Добірка наукової літератури з теми "Phantom arteries"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Phantom arteries".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Phantom arteries":
1
Roldan, Maria, and Panicos A. Kyriacou. "Head Phantom for the Acquisition of Pulsatile Optical Signals for Traumatic Brain Injury Monitoring." Photonics 10, no. 5 (April 26, 2023): 504. http://dx.doi.org/10.3390/photonics10050504.
Анотація:
(1) Background: Tissue phantoms can provide a rigorous, reproducible and convenient approach to evaluating an optical sensor’s performance. The development, characterisation and evaluation of a vascular head/brain phantom is described in this study. (2) Methods: The methodology includes the development of mould-cast and 3D-printed anatomical models of the brain and the skull and a custom-made in vitro blood circulatory system used to emulate haemodynamic changes in the brain. The optical properties of the developed phantom were compared to literature values. Artificial cerebrospinal fluid was also incorporated to induce changes in intracranial pressure. (3) Results: A novel head model was successfully developed to mimic the brain and skull anatomies and their optical properties within the near-infrared range (660–900 nm). The circulatory system developed mimicked normal arterial blood pressure values, with a mean systole of 118 ± 8.5 mmHg and diastole of 70 ± 8.5 mmHg. Similarly, the cerebrospinal fluid circulation allowed controlled intracranial pressure changes from 5 to 30 mmHg. Multiwavelength pulsatile optical signals (photoplethysmograms (PPGs)) from the phantom’s cerebral arteries were successfully acquired. Conclusions: This unique head phantom technology forms the basis of a novel research tool for investigating the relationship between cerebral pulsatile optical signals and changes in intracranial pressure and brain haemodynamics.
2
Yang, Ke, Peter R. Hoskins, George A. Corner, Chunming Xia, and Zhihong Huang. "Wall Shear Stress Measurement in Carotid Artery Phantoms with Variation in Degree of Stenosis Using Plane Wave Vector Doppler." Applied Sciences 13, no. 1 (January 2, 2023): 617. http://dx.doi.org/10.3390/app13010617.
Анотація:
Wall shear stress (WSS) plays an important role in the formation, growth, and rupture of atherosclerotic plaques in arteries. This study measured WSS in diseased carotid artery phantoms with degrees of stenosis varying from 0 to 60% with both steady and pulsatile flow. Experiments were performed using in silico and real flow phantoms. Blood velocities were estimated using plane wave (PW) vector Doppler. Wall shear stress was then estimated from the velocity gradient near the wall multiplied by the viscosity of a blood-mimicking fluid. The estimated WSS using the in silico phantom agreed within 10% of the ground-truth values (root-mean-square error). The phantom experiment showed that the mean WSS and maximum WSS increased with the increasing degree of stenosis. The simulation and experiment results provide the necessary validation data to give confidence in WSS measurements in patients using the PW vector Doppler technique.
3
Chamaani, Somayyeh, Jürgen Sachs, Alexandra Prokhorova, Carsten Smeenk, Tim Erich Wegner, and Marko Helbig. "Microwave Angiography by Ultra-Wideband Sounding: A Preliminary Investigation." Diagnostics 13, no. 18 (September 14, 2023): 2950. http://dx.doi.org/10.3390/diagnostics13182950.
Анотація:
Angiography is a very informative method for physicians such as cardiologists, neurologists and neuroscientists. The current modalities experience some shortages, e.g., ultrasound is very operator dependent. The computerized tomography (CT) and magnetic resonance (MR) angiography are very expensive and near infrared spectroscopy cannot capture the deep arteries. Microwave technology has the potential to address some of these issues while compromising between operator dependency, cost, speed, penetration depth and resolution. This paper studies the feasibility of microwave signals for monitoring of arteries. To this aim, a homogenous phantom mimicking body tissue is built. Four elastic tubes simulate arteries and a mechanical system creates pulsations in these arteries. A multiple input multiple output (MIMO) array of ultra-wideband (UWB) transmitters and receivers illuminates the phantom and captures the reflected signals over the desired observation time period. Since we are only interested in the imaging of dynamic parts, i.e., arteries, the static clutters can be suppressed easily by background subtraction method. To obtain a fast image of arteries, which are pulsating with the heartbeat rate, we calculate the Fourier transform of each channel of the MIMO system over the observation time and apply delay and sum (DAS) beamforming method on the heartbeat rate aligned spectral component. The results show that the lateral and longitudinal images and motion mode (M-mode) time series of different points of phantom have the potential to be used for diagnosis.
4
Ngaile, Justin E., Peter K. Msaki, Evarist M. Kahuluda, Furaha M. Chuma, Jerome M. Mwimanzi, and Ahmed M. Jusabani. "Effect of Lowering Tube Potential and Increase Iodine Concentration of Contrast Medium on Radiation Dose and Image Quality in Computed Tomography Pulmonary Angiography Procedure: A Phantom Study." Tanzania Journal of Science 47, no. 3 (August 15, 2021): 1211–24. http://dx.doi.org/10.4314/tjs.v47i3.29.
Анотація:
The aim of the study was to examine the effect of lowering tube potential and increase iodine concentration on image quality and radiation dose in computed tomography pulmonary angiography procedure. The pulmonary arteries were simulated by three syringes. The syringes were filled with 1:10 diluted solutions of 300 mg, 350 mg and 370 mg of iodine per millilitre concentration in three water-filled phantoms simulating thin, intermediate and thick patients. The phantoms were scanned at 80 kVp, 110 kVp and 130 kVp and 0.6 second rotation time using a 16 slice computed tomography (CT) scanner. The tube current was either fixed at 80, 100, 200, 250 and 300 mA or automatically adjusted with quality reference tube current-time product (mAsQR). In comparison with 130 kVp, images acquired at 80 kVp and 110 kVp, respectively, showed 76.2% to 99% and 19% to 26% enhancement in CT attenuation of iodinated contrast material. A volume CT dose index (CTDIvol) reduction by 35.3% was attained in small phantom with the use of 80 kVp, while in the medium phantom, a CTDIvol reduction by 29.9% was attained with the use of 110 kVp instead of 130 kVp. In light of the above, lowering tube potential and increase iodinated CM could substantially reduce the dose to small-sized adults and children.
Keywords: Angiography; Computed tomography; Low tube potential; Iodinated contrast medium; Radiation dose
5
Cooper, Benjamin Z., Jon D. Kirwin, Thomas F. Panetta, F. Michele Weinreb, Jose A. Ramirez, John G. Najjar, Seth B. Blattman, William Rodino, and Mark Song. "Accuracy of Intravascular Ultrasound for Diameter Measurement of Phantom Arteries." Journal of Surgical Research 100, no. 1 (September 2001): 99–105. http://dx.doi.org/10.1006/jsre.2001.6214.
6
Johnson, Jami L., Kasper van Wijk, and Michelle Sabick. "Characterizing Phantom Arteries with Multi-channel Laser Ultrasonics and Photo-acoustics." Ultrasound in Medicine & Biology 40, no. 3 (March 2014): 513–20. http://dx.doi.org/10.1016/j.ultrasmedbio.2013.10.011.
7
Mai, Jerome J., Fermin A. Lupotti, and Michael F. Insana. "Vascular Elasticity from Regional Displacement Estimates." Ultrasonic Imaging 25, no. 3 (July 2003): 171–92. http://dx.doi.org/10.1177/016173460302500305.
Анотація:
A recently-developed ultrasonic technique for measuring elastic properties of vascular tissue is evaluated using computer simulations, phantom and in vivo human measurements. A time sequence of displacement images is measured over the cardiac cycle to describe the spatial and temporal patterns of deformation surrounding arteries. This information is combined with a mathematical model to estimate an elastic modulus. Computer simulations of ultrasonic echo data from deformed tissues are analyzed to define a signal processing approach. Measurements in flow phantoms, with and without vessel-simulating channel walls, provide an assessment of the accuracy and precision of this technique for vascular elasticity measurements. Finally, preliminary results for the stiffness index (β) in a study group of healthy human volunteers are compared with previously reported data. We find that careful measurement technique is required to control measurement variability.
8
Udekwe, Charles Nnamdi, and Akinlolu Adeniran Ponnle. "Application of Cardinal Points Symmetry Landmarks Distribution Model to B-Mode Ultrasound Images of Transverse Cross-section of Thin-walled Phantom Carotid Arteries." European Journal of Engineering Research and Science 4, no. 12 (December 19, 2019): 96–101. http://dx.doi.org/10.24018/ejers.2019.4.12.1656.
Анотація:
We had earlier developed a technique based on cardinal point symmetry landmark distribution model (CPS-LDM) to completely characterize the Region of Interest (ROI) of the geometric shape of thick-walled simulated B-mode ultrasound images of carotid artery imaged in the transverse plane. In this paper, this developed technique was applied to completely characterize the region of interest of the geometric shape of B-mode ultrasound images of thin-walled phantom carotid artery imaged in the transverse plane. The developed model employs a combination of fixed landmarks (FLs) and movable landmarks (MLs) to obtain the total landmarks (TLs) that can sufficiently segment the shape of the ROI of the carotid artery. For the phantom carotid arteries, three FLs are fixed on each of the four ROIs determined by the cardinal points North (N), South (S), East (E) and West (W) drawn on the ROIs of the phantom carotid artery. The MLs are determined by the inter-cardinal directions such as North-East (NE), North-West (NW) and so on. The obtained CPS-LDM equation developed allows graphical visualization the optimum number of points that can sufficiently segment the ROIs. ImageJ2 software was used to generate the Cartesian coordinates for each landmark which were then used to generate the Shape Space Pattern (SSP) of the phantom carotid artery ready for further statistical analysis. The results showed that the CPS-LD model is generic and adaptable to a variety of transverse cross-sectional B-mode ultrasound images of thin-walled phantom carotid artery
9
Udekwe, Charles Nnamdi, and Akinlolu Adeniran Ponnle. "Application of Cardinal Points Symmetry Landmarks Distribution Model to B-Mode Ultrasound Images of Transverse Cross-section of Thin-walled Phantom Carotid Arteries." European Journal of Engineering and Technology Research 4, no. 12 (December 19, 2019): 96–101. http://dx.doi.org/10.24018/ejeng.2019.4.12.1656.
Анотація:
We had earlier developed a technique based on cardinal point symmetry landmark distribution model (CPS-LDM) to completely characterize the Region of Interest (ROI) of the geometric shape of thick-walled simulated B-mode ultrasound images of carotid artery imaged in the transverse plane. In this paper, this developed technique was applied to completely characterize the region of interest of the geometric shape of B-mode ultrasound images of thin-walled phantom carotid artery imaged in the transverse plane. The developed model employs a combination of fixed landmarks (FLs) and movable landmarks (MLs) to obtain the total landmarks (TLs) that can sufficiently segment the shape of the ROI of the carotid artery. For the phantom carotid arteries, three FLs are fixed on each of the four ROIs determined by the cardinal points North (N), South (S), East (E) and West (W) drawn on the ROIs of the phantom carotid artery. The MLs are determined by the inter-cardinal directions such as North-East (NE), North-West (NW) and so on. The obtained CPS-LDM equation developed allows graphical visualization the optimum number of points that can sufficiently segment the ROIs. ImageJ2 software was used to generate the Cartesian coordinates for each landmark which were then used to generate the Shape Space Pattern (SSP) of the phantom carotid artery ready for further statistical analysis. The results showed that the CPS-LD model is generic and adaptable to a variety of transverse cross-sectional B-mode ultrasound images of thin-walled phantom carotid artery
10
Cha, Hyo-Jeong, Byung-Ju Yi, and Jong Yun Won. "An assembly-type master–slave catheter and guidewire driving system for vascular intervention." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 231, no. 1 (December 22, 2016): 69–79. http://dx.doi.org/10.1177/0954411916679328.
Анотація:
Current vascular intervention inevitably exposes a large amount of X-ray to both an operator and a patient during the procedure. The purpose of this study is to propose a new catheter driving system which assists the operator in aspects of less X-ray exposure and convenient user interface. For this, an assembly-type 4-degree-of-freedom master–slave system was designed and tested to verify the efficiency. First, current vascular intervention procedures are analyzed to develop a new robotic procedure that enables us to use conventional vascular intervention devices such as catheter and guidewire which are commercially available in the market. Some parts of the slave robot which contact the devices were designed to be easily assembled and dissembled from the main body of the slave robot for sterilization. A master robot is compactly designed to conduct insertion and rotational motion and is able to switch from the guidewire driving mode to the catheter driving mode or vice versa. A phantom resembling the human arteries was developed, and the master–slave robotic system is tested using the phantom. The contact force of the guidewire tip according to the shape of the arteries is measured and reflected to the user through the master robot during the phantom experiment. This system can drastically reduce radiation exposure by replacing human effort by a robotic system for high radiation exposure procedures. Also, benefits of the proposed robot system are low cost by employing currently available devices and easy human interface.
Дисертації з теми "Phantom arteries":
1
Zhou, Xiaowei. "Investigation of ultrasound-measured blood flow related parameters in radial and ulnar arteries." Thesis, University of Dundee, 2017. https://discovery.dundee.ac.uk/en/studentTheses/cb2a68cb-949a-413f-b561-c137b7605583.
Анотація:
The incidence of disease of the cardiovascular system is very high and increasing worldwide, especially in the developing world. The radial and ulnar arteries are implicated in some important ailments where blood flow related parameters such as flow rate (FR), wall shear rate (WSR), arterial wall motion (AWM) and pressure, all of which can be measured using ultrasound techniques, are useful in diagnosis and patient management. However these measurements are prone to error due to the manner of image formation and the complex flow conditions within the vessels. In this thesis, the errors in ultrasound-measured parameters in the radial and ulnar arteries are investigated using experimental phantoms, computer simulation and on volunteers. Using the Womersley theory, FR and WSR were estimated using a clinical ultrasound scanner with the pulsed wave (PW) mode and B mode. Experimental flow phantoms were designed to evaluate those measurements under different circumstances. A simulation technique which combined image-based computational fluid dynamics and ultrasound simulation was also used to evaluate ultrasound estimation of these parameters. A case study was then conducted on healthy volunteers to evaluate the method of measuring FR and WSR in-vivo. For the AWM in the radial artery, an auto-correlation method was used based on the radio-frequency (RF) data and validations were done by a flow phantom, simulation, and in-vivo trial. The blood pressure waveform in a volunteer’s radial artery was derived from the ultrasound measured AWM and compared with the waveform from a tonometry. FR and WSR were both found to be overestimated by up to 50%, mainly due to the beam-vessel angle in the PW Doppler ultrasound. Measurement of the vessel diameter and assumption of the blood flow direction can also influence the estimations. Other factors, such as flow amplitude, vessel size, imaging depth and flow waveforms, do not seem to affect the estimation of these two parameters. Results taken from the flow phantoms agree with those from simulation and the estimations from the in-vivo case study also agree with the published data. The auto-correlation method for the AWM was validated from the phantom and simulation. It is able to detect motion amplitude of about tens of micrometres. The trial on volunteers proved the feasibility of this motion detection method. Blood pressure waveforms at the radial artery of a volunteer, derived from this ultrasound-measured wall motion and from the tonometry, were very similar. The Womersley-based method is able to estimate the FR and WSR in the radial and ulnar arteries with high accuracy. Sources of the error and their magnitudes in estimation of the two parameters by ultrasound pointed out in this thesis are beam-vessel angle, vessel diameter measurement and flow direction assumption. Researchers and clinicians using these measurements in practice and research should be aware. The capability of ultrasound imaging to measure arterial AWM in the radial artery is demonstrated and it is found that the blood pressure waveform can also be derived from the arterial AWM.
2
Zauli, Matteo. "Sviluppo di un phantom per l’analisi del flusso in carotidi mediante acquisizioni ultrasoniche." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Анотація:
In questa tesi viene illustrato il percorso di progettazione di un simulatore di flusso sanguigno. Ovvero un sistema in grado di imprimere ad un liquido posto all’interno di un circuito idraulico un certo profilo di flusso, profilo che abbia le caratteristiche di quello sanguigno in una certa parte anatomica.
Nel progetto realizzato la parte anatomica presa in esame è l’arteria carotide ed essa è riprodotta in un modello detto Phantom. Questa modello ha lo scopo di replicare una certa parte del corpo umano integrando certe caratteristiche a seconda dell’uso a cui sarà destinato.
Il Phantom in oggetto nello specifico si tratta di un Phantom vascolare, cioè di una riproduzione vascolarizzata, per cui si deduce facilmente l’importanza nell’avere a disposizione un macchinario che permetta questa vascolarizzazione in modo corretto e analogo al sistema corpo umano, al fine di potervi eseguire delle acquisizioni coerenti con le strumentazioni che vi saranno applicate.
Quindi, è stato intrapreso un percorso di progettazione che è partito dallo studio del problema raccogliendo informazioni sul sistema arteria carotide e informazioni quali nozioni di idraulica e bioingegneria. Dopo questa fase preliminare ci si è cimentati nella scelta dei componenti ritenuti idonei, in base alle caratteristiche identificate in fase di studio.
La progettazione si è composta sia nella scrittura di firmware, sia nella realizzazione dell'hardware necessario per interfacciare i vari componenti.
Si è arrivati a realizzare due prototipo, l'ultimo dei quali vicino al prodotto finale.
I risultati finali sono stati ottimi, per quanto riguarda un sistema di controllo in catena aperta. Mentre, un controllo in retroazione ha avuto esiti negativi e necessita ulteriore studio.
3
Raviol, Jolan. "Vers l'évaluation du risque de rupture des anévrismes intracrâniens : caractérisation mécanique in vivo de la paroi artérielle." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0011.
Анотація:
Les anévrismes intracrâniens constituent une pathologie critique de santé publique liée à la dégradation de la paroi d’artères cérébrales. Il n’existe actuellement aucune méthode permettant d'estimer le risque de rupture d’un anévrisme qui prenne en compte les propriétés mécaniques in vivo de la paroi anévrismale, pourtant reconnues comme essentielles dans le phénomène de rupture. Ce travail de doctorat s'inscrit dans un projet de grande envergure visant à améliorer les critères d’intervention, actuellement disponibles pour les praticiens, en développant un outil d'aide à la décision non invasif se basant sur l’état mécanique du tissu pour en évaluer la probabilité de rupture. Cet outil reposera sur la définition d'une relation entre la forme de l'anévrisme observé par imagerie clinique et une base de données contenant un ensemble d’images cliniques issues d’études préalables, associées aux propriétés mécaniques in vivo de la paroi et à une caractérisation de sa rupture. Pour produire cette base de données, un dispositif de déformation de la paroi anévrismale est développé dans le cadre du projet global. Ce travail doctoral se focalise sur (1) la calibration, l'optimisation et les tests in vitro de ce dispositif sur artères fantômes et (2) l’application in vivo du dispositif sur un modèle animal d'anévrisme intracrânien. Pour ce faire, un modèle numérique de l'expérimentation in vitro a été implémenté et validé au regard des résultats expérimentaux, grâce au développement d’une méthode de validation originale. Ce modèle éléments finis d’interaction fluide-structure a permis d'appréhender les incertitudes d'utilisation du dispositif au sein de l'anévrisme et d’aider au dimensionnement des artères fantômes. Le meilleur compromis en termes d'épaisseur et de souplesse de la paroi des artères fantômes a ainsi été identifié compte tenu des limites des techniques de fabrication. De plus, une procédure d'analyse inverse a été développée de sorte à estimer les caractéristiques mécaniques de la paroi anévrismale in vivo. Son utilisation repose sur la quantification de la déformation engendrée par le dispositif et visualisée par scanner spectral à comptage photonique, technique d’imagerie médicale émergente dont les résolutions spatio-temporelles permettent une sollicitation contrôlée du tissu sans risque accru de rupture. Les propriétés mécaniques identifiées sont cohérentes avec celles issues des caractérisations ex vivo d'anévrismes similaires disponibles dans la littérature. Enfin, un premier critère de rupture patient-spécifique de la paroi anévrismale, prenant en compte l’état de contrainte in vivo dans le tissu, a été proposéIntracranial aneurysms are a critical public health condition linked to the degradation of the cerebral artery wall. There is currently no method for estimating the risk of aneurysm rupture that takes into account the in vivo mechanical properties of the aneurysm wall, which are believed to be essential in the rupture phenomenon. This doctoral work is part of a large-scale project aimed at improving the intervention criteria currently available to practitioners by developing a non-invasive decision-support tool based on the mechanical state of the tissue to assess the probability of rupture. This tool will be based on the definition of a relationship between the shape of the aneurysm observed by clinical imaging and a database containing a set of clinical images from previous studies, associated with the in vivo mechanical properties of the wall and a characterisation of the rupture. To produce this database, an aneurysm wall deformation device was developed as part of the overall project. This doctoral work focuses on (1) the calibration, the optimisation and in vitro testing of this device on phantom arteries and (2) the in vivo application of the device on an animal model of intracranial aneurysm. To do this, a numerical model of the in vitro experiment was implemented and validated against the experimental results by developing an original validation method. This finite element model of fluid-structure interaction was used to understand the uncertainties involved in using the device within the aneurysm and to help for dimensioning the phantom arteries. The best compromise in terms of phantom artery wall thickness and flexibility was identified, taking into account the limitations of the fabrication techniques. In addition, an inverse analysis procedure was developed to estimate the mechanical characteristics of the aneurysm wall in vivo. Its use is based on quantifying the deformation generated by the device and visualised by spectral photon-counting computed tomography, an emerging medical imaging technique whose spatio-temporal resolutions allow controlled stressing of the tissue without increasing the risk of rupture. The mechanical properties identified were consistent with those derived from ex vivo characterisations of similar aneurysms available in the literature. Finally, a first patient-specific criterion for rupture of the aneurysm wall, taking into account the state of stress in vivo in the tissue, was proposed
4
Larsson, David. "Accuracy Assessment of Shear Wave Elastography for Arterial Applications by Mechanical Testing." Thesis, KTH, Hållfasthetslära (Avd.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160091.
Анотація:
Arterial stiffness is an important biometric in predicting cardiovascular diseases, since mechanical properties serve as indicators of several pathologies such as e.g. atherosclerosis. Shear Wave Elastography (SWE) could serve as a valuable non-invasive diagnostic tool for assessing arterial stiffness, with the technique proven efficient in large homogeneous tissue. However the accuracy within arterial applications is still uncertain, following the lack of proper validation. Therefore, the aim of this study was to assess the accuracy of SWE in arterial phantoms of poly(vinyl alcohol) cryogel by developing an experimental setup with an additional mechanical testing setup as a reference method. The two setups were developed to generate identical stress states on the mounted phantoms, with a combination of axial loads and static intraluminal pressures. The acquired radiofrequency-data was analysed in the frequency domain with retrieved dispersion curves fitted to a Lamb-wave based wave propagation model. The results indicated a significant correlation between SWE and mechanical measurements for the arterial phantoms, with an average relative error of 10 % for elastic shear moduli in the range of 23 to 108 kPa. The performed accuracy quantification implies a satisfactory performance level and as well as a general feasibility of SWE in arterial vessels, indicating the potential of SWE as a future cardiovascular diagnostic tool.
5
Berlin, Clara [Verfasser], Alex [Akademischer Betreuer] Frydrychowicz, and Franz [Akademischer Betreuer] Hartmann. "Vierdimensionale Fluss-MRT der Arteria pulmonalis : Validierung und Fehlerquantifizierung an einem 3T-Scannermit gesunden Probanden und Phantom / Clara Berlin ; Akademische Betreuer: Alex Frydrychowicz, Franz Hartmann." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2021. http://d-nb.info/1225892112/34.
6
Kokkalis, Efstratios. "Fluid dynamic assessments of spiral flow induced by vascular grafts." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/5b96492f-983f-4baa-8e48-20da6939e65c.
Анотація:
Peripheral vascular grafts are used for the treatment of peripheral arterial disease and arteriovenous grafts for vascular access in end stage renal disease. The development of neo-intimal hyperplasia and thrombosis in the distal anastomosis remains the main reason for occlusion in that region. The local haemodynamics produced by a graft in the host vessel is believed to significantly affect endothelial function. Single spiral flow is a normal feature in medium and large sized vessels and it is induced by the anatomical structure and physiological function of the cardiovascular system. Grafts designed to generate a single spiral flow in the distal anastomosis have been introduced in clinical practice and are known as spiral grafts. In this work, spiral peripheral vascular and arteriovenous grafts were compared with conventional grafts using ultrasound and computational methods to identify their haemodynamic differences. Vascular-graft flow phantoms were developed to house the grafts in different surgical configurations. Mimicking components, with appropriate acoustic properties, were chosen to minimise ultrasound beam refraction and distortion. A dual-beam two-dimensional vector Doppler technique was developed to visualise and quantify vortical structures downstream of each graft outflow in the cross-flow direction. Vorticity mapping and measurements of circulation were acquired based on the vector Doppler data. The flow within the vascular-graft models was simulated with computed tomography based image-guided modelling for further understanding of secondary flow motions and comparison with the experimental results. The computational assessments provided a three-dimensional velocity field in the lumen of the models allowing a range of fluid dynamic parameters to be predicted. Single- or double-spiral flow patterns consisting of a dominant and a smaller vortex were detected in the outflow of the spiral grafts. A double- triple- or tetra-spiral flow pattern was found in the outflow of the conventional graft, depending on model configuration and Reynolds number. These multiple-spiral patterns were associated with increased flow stagnation, separation and instability, which are known to be detrimental for endothelial behaviour. Increased in-plane mixing and wall shear stress, which are considered atheroprotective in normal vessels, were found in the outflow of the spiral devices. The results from the experimental approach were in agreement with those from the computational approach. This study applied ultrasound and computational methods to vascular-graft phantoms in order to characterise the flow field induced by spiral and conventional peripheral vascular and arteriovenous grafts. The results suggest that spiral grafts are associated with advanced local haemodynamics that may protect endothelial function and thereby may prevent their outflow anastomosis from neo-intimal hyperplasia and thrombosis. Consequently this work supports the hypothesis that spiral grafts may decrease outflow stenosis and hence improve patency rates in patients.
7
Janvier, Marie-Ange. "Optimization and validation of a new 3D-US imaging robot to detect, localize and quantify lower limb arterial stenoses." Thèse, 2010. http://hdl.handle.net/1866/4758.
Анотація:
L’athérosclérose est une maladie qui cause, par l’accumulation de plaques lipidiques, le durcissement de la paroi des artères et le rétrécissement de la lumière. Ces lésions sont généralement localisées sur les segments artériels coronariens, carotidiens, aortiques, rénaux, digestifs et périphériques. En ce qui concerne l’atteinte périphérique, celle des membres inférieurs est particulièrement fréquente. En effet, la sévérité de ces lésions artérielles est souvent évaluée par le degré d’une sténose (réduction >50 % du diamètre de la lumière) en angiographie, imagerie par résonnance magnétique (IRM), tomodensitométrie ou échographie. Cependant, pour planifier une intervention chirurgicale, une représentation géométrique artérielle 3D est notamment préférable. Les méthodes d’imagerie par coupe (IRM et tomodensitométrie) sont très performantes pour générer une imagerie tridimensionnelle de bonne qualité mais leurs utilisations sont dispendieuses et invasives pour les patients.
L’échographie 3D peut constituer une avenue très prometteuse en imagerie pour la localisation et la quantification des sténoses. Cette modalité d’imagerie offre des avantages distincts tels la commodité, des coûts peu élevés pour un diagnostic non invasif (sans irradiation ni agent de contraste néphrotoxique) et aussi l’option d’analyse en Doppler pour quantifier le flux sanguin. Étant donné que les robots médicaux ont déjà été utilisés avec succès en chirurgie et en orthopédie, notre équipe a conçu un nouveau système robotique d’échographie 3D pour détecter et quantifier les sténoses des membres inférieurs. Avec cette nouvelle technologie, un radiologue fait l’apprentissage manuel au robot d’un balayage échographique du vaisseau concerné. Par la suite, le robot répète à très haute précision la trajectoire apprise, contrôle simultanément le processus d’acquisition d’images échographiques à un pas d’échantillonnage constant et conserve de façon sécuritaire la force appliquée par la sonde sur la peau du patient. Par conséquent, la reconstruction d’une géométrie artérielle 3D des membres inférieurs à partir de ce système pourrait permettre une localisation et une quantification des sténoses à très grande fiabilité. L’objectif de ce projet de recherche consistait donc à valider et optimiser ce système robotisé d’imagerie échographique 3D.
La fiabilité d’une géométrie reconstruite en 3D à partir d’un système référentiel robotique dépend beaucoup de la précision du positionnement et de la procédure de calibration. De ce fait, la précision pour le positionnement du bras robotique fut évaluée à travers son espace de travail avec un fantôme spécialement conçu pour simuler la configuration des artères des membres inférieurs (article 1 - chapitre 3). De plus, un fantôme de fils croisés en forme de Z a été conçu pour assurer une calibration précise du système robotique (article 2 - chapitre 4). Ces méthodes optimales ont été utilisées pour valider le système pour l’application clinique et trouver la transformation qui convertit les coordonnées de l’image échographique 2D dans le référentiel cartésien du bras robotisé. À partir de ces résultats, tout objet balayé par le système robotique peut être caractérisé pour une reconstruction 3D adéquate.
Des fantômes vasculaires compatibles avec plusieurs modalités d’imagerie ont été utilisés pour simuler différentes représentations artérielles des membres inférieurs (article 2 - chapitre 4, article 3 - chapitre 5). La validation des géométries reconstruites a été effectuée à l`aide d`analyses comparatives. La précision pour localiser et quantifier les sténoses avec ce système robotisé d’imagerie échographique 3D a aussi été déterminée. Ces évaluations ont été réalisées in vivo pour percevoir le potentiel de l’utilisation d’un tel système en clinique (article 3- chapitre 5).Atherosclerosis is a disease caused by the accumulation of lipid deposits inducing the remodeling and hardening of the vessel wall, which leads to a progressive narrowing of arteries. These lesions are generally located on the coronary, carotid, aortic, renal, digestive and peripheral arteries. With regards to peripheral vessels, lower limb arteries are frequently affected. The severity of arterial lesions are evaluated by the stenosis degree (reduction > 50.0 % of the lumen diameter) using angiography, magnetic resonance angiography (MRA), computed tomography (CT) and ultrasound (US). However, to plan a surgical therapeutic intervention, a 3D arterial geometric representation is notably preferable. Imaging methods such as MRA and CT are very efficient to generate a three-dimensional imaging of good quality even though their use is expensive and invasive for patients. 3D-ultrasound can be perceived as a promising avenue in imaging for the location and the quantification of stenoses. This non invasive, non allergic (i.e, nephrotoxic contrast agent) and non-radioactive imaging modality offers distinct advantages in convenience, low cost and also multiple diagnostic options to quantify blood flow in Doppler. Since medical robots already have been used with success in surgery and orthopedics, our team has conceived a new medical 3D-US robotic imaging system to localize and quantify arterial stenoses in lower limb vessels. With this new technology, a clinician manually teaches the robotic arm the scanning path. Then, the robotic arm repeats with high precision the taught trajectory and controls simultaneously the ultrasound image acquisition process at even sampling and preserves safely the force applied by the US probe. Consequently, the reconstruction of a lower limb arterial geometry in 3D with this system could allow the location and quantification of stenoses with high accuracy. The objective of this research project consisted in validating and optimizing this 3D-ultrasound imaging robotic system. The reliability of a 3D reconstructed geometry obtained with 2D-US images captured with a robotic system depends considerably on the positioning accuracy and the calibration procedure. Thus, the positioning accuracy of the robotic arm was evaluated in the workspace with a lower limb-mimicking phantom design (article 1 - chapter 3). In addition, a Z-phantom was designed to assure a precise calibration of the robotic system. These optimal methods were used to validate the system for the clinical application and to find the transformation which converts image coordinates of a 2D-ultrasound image into the robotic arm referential. From these results, all objects scanned by the robotic system can be adequately reconstructed in 3D. Multimodal imaging vascular phantoms of lower limb arteries were used to evaluate the accuracy of the 3D representations (article 2 - chapter 4, article 3 - chapter 5). The validation of the reconstructed geometry with this system was performed by comparing surface points with the manufacturing vascular phantom file surface points. The accuracy to localize and quantify stenoses with the 3D-ultrasound robotic imaging system was also determined. These same evaluations were analyzed in vivo to perceive the feasibility of the study.
8
Merouche, Samir. "Suivi des vaisseaux sanguins en temps réel à partir d’images ultrasonores mode-B et reconstruction 3D : application à la caractérisation des sténoses artérielles." Thèse, 2013. http://hdl.handle.net/1866/12733.
Анотація:
La maladie des artères périphériques (MAP) se manifeste par une réduction (sténose) de la lumière de l’artère des membres inférieurs. Elle est causée par l’athérosclérose, une accumulation de cellules spumeuses, de graisse, de calcium et de débris cellulaires dans la paroi artérielle, généralement dans les bifurcations et les ramifications. Par ailleurs, la MAP peut être causée par d`autres facteurs associés comme l’inflammation, une malformation anatomique et dans de rares cas, au niveau des artères iliaques et fémorales, par la dysplasie fibromusculaire.
L’imagerie ultrasonore est le premier moyen de diagnostic de la MAP. La littérature clinique rapporte qu’au niveau de l’artère fémorale, l’écho-Doppler montre une sensibilité de 80 à 98 % et une spécificité de 89 à 99 % à détecter une sténose supérieure à 50 %. Cependant, l’écho-Doppler ne permet pas une cartographie de l’ensemble des artères des membres inférieurs. D’autre part, la reconstruction 3D à partir des images échographiques 2D des artères atteintes de la MAP est fortement opérateur dépendant à cause de la grande variabilité des mesures pendant l’examen par les cliniciens. Pour planifier une intervention chirurgicale, les cliniciens utilisent la tomodensitométrie (CTA), l’angiographie par résonance magnétique (MRA) et l’angiographie par soustraction numérique (DSA).
Il est vrai que ces modalités sont très performantes. La CTA montre une grande précision dans la détection et l’évaluation des sténoses supérieures à 50 % avec une sensibilité de 92 à 97 % et une spécificité entre 93 et 97 %. Par contre, elle est ionisante (rayon x) et invasive à cause du produit de contraste, qui peut causer des néphropathies. La MRA avec injection de contraste (CE MRA) est maintenant la plus utilisée. Elle offre une sensibilité de 92 à 99.5 % et une spécificité entre 64 et 99 %. Cependant, elle sous-estime les sténoses et peut aussi causer une néphropathie dans de rares cas. De plus les patients avec stents, implants métalliques ou bien claustrophobes sont exclus de ce type d`examen. La DSA est très performante mais s`avère invasive et ionisante.
Aujourd’hui, l’imagerie ultrasonore (3D US) s’est généralisée surtout en obstétrique et échocardiographie. En angiographie il est possible de calculer le volume de la plaque grâce à l’imagerie ultrasonore 3D, ce qui permet un suivi de l’évolution de la plaque athéromateuse au niveau des vaisseaux. L’imagerie intravasculaire ultrasonore (IVUS) est une technique qui mesure ce volume. Cependant, elle est invasive, dispendieuse et risquée. Des études in vivo ont montré qu’avec l’imagerie 3D-US on est capable de quantifier la plaque au niveau de la carotide et de caractériser la géométrie 3D de l'anastomose dans les artères périphériques. Par contre, ces systèmes ne fonctionnent que sur de courtes distances. Par conséquent, ils ne sont pas adaptés pour l’examen de l’artère fémorale, à cause de sa longueur et de sa forme tortueuse.
L’intérêt pour la robotique médicale date des années 70. Depuis, plusieurs robots médicaux ont été proposés pour la chirurgie, la thérapie et le diagnostic. Dans le cas du diagnostic artériel, seuls deux prototypes sont proposés, mais non commercialisés. Hippocrate est le premier robot de type maitre/esclave conçu pour des examens des petits segments d’artères (carotide). Il est composé d’un bras à 6 degrés de liberté (ddl) suspendu au-dessus du patient sur un socle rigide. À partir de ce prototype, un contrôleur automatisant les déplacements du robot par rétroaction des images échographiques a été conçu et testé sur des fantômes. Le deuxième est le robot de la Colombie Britannique conçu pour les examens à distance de la carotide. Le mouvement de la sonde est asservi par rétroaction des images US. Les travaux publiés avec les deux robots se limitent à la carotide.
Afin d’examiner un long segment d’artère, un système robotique US a été conçu dans notre laboratoire. Le système possède deux modes de fonctionnement, le mode teach/replay (voir annexe 3) et le mode commande libre par l’utilisateur. Dans ce dernier mode, l’utilisateur peut implémenter des programmes personnalisés comme ceux utilisés dans ce projet afin de contrôler les mouvements du robot.
Le but de ce projet est de démontrer les performances de ce système robotique dans des conditions proches au contexte clinique avec le mode commande libre par l’utilisateur. Deux objectifs étaient visés: (1) évaluer in vitro le suivi automatique et la reconstruction 3D en temps réel d’une artère en utilisant trois fantômes ayant des géométries réalistes. (2) évaluer in vivo la capacité de ce système d'imagerie robotique pour la cartographie 3D en temps réel d'une artère fémorale normale. Pour le premier objectif, la reconstruction 3D US a été comparée avec les fichiers CAD (computer-aided-design) des fantômes. De plus, pour le troisième fantôme, la reconstruction 3D US a été comparée avec sa reconstruction CTA, considéré comme examen de référence pour évaluer la MAP.
Cinq chapitres composent ce mémoire. Dans le premier chapitre, la MAP sera expliquée, puis dans les deuxième et troisième chapitres, l’imagerie 3D ultrasonore et la robotique médicale seront développées. Le quatrième chapitre sera consacré à la présentation d’un article intitulé " A robotic ultrasound scanner for automatic vessel tracking and three-dimensional reconstruction of B-mode images" qui résume les résultats obtenus dans ce projet de maîtrise. Une discussion générale conclura ce mémoire.
L’article intitulé " A 3D ultrasound imaging robotic system to detect and quantify lower limb arterial stenoses: in vivo feasibility " de Marie-Ange Janvier et al dans l’annexe 3, permettra également au lecteur de mieux comprendre notre système robotisé. Ma contribution dans cet article était l’acquisition des images mode B, la reconstruction 3D et l’analyse des résultats pour le patient sain.Locating and quantifying stenosis length and severity are essential for planning adequate treatment of peripheral arterial disease (PAD). To do this, clinicians use imaging methods such as ultrasound (US), Magnetic Resonance Angiography (MRA) and Computed Tomography Angiography (CTA). However, US examination cannot provide maps of entire lower limb arteries in 3D, MRA is expensive and invasive, CTA is ionizing and also invasive. We propose a new 3D-US robotic system with B-mode images, which is non-ionizing, non-invasive, and is able to track and reconstruct in 3D the superficial femoral artery from the iliac down to the popliteal artery, in real time. In vitro, 3D-US reconstruction was evaluated for simple and complex geometries phantoms in comparison with their computer-aided-design (CAD) file in terms of lengths, cross sectional areas and stenosis severity. In addition, for the phantom with a complex geometry, an evaluation was realized using Hausdorff distance, cross-sectional area and stenosis severity in comparison with 3D reconstruction with CTA. A mean Hausdorff distance of 0.97± 0.46 mm was found for 3D-US compared to 3D-CTA vessel representations. In vitro investigation to evaluate stenosis severity when compared with the original phantom CAD file showed that 3D-US reconstruction, with 3%-6% error, is better than 3D-CTA reconstruction, with 4-13% error. The in vivo system’s feasibility to reconstruct a normal femoral artery segment of a volunteer was also investigated. All of these promising results show that our ultrasound robotic system is able to track automatically the vessel and reconstruct it in 3D as well as CTA. Clinically, our system will allow firstly to the radiologist to have 3D images readily interpretable and secondly, to avoid radiation and contrast agent for patients.
Частини книг з теми "Phantom arteries":
1
Beauman, Glenn J., Johan H. C. Reiber, Gerhard Koning, Ronald C. M. Van Houdt, and Robert A. Vogel. "Angiographic core laboratory analyses of arterial phantom images: Comparative evaluations of accuracy and precision." In Developments in Cardiovascular Medicine, 87–104. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1172-0_6.
2
Phellan, Renzo, Thomas Lindner, Michael Helle, Alexandre X. Falcão, and Nils D. Forkert. "The Effect of Labeling Duration and Temporal Resolution on Arterial Transit Time Estimation Accuracy in 4D ASL MRA Datasets - A Flow Phantom Study." In Machine Learning and Medical Engineering for Cardiovascular Health and Intravascular Imaging and Computer Assisted Stenting, 141–48. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-33327-0_17.
Тези доповідей конференцій з теми "Phantom arteries":
1
Fabbri, Dario, Quan Long, Saroj Das, and Michele Pinelli. "Study of Embolic Particle Migration in Cerebral Arteries by Computational Modelling." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80314.
Анотація:
As known, embolism is one of the major causes of stroke, which represents the rapid loss of brain functions. Two major sources of emboli which may cause ischemic attack were emboli formed in heart and from a ruptured arterial plaque in carotid arties. Due to the different characteristics of emboli formed from different mechanisms, the migration route of specific emboli in cerebral arteries may be different, so does the territory of the ischemic attack caused by them. Therefore, a good understanding of emboli migration in the complex cerebral arterial network may provide a good guidance for the diagnosis and treatment of stroke. Studies on the emboli motion in cerebral arteries so far were based on phantom models [1]. Although CFD simulation has been used on prediction of cerebral blood perfusion for many years, CFD particle tracking technique is rarely applied on study emboli migration in cerebral arteries. The present study aims to demonstrate the feasibility of using CFD particle tracking on emboli migration study with emphasis on the discussions of the particle tracking result by different coupling algorithms between blood flow and embolic particles.
2
Pazos, Valérie, Jean-Claude Tardif, and Rosarie Mongrain. "Gel Based Mechanical Phantom of Stenotic Coronary Artery." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-175398.
Анотація:
Intravascular ultrasound (IVUS) is currently the only commercially available clinical imaging modality providing real-time high-resolution cross-sectional images of human coronary arteries in patients. New techniques and models are being developed to derive pertinent information from IVUS images about atherosclerotic tissues properties. Their evaluation and optimization often require the use of realistic test phantoms that can be made precisely, with a known, and generally simpler, structure that is used as reference and allows for a simplification of the problem.
3
Zheng, Yihao, Jingxuan Lyu, Yang Liu, Jason Lo, Ata Susamaz, Hitinder S. Gurm, and Albert J. Shih. "Grinding Wheel Motion and Force During Plaque Removal by Rotational Atherectomy in Angulated Coronary Artery." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6686.
Анотація:
Rotational atherectomy (RA) utilizes a high-speed diamond grinding wheel to remove the calcified atherosclerotic plaque off the vessel wall via a catheter inside an artery for blood flow restoration and treatment of cardiovascular diseases. RA in angulated lesions is challenging due to the geometric constrains on the wheel motion, potentially leading to vessel dissection and perforation. To understand the grinding wheel motion and force during RA in curved arteries, experiments were conducted based on 3D printed anatomically accurate coronary artery phantoms with plaster coating as the plaque surrogate, a high-speed camera, and a multi-axis force transducer. Results showed that the grinding wheel did not orbit inside right coronary artery phantom which led to a highly biased ground region aligned with several contact points between the guidewire and the arterial wall. The grinding wheel orbital motion facilitated an even treatment of several segments in left anterior descending coronary artery phantom. The grinding force, ranging from 0.05 to 0.20 N, increased with the wheel rotational speed when the wheel orbited and was insensitive to the wheel speed without wheel orbital motion. This study explained the clinically observed guidewire bias from the engineering perspective and further revealed the RA mechanism of action in angulated artery, which may assist to improve the device design and the operating technique.
4
Pickens, David R., and J. Michael Fitzpatrick. "Phantom Design To Evaluate A Three-Dimensional Motion Correction Algorithm In DSA Of The Coronary Arteries." In Medical Imaging II, edited by Roger H. Schneider and Samuel J. Dwyer III. SPIE, 1988. http://dx.doi.org/10.1117/12.968703.
5
Sturgeon, Victoria, O¨mer Savas, and David Saloner. "An Experimental Study of Transitional Behavior in Physiological Flow Regimes." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13802.
Анотація:
An experimental study is made of flow through models simulating the human abdominal aorta and human coronary arteries. Compliant silicone models are used to investigate fluid-wall interactions of geometries simulating arteries in healthy and diseased states, with the difference between the two being a localized wall thickening on the diseased model to simulate plaque deposition. Physiological flow waveforms and constant pressure external to the model wall are used as input conditions. Using flow visualization and particle image velocimetry, flow stability and transitional behaviors are studied and compared with velocity profiles for resting and exercise states deduced from clinical flow rate data. In these Reynolds and Sexl-Womersley matched experiments, the flow phantom representing the diseased slate demonstrates recirculation zones both upstream and downstream of the stenosis, while the healthy artery demonstrates a more unidirectional flow pattern. The contrast between the high-Reynolds, high-Sexl-Womersley number flow regime of the abdominal aorta and the lower-Reynolds, lower-Sexl-Womersley number behavior of the coronary arteries illustrates the importance of transitional behaviors in the human body and specifically in the progression of atherosclerosis.
6
Lambert, Jack W., Karen G. Ordovas, Yuxin Sun, and Benjamin M. Yeh. "Enhanced diagnostic value for coronary CT angiography of calcified coronary arteries using dual energy and a novel high-Z contrast material: a phantom study." In SPIE Medical Imaging, edited by Despina Kontos, Thomas G. Flohr, and Joseph Y. Lo. SPIE, 2016. http://dx.doi.org/10.1117/12.2217165.
7
Kargar, Soudabeh, Loren Bridges, and Dawn M. Bardot. "Strategies for Building an Arterial Flow Phantom." In ASME 2011 6th Frontiers in Biomedical Devices Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/biomed2011-66008.
Анотація:
Flow phantoms are used to simulate and study the cardiovascular system, associated disease states and boundary conditions. A flow phantom reproduces the flow and pressure of a portion of the vascular system for use in bench top studies of the effect of different changes or devices on the pressure response and deformation of the vessels.
8
Kato, Mitsuaki, Kenji Hirohata, Akira Kano, Shinya Higashi, Akihiro Goryu, Takuya Hongo, Shigeo Kaminaga, and Yasuko Fujisawa. "Fast CT-FFR Analysis Method for the Coronary Artery Based on 4D-CT Image Analysis and Structural and Fluid Analysis." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51124.
Анотація:
Non invasive fractional flow reserve derived from CT coronary angiography (CT-FFR) has to date been typically performed using the principles of computational fluid analysis in which a lumped parameter coronary vascular bed model is assigned to represent the impedance of the downstream coronary vascular networks absent in the computational domain for each coronary outlet. This approach may have a number of limitations. It may not account for the impact of the myocardial contraction and relaxation during the cardiac cycle, patient-specific boundary conditions for coronary artery outlets and vessel stiffness. We have developed a novel approach based on 4D-CT image tracking (registration) and structural and fluid analysis based on one dimensional mechanical model, to address these issues. In our approach, we analyzed the deformation variation of vessels and the volume variation of vessels to better define boundary conditions and stiffness of vessels. We focused on the blood flow and vessel deformation of coronary arteries and aorta near coronary arteries in the diastolic cardiac phase from 70% to 100 %. The blood flow variation of coronary arteries relates to the deformation of vessels, such as expansion and contraction of the cross-sectional area, during this period where resistance is stable, pressure loss is approximately proportional to flow. We used a statistical estimation method based on a hierarchical Bayes model to integrate 4D-CT measurements and structural and fluid analysis data. Under these analysis conditions, we performed structural and fluid analysis to determine pressure, flow rate and CT-FFR. Furthermore, the reduced-order model based on fluid analysis was studied in order to shorten the computational time for 4D-CT-FFR analysis. The consistency of this method has been verified by a comparison of 4D-CT-FFR analysis results derived from five clinical 4D-CT datasets with invasive measurements of FFR. Additionally, phantom experiments of flexible tubes with and without stenosis using pulsating pumps, flow sensors and pressure sensors were performed. Our results show that the proposed 4D-CT-FFR analysis method has the potential to accurately estimate the effect of coronary artery stenosis on blood flow.
9
Zhang, Xiaoming, Mostafa Fatemi, and James F. Greenleaf. "A New Imaging Method for Arterial Tubes Based on Vibration Measurement." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41395.
Анотація:
A new method for imaging and detecting modal shapes of vessels is introduced. Theory is developed that predicts the measured velocity is proportional to the value of the mode shape at the focal point of the ultrasound beam. Experimental a cylindrical gel phantom of large radius. This model simulates approximately a large artery and the surrounding body. The fundamental frequency was measured 83 Hz for the tube-phantom system. At this frequency the ultrasound transducer was scanned across the vessel plane with velocity measurement at one single point on the vessel and on the phantom by laser. The images obtained show clearly the interior tube and the modal shape of the tube.
10
Bisaillon, Charles-Etienne, Marc L. Dufour, and Guy Lamouche. "Durable phantoms of atherosclerotic arteries for optical coherence tomography." In BiOS, edited by Nikiforos Kollias, Bernard Choi, Haishan Zeng, Reza S. Malek, Brian J. Wong, Justus F. R. Ilgner, Kenton W. Gregory, et al. SPIE, 2010. http://dx.doi.org/10.1117/12.842403.