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Li Z, Luo T, Wang S, Jia H, Gong Q, Liu X, Sutcliffe MPF, Zhu H, Liu Q, Chen D, Xiong J, Teng Z. Mechanical and histological characteristics of aortic dissection tissues. Acta Biomater 2022; 146:284-294. [PMID: 35367380 DOI: 10.1016/j.actbio.2022.03.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 12/14/2022]
Abstract
AIMS This study investigated the association between the macroscopic mechanical response of aortic dissection (AoD) flap, its fibre features, and patient physiological features and clinical presentations. METHODS Uniaxial test was performed with tissue strips in both circumferential and longitudinal directions from 35 patients with (AoD:CC) and without (AoD:w/oCC) cerebral/coronary complications, and 19 patients with rheumatic or valve-related heart diseases (RH). A Bayesian inference framework was used to estimate the expectation of material constants (C1, D1, and D2) of the modified Mooney-Rivlin strain energy density function. Histological examination was used to visualise the elastin and collagen in the tissue strips and image processing was performed to quantify their area percentages, fibre misalignment and waviness. RESULTS The elastin area percentage was negatively associated with age (p = 0.008), while collagen increased about 6% from age 40 to 70 (p = 0.03). Elastin fibre was less dispersed and wavier in old patients and no significant association was found between patient age and collagen fibre dispersion or waviness. Features of fibrous microstructures, either elastin or collagen, were comparable between AoD:CC and AoD:w/oCC group. Elastin and collagen area percentages were positively correlated with C1 and D2, respectively, while the elastin and collagen waviness were negatively correlated with C1 and D2, respectively. Elastin dispersion was negatively correlated to D2. Multivariate analysis showed that D2 was an effective parameter which could differentiate patient groups with different age and clinical presentations, as well as the direction of tissue strip. CONCLUSION Fibre dispersion and waviness in the aortic dissection flap changed with patient age and clinical presentations, and these can be captured by the material constants in the strain energy density function. STATEMENT OF SIGNIFICANCE Aortic dissection (AoD) is a severe cardiovascular disease. Understanding the mechanical property of intimal flap is essential for its risk evaluation. In this study, mechanical testing and histology examination were combined to quantify the relationship between mechanical presentations and microstructure features. A Bayesian inference framework was employed to estimate the expectation of the material constants in the modified Mooney-Rivlin constitutive equation. It was found that fibre dispersion and waviness in the AoD flap changed with patient age and clinical presentations, and these could be captured by the material constants. This study firstly demonstrated that the expectation of material constants can be used to characterise tissue microstructures and differentiate patients with different clinical presentations.
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Alan B, Alan S. Evaluation of carotid artery stiffness in patients with coronary artery disease using acoustic radiation force impulse elastography. Vascular 2022; 31:564-572. [PMID: 35226579 DOI: 10.1177/17085381221076679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVES We evaluated carotid artery stiffness in patients with coronary artery disease (CAD) using acoustic radiation force impulse (ARFI) elastography and investigated the relationship between stiffness and CAD. METHODS This study examined 76 CAD patients (aged 60.7 ± 11) and 70 healthy individuals (aged 59.6 ± 9). The left common carotid artery mean shear wave velocity (LCmeanSWV) and the right common carotid artery mean shear wave velocity (RCmeanSWV) of the anterior walls were measured using ARFI elastography, and the results of the patient group and the healthy group were compared. The common carotid intima-media thickness (CIMT) was measured in both groups and compared with mean SWV. RESULTS The RCmeanSWVs in the patient and healthy groups were 3.47 ± 1 m/s and 2.69 ± 0.90 m/s, respectively (p < 0.001). The LCmeanSWVs in the patient and healthy groups were 3.60 ± 0.9 m/s and 2.90 ± 0.80 m/s, respectively (p < 0.001). A significant correlation was found between the RCmeanSWV and the right CIMT values and between the LCmeanSWV and the left CIMT values (r = 0.231, p = 0.03 and r = 0.331, p = 0.002, respectively). CONCLUSIONS The mean SWV values of carotid arteries of CAD patients measured with ARFI elastography were significantly higher than the mean SWV values of the carotid arteries of healthy individuals. Thus, measurement of the carotid artery SWV could be a potential tool in the risk evaluation of cardiovascular disease. Nonetheless, new studies are required to determine whether this method serves as a useful additional tool.
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Affiliation(s)
- Bircan Alan
- Department of Radiology, 52942Bolu Abant İzzet Baysal University Medical Faculty, Bolu, Turkey
| | - Sait Alan
- Department of Cardiology, 52942Bolu Abant İzzet Baysal University Medical Faculty, Bolu, Turkey
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Hossain MM, Saharkhiz N, Konofagou EE. Feasibility of Harmonic Motion Imaging Using a Single Transducer: In Vivo Imaging of Breast Cancer in a Mouse Model and Human Subjects. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:1390-1404. [PMID: 33523806 PMCID: PMC8136334 DOI: 10.1109/tmi.2021.3055779] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Harmonic motion imaging (HMI) interrogates the mechanical properties of tissues by simultaneously generating and tracking harmonic oscillation using focused ultrasound and imaging transducers, respectively. Instead of using two transducers, the objective of this work is to develop a single transducer HMI (ST-HMI) to both generate and track harmonic motion at "on-axis" to the force for facilitating data acquisition. In ST-HMI, the amplitude-modulated force was generated by modulating excitation pulse duration and tracking of motion was performed by transmitting tracking pulses interleaved between excitation pulses. The feasibility of ST-HMI was performed by imaging two elastic phantoms with three inclusions (N = 6) and comparing it with acoustic radiation force impulse (ARFI) imaging, in vivo longitudinal monitoring of 4T1, orthotropic breast cancer mice (N = 4), and patients (N = 3) with breast masses in vivo. Six inclusions with Young's moduli of 8, 10, 15, 20, 40, and 60 kPa were embedded in a 5 kPa background. The ST-HMI-derived peak-to-peak displacement (P2PD) successfully detected all inclusions with [Formula: see text] of the linear regression between the P2PD ratio of background to inclusion versus Young's moduli ratio of inclusion to background. The contrasts of 10 and 15 kPa inclusions were higher in ST-HMI than ARFI-derived images. In the mouse study, the median P2PD ratio of tumor to non-cancerous tissues was 3.0, 5.1, 6.1, and 7.7 at 1, 2, 3, and 4 weeks post-injection of the tumor cells, respectively. In the clinical study, ST-HMI detected breast masses including fibroadenoma, pseudo angiomatous stromal hyperplasia, and invasive ductal carcinoma with a P2PD ratio of 1.37, 1.61, and 1.78, respectively. These results indicate that ST-HMI can assess the mechanical properties of tissues via generation and tracking of harmonic motion "on-axis" to the ARF. This study is the first step towards translating ST-HMI in clinics.
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Varghese T, Meshram NH, Mitchell CC, Wilbrand SM, Hermann BP, Dempsey RJ. Lagrangian carotid strain imaging indices normalized to blood pressure for vulnerable plaque. JOURNAL OF CLINICAL ULTRASOUND : JCU 2019; 47:477-485. [PMID: 31168787 PMCID: PMC6760247 DOI: 10.1002/jcu.22739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/10/2019] [Accepted: 05/22/2019] [Indexed: 05/14/2023]
Abstract
OBJECTIVE Ultrasound Lagrangian carotid strain imaging (LCSI) utilizes physiological deformation caused by arterial pressure variations to generate strain tensor maps of the vessel walls and plaques. LCSI has been criticized for the lack of normalization of magnitude-based strain indices to physiological stimuli, namely blood pressure. We evaluated the impact of normalization of magnitude-based strain indices to blood pressure measured immediately after the acquisition of radiofrequency (RF) data loops for LCSI. MATERIALS AND METHODS A complete clinical ultrasound examination along with RF data loops for LCSI was performed on 50 patients (30 males and 20 females) who presented with >60% carotid stenosis and were scheduled for carotid endarterectomy. Cognition was assessed using the 60-minute neuropsychological test protocol. RESULTS For axial strains correlation of maximum accumulated strain indices (MASI), cognition scores were -0.46 for non-normalized and -0.45, -0.49, -0.37, and -0.48 for systolic, diastolic, pulse pressure, and mean arterial pressure normalized data, respectively. The corresponding area under the curve (AUC) values for classifiers designed using maximum likelihood estimation of a binormal distribution with a median-split of the executive function cognition scores were 0.73, 0.70, 0.71, 0.70, and 0.71, respectively. CONCLUSIONS No significant differences in the AUC estimates were obtained between normalized and non-normalized magnitude-based strain indices.
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Affiliation(s)
- Tomy Varghese
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Nirvedh H Meshram
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Carol C Mitchell
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Stephanie M Wilbrand
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Bruce P Hermann
- Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Robert J Dempsey
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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Torres G, Czernuszewicz TJ, Homeister JW, Caughey MC, Huang BY, Lee ER, Zamora CA, Farber MA, Marston WA, Huang DY, Nichols TC, Gallippi CM. Delineation of Human Carotid Plaque Features In Vivo by Exploiting Displacement Variance. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2019; 66:481-492. [PMID: 30762544 PMCID: PMC7952026 DOI: 10.1109/tuffc.2019.2898628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
While in vivo acoustic radiation force impulse (ARFI)-induced peak displacement (PD) has been demonstrated to have high sensitivity and specificity for differentiating soft from stiff plaque components in patients with carotid plaque, the parameter exhibits poorer performance for distinguishing between plaque features with similar stiffness. To improve discrimination of carotid plaque features relative to PD, we hypothesize that signal correlation and signal-to-noise ratio (SNR) can be combined, outright or via displacement variance. Plaque feature detection by displacement variance, evaluated as the decadic logarithm of the variance of acceleration and termed "log(VoA)," was compared to that achieved by exploiting SNR, cross correlation coefficient, and ARFI-induced PD outcome metrics. Parametric images were rendered for 25 patients undergoing carotid endarterectomy, with spatially matched histology confirming plaque composition and structure. On average, across all plaques, log(VoA) was the only outcome metric with values that statistically differed between regions of lipid-rich necrotic core (LRNC), intraplaque hemorrhage (IPH), collagen (COL), and calcium (CAL). Further, log(VoA) achieved the highest contrast-to-noise ratio (CNR) for discriminating between LRNC and IPH, COL and CAL, and grouped soft (LRNC and IPH) and stiff (COL and CAL) plaque components. More specifically, relative to the previously demonstrated ARFI PD parameter, log(VoA) achieved 73% higher CNR between LRNC and IPH and 59% higher CNR between COL and CAL. These results suggest that log(VoA) enhances the differentiation of LRNC, IPH, COL, and CAL in human carotid plaques, in vivo, which is clinically relevant to improving stroke risk prediction and medical management.
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Niu L, Zhu X, Pan M, Derek A, Xu L, Meng L, Zheng H. Influence of vascular geometry on local hemodynamic parameters: phantom and small rodent study. Biomed Eng Online 2018; 17:30. [PMID: 29499760 PMCID: PMC5833153 DOI: 10.1186/s12938-018-0458-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/21/2018] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Many studies have demonstrated that the geometry of the carotid bifurcation enables prediction of blood flow variation associated with atherosclerotic plaque formation. The phase angle between the arterial wall circumferential strain and its instantaneous wall shear stress is known as stress phase angle (SPA). This parameter is used to evaluate hemodynamic factors of atherogenesis. Note that SPA can be numerically computed for the purpose of locating atherosclerosis in different artery geometries. However, there is no experimental data to verify its role in the location of atherosclerosis in different artery geometries. In this study, we use an ultrasonic biomechanical method to experimentally evaluate the role of SPA for locating atherosclerosis in carotid bifurcation. RESULTS For carotid anthropomorphic vascular phantom experiments, the SPAs of common carotid arteries (CCAs), external carotid arteries (ECAs) and internal carotid arteries (ICAs) are - 148.53 ± 6.92°, - 153.95 ± 5.11°, and - 238.69 ± 1.72°, respectively. The corresponding SPAs are - 173.47 ± 0.065°, - 115.57 ± 4.83° and - 233.9 ± 8.12° for the polyvinyl alcohol (PVA-c) phantoms. In vivo mouse experiments indicated that the wall shear stress and circumferential strain were out of phase in the ICAs (- 280.08 ± 13.12°) to a greater extent as compared to CCAs (- 141.97 ± 8.03°) and ECAs (- 170.07 ± 9.24°). CONCLUSIONS The results suggested that SPA may be a useful indicator to locate the atherosclerosis position in carotid bifurcation.
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Affiliation(s)
- Lili Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Ave., Nanshan District, Shenzhen, 518055, People's Republic of China
| | - Xiliang Zhu
- Department of Cardiovascular Surgery, Henan Province People's Hospital, Fuwai Central China Cardiovascular Hospital, Zhengzhou University People's Hospital and Medical School of Henan University, Zhengzhou, 450000, Henan Province, People's Republic of China
| | - Min Pan
- Guangzhou University of Chinese Medicine, Guangzhou, People's Republic of China
| | - Abbott Derek
- Centre for Biomedical Engineering, School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, Australia
| | - Lisheng Xu
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, 195 Chuangxin Ave., Hunnan District, Shenyang, 110819, People's Republic of China. .,Key Laboratory of Medical Image Computing, Ministry of Education, Northeastern University, Shenyang, China.
| | - Long Meng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Ave., Nanshan District, Shenzhen, 518055, People's Republic of China.
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Ave., Nanshan District, Shenzhen, 518055, People's Republic of China
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Astaneh AV, Urban MW, Aquino W, Greenleaf JF, Guddati MN. Arterial waveguide model for shear wave elastography: implementation andin vitrovalidation. Phys Med Biol 2017; 62:5473-5494. [DOI: 10.1088/1361-6560/aa6ee3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Czernuszewicz TJ, Gallippi CM. On the Feasibility of Quantifying Fibrous Cap Thickness With Acoustic Radiation Force Impulse (ARFI) Ultrasound. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2016; 63:1262-75. [PMID: 26955026 PMCID: PMC5084842 DOI: 10.1109/tuffc.2016.2535440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Acute cerebrovascular accidents are associated with the rupture of vulnerable atherosclerotic plaques in the carotid arteries. Fibrous cap (FC) thickness has been shown to be an important predictor of plaque rupture but has been challenging to measure accurately with clinical noninvasive imaging modalities. The goals of this investigation were first, to evaluate the feasibility of using transcutaneous acoustic radiation force impulse (ARFI) ultrasound to quantify FC thickness and second, to optimize both imaging and motion-tracking parameters to support such measurements. FCs with varying thickness (0.1-1.0 mm) were simulated using a simple-layered geometry, and their mechanical response to an impulse of radiation force was solved using finite-element method (FEM) modeling. Ultrasound tracking of FEM displacements was performed in Field II utilizing three center frequencies (6, 9, and 12 MHz) and eight motion-tracking kernel lengths ( 0.5λ-4λ). Additionally, FC thickness in two carotid plaques imaged in vivo was measured with ARFI and compared to matched histology. The results of this study demonstrate that 1) tracking pulse frequencies around 12 MHz are necessary to resolve caps around 0.2 mm; 2) large motion-tracking kernel sizes introduce bias into thickness measurements and overestimate the true cap thickness; and 3) color saturation settings on ARFI peak displacement images can impact thickness measurement accuracy substantially.
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Affiliation(s)
- Tomasz J. Czernuszewicz
- Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC, USA
| | - Caterina M. Gallippi
- Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC, USA. Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC, USA
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Ebbini ES, ter Haar G. Ultrasound-guided therapeutic focused ultrasound: current status and future directions. Int J Hyperthermia 2015; 31:77-89. [PMID: 25614047 DOI: 10.3109/02656736.2014.995238] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
This paper reviews ultrasound imaging methods for the guidance of therapeutic focused ultrasound (USgFUS), with emphasis on real-time preclinical methods. Guidance is interpreted in the broadest sense to include pretreatment planning, siting of the FUS focus, real-time monitoring of FUS-tissue interactions, and real-time control of exposure and damage assessment. The paper begins with an overview and brief historical background of the early methods used for monitoring FUS-tissue interactions. Current imaging methods are described, and discussed in terms of sensitivity and specificity of the localisation of the FUS effects in both therapeutic and sub-therapeutic modes. Thermal and non-thermal effects are considered. These include cavitation-enhanced heating, tissue water boiling and cavitation. Where appropriate, USgFUS methods are compared with similar methods implemented using other guidance modalities, e.g. magnetic resonance imaging. Conclusions are drawn regarding the clinical potential of the various guidance methods, and the feasibility and current status of real-time implementation.
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Affiliation(s)
- Emad S Ebbini
- Electrical and Computer Engineering, University of Minnesota Twin Cities , Minneapolis, Minnesota , USA and
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Brezinski ME. Practical Challenges of Current Video Rate OCT Elastography: Accounting for Dynamic and Static Tissue Properties. JOURNAL OF LASERS, OPTICS & PHOTONICS 2014; 1:112. [PMID: 29286052 PMCID: PMC5743221 DOI: 10.4172/2469-410x.1000112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Optical coherence tomography (OCT) elastography (OCTE) has the potential to be an important diagnostic tool for pathologies including coronary artery disease, osteoarthritis, malignancies, and even dental caries. Many groups have performed OCTE, including our own, using a wide range of approaches. However, we will demonstrate current OCTE approaches are not scalable to real-time, in vivo imaging. As will be discussed, among the most important reasons is current designs focus on the system and not the target. Specifically, tissue dynamic responses are not accounted, with examples being the tissue strain response time, preload variability, and conditioning variability. Tissue dynamic responses, and to a lesser degree static tissue properties, prevent accurate video rate modulus assessments for current embodiments. Accounting for them is the focus of this paper. A top-down approach will be presented to overcome these challenges to real time in vivo tissue characterization. Discussed first is an example clinical scenario where OTCE would be of substantial relevance, the prevention of acute myocardial infarction or heart attacks. Then the principles behind OCTE are examined. Next, constrains on in vivo application of current OCTE are evaluated, focusing on dynamic tissue responses. An example is the tissue strain response, where it takes about 20 msec after a stress is applied to reach plateau. This response delay is not an issue at slow acquisition rates, as most current OCTE approaches are preformed, but it is for video rate OCTE. Since at video rate each frame is only 30 msec, for essentially all current approaches this means the strain for a given stress is changing constantly during the B-scan. Therefore the modulus can't be accurately assessed. This serious issue is an even greater problem for pulsed techniques as it means the strain/modulus for a given stress (at a location) is unpredictably changing over a B-scan. The paper concludes by introducing a novel video rate approach to overcome these challenges.
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Affiliation(s)
- Mark E Brezinski
- Center for Optics and Modern Physics, Brigham and Women’s Hospital, 75 Francis Street, Boston, M.A. 02115, USA
- Harvard Medical School, 25 Shattuck Street, Boston, M.A. 02115, USA
- Department of Electrical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, M.A. 02139, USA
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Martorell J, Santomá P, Kolandaivelu K, Kolachalama VB, Melgar-Lesmes P, Molins JJ, Garcia L, Edelman ER, Balcells M. Extent of flow recirculation governs expression of atherosclerotic and thrombotic biomarkers in arterial bifurcations. Cardiovasc Res 2014; 103:37-46. [PMID: 24841070 PMCID: PMC4670884 DOI: 10.1093/cvr/cvu124] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 04/10/2014] [Accepted: 05/01/2014] [Indexed: 11/12/2022] Open
Abstract
AIMS Atherogenesis, evolution of plaque, and outcomes following endovascular intervention depend heavily on the unique vascular architecture of each individual. Patient-specific, multiscale models able to correlate changes in microscopic cellular responses with relevant macroscopic flow, and structural conditions may help understand the progression of occlusive arterial disease, providing insights into how to mitigate adverse responses in specific settings and individuals. METHODS AND RESULTS Vascular architectures mimicking coronary and carotid bifurcations were derived from clinical imaging and used to generate conjoint computational meshes for in silico analysis and biocompatible scaffolds for in vitro models. In parallel with three-dimensional flow simulations, geometrically realistic scaffolds were seeded with human smooth muscle cells (SMC) or endothelial cells and exposed to relevant, physiological flows. In vitro surrogates of endothelial health, atherosclerotic progression, and thrombosis were locally quantified and correlated best with an quantified extent of flow recirculation occurring within the bifurcation models. Oxidized low-density lipoprotein uptake, monocyte adhesion, and tissue factor expression locally rose up to three-fold, and phosphorylated endothelial nitric oxide synthase and Krüppel-like factor 2 decreased up to two-fold in recirculation areas. Isolated testing in straight-tube idealized constructs subject to static, oscillatory, and pulsatile conditions, indicative of different recirculant conditions corroborated these flow-mediated dependencies. CONCLUSIONS Flow drives variations in vascular reactivity and vascular beds. Endothelial health was preserved by arterial flow but jeopardized in regions of flow recirculation in a quasi-linear manner. Similarly, SMC exposed to flow were more thrombogenic in large recirculating regions. Health, thrombosis, and atherosclerosis biomarkers correlate with the extent of recirculation in vascular cells lining certain vascular geometries.
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Affiliation(s)
- Jordi Martorell
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA Department of Chemical Engineering, IQS School of Engineering, URL, Via Augusta 390, 08017 Barcelona, Spain
| | - Pablo Santomá
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA Department of Chemical Engineering, IQS School of Engineering, URL, Via Augusta 390, 08017 Barcelona, Spain
| | - Kumaran Kolandaivelu
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Vijaya B Kolachalama
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA Charles Stark Draper Laboratory, Cambridge, MA, USA
| | - Pedro Melgar-Lesmes
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - José J Molins
- Department of Chemical Engineering, IQS School of Engineering, URL, Via Augusta 390, 08017 Barcelona, Spain
| | - Lawrence Garcia
- Department of Interventional Cardiology and Vascular Medicine, St. Elizabeth's Medical Center, Boston, MA, USA
| | - Elazer R Edelman
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA Cardiovascular Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Mercedes Balcells
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA Department of Biological Engineering, IQS School of Engineering, URL, Barcelona, Spain
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Wan J, He F, Zhao Y, Zhang H, Zhou X, Wan M. Non-invasive vascular radial/circumferential strain imaging and wall shear rate estimation using video images of diagnostic ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:622-636. [PMID: 24361217 DOI: 10.1016/j.ultrasmedbio.2013.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 09/28/2013] [Accepted: 10/13/2013] [Indexed: 06/03/2023]
Abstract
The aim of this work was to develop a convenient method for radial/circumferential strain imaging and shear rate estimation that could be used as a supplement to the current routine screening for carotid atherosclerosis using video images of diagnostic ultrasound. A reflection model-based correction for gray-scale non-uniform distribution was applied to B-mode video images before strain estimation to improve the accuracy of radial/circumferential strain imaging when applied to vessel transverse cross sections. The incremental and cumulative radial/circumferential strain images can then be calculated based on the displacement field between consecutive B-mode images. Finally, the transverse Doppler spectra acquired at different depths along the vessel diameter were used to construct the spatially matched instantaneous wall shear values in a cardiac cycle. Vessel phantom simulation results revealed that the signal-to-noise ratio and contrast-to-noise ratio of the radial and circumferential strain images were increased by 2.8 and 5.9 dB and by 2.3 and 4.4 dB, respectively, after non-uniform correction. Preliminary results for 17 patients indicated that the accuracy of radial/circumferential strain images was improved in the lateral direction after non-uniform correction. The peak-to-peak value of incremental strain and the maximum cumulative strain for calcified plaques are evidently lower than those for other plaque types, and the echolucent plaques had higher values, on average, than the mixed plaques. Moreover, low oscillating wall shear rate values, found near the plaque and stenosis regions, are closely related to plaque formation. In conclusion, the method described can provide additional valuable results as a supplement to the current routine ultrasound examination for carotid atherosclerosis and, therefore, has significant potential as a feasible screening method for atherosclerosis diagnosis in the future.
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Affiliation(s)
- Jinjin Wan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Fangli He
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Yongfeng Zhao
- Department of Ultrasound, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Hongmei Zhang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Xiaodong Zhou
- Department of Ultrasound, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Mingxi Wan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
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13
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Teng Z, Sadat U, Brown AJ, Gillard JH. Plaque hemorrhage in carotid artery disease: pathogenesis, clinical and biomechanical considerations. J Biomech 2014; 47:847-58. [PMID: 24485514 PMCID: PMC3994507 DOI: 10.1016/j.jbiomech.2014.01.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2014] [Indexed: 12/21/2022]
Abstract
Stroke remains the most prevalent disabling illness today, with internal carotid artery luminal stenosis due to atheroma formation responsible for the majority of ischemic cerebrovascular events. Severity of luminal stenosis continues to dictate both patient risk stratification and the likelihood of surgical intervention. But there is growing evidence to suggest that plaque morphology may help improve pre-existing risk stratification criteria. Plaque components such a fibrous tissue, lipid rich necrotic core and calcium have been well investigated but plaque hemorrhage (PH) has been somewhat overlooked. In this review we discuss the pathogenesis of PH, its role in dictating plaque vulnerability, PH imaging techniques, marterial properties of atherosclerotic tissues, in particular, those obtained based on in vivo measurements and effect of PH in modulating local biomechanics.
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Affiliation(s)
- Zhongzhao Teng
- University Department of Radiology, University of Cambridge, UK; Department of Engineering, University of Cambridge, UK.
| | - Umar Sadat
- Department of Surgery, Cambridge University Hospitals NHS Foundation Trust, UK
| | - Adam J Brown
- Department of Cardiovascular Medicine, University of Cambridge, UK
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Behler RH, Czernuszewicz TJ, Wu CD, Nichols TC, Zhu H, Homeister JW, Merricks EP, Gallippi CM. Acoustic radiation force beam sequence performance for detection and material characterization of atherosclerotic plaques: preclinical, ex vivo results. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:2471-87. [PMID: 24297014 PMCID: PMC4097991 DOI: 10.1109/tuffc.2013.2847] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
This work presents preclinical data demonstrating performance of acoustic radiation force (ARF)-based elasticity imaging with five different beam sequences for atherosclerotic plaque detection and material characterization. Twelve trained, blinded readers evaluated parametric images taken ex vivo under simulated in vivo conditions of 22 porcine femoral arterial segments. Receiver operating characteristic (ROC) curve analysis was carried out to quantify reader performance using spatially-matched immunohistochemistry for validation. The beam sequences employed had high sensitivity (sens) and specificity (spec) for detecting Type III+ plaques (sens: 85%, spec: 79%), lipid pools (sens: 80%, spec: 86%), fibrous caps (sens: 86%, spec: 82%), calcium (sens: 96%, spec: 85%), collagen (sens: 78%, spec: 77%), and disrupted internal elastic lamina (sens: 92%, spec: 75%). 1:1 single-receive tracking yielded the highest median areas under the ROC curve (AUC), but was not statistically significantly higher than 4:1 parallel-receive tracking. Excitation focal configuration did not result in statistically different AUCs. Overall, these results suggest ARF-based imaging is relevant to detecting and characterizing plaques and support its use for diagnosing and monitoring atherosclerosis.
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Ballyns JJ, Turo D, Otto P, Shah JP, Hammond J, Gebreab T, Gerber LH, Sikdar S. Office-based elastographic technique for quantifying mechanical properties of skeletal muscle. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2012; 31:1209-19. [PMID: 22837285 PMCID: PMC3493148 DOI: 10.7863/jum.2012.31.8.1209] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
OBJECTIVES Our objectives were to develop a new, efficient, and easy-to-administer approach to ultrasound elastography and assess its ability to provide quantitative characterization of viscoelastic properties of skeletal muscle in an outpatient clinical environment. We sought to show its validity and clinical utility in assessing myofascial trigger points, which are associated with myofascial pain syndrome. METHODS Ultrasound imaging was performed while the muscle was externally vibrated at frequencies in the range of 60 to 200 Hz using a handheld vibrator. The spatial gradient of the vibration phase yielded the shear wave speed, which is related to the viscoelastic properties of tissue. The method was validated using a calibrated experimental phantom, the biceps brachii muscle in healthy volunteers (n = 6), and the upper trapezius muscle in symptomatic patients with axial neck pain (n = 13) and asymptomatic (pain-free) control participants (n = 9). RESULTS Using the experimental phantom, our method was able to quantitatively measure the shear moduli with error rates of less than 20%. The mean shear modulus ± SD in the normal biceps brachii measured 12.5 ± 3.4 kPa, within the range of published values using more sophisticated methods. Shear wave speeds in active myofascial trigger points and the surrounding muscle tissue were significantly higher than those in normal tissue at high frequency excitations (>100 Hz; P < .05). CONCLUSIONS Off-the-shelf office-based equipment can be used to quantitatively characterize skeletal muscle viscoelastic properties with estimates comparable to those using more sophisticated methods. Our preliminary results using this method indicate that patients with spontaneous neck pain and symptomatic myofascial trigger points have increased tissue heterogeneity at the trigger point site and the surrounding muscle tissue.
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Affiliation(s)
- Jeffrey J Ballyns
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22030, USA
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Teng Z, He J, Degnan AJ, Chen S, Sadat U, Bahaei NS, Rudd JHF, Gillard JH. Critical mechanical conditions around neovessels in carotid atherosclerotic plaque may promote intraplaque hemorrhage. Atherosclerosis 2012; 223:321-6. [PMID: 22762729 PMCID: PMC3437553 DOI: 10.1016/j.atherosclerosis.2012.06.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 06/01/2012] [Accepted: 06/11/2012] [Indexed: 12/02/2022]
Abstract
Objective Intraplaque hemorrhage is an increasingly recognized contributor to plaque instability. Neovascularization of plaque is believed to facilitate the entry of inflammatory and red blood cells (RBC). Under physiological conditions, neovessels are subject to mechanical loading from the deformation of atherosclerotic plaque by blood pressure and flow. Local mechanical environments around neovessels and their relevant pathophysiologic significance have not yet been examined. Methods and results Four carotid plaque samples removed at endarcterectomy were collected for histopathological examination. Neovessels and other components were manually segmented to build numerical models for mechanical analysis. Each component was assumed to be non-linear isotropic, piecewise homogeneous and incompressible. The results indicated that local maximum principal stress and stretch and their variations during one cardiac cycle were greatest around neovessels. Neovessels surrounded by RBC underwent a much larger stretch during systole than those without RBCs present nearby (median [inter quartile range]; 1.089 [1.056, 1.131] vs. 1.034 [1.020, 1.067]; p < 0.0001) and much larger stress (5.3 kPa [3.4, 8.3] vs. 3.1 kPa [1.6, 5.5]; p < 0.0001) and stretch (0.0282 [0.0190, 0.0427] vs. 0.0087 [0.0045, 0.0185]; p < 0.0001) variations during the cardiac cycle. Conclusions Local critical mechanical conditions may lead to the rupture of neovessels resulting in the formation and expansion of intraplaque hemorrhage.
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Affiliation(s)
- Zhongzhao Teng
- University Department of Radiology, University of Cambridge, UK.
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Tzschätzsch H, Elgeti T, Rettig K, Kargel C, Klaua R, Schultz M, Braun J, Sack I. In Vivo time harmonic elastography of the human heart. ULTRASOUND IN MEDICINE & BIOLOGY 2012; 38:214-222. [PMID: 22178163 DOI: 10.1016/j.ultrasmedbio.2011.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 11/04/2011] [Accepted: 11/05/2011] [Indexed: 05/31/2023]
Abstract
Time harmonic elastography is introduced as a modality for assessing myocardial elasticity changes during the cardiac cycle. It is based on external stimulation and real-time analysis of 30-Hz harmonic shear waves in axial direction of a parasternal line of sight through the lateral heart wall. In 20 healthy volunteers, the externally induced waves showed smaller amplitudes during systole (76.0 ± 30.8 μm) and higher amplitudes during diastole (126.7 ± 52.1 μm). This periodic wave amplitude alteration preceded ventricular contraction and dilation by about 100 ms. The amplitude ratio of 1.75 ± 0.49 indicates a relative change in myocardial shear elasticity on the order of 14 ± 11. These results well agree with observations made by cardiac magnetic resonance elastography for a similar displacement component and region of the heart. The proposed method provides reproducible elastodynamic information on the heart in real-time and may help in diagnosing myocardial relaxation abnormalities in the future.
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Affiliation(s)
- Heiko Tzschätzsch
- Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
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