Coronary Artery Wall Strain Estimation From Clinical IVUS Images

2007 ◽  
Author(s):  
Yun Liang ◽  
Hui Zhu ◽  
Thomas Gehrig ◽  
Morton H. Friedman
Keyword(s):  
Arterial Wall ◽  
Mechanical Response ◽  
Plaque Rupture ◽  
Radial Strain ◽  
Estimation Method ◽  
Pressure Change ◽  
Tissue Deformation ◽  
Cross Sectional ◽  
Strain Estimation

Atherosclerotic plaque rupture is responsible for the majority of acute coronary syndromes and myocardial infarctions. Intravascular ultrasound (IVUS) imaging is a widely available clinical technique providing real time cross-sectional images of the vessel wall and plaque morphometry. However, IVUS echo images have limited ability to predict the vulnerability of the plaque. The mechanical behavior of the plaque is consistent with its underlying components, suggesting that measurements of plaque mechanical response can be used to assess the likelihood of plaque rupture [1]. Arterial wall strain in response to luminal pressure change is such a measurable quantity. IVUS elastography has been developed to measure the radial strain through correlation analysis of the IVUS radiofrequency (RF) signal [2]. Due to the movements of IVUS catheter caused by cardiac motion and the nonlinearity of tissue deformation, reliable strain is obtained by elastography only when the tissue motion is aligned with the RF direction and the RF traces correspond to the same axial location. This is difficult to achieve in vivo. We have developed a strain estimation method based on IVUS image registration. This 2D processing method has the ability to overcome in-plane catheter movement and heterogeneous tissue deformation, thereby increasing its accuracy. Using retrospectively retrieved cardiac phase information, we propose a practical method to estimate cross-sectional coronary arterial wall strain distribution from clinically acquired images during a conventional IVUS procedure.

Measurement of Coronary Artery Wall Strain In Situ Using IVUS

2007 ◽  
Author(s):  
Yun Liang ◽  
Hui Zhu ◽  
Morton H. Friedman
Keyword(s):  
Plaque Rupture ◽  
Radial Strain ◽  
Estimation Method ◽  
Pressure Change ◽  
Cross Sectional ◽  
Strain Estimation ◽  
2D Strain ◽  
Rf Signals ◽  
Ivus Image ◽  
Atherosclerotic Plaque Rupture

Atherosclerotic plaque rupture is the leading cause of mortality in cardiovascular diseases. Studying biomechanics of plaque provides important insights into its vulnerability, since a plaque behaves consistently with its underlying contents. Arterial wall strain in response to luminal pressure change is such a measurable quantity. Intravascular ultrasound (IVUS) imaging is a wildly available clinical technique providing real time cross-sectional images of the vessel wall and plaque morphometry. IVUS elastography has been used to measure the radial strain through correlation analysis of the IVUS radiofrequency (RF) signals. We have developed a strain estimation method based on IVUS image registration. Our method has the ability to overcome nonlinear tissue deformation and measure 2D strain.

Strain Measurement in Coronary Arteries Using Intravascular Ultrasound and Deformable Images

2002 ◽  
Vol 124 (6) ◽  
pp. 734-741 ◽  
Author(s):  
Alexander I. Veress ◽  
Jeffrey A. Weiss ◽  
Grant T. Gullberg ◽  
D. Geoffrey Vince ◽  
Richard D. Rabbitt
Keyword(s):  
Finite Element ◽  
Intravascular Ultrasound ◽  
Coronary Arteries ◽  
Strain Distribution ◽  
Plaque Rupture ◽  
Element Model ◽  
Cross Sectional ◽  
Image Pairs

Atherosclerotic plaque rupture is responsible for the majority of myocardial infarctions and acute coronary syndromes. Rupture is initiated by mechanical failure of the plaque cap, and thus study of the deformation of the plaque in the artery can elucidate the events that lead to myocardial infarction. Intravascular ultrasound (IVUS) provides high resolution in vitro and in vivo cross-sectional images of blood vessels. To extract the deformation field from sequences of IVUS images, a registration process must be performed to correlate material points between image pairs. The objective of this study was to determine the efficacy of an image registration technique termed Warping to determine strains in plaques and coronary arteries from paired IVUS images representing two different states of deformation. The Warping technique uses pointwise differences in pixel intensities between image pairs to generate a distributed body force that acts to deform a finite element model. The strain distribution estimated by image-based Warping showed excellent agreement with a known forward finite element solution, representing the gold standard, from which the displaced image was created. The Warping technique had a low sensitivity to changes in material parameters or material model and had a low dependency on the noise present in the images. The Warping analysis was also able to produce accurate strain distributions when the constitutive model used for the Warping analysis and the forward analysis was different. The results of this study demonstrate that Warping in conjunction with in vivo IVUS imaging will determine the change in the strain distribution resulting from physiological loading and may be useful as a diagnostic tool for predicting the likelihood of plaque rupture through the determination of the relative stiffness of the plaque constituents.

In Vivo Measurements of Change in Viscoelasticity of Arterial Wall During the Flow-Mediated Dilation

2009 ◽  
Author(s):  
Hiroshi Kanai ◽  
Hideyuki Hasegawa ◽  
Kazuki Ikeshita
Keyword(s):  
Elastic Modulus ◽  
Endothelial Function ◽  
Hysteresis Loop ◽  
Arterial Wall ◽  
Radial Strain ◽  
Least Square ◽  
Flow Mediated Dilation ◽  
Transient Change ◽  
In Vivo Measurements

The present paper introduces in vivo measurements of viscoelasticity of arterial wall developed in our laboratory. The endothelial dysfunction is considered to be an earliest stage of atherosclerosis. Moreover, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics due to atherosclerosis. Therefore, it is essential to develop an in vivo measurement method to assess the regional endothelial function and mechanical property (viscoelasticity) of the arterial wall. To evaluate the endothelial function, there is a conventional technique for measuring the transient change in the diameter of the brachial artery caused by flow mediated dilation (FMD) after the release of avascularization. However, this method does not directly evaluate the viscoelasticity of the intima-media region of the arterial wall. In the present paper, therefore, we proposed a method for simultaneous measurement of waveforms of the radial strain and blood pressure at the radial artery, and we developed its measurement system. From in vivo experiments, the viscoelasticity parameters of the arterial wall were estimated from the measured stress-strain relationship (hysteresis loop) using the least-square method and their transient changes after the release of avascularization were revealed. For healthy young persons, the slope of the hysteresis loop decreased due to the FMD, which corresponds to decrease in the elastic modulus. At the same time, the area of the loop increased after recirculation, which corresponds to the increase of the ratio of the loss modulus (viscosity) to the elastic modulus when the Voigt model is assumed. These results show a potential of the proposed method for thorough analysis of the transient change in viscoelasticity due to FMD.

scholarly journals In-Vivo Measurement of Ocular Deformation in Response to Ambient Pressure Modulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Sabine Kling
Keyword(s):  
Ambient Pressure ◽  
Compressive Strain ◽  
Crystalline Lens ◽  
Pressure Change ◽  
Axial Displacement ◽  
Healthy Human ◽  
Cross Sectional ◽  
Mechanical Responses ◽  
Pressure Modulation

A novel approach is presented for the non-invasive quantification of axial displacement and strain in corneal and anterior crystalline lens tissue in response to a homogenous ambient pressure change. A spectral domain optical coherence tomography (OCT) system was combined with a custom-built set of swimming goggles and a pressure control unit to acquire repetitive cross-sectional scans of the anterior ocular segment before, during and after ambient pressure modulation. The potential of the technique is demonstrated in vivo in a healthy human subject. The quantification of the dynamic deformation response, consisting of axial displacement and strain, demonstrated an initial retraction of the eye globe (−0.43 to −1.22 nm) and a subsequent forward motion (1.99 nm) in response to the pressure change, which went along with a compressive strain induced in the anterior crystalline lens (−0.009) and a tensile strain induced in the cornea (0.014). These mechanical responses appear to be the result of a combination of whole eye motion and eye globe expansion. The latter simulates a close-to-physiologic variation of the intraocular pressure and makes the detected mechanical responses potentially relevant for clinical follow-up and pre-surgical screening. The presented measurements are a proof-of-concept that non-contact low-amplitude ambient pressure modulation induces tissue displacement and strain that is detectable in vivo with OCT. To take full advantage of the high spatial resolution this imaging technique could offer, further software and hardware optimization will be necessary to overcome the current limitation of involuntary eye motions.

A STRUCTURE-MOTIVATED MODEL OF THE PASSIVE MECHANICAL RESPONSE OF THE PRIMARY PORCINE RENAL ARTERY

2014 ◽  
Vol 14 (03) ◽  
pp. 1450033 ◽  
Author(s):  
BORAN ZHOU ◽  
LAUREN WOLF ◽  
ALEXANDER RACHEV ◽  
TAREK SHAZLY
Keyword(s):  
Renal Artery ◽  
Arterial Wall ◽  
Mechanical Response ◽  
Physiological Function ◽  
Functional Dependence ◽  
Stretch Ratio ◽  
Comprehensive Description ◽  
Axial Stretch ◽  
Theoretical Predictions

The primary renal arteries transport up to one fourth of cardiac output to the kidneys for blood plasma ultrafiltration, with a functional dependence on the vessel geometry, composition and mechanical properties. Despite the critical physiological function of the renal artery, the few biomechanical studies that have focused on this vessel are either uniaxial or only partially describe its bi-axial mechanical behavior. In this study, we quantify the passive mechanical response of the primary porcine renal artery through bi-axial mechanical testing that probes the pressure-deformed diameter and pressure-axial force relationships at various longitudinal extensions, including the in-vivo axial stretch ratio. Mechanical data are used to parameterize and validate a structure-motivated constitutive model of the arterial wall. Together, experimental data and theoretical predictions of the stress distribution within the arterial wall provide a comprehensive description of the passive mechanical response of the porcine renal artery.

In Vivo Response to Compression of 35 Breast Lesions Observed with a Two-Dimensional Locally Regularized Strain Estimation Method

2014 ◽  
Vol 40 (2) ◽  
pp. 300-312 ◽  
Author(s):  
Elisabeth Brusseau ◽  
Valérie Detti ◽  
Agnès Coulon ◽  
Emmanuèle Maissiat ◽  
Nawele Boublay ◽  
...  
Keyword(s):  
Estimation Method ◽  
Breast Lesions ◽  
Two Dimensional ◽  
Strain Estimation

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

Oxidation of Plasma Low-Density Lipoprotein Accelerates Its Accumulation and Degradation in the Arterial Wall In Vivo

Circulation ◽  
1996 ◽  
Vol 94 (7) ◽  
pp. 1698-1704 ◽  
Author(s):  
Klaus Juul ◽  
Lars B. Nielsen ◽  
Klaus Munkholm ◽  
Steen Stender ◽  
Børge G. Nordestgaard
Keyword(s):  
Arterial Wall ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density

scholarly journals Occupational Exposure to Carbon Nanotubes and Carbon Nanofibres: More Than a Cobweb

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 745
Author(s):  
Enrico Bergamaschi ◽  
Giacomo Garzaro ◽  
Georgia Wilson Jones ◽  
Martina Buglisi ◽  
Michele Caniglia ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Animal Studies ◽  
Chemical Properties ◽  
Biological Behavior ◽  
Cross Sectional ◽  
Carbon Nanofibres ◽  
Material Entity ◽  
Cross Sectional Design

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are erroneously considered as singular material entities. Instead, they should be regarded as a heterogeneous class of materials bearing different properties eliciting peculiar biological outcomes both in vitro and in vivo. Given the pace at which the industrial production of CNTs/CNFs is increasing, it is becoming of utmost importance to acquire comprehensive knowledge regarding their biological activity and their hazardous effects in humans. Animal studies carried out by inhalation showed that some CNTs/CNFs species can cause deleterious effects such as inflammation and lung tissue remodeling. Their physico-chemical properties, biological behavior and biopersistence make them similar to asbestos fibers. Human studies suggest some mild effects in workers handling CNT/CNF. However, owing to their cross-sectional design, researchers have been as yet unable to firmly demonstrate a causal relationship between such an exposure and the observed effects. Estimation of acceptable exposure levels should warrant a proper risk management. The aim of this review is to challenge the conception of CNTs/CNFs as a single, unified material entity and prompt the establishment of standardized hazard and exposure assessment methodologies able to properly feeding risk assessment and management frameworks.

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