Toward a better quantitative measurement of aortic flow

Tortoli, Piero; Bambi, G.; Guidi, Francesco; Muchada, R.

doi:10.1016/s0301-5629(01)00462-8

Cited by 38 publications

(24 citation statements)

References 17 publications

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“…Recently, three-dimensional reconstruction of the blood vessel configuration, velocity profile, and pressure distribution from the ultrasonic measurement have been investigated. 1,18,21,28 Capineri et al developed a technique for dynamic displays of vector velocity maps, in which the velocity vectors obtained by Doppler measurements in two independent directions are properly interpolated. 1 Tortoli et al presented the real-time two-dimensional velocity profile of descending aortic blood flow using a set-up based on an esophageal probe connected to a multigate Doppler-processing system, and confirmed extremely complex flow in the proximal portion of the aortic arch or in the case of aortic diseases.…”

Section: Introductionmentioning

confidence: 99%

“…1 Tortoli et al presented the real-time two-dimensional velocity profile of descending aortic blood flow using a set-up based on an esophageal probe connected to a multigate Doppler-processing system, and confirmed extremely complex flow in the proximal portion of the aortic arch or in the case of aortic diseases. 28 Ohtsuki et al developed a new method for nondisturbing, quantitative measurement of pressure, in which the velocity component orthogonal to the Doppler velocity is deduced after measurement of the velocity field by the pulse Doppler technique, and the pressure is calculated from the acceleration. 18 However, in experimental works, there are some limitations such as the direct effects of noise and the Doppler transducer position on data acquisition and the assumption of symmetrical flow in the calculation, so that no method to obtain complete information in real time yet exists.…”

Section: Introductionmentioning

confidence: 99%

“…15 In the descending aorta, however, extension by adding the ascending aorta and the aortic arch does not eliminate the effect of the upstream boundary condition on reproduction of the complicated flow structure (e.g., Kilner et al observed helical and retrograde secondary flow patterns in the aortic arch using magnetic resonance velocity mapping). 13,28 By numerical simulation with an integrated model of the left ventricle and the aorta, Nakamura et al revealed that the upstream boundary condition strongly influences development of the helical flow. 16 Glor et al performed MRI velocity measurements and computation in the U bend, confirming the importance of accurate inflow boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

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Fundamental Study of Ultrasonic-Measurement-Integrated Simulation of Real Blood Flow in the Aorta

et al. 2005

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Abstract-Acquisition of detailed information on the velocity and pressure fields of the blood flow is essential to achieve accurate diagnosis or treatment for serious circulatory diseases such as aortic aneurysms. A possible way to obtain such information is integration of numerical simulation and color Doppler ultrasonography in the framework of a flow observer. This methodology, namely, Ultrasonic-Measurement-Integrated (UMI) Simulation, consists of the following processes. At each time step of numerical simulation, the difference between the measurable output signal and the signal indicated by numerical simulation is evaluated. Feedback signals are generated from the difference, and numerical simulation is updated applying the feedback signal to compensate for the difference. This paper deals with a numerical study on the fundamental characteristics of UMI simulation using a simple two-dimensional model problem for the blood flow in an aorta with an aneurysm. The effect of the number of feedback points and the feedback formula are investigated systematically. It is revealed that the result of UMI simulation in the feedback domain rapidly converges to the standard solution, even with usually inevitable incorrect upstream boundary conditions. Finally, an example of UMI simulation with feedback from real color Doppler measurement also shows a good agreement with measurement.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fundamental Study of Ultrasonic-Measurement-Integrated Simulation of Real Blood Flow in the Aorta

et al. 2005

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“…In the present work, this technology was tested in vitro as well as in different clinical applications and in different vessels, with a variety of transducer typologies. The considered clinical studies were: Vascular, regarding both arteries and veins at the neck district level (Common Carotid Artery -CCA, Internal Jugular Vein -IJV and Vertebral Vein VV) [1] Cardiology, regarding both Adult and Pediatric (Aorta and Inferior Vena Cava -IVC) [2][3] Obstetrics, about the study of uterine arteries in pregnancy [4][5] In all cases, QDP was used together with classic Doppler technologies such as PW and Color Doppler (CD), as well as a stand-alone Doppler tool. Longitudinal scanning of the examined vessels was considered with linear and convex transducers.…”

Section: Introductionmentioning

confidence: 99%

Multigate Quality Doppler Profiles Technology in Vascular, Obstetrics and Cardiology Applications

Forzoni

Righi

Ciuti

et al. 2012

Biomedical Engineering / Biomedizinische Technik

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Multigate Quality Doppler Profiles (QDP) is a Fast Fourier Transform (FFT) -based Doppler technology recently integrated within a commercial ultrasound scanner. QDP represents a novel analysis tool, which is able to simultaneously detect and show the velocity components, present in the blood flow of multiple vessels, without any frame rate reduction. QDP can be used in conjunction with the DIR algorithm to enhance the visibility of the flow direction information. The present work describes the use of QDP in Cardiology (Pediatric and Adult), Vascular (cervical venous and arterial system) and Obstetrics (uterine arteries). In vivo and in vitro tests are reported, showing the QDP behavior with respect to insonation angle changes and its advantages with respect to classic Doppler technologies. The QDP is demonstrated to be a precise positioning tool for the Pulsed Wave Doppler (PW) sample volume (SV) and a qualitative direct real time indicator of blood flow variations. It is also shown ideal for the study of turbulent flow, for minor reflux detection and for easier sampling of the blood flow signal within the examined vessel (or vessels) in case of movements. IntroductionQDP is a technique processing the echo signals backscattered from multiple depths along the ultrasound beam to produce and display the spectral profiles in real-time. MethodsThe QDP technology, developed by the Microelectronics Systems Design Laboratory of the University of Firenze (Italy), was integrated in a commercial diagnostic ultrasound scanner (MyLab30Gold, Esaote S.p.A., Italy). The QDP tool was made available with all US probes compatible with the PW modality. In particular, the probes used for the present work where: a phased array probe with frequency range 1-4 MHz (PA240, Esaote, Imaging frequencies: 2.0-2.5-3.5 MHz; Doppler frequencies: 2.0-2.5 MHz); a linear array probe with frequency range 3-11 MHz (LA332, Esaote, Imaging frequencies: 3.5-5.0-6.6-10.0 MHz; Doppler frequencies: 3.3-5.0 MHz) and a convex array probe with frequency range 1-8 MHz (CA631, Esaote, Imaging frequencies: 2.5-3.5-5.0-6.6 MHz; Doppler frequencies: 2.5-3.3 MHz). QDP is a Multigate Spectral Doppler technology that processes the echo signals backscattered from multiple depths along the US beam, producing and displaying in real-time the so-called spectral profile [6]. This is a matrix of power spectral densities corresponding to the simultaneously investigated depths. The spectral profile is obtained by calculating, through the classic Fast Fourier Transform (FFT) algorithm, the Doppler spectrum of the echo samples gathered from one depth and by repeating the procedure over 128 or 256 consecutive depths (covering a total length up to 9 cm). The QDP approach extends the known benefits of spectral analysis [7] to a large depth range without sacrificing the axial resolution. QDP technology investigates the "third dimension of Doppler" in graphical form, where spatial distribution is on the vertical axis and velocity on the horizontal one, while the brightness...

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“…This was calculated by McDonald and Womersley, whose velocity profiles are shown in the Figure for an artery of similar caliber to the brachial artery in humans and concur with those measured experimentally. 8,9 Clearly, this field remains controversial and requires new and different approaches. The beauty of the present study is that it was conducted in a large, well characterized group of normal subjects as part of an extensive screening process during a half-day period.…”

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confidence: 99%

Shear Stress and Flow-Mediated Dilation

O’Rourke

Nichols

2004

Hypertension

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I n this edition of Hypertension, the Framingham Heart Study group reports on the relationship between diastolic shear stress and brachial artery flow mediated dilation (FMD) in 2045 participants of the Framingham Offspring group. 1 Clinical correlates and heritability of FMD in the participants have been published previously. 2 The new report 1 challenges conventional concepts on endothelial function and on modification of endothelial function by risk factors of cardiovascular disease. The authors conclude that when present, impaired FMD of the brachial artery may be due not to impaired release of NO from the vascular endothelium, but from a lesser stimulus to NO release as a consequence of decreased flow velocity (and shear stress) during reactive hyperemia caused by impaired microvascular response. Are there fewer peripheral vessels capable of responding to local ischemia?The method used by the authors differed from those previously applied in that they related FMD to systolic dilation to diastolic shear stress (DSS), not to systolic shear stress or to shear stress averaged over the whole cardiac cycle. They calculated shear stress from constant blood viscosity, mean diastolic flow velocity, and baseline end-diastolic diameter, assuming a parabolic velocity profile. Expressed this way, they found a close relationship between DSS and FMD that was not related to most conventional risk factors, including gender. These results 1 add a new twist to the study of endothelial function and NO production, and raise other possibilities as to how disease, drugs, and/or risk factors affect arteries that are not subject to atherosclerosis. Present techniques of measuring FMD are time consuming, have low reproducibility, and are imprecise (because dilation is so small, averaging just 2.3% in the males of this series). If a fault lies in the peripheral circulation, then more attention should be given to absolute flow in the smaller vessels, using old-fashioned, conventional venous occlusive plethysmography. Many investigators have done this previously; Irace et

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Toward a better quantitative measurement of aortic flow

Cited by 38 publications

References 17 publications

Fundamental Study of Ultrasonic-Measurement-Integrated Simulation of Real Blood Flow in the Aorta

Fundamental Study of Ultrasonic-Measurement-Integrated Simulation of Real Blood Flow in the Aorta

Multigate Quality Doppler Profiles Technology in Vascular, Obstetrics and Cardiology Applications

Shear Stress and Flow-Mediated Dilation

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