: 10.1002/mp.15363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 11/01/2021] [Accepted: 11/01/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Coronary outlet resistance is influenced by the quantification and distribution of resting coronary blood flow. It is crucial for a more physiologically accurate estimation of fractional flow reserve (FFR) derived from computed tomography angiography (CTA), referred to as FFRCT. This study presents a physiologically personalized (PP)-based coronary blood flow model involving the outlet boundary condition (BC) and a standardized outlet truncation strategy to estimate the outlet resistance and FFRCT. METHODS In this study, a total of 274 vessels were retrospectively collected from 221 patients who underwent coronary CTA and invasive FFR within 14 days. For FFRCT determination, we have employed a PP-based outlet BC model involving personalized physiological parameters and left ventricular mass (LVM) to quantify resting coronary blood flow. We evaluated the improvement achieved in the diagnostic performance of FFRCT by using the PP-based outlet BC model relative to the LVM-based model, with respect to the invasive FFR. Additionally, in order to evaluate the impact of the outlet truncation strategy on FFRCT, 68 vessels were randomly selected and analyzed independently by two operators, by using two different outlet truncation strategies at 1-month intervals. RESULTS The per-vessel diagnostic performance of the PP-based outlet BC model was improved, based on invasive FFR as reference, compared to the LVM-based model: (i) accuracy/sensitivity/specificity: 91.2%/90.4%/91.8% versus 86.5%/84.6%/87.6%, for the entire dataset of 274 vessels, (ii) accuracy/sensitivity/specificity: 88.7%/82.4%/90.4% versus 82.4%/ 76.5%/84.0%, for moderately stenosis lesions. The standardized outlet truncation strategy showed good repeatability with the Kappa coefficient of 0.908. CONCLUSIONS It has been shown that our PP-based outlet BC model and standardized outlet truncation strategy can improve the diagnostic performance and repeatability of FFRCT.
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Affiliation(s)
- Xiujian Liu
- School of Biomedical Engineering, Sun Yat-sen University, Shenzhen, China
| | - Chuangye Xu
- School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Simin Rao
- Beijing GuanShengYun Medical Technology Co.,Ltd, Beijing, China
| | - Ye Zhang
- Beijing GuanShengYun Medical Technology Co.,Ltd, Beijing, China
| | - Dhanjoo Ghista
- University 2020 Foundation, Northborough, Massachusetts, USA
| | - Zhifan Gao
- School of Biomedical Engineering, Sun Yat-sen University, Shenzhen, China
| | - Guang Yang
- National Heart and Lung Institute, Imperial College London, London, UK
- Cardiovascular Research Centre, Royal Brompton Hospital, London, UK
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Wu C, Liu X, Ghista D, Yin Y, Zhang H. Effect of plaque compositions on fractional flow reserve in a fluid-structure interaction analysis. Biomech Model Mechanobiol 2021; 21:203-220. [PMID: 34713361 DOI: 10.1007/s10237-021-01529-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 10/13/2021] [Indexed: 01/14/2023]
Abstract
Coronary artery disease involves the reduction of blood flow to the myocardium due to atherosclerotic plaques. The findings of myocardial ischemia may indicate severe coronary stenosis, but many studies have demonstrated a mismatch between lumen stenosis and fractional flow reserve (FFR). Recently, some clinical studies have found that the composition of atherosclerotic plaques may be a potential missing link between stenosis and ischemia. To investigate the relationship between myocardial ischemia and plaque composition, we have developed and adopted a new fluid-structure interaction (FSI) patient-specific coronary plaque model, based on computed tomography angiography data, to assess the impact on FFR as a biomechanical indicator of ischemia. A total of 180 analyses have been performed in 3D-FSI coronary artery disease models based on plaque compositions, plaque location, and stenosis degree. Hemodynamic analysis of simulation results and comparisons with other methods has been conducted to validate our models. Our results have successfully verified that the different compositions of plaques have resulted in differences in the calculated FFR. The mean FFR values with lipid plaques are [Formula: see text] as compared to the mean FFR values in lesions with fibrous plaques [Formula: see text] and calcified plaques [Formula: see text]. Besides, FFR differences between the three different plaque compositions have been shown to increase as the diameter stenosis increased. Plaque composition affects vascular stiffness and vascular dilation ability, and thereby affects the stenosis degree, resulting in abnormal FFR leading to myocardial ischemia. This interrelationship can help to diagnose the cause of high-risk coronary artery disease, leading to myocardial ischemia.
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Affiliation(s)
- Chulin Wu
- School of Biomedical Engineering, Sun Yat-sen University, Shenzhen, 518107, China
| | - Xiujian Liu
- School of Biomedical Engineering, Sun Yat-sen University, Shenzhen, 518107, China
| | - Dhanjoo Ghista
- University 2020 Foundation, Northborough, MA, 01532, USA
| | - Youbin Yin
- Shenzhen Keya Medical Technology Corporation, Shenzhen, 518172, China
| | - Heye Zhang
- School of Biomedical Engineering, Sun Yat-sen University, Shenzhen, 518107, China.
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Chen Z, Zhou YP, Liu X, Jiang X, Wu T, Ghista D, Xu XQ, Zhang H, Jing ZC. A Personalized Pulmonary Circulation Model to Non-Invasively Calculate Fractional Flow Reserve for Artery Stenosis Detection. IEEE Trans Biomed Eng 2021; 69:1435-1448. [PMID: 34633925 DOI: 10.1109/tbme.2021.3119188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Fractional Flow Reserve (FFR) is regarded as a fundamental index to assess pulmonary artery stenosis. The application of FFR can increase the accuracy of detection of pulmonary artery stenosis. However, the invasive examination may carry a number of physiological risks for patients. Therefore, we propose a personalized pulmonary circulation model to non- invasively calculate FFR of pulmonary artery stenosis. Method- ology: We employed a personalized pulmonary circulation model to non-invasively calculate FFR using only computed tomography angiogram (CTA) data. This model combined boundary conditions estimation and 3D pulmonary artery morphology reconstruction for CFD simulation. First, we obtained patient-specific boundary conditions by adapting the right ventricle stroke volume and main pulmonary artery pressure feature points (systolic, diastolic, and mean pressure). Secondly, the 3D pulmonary artery morphology was reconstructed by threshold segmentation. The CFD simulation was then performed to obtain pressure distribution in the entire pulmonary artery. Finally, the FFR in pulmonary artery stenoses was calculated as the ratio of distal pressure and proximal pres- sure. RESULTS To validate our model, we compared the calculated FFR with measured FFR by pressure guide wires examination of 8 patients. The FFR calculated by our model showed a good agreement with measured FFR by pressure guide wires exami- nation. The average accuracy rate was 91.41%. CONCLUSION The proposed personalized pulmonary model is capable of reasonably non-invasively calculating FFR with sufficient accuracy. SIGNIFICANCE FFR calculated in our model may contribute to non-invasive detection of pulmonary artery stenosis and to the assessment of invasive interventions.
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Zhang D, Yang G, Zhao S, Zhang Y, Ghista D, Zhang H, Li S. Direct Quantification of Coronary Artery Stenosis Through Hierarchical Attentive Multi-View Learning. IEEE Trans Med Imaging 2020; 39:4322-4334. [PMID: 32804646 DOI: 10.1109/tmi.2020.3017275] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Quantification of coronary artery stenosis on X-ray angiography (XRA) images is of great importance during the intraoperative treatment of coronary artery disease. It serves to quantify the coronary artery stenosis by estimating the clinical morphological indices, which are essential in clinical decision making. However, stenosis quantification is still a challenging task due to the overlapping, diversity and small-size region of the stenosis in the XRA images. While efforts have been devoted to stenosis quantification through low-level features, these methods have difficulty in learning the real mapping from these features to the stenosis indices. These methods are still cumbersome and unreliable for the intraoperative procedures due to their two-phase quantification, which depends on the results of segmentation or reconstruction of the coronary artery. In this work, we are proposing a hierarchical attentive multi-view learning model (HEAL) to achieve a direct quantification of coronary artery stenosis, without the intermediate segmentation or reconstruction. We have designed a multi-view learning model to learn more complementary information of the stenosis from different views. For this purpose, an intra-view hierarchical attentive block is proposed to learn the discriminative information of stenosis. Additionally, a stenosis representation learning module is developed to extract the multi-scale features from the keyframe perspective for considering the clinical workflow. Finally, the morphological indices are directly estimated based on the multi-view feature embedding. Extensive experiment studies on clinical multi-manufacturer dataset consisting of 228 subjects show the superiority of our HEAL against nine comparing methods, including direct quantification methods and multi-view learning methods. The experimental results demonstrate the better clinical agreement between the ground truth and the prediction, which endows our proposed method with a great potential for the efficient intraoperative treatment of coronary artery disease.
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Su B, Zhang JM, Zou H, Ghista D, Le TT, Chin C. Generating wall shear stress for coronary artery in real-time using neural networks: Feasibility and initial results based on idealized models. Comput Biol Med 2020; 126:104038. [PMID: 33039809 DOI: 10.1016/j.compbiomed.2020.104038] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 09/14/2020] [Accepted: 10/03/2020] [Indexed: 11/17/2022]
Abstract
Computational fluid dynamics (CFD) and medical imaging can be integrated to derive some important hemodynamic parameters such as wall shear stress (WSS). However, CFD suffers from a relatively long computational time that usually varies from dozens of minutes to hours. Machine learning is a popular tool that has been applied to many fields, and it can predict outcomes fast and even instantaneously in most applications. This study aims to use machine learning as an alternative to CFD for generating hemodynamic parameters in real-time diagnosis during medical examinations. To perform the feasibility study, we used CFD to model the blood flow in 2000 idealized coronary arteries, and the calculated WSS values in these models were used as the dataset for training and testing. The preparation of the dataset was automated by scripts programmed in Python, and OpenFOAM was used as the CFD solver. We have explored multivariate linear regression, multi-layer perceptron, and convolutional neural network architectures to generate WSS values from coronary artery geometry directly without CFD. These architectures were implemented in TensorFlow 2.0. Our results showed that these algorithms were able to generate results in less than 1 s, proving its capability in real-time applications, in terms of computational time. Based on the accuracy, convolutional neural network outperformed the other architectures with a normalized mean absolute error of 2.5%. Although this study is based on idealized models, to the best of our knowledge, it is the first attempt to predict WSS in a stenosed coronary artery using machine learning approaches.
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Affiliation(s)
- Boyang Su
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore.
| | - Jun-Mei Zhang
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore; Cardiovascular Sciences ACP, Duke NUS Medical School, Singapore
| | - Hua Zou
- Department of Statistics, Texas A&M University, TX, USA
| | | | - Thu Thao Le
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore; Cardiovascular Sciences ACP, Duke NUS Medical School, Singapore
| | - Calvin Chin
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore; Cardiovascular Sciences ACP, Duke NUS Medical School, Singapore
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Li M, Dong S, Gao Z, Feng C, Xiong H, Zheng W, Ghista D, Zhang H, de Albuquerque VHC. Unified model for interpreting multi-view echocardiographic sequences without temporal information. Appl Soft Comput 2020. [DOI: 10.1016/j.asoc.2019.106049] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Xu C, Xu L, Gao Z, Zhao S, Zhang H, Zhang Y, Du X, Zhao S, Ghista D, Liu H, Li S. Direct delineation of myocardial infarction without contrast agents using a joint motion feature learning architecture. Med Image Anal 2018; 50:82-94. [DOI: 10.1016/j.media.2018.09.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/25/2018] [Accepted: 09/05/2018] [Indexed: 11/28/2022]
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Zhao S, Gao Z, Zhang H, Xie Y, Luo J, Ghista D, Wei Z, Bi X, Xiong H, Xu C, Li S. Robust Segmentation of Intima–Media Borders With Different Morphologies and Dynamics During the Cardiac Cycle. IEEE J Biomed Health Inform 2018; 22:1571-1582. [DOI: 10.1109/jbhi.2017.2776246] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Zhang B, Gu J, Qian M, Niu L, Ghista D. Study of correlation between wall shear stress and elasticity in atherosclerotic carotid arteries. Biomed Eng Online 2018; 17:5. [PMID: 29338745 PMCID: PMC5771221 DOI: 10.1186/s12938-017-0431-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/23/2017] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE This paper presents the use of the texture matching method to measure the rabbit carotid artery elasticity value of the experimental group and control group respectively. It compares the experimental rabbits, when they are prompted by pathological histology to be at the period of carotid atherosclerosis fatty streaks and fiber plaques, with the control group. METHODS We have used ultrasound linear array probe for scanning the rabbit carotid arteries. This allows us to obtain the wall shear stress (WSS) and the elasticity values in the atherosclerotic arteries. Using statistical analysis, we are able to clarify whether the texture matching method can diagnose atherosclerosis at the early stage. We also analyze the rabbit carotid artery elasticity and WSS values to make sure whether there is a correlation between both. Combining the texture matching method with the WSS quantitative analysis in the future can enable better prediction of the occurrence and development of atherosclerosis by using noninvasive medical imaging techniques. RESULTS This study has confirmed that from the 2nd to the 10th week, with the development of atherosclerosis, the arterial WSS reduction has a negative correlation with the increasing of artery wall elasticity, which means that as the arterial WSS decreases the arterial wall becomes less elastic. Correlating shear stress with atherosclerosis can clarify that WSS can be used as one of the effective parameters of early diagnosis of atherosclerosis. CONCLUSION In summary, we have found that the elasticity value can reflect the degree of atherosclerosis more objectively. Therefore, by using noninvasive imaging, the quantitative analysis of shear stress and combined with texture matching method can assist in the early diagnosis of atherosclerosis.
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Affiliation(s)
- Bo Zhang
- Department of Ultrasound in Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.
| | - Junyi Gu
- Department of Ultrasound in Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China
| | - Ming Qian
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Lili Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Dhanjoo Ghista
- University 2020 Foundation, Northborough, MA, 01532, USA
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Zhang B, Gu J, Qian M, Niu L, Zhou H, Ghista D. Correlation between quantitative analysis of wall shear stress and intima-media thickness in atherosclerosis development in carotid arteries. Biomed Eng Online 2017; 16:137. [PMID: 29208019 PMCID: PMC5718157 DOI: 10.1186/s12938-017-0425-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 11/11/2017] [Indexed: 01/17/2023] Open
Abstract
Background This paper presents quantitative analysis of blood flow shear stress by measuring the carotid arterial wall shear stress (WSS) and the intima-media thickness (IMT) of experimental rabbits fed with high-fat feedstuff on a weekly basis in order to cause atherosclerosis. Methods This study is based on establishing an atherosclerosis model of high-fat rabbits, and measuring the rabbits’ common carotid arterial WSS of the experimental group and control group on a weekly basis. Detailed analysis was performed by using WSS quantification. Results We have demonstrated small significant difference of rabbit carotid artery WSS between the experimental group and the control group (P<0.01) from the 1st week onwards, while the IMT of experimental group had larger differences from 5th week compared with the control group (P<0.05). Next, we have shown that with increasing blood lipids, the rabbit carotid artery shear stress decreases and the rabbit carotid artery IMT goes up. The decrease of shear stress appears before the start of IMT growth. Furthermore, our receiver operator characteristic (ROC) curve analysis showed that when the mean value of shear stress is 1.198 dyne/cm2, the rabbit common carotid atherosclerosis fatty streaks sensitivity is 89.8%, and the specificity is 81.3%. The area under the ROC curve is 0.9283. Conclusions All these data goes to show that WSS decreasing to 1.198 dyne/cm2 can be used as an indicator that rabbit common carotid artery comes into the period of fibrous plaques. In conclusion, our study is able to find and confirm that the decrease of the arterial WSS can predict the occurrence of atherosclerosis earlier, and offer help for positive clinical intervention.
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Affiliation(s)
- Bo Zhang
- Department of Ultrasound in Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.
| | - Junyi Gu
- Department of Ultrasound in Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China
| | - Ming Qian
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Lili Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Hui Zhou
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Dhanjoo Ghista
- University 2020 Foundation, Northborough, MA, 01532, USA
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Han S, Huang Y, Ghista D. An Empirical Analysis Based on Double Difference Model Applied to Health Informatics Using Biodegradation Data. j med imaging hlth inform 2017. [DOI: 10.1166/jmihi.2017.2155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Xu C, Xu L, Gao Z, Zhao S, Zhang H, Zhang Y, Du X, Zhao S, Ghista D, Li S. Direct Detection of Pixel-Level Myocardial Infarction Areas via a Deep-Learning Algorithm. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/978-3-319-66179-7_28] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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Wong KKL, Wang D, Ko JKL, Mazumdar J, Le TT, Ghista D. Computational medical imaging and hemodynamics framework for functional analysis and assessment of cardiovascular structures. Biomed Eng Online 2017; 16:35. [PMID: 28327144 PMCID: PMC5359907 DOI: 10.1186/s12938-017-0326-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/13/2017] [Indexed: 11/10/2022] Open
Abstract
Cardiac dysfunction constitutes common cardiovascular health issues in the society, and has been an investigation topic of strong focus by researchers in the medical imaging community. Diagnostic modalities based on echocardiography, magnetic resonance imaging, chest radiography and computed tomography are common techniques that provide cardiovascular structural information to diagnose heart defects. However, functional information of cardiovascular flow, which can in fact be used to support the diagnosis of many cardiovascular diseases with a myriad of hemodynamics performance indicators, remains unexplored to its full potential. Some of these indicators constitute important cardiac functional parameters affecting the cardiovascular abnormalities. With the advancement of computer technology that facilitates high speed computational fluid dynamics, the realization of a support diagnostic platform of hemodynamics quantification and analysis can be achieved. This article reviews the state-of-the-art medical imaging and high fidelity multi-physics computational analyses that together enable reconstruction of cardiovascular structures and hemodynamic flow patterns within them, such as of the left ventricle (LV) and carotid bifurcations. The combined medical imaging and hemodynamic analysis enables us to study the mechanisms of cardiovascular disease-causing dysfunctions, such as how (1) cardiomyopathy causes left ventricular remodeling and loss of contractility leading to heart failure, and (2) modeling of LV construction and simulation of intra-LV hemodynamics can enable us to determine the optimum procedure of surgical ventriculation to restore its contractility and health This combined medical imaging and hemodynamics framework can potentially extend medical knowledge of cardiovascular defects and associated hemodynamic behavior and their surgical restoration, by means of an integrated medical image diagnostics and hemodynamic performance analysis framework.
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Affiliation(s)
- Kelvin K L Wong
- School of Medicine, University of Western Sydney, Campbelltown, Sydney, NSW, 2560, Australia. .,School of Medicine, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
| | - Defeng Wang
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Jacky K L Ko
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Jagannath Mazumdar
- Centre for Biomedical Engineering and School of Electrical and Electronics Engineering, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Thu-Thao Le
- National Heart Centre, Mistri Wing, 17 Third Hospital Avenue, Singapore, 168752, Singapore
| | - Dhanjoo Ghista
- University 2020 Foundation, Northborough, MA, 01532, USA
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17
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Abstract
Cardiovascular disease (CVD), the leading cause of death today, incorporates a wide range of cardiovascular system malfunctions that affect heart functionality. It is believed that the hemodynamic loads exerted on the cardiovascular system, the left ventricle (LV) in particular, are the leading cause of CVD initiation and propagation. Moreover, it is believed that the diagnosis and prognosis of CVD at an early stage could reduce its high mortality and morbidity rate. Therefore, a set of robust clinical cardiovascular assessment tools has been introduced to compute the cardiovascular hemodynamics in order to provide useful insights to physicians to recognize indicators leading to CVD and also to aid the diagnosis of CVD. Recently, a combination of computational fluid dynamics (CFD) and different medical imaging tools, image-based CFD (IB-CFD), has been widely employed for cardiovascular functional assessment by providing reliable hemodynamic parameters. Even though the capability of CFD to provide reliable flow dynamics in general fluid mechanics problems has been widely demonstrated for many years, up to now, the clinical implications of the IB-CFD patient-specific LVs have not been applicable due to its limitations and complications. In this paper, we review investigations conducted to numerically simulate patient-specific human LV over the past 15 years using IB-CFD methods. Firstly, we divide different studies according to the different LV types (physiological and different pathological conditions) that have been chosen to reconstruct the geometry, and then discuss their contributions, methodologies, limitations, and findings. In this regard, we have studied CFD simulations of intraventricular flows and related cardiology insights, for (i) Physiological patient-specific LV models, (ii) Pathological heart patient-specific models, including myocardial infarction, dilated cardiomyopathy, hypertrophic cardiomyopathy and hypoplastic left heart syndrome. Finally, we discuss the current stage of the IB-CFD LV simulations in order to mimic realistic hemodynamics of patient-specific LVs. We can conclude that heart flow simulation is on the right track for developing into a useful clinical tool for heart function assessment, by (i) incorporating most of heart structures' (such as heart valves) operations, and (ii) providing useful diagnostic indices based hemodynamic parameters, for routine adoption in clinical usage.
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Affiliation(s)
- Siamak N Doost
- Biomechanics and Tissue Engineering Lab, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, Australia
| | | | - Boyang Su
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore, Singapore
| | - Liang Zhong
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore, Singapore. .,Duke-NUS Medical School, Singapore, Singapore.
| | - Yosry S Morsi
- Biomechanics and Tissue Engineering Lab, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, Australia
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Liu X, Gao Z, Xiong H, Ghista D, Ren L, Zhang H, Wu W, Huang W, Hau WK. Three-dimensional hemodynamics analysis of the circle of Willis in the patient-specific nonintegral arterial structures. Biomech Model Mechanobiol 2016; 15:1439-1456. [PMID: 26935302 DOI: 10.1007/s10237-016-0773-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/17/2016] [Indexed: 01/11/2023]
Abstract
The hemodynamic alteration in the cerebral circulation caused by the geometric variations in the cerebral circulation arterial network of the circle of Wills (CoW) can lead to fatal ischemic attacks in the brain. The geometric variations due to impairment in the arterial network result in incomplete cerebral arterial structure of CoW and inadequate blood supply to the brain. Therefore, it is of great importance to understand the hemodynamics of the CoW, for efficiently and precisely evaluating the status of blood supply to the brain. In this paper, three-dimensional computational fluid dynamics of the main CoW vasculature coupled with zero-dimensional lumped parameter model boundary condition for the CoW outflow boundaries is developed for analysis of the blood flow distribution in the incomplete CoW cerebral arterial structures. The geometric models in our study cover the arterial segments from the aorta to the cerebral arteries, which can allow us to take into account the innate patient-specific resistance of the arterial trees. Numerical simulations of the governing fluid mechanics are performed to determine the CoW arterial structural hemodynamics, for illustrating the redistribution of the blood flow in CoW due to the structural variations. We have evaluated our coupling methodology in five patient-specific cases that were diagnosed with the absence of efferent vessels or impairment in the connective arteries in their CoWs. The velocity profiles calculated by our approach in the segments of the patient-specific arterial structures are found to be very close to the Doppler ultrasound measurements. The accuracy and consistency of our hemodynamic results have been improved (to [Formula: see text] %) compared to that of the pure-resistance boundary conditions (of 43.5 [Formula: see text] 28 %). Based on our grouping of the five cases according to the occurrence of unilateral occlusion in vertebral arteries, the inter-comparison has shown that (i) the flow reduction in posterior cerebral arteries is the consequence of the unilateral vertebral arterial occlusion, and (ii) the flow rate in the anterior cerebral arteries is correlated with the posterior structural variations. This study shows that our coupling approach is capable of providing comprehensive information of the hemodynamic alterations in the pathological CoW arterial structures. The information generated by our methodology can enable evaluation of both the functional and structural status of the clinically significant symptoms, for assisting the treatment decision-making.
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Affiliation(s)
- Xin Liu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Shenzhen, 518055, China
| | - Zhifan Gao
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Shenzhen, 518055, China
- Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Huahua Xiong
- Department of Ultrasound, Shenzhen Second People's Hospital, Shenzhen University 1st Affiliated Hospital, Shenzhen, 518029, China
| | - Dhanjoo Ghista
- University 2020 Foundation, Northborough, MA, 01532, USA
| | - Lijie Ren
- Department of Neurology, Shenzhen Second People's Hospital, Shenzhen University 1st Affiliated Hospital, Shenzhen, 518029, China
| | - Heye Zhang
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Shenzhen, 518055, China.
| | - Wanqing Wu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Shenzhen, 518055, China
| | - Wenhua Huang
- Department of Anatomy, Guangdong Provincial Key Laboratory of Medical Biomechanics, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, China
| | - William Kongto Hau
- Institute of Cardiovascular Medicine and Research, LiKaShing Faculty of Medicine, University of Hong Kong, Portfulam, Hong Kong
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Abstract
Most heart diseases are associated with and reflected by the sounds that the heart produces. Heart auscultation, defined as listening to the heart sound, has been a very important method for the early diagnosis of cardiac dysfunction. Traditional auscultation requires substantial clinical experience and good listening skills. The emergence of the electronic stethoscope has paved the way for a new field of computer-aided auscultation. This article provides an in-depth study of (1) the electronic stethoscope technology, and (2) the methodology for diagnosis of cardiac disorders based on computer-aided auscultation. The paper is based on a comprehensive review of (1) literature articles, (2) market (state-of-the-art) products, and (3) smartphone stethoscope apps. It covers in depth every key component of the computer-aided system with electronic stethoscope, from sensor design, front-end circuitry, denoising algorithm, heart sound segmentation, to the final machine learning techniques. Our intent is to provide an informative and illustrative presentation of the electronic stethoscope, which is valuable and beneficial to academics, researchers and engineers in the technical field, as well as to medical professionals to facilitate its use clinically. The paper provides the technological and medical basis for the development and commercialization of a real-time integrated heart sound detection, acquisition and quantification system.
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Affiliation(s)
- Shuang Leng
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609, Singapore.
| | - Ru San Tan
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609, Singapore.
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, 8 College Road, Singapore, 169857, Singapore.
| | - Kevin Tshun Chuan Chai
- Institute of Microelectronics, A*STAR, 11 Science Park Road, Singapore, 117685, Singapore.
| | - Chao Wang
- Institute of Microelectronics, A*STAR, 11 Science Park Road, Singapore, 117685, Singapore.
| | | | - Liang Zhong
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609, Singapore.
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, 8 College Road, Singapore, 169857, Singapore.
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Su Y, Zhong L, Lim CW, Ghista D, Chua T, Tan RS. A geometrical approach for evaluating left ventricular remodeling in myocardial infarct patients. Comput Methods Programs Biomed 2012; 108:500-510. [PMID: 21507502 DOI: 10.1016/j.cmpb.2011.03.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 02/14/2011] [Accepted: 03/16/2011] [Indexed: 05/30/2023]
Abstract
A computational method for quantifying left ventricle (LV) remodeling using 3D mesh models reconstructed from magnetic resonance imaging is proposed. The underlying geometry of the LV mesh is obtained by using a quadric fitting method, and its quantification is performed by using a curvedness shape descriptor. To achieve robustness, we have performed detailed studies of the effects of n-ring parameter selection on the accuracy of this method with in vitro and in vivo LV models. We have found that curvedness calculations based on a 5-ring selection can accurately depict anomalies in LV shape despite the presence of noise due to manual image segmentation. Our studies show that patients after myocardial infarction exhibit significant LV shape alteration in terms of curvedness, in particular at the apex. The diastole-to-systole change in regional curvedness was significantly lower suggesting regional differences in hypokinesis due to infarcted myocardium. This approach may add new insights into ventricular deformation and enable better discrimination between normal and pathologic conditions.
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Affiliation(s)
- Yi Su
- Institute of High Performance Computing, 1 Fusionopolis Way #16-16 Connexis, S138632, Singapore
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Zhong L, Tan LK, Finn CJ, Ghista D, Liew R, Ding ZP. Effects of Age and Gender on Left Atrial Ejection Force and Volume from Real-Time Three-Dimensional Echocardiography. Ann Acad Med Singap 2012. [DOI: 10.47102/annals-acadmedsg.v41n4p161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Introduction: This study was carried out to (i) provide the methodology for determining left atrial (LA) volume, emptying fraction and ejection force (LAEF), from real-time 3-dimensional echocardiography (RT3DE), and (ii) evaluate the effects of age and gender on LA volume and LAEF in a wide age range of healthy participants. Materials and Methods: RT3DE was performed in 102 healthy participants (age range, 20 to 80 years). From full-volume data sets, LA endocardial borders were automatically traced and LA volumes were determined. LAEF was calculated as 1/3×mitral annular area × (blood density) × (peak velocity of A wave)2 according to Newton’s law of motion and hydrodynamics; wherein the mitral annular area (MVA) is traced using RT3DE and A is the peak Doppler-derived blood velocity at atrial systole with the sample volume placed at the mitral annulus level. Results: ANOVA analysis revealed that LA volume indices were significantly correlated with age (r = 0.366, P <0.0001 for maximal volume index and r = 0.288, P <0.005 for minimal volume index). LAEF was also significantly positively correlated with age (r = 0.49, P <0.0001). The LA emptying fraction was maintained across ages. LA volume indices and LAEF did not differ significantly with gender. Conclusion: Our data can be used as normal reference values for LA volumes and LAEF. We have demonstrated that age is positively related to LA volume indices and LAEF, which suggests that age-dependent cut-off values should be considered in those with heart disease.
Key words: Age, LA Ejection Force, RT3DE, Volume
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Affiliation(s)
| | | | - Chris J Finn
- Sir Charles Gairdner Hospital Perth, WA, Australia
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Zhong L, Tan LK, Finn CJ, Ghista D, Liew R, Ding ZP. Effects of age and gender on left atrial ejection force and volume from real-time three-dimensional echocardiography. Ann Acad Med Singap 2012; 41:161-169. [PMID: 22635280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
INTRODUCTION This study was carried out to (i) provide the methodology for determining left atrial (LA) volume, emptying fraction and ejection force (LAEF), from real-time 3-dimensional echocardiography (RT3DE), and (ii) evaluate the effects of age and gender on LA volume and LAEF in a wide age range of healthy participants. MATERIALS AND METHODS RT3DE was performed in 102 healthy participants (age range, 20 to 80 years). From full-volume data sets, LA endocardial borders were automatically traced and LA volumes were determined. LAEF was calculated as 1/3×mitral annular area × (blood density) × (peak velocity of A wave)(2) according to Newton's law of motion and hydrodynamics; wherein the mitral annular area (MVA) is traced using RT3DE and A is the peak Doppler-derived blood velocity at atrial systole with the sample volume placed at the mitral annulus level. RESULTS ANOVA analysis revealed that LA volume indices were significantly correlated with age (r = 0.366, P <0.0001 for maximal volume index and r = 0.288, P <0.005 for minimal volume index). LAEF was also significantly positively correlated with age (r = 0.49, P <0.0001). The LA emptying fraction was maintained across ages. LA volume indices and LAEF did not differ significantly with gender. CONCLUSION Our data can be used as normal reference values for LA volumes and LAEF. We have demonstrated that age is positively related to LA volume indices and LAEF, which suggests that age-dependent cut-off values should be considered in those with heart disease.
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Affiliation(s)
- Liang Zhong
- Cardiac Mechanics Engineering and Physiology Unit, National Heart Centre Singapore.
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Zhong L, Gobeawan L, Su Y, Tan JL, Ghista D, Chua T, Tan RS, Kassab G. Right ventricular regional wall curvedness and area strain in patients with repaired tetralogy of Fallot. Am J Physiol Heart Circ Physiol 2011; 302:H1306-16. [PMID: 22210750 DOI: 10.1152/ajpheart.00679.2011] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A quantitative understanding of right ventricular (RV) remodeling in repaired tetralogy of Fallot (rTOF) is crucial for patient management. The objective of this study is to quantify the regional curvatures and area strain based on three-dimensional (3-D) reconstructions of the RV using cardiac magnetic resonance imaging (MRI). Fourteen (14) rTOF patients and nine (9) normal subjects underwent cardiac MRI scan. 3-D RV endocardial surface models were reconstructed from manually delineated contours and correspondence between end-diastole (ED) and end systole (ES) was determined. Regional curvedness (C) and surface area at ED and ES were calculated as well as the area strain. The RV shape and deformation in rTOF patients differed from normal subjects in several respects. Firstly, the curvedness at ED (mean for 13 segments, 0.030 ± 0.0076 vs. 0.029 ± 0.0065 mm(-1); P < 0.05) and ES (mean for 13 segments, 0.040 ± 0.012 vs. 0.034 ± 0.0072 mm(-1); P < 0.001) was decreased by chronic pulmonary regurgitation. Secondly, the surface area increased significantly at ED (mean for 13 segments, 982 ± 192 vs. 1,397 ± 387 mm(2); P < 0.001) and ES (mean for 13 segments, 576 ± 130 vs. 1,012 ± 302 mm(2); P < 0.001). In particular, rTOF patients had significantly larger surface area than that in normal subjects in the free wall but not for the septal wall. Thirdly, area strain was significantly decreased (mean for 13 segments, 56 ± 6 vs. 34 ± 7%; P < 0.0001) in rTOF patients. Fourthly, there were increases in surface area at ED (5,726 ± 969 vs. 6,605 ± 1,122 mm(2); P < 0.05) and ES (4,280 ± 758 vs. 5,569 ± 1,112 mm(2); P < 0.01) and decrease in area strain (29 ± 8 vs. 18 ± 8%; P < 0.001) for RV outflow tract. These findings suggest significant geometric and strain differences between rTOF and normal subjects that may help guide therapeutic treatment.
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Affiliation(s)
- Liang Zhong
- Cardiac Mechanics Engineering and Physiology Unit, National Heart Centre Singapore, Singapore
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Zhong L, Ghista D, Tan RS. Improved aorto-ventricular matching in ischemic dilated cardiomyopathy patients after surgical ventricular restoration. Med Eng Phys 2011; 33:1120-6. [DOI: 10.1016/j.medengphy.2011.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 04/30/2011] [Accepted: 05/06/2011] [Indexed: 10/18/2022]
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Ghista D, Miftahof R, Acharya R, Desai K. Biophysical Model of Sinoatrial Nodes Bioelectrical Activity to Simulate Heart Rate Variability in Normal and Diabetic Patients. Curr Bioinform 2009. [DOI: 10.2174/157489309788184756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Zhong L, Yeo SY, Su Y, Le TT, Tan RS, Ghista D. Regional assessment of left ventricular surface shape from magnetic resonance imaging. ACTA ACUST UNITED AC 2008; 2007:884-7. [PMID: 18002098 DOI: 10.1109/iembs.2007.4352432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Left ventricular functional abnormalities are postulated to be associated with regional modification of surface curvature. This study describes the computation of the differential properties of the LV surface via an analytic approach using local surface fitting. Quantification was implemented with cine magnetic resonance imaging (MRI), which was used as the source to derive 3D wire-frame models and the related shape descriptors. Based on these shape descriptors, the shape of LV could be represented in both static and dynamic manners. These may have implications for diverse cardiac diseases.
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Affiliation(s)
- Liang Zhong
- Department of Cardiology, National Heart Centre, Third Hospital Avenue, Singapore. 65-64367580.
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Zhong L, Chua L, Ng EYK, Ghista D, Lim S, Tan R. A non-invasive system for assessment of aortic stiffness in clinical practice. Conf Proc IEEE Eng Med Biol Soc 2007; 2005:2248-51. [PMID: 17282680 DOI: 10.1109/iembs.2005.1616911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Previously aortic stiffness is frequently assessed through pulse pressure and pulse wave velocity (PWV) measurements. However, these methods need aortic pressure obtained by catheterization. A new model has been developed to rapidly determine the aortic pressure profile and simultaneously calculate aortic stiffness. Comparison between the aortic pressure result obtained from this and catheterization data demonstrates good agreement, while this method is non-invasive. This totally non-invasive method should be useful in assessing arteriosclerotic disease in clinical setting.
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Affiliation(s)
- L Zhong
- Sch. of Mechanical & Aerosp. Eng., Nanyang Technol. Univ
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Sankaranarayanan M, Leok Poh C, Li L, Ghista D, Yong Seng T. Influence of aorto-left coronary bypass graft geometry on wall shear stress distribution. Conf Proc IEEE Eng Med Biol Soc 2007; 2006:615-8. [PMID: 17282257 DOI: 10.1109/iembs.2005.1616488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Idealized geometries of bypass grafts have been constructed to analyze the blood flow in an aorto-coronary bypass graft system. In this paper we discuss the influence of the realistic bypass graft geometry for the in-plane and out-of-plane aorto-left bypass graft models on the wall shear stress distribution. In the in-plane aorto-left coronary bypass graft model we have the centerlines of the aorta, the left coronary vessel and the bypass graft to lie in the same plane (planar geometry) where as in the out-of-plane model the centerlines of the vessels no longer lie in a constant plane (non-planar geometry). Computational fluid dynamic (CFD) studies are carried out using the commercial software FLUENT. It is known that the coronaries are well perfused during the diastole and hence even though simulations are performed at different instances (both the systole and diastole phase) of the cardiac cycle, we have demonstrated the wall shear stress distribution in the distal anastomotic section for both the models at two specific instances of the diastolic phase, namely, early diastole (t=0.45 s) and mid-diastole (t=0.7 s). Our results reveal that in comparison to the in-plane model, the wall shear stress magnitude in the out-of-plane model is greatly reduced at the bed of the anastomosis. Thus a subtle change in the geometry can affect the flow field significantly that may promote graft patency.
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Kah Meng L, Ng D, Ghista D, Rudolph H. Quantitation of renal function based on two-compartmental modeling of renal pelvis. Conf Proc IEEE Eng Med Biol Soc 2007; 2005:2349-52. [PMID: 17282706 DOI: 10.1109/iembs.2005.1616937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The primary functions of the kidney are: (i) to get rid of the body waste materials that are either ingested or produced by metabolism, and (ii) to control the volume and composition of the body fluids. Herein, we provide a noninvasive methodology to assess physiological function of the kidneys. For this purpose, we analyze the renograms with 2-compartmental modelling of the kidney-renal outflow system, and therefrom compute the amount of flow of renal radionuclide into and out of the renal pelvis compartment. The derived information of uptake (k/A) and washout (e(beta/2V<sub>2</sub>)t sinhAt) rates can be of considerable use. The paper provides a number of case studies for the verification of the derived system governing equations against clinical renograms.
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Chew Yan T, Liang Z, Alirio M, Sankaranarayanan M, Ghista D. Role of sphingosine kinase in the expression of adhesion molecules on monocytes induced by tumor necrosis factor-alpha (relevant to atherosclerosis). Conf Proc IEEE Eng Med Biol Soc 2007; 2006:70-3. [PMID: 17282113 DOI: 10.1109/iembs.2005.1616344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
TNFα stimulates SPHK in the monocyte, which leads to the expression of adhesion molecules on the cell surface. The adhesion of leukocytes to the endothelium is one of the early stages of the onset of atherosclerosis. In this paper, we have delineated the TNFα-induced and SPHK-dependent signaling pathway. In addition, we have developed a biomathematical model to qualify the SPHK time-dependent activity at a specific site in the cell upon TNFα stimulation. Thus, this study provides a biochemical and mechanistic approaches to the understanding of leukocyte-endothelial attachment, so that measures could be designed to minimize the onset of atherosclerosis.
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Affiliation(s)
- Tuang Chew Yan
- Nanyang Technological University, College of Engineering, School of Chemical and Biomedical Engineering, 50 Nanyang Avenue, Singapore 639798
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Chiang Lee H, Wah Khong P, Ghista D. Bioenergy based Medical Diagnostic Application based on Gas Discharge Visualization. Conf Proc IEEE Eng Med Biol Soc 2007; 2005:1533-6. [PMID: 17282494 DOI: 10.1109/iembs.2005.1616725] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Allopathic medical diagnostic divides the human body into physiological and organ systems and analyzes the condition of these systems individually based on their anatomy, physiology, biochemistry and pathology. However, without analysis of intricate signals between these systems, it is difficult to provide a deeper insight of a patient's health, therefore reliable detection of diseases. This purpose of this paper is to demonstrate the possibilities of providing holistic medical screening through measurement of bioenergy fields which have both biophysical and biophysic bearings.
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Li L, Liang Z, Ghista D, Leok Poh C, Sankaranarayanan M, San Tan R, Seng Tan Y. Determination of the left ventricular myofiber angle analytically and its significance. Conf Proc IEEE Eng Med Biol Soc 2007; 2005:5719-22. [PMID: 17281556 DOI: 10.1109/iembs.2005.1615786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
It is known that the tremendous internal pressure build-up in the left ventricle (LV) cavity during isovolumic contraction is due to the contraction of the spirally woven myocardial fibers. In this paper, a biomathematical model is developed to investigate the fiber angle using the theory of elasticity. Simultaneously, another simplified model in order to reduce the mathematical complexity was also developed to determine the fiber angle. The results of these two models showed that both the myocardial fiber angles are in same magnitude.
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Affiliation(s)
- Liu Li
- Sch. of Mech. & Aerosp. Eng., Nanyang Technol. Univ. Singapore
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Fan S, Ghista D, Sridhar I, Ramakrishna K. Biomechanics of the intrinsically optimal design of the intervertebral disc. Conf Proc IEEE Eng Med Biol Soc 2007; 2005:4408-11. [PMID: 17281213 DOI: 10.1109/iembs.2005.1615443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The spinal shock-absorbing disc needs to have the flexibility to enable the spine to bend and twist. At the same time under loading, its lateral and axial deformations have to be contained, so that it does not herniate and impinge on the spinal-chord. The disc is composed of a fluid-like nucleus pulposus (NP) contained within an annulus. Hence when the disc is loaded, the NP gets pressurized and stresses the surrounding annulus. Now, because its elastic modulus is stress-dependent (i.e. E-E <sub>0</sub> = ksigma, where k is a constitutive parameter ), the annulus stiffens under loading. In this way, the flexible disc is able to sustain its loading with minimal deformation and thereby contain its deformation. In this paper, we have carried out a stress and deformation analysis of the spinal disc, and demonstrated that its deformations are invariant with the load intensity and only dependent on its dimensions and its constitutive property parameter k. Thus, we demonstrate that the intrinsic design of the spinal disc makes it an optimal structure.
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Affiliation(s)
- S Fan
- Sch. of Civil Eng., Nanyang Technol. Univ
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Adeyemi EO, Desai KD, Towsey M, Ghista D. Characterization of autonomic dysfunction in patients with irritable bowel syndrome by means of heart rate variability studies. Am J Gastroenterol 1999; 94:816-23. [PMID: 10086672 DOI: 10.1111/j.1572-0241.1999.00861.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Our aim was to characterize autonomic dysfunction in patients with irritable bowel syndrome (IBS) using heart rate variability (HRV) studies. METHODS EKG signals were obtained from 35 patients (mean age, 39.1 +/- 9.5 yr, M:F ratio = 2.9:1) and 18 healthy controls (mean age, 38.2 +/- 6.5 yr, M:F ratio = 2:1) in supine, standing, and deep-breathing modes. Fast Fourier transformation and autoregressive techniques were used to analyze the HRV power spectra in very low (VLF, 0.0078-0.04 Hz), low (LF, 0.04-0.14 Hz), and high (HF, 0.14-0.4 Hz) frequency bands. RESULTS In the supine position, the VLF power spectral density (PSD) in IBS was significantly higher than normal (3 vs 1.3 beats per minute [bpm]2/Hz, p < 0.01). On changing from the supine to standing position, the normals (NC) had raised median PSDs in the VLF (1.3 vs 12.8 bpm2/Hz, p < 0.01) and LF (1.6 vs 6.1 bpm2/Hz, p < 0.01) bands, as a sign of increased sympathetic tone, whereas the median HF PSDs (parasympathetic tone) remained unchanged (1.8 bpm2/Hz each, p = 0.8). Similarly, the IBS patients had increased VLF (3.04 vs 14.93 bpm2/Hz, p < 0.01) and LF (2.8 vs 8.7 bpm2/Hz, p < 0.01) PSDs on standing up, but the HF PSD was also raised (from 2.4 to 5.7 bpm2/Hz, p = 0.04). On changing from standing to the deep-breathing mode, the normals had a significant increase in the HF (from 1.8 to 10.3 bpm2/Hz, p < 0.001) and a significant reduction of the VLF (from 12.8 to 2.2 bpm2/Hz, p < 0.01) PSDs. The reduction of the LF PSD was not significant (from 6.1 to 5.6 bpm2/Hz, p = 0.6). In IBS, HF PSD remained constant (5.7 bpm2/Hz each, p = 0.6), whereas the LF PSD increased from 8.7 to 24.2 bpm2/Hz (p < 0.0001). The VLF PSD was reduced (from 14.9 to 4.1 bpm2/Hz, p < 0.0001). In IBS, the median sympathovagal outflow ratio was significantly lower in the standing position (1.4 vs 2.8, p < 0.02) and higher in the deep-breathing mode (7.33 vs 0.42, p < 0.0001) than normal. CONCLUSIONS IBS patients have reduced sympathetic influence on the heart period in response to orthostatic stress and diminished parasympathetic modulation during deep breathing.
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Affiliation(s)
- E O Adeyemi
- Department of Medicine, FMHS, UAE University, Al Ain, United Arab Emirates
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Abstract
The human scoliotic spine is mathematically modelled by employing the classical non-linear theory of curved beam-columns. A realistically representative muscle force system is included in the model. Scoliosis due to asymmetrical bi-lateral muscular contractions has been studied and arbitrary large displacements and curvatures are allowed. The two-dimensional model allowing curvature in the frontal plane can show the progression of a scoliotic curve from an initially straight configuration. For various parameter values, particularly muscle asymmetry, the model attempts to simulate the progression of actual scoliotic curves. Once these curves have been simulated, forces corresponding to corrective surgical systems are applied to the scoliotic spine. The corresponding corrected curves are then compared with those produced by a finite element model and also to the actual clinical curve. The comparisons were very favourable, considering the simplicity of the continuous model. The commonly observed phenomenon of the scoliotic curve lying to the weaker side of the back in terms of muscle strength is reproduced and explained by the model. The possible usefulness of continuous spinal models to analyse the overall deformation of the spine under various loading conditions can then be deduced.
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Affiliation(s)
- G Noone
- Department of Applied Mathematics, Adelaide University, South Australia
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Ghista D, Toridis T, Srinivasan TM. Human gait analysis: determination of instantaneous joint reactive forces, muscle forces and the stress distribution in bone segments. Part 11. BIOMED ENG-BIOMED TE 1976; 21:66-74. [PMID: 1268302 DOI: 10.1515/bmte.1976.21.3.66] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Gould P, Ghista D, Brombolich L, Mirsky I. In vivo stresses in the human left ventricular wall: analysis accounting for the irregular 3-dimensional geometry and comparison with idealised geometry analyses. J Biomech 1972; 5:521-39. [PMID: 4667276 DOI: 10.1016/0021-9290(72)90009-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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