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Journal articles on the topic 'Vector flow imaging (VFI)'

Author: Grafiati

Published: 10 March 2023

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1

Hansen, Kristoffer, Klaus Juul, Hasse Møller-Sørensen, Jens Nilsson, Jørgen Jensen, and Michael Nielsen. "Pediatric Transthoracic Cardiac Vector Flow Imaging – A Preliminary Pictorial Study." Ultrasound International Open 05, no. 01 (December 21, 2018): E20—E26. http://dx.doi.org/10.1055/a-0656-5430.

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Abstract Purpose Conventional pediatric echocardiography is crucial for diagnosing congenital heart disease (CHD), but the technique is impaired by angle dependency. Vector flow imaging (VFI) is an angle-independent noninvasive ultrasound alternative for blood flow assessment and can assess complex flow patterns not visible on conventional Doppler ultrasound. Materials and Methods 12 healthy newborns and 3 infants with CHD were examined with transthoracic cardiac VFI using a conventional ultrasound scanner and a linear array. Results VFI examinations revealed common cardiac flow patterns among the healthy newborns, and flow changes among the infants with CHD not previously reported with conventional echocardiography. Conclusion For assessment of cardiac flow in the normal and diseased pediatric heart, VFI may provide additional information compared to conventional echocardiography and become a useful diagnostic tool.

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Brandt, Andreas Hjelm, Jacob Bjerring Olesen, Ramin Moshavegh, Jørgen Arendt Jensen, Michael Bachmann Nielsen, and Kristoffer Lindskov Hansen. "Common Carotid Artery Volume Flow: A Comparison Study between Ultrasound Vector Flow Imaging and Phase Contrast Magnetic Resonance Imaging." Neurology International 13, no. 3 (June 23, 2021): 269–78. http://dx.doi.org/10.3390/neurolint13030028.

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Volume flow estimation in the common carotid artery (CCA) can assess the absolute hemodynamic effect of a carotid stenosis. The aim of this study was to compare a commercial vector flow imaging (VFI) setup against the reference method magnetic resonance phase contrast angiography (MRA) for volume flow estimation in the CCA. Ten healthy volunteers were scanned with VFI and MRA over the CCA. VFI had an improved precision of 19.2% compared to MRA of 31.9% (p = 0.061). VFI estimated significantly lower volume flow than MRA (mean difference: 63.2 mL/min, p = 0.017), whilst the correlation between VFI and MRA was strong (R2 = 0.81, p < 0.0001). A Bland–Altman plot indicated a systematic bias. After bias correction, the percentage error was reduced from 41.0% to 25.2%. This study indicated that a VFI setup for volume flow estimation is precise and strongly correlated to MRA volume flow estimation, and after correcting for the systematic bias, VFI and MRA become interchangeable.

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Fiorina, Ilaria, Maria Vittoria Raciti, Alfredo Goddi, Vito Cantisani, Chandra Bortolotto, Shane Chu, and Fabrizio Calliada. "Ultrasound Vector Flow Imaging – could be a new tool in evaluation of arteriovenous fistulas for hemodialysis?" Journal of Vascular Access 18, no. 4 (May 24, 2017): 284–89. http://dx.doi.org/10.5301/jva.5000721.

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Introduction We report the use of a new ultrasound technique to evaluate the axial and lateral components of a complex flow in the arteriovenous fistula (AVF). Vector Flow Imaging (VFI) allows to identify different components of the flow in every direction, even orthogonal to the flow streamline, represented by many single vectors. VFI could help to identify flow alterations in AVF, probably responsible for its malfunction. Methods From February to June 2016, 14 consecutive patients with upper-limb AVF were examined with a Resona 7 (Mindray, Shenzhen, China) ultrasound scanner equipped with VFI. An analysis of mean velocity, angular direction and mean number of vectors impacting the vessel wall was carried out. We also identified main flow patterns present in the arterial side, into the venous aneurysm and in correspondence of significant stenosis. Results A disturbed flow with the presence of vectors directed against the vessel walls was found in 9/14 patients (64.28%): in correspondence of the iuxta-anastomotic venous side (4/9; 44.4%), into the venous aneurysmal tracts (3/9; 33.3%) and in concomitance of stenosis (2/9; 22.2%). The mean velocity of the vectors was around 20-25 cm/s, except in presence of stenosis, where the velocities were much higher (45-50 cm/s). The vectors directed against the vessel walls presented high angle attack (from 45° to 90°, with a median angular deviation 65°). Conclusions VFI was confirmed to be an innovative and intuitive imaging technology to study the flow complexity in the arteriovenous fistulas.

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Bechsgaard, Thor, Kristoffer Hansen, Andreas Brandt, Ramin Moshavegh, Julie Forman, Pia Føgh, Lotte Klitfod, et al. "Evaluation of Peak Reflux Velocities with Vector Flow Imaging and Spectral Doppler Ultrasound in Varicose Veins." Ultrasound International Open 04, no. 03 (September 2018): E91—E98. http://dx.doi.org/10.1055/a-0643-4430.

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Abstract Purpose Spectral Doppler ultrasound (SDUS) is used for quantifying reflux in lower extremity varicose veins. The technique is angle-dependent opposed to the new angle-independent Vector Flow Imaging (VFI) method. The aim of this study was to compare peak reflux velocities obtained with VFI and SDUS in patients with chronic venous disease, i. e., pathological retrograde blood flow caused by incompetent venous valves. Materials and Methods 64 patients with chronic venous disease were scanned with VFI and SDUS in the great or the small saphenous vein, and reflux velocities were compared to three assessment tools for chronic venous disease. A flow rig was used to assess the accuracy and precision of the two methods. Results The mean peak reflux velocities differed significantly (VFI: 47.4 cm/s vs. SDUS: 62.0 cm/s, p<0.001). No difference in absolute precision (p=0.18) nor relative precision (p=0.79) was found. No correlation to disease severity, according to assessment tools, was found for peak reflux velocities obtained with either method. In vitro, VFI was more accurate but equally precise when compared to SDUS. Conclusion Both VFI and SDUS detected the pathologic retrograde flow in varicose veins but measured different reflux velocities with equal precision. VFI may play a role in evaluating venous disease in the future.

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5

Nguyen, Tin-Quoc, Thor Bechsgaard, Michael Rahbek Schmidt, Klaus Juul, Ramin Moshavegh, Lars Lönn, Michael Bachmann Nielsen, Jørgen Arendt Jensen, and Kristoffer Lindskov Hansen. "Transthoracic Vector Flow Imaging in Pediatric Patients with Valvular Stenosis – A Proof of Concept Study." Ultrasound International Open 07, no. 02 (August 2021): E48—E54. http://dx.doi.org/10.1055/a-1652-1261.

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Abstract Purpose Continuous wave Doppler ultrasound is routinely used to detect cardiac valve stenoses. Vector flow imaging (VFI) is an angle-independent real-time ultrasound method that can quantify flow complexity. We aimed to evaluate if quantification of flow complexity could reliably assess valvular stenosis in pediatric patients. Materials and Methods Nine pediatric patients with echocardiographically confirmed valvular stenosis were included in the study. VFI and Doppler measurements were compared with transvalvular peak-to-peak pressure differences derived from invasive endovascular catheterization. Results Vector concentration correlated with the catheter measurements before intervention after exclusion of one outlier (r=−0.83, p=0.01), whereas the Doppler method did not (r=0.49, p=0.22). The change in vector concentration after intervention correlated strongly with the change in the measured catheter pressure difference (r=−0.86, p=0.003), while Doppler showed a tendency for a moderate correlation (r=0.63, p=0.07). Conclusion Transthoracic flow complexity quantification calculated from VFI data is feasible and may be useful for assessing valvular stenosis severity in pediatric patients.

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Hansen, Peter, Kristoffer Hansen, Mads Pedersen, Theis Lange, Lars Lönn, Jørgen Jensen, and Michael Nielsen. "Atherosclerotic Lesions in the Superficial Femoral Artery (SFA) Characterized with Velocity Ratios using Vector Velocity Ultrasound." Ultrasound International Open 04, no. 03 (September 2018): E79—E84. http://dx.doi.org/10.1055/a-0637-2437.

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Abstract Purpose Atherosclerotic arteries are challenging to evaluate quantitatively using spectral Doppler ultrasound because of the turbulent flow conditions that occur in relation to the atherosclerotic stenoses. Vector velocity ultrasound is angle independent and provides flow information, which could potentially improve the diagnosis of arterial stenoses. The purpose of the study is to distinguish significant stenoses in the superficial femoral artery (> 50% diameter reduction) from non-significant stenoses based on velocity ratios derived from the commercially available vector velocity ultrasound technique Vector Flow Imaging (VFI). Materials and Methods Velocity ratios (intrastenotic blood flow velocity divided by pre- or poststenotic velocity) from a total of 16 atherosclerotic stenoses and plaques in the superficial femoral artery of 11 patients were obtained using VFI. The stenosis degree, expressed as percentage diameter reduction of the artery, was determined from digital subtraction angiography and compared to the velocity ratios. Results A velocity ratio of 2.5 was found to distinguish clinically relevant stenoses with>50% diameter reduction from clinically non-relevant stenoses with<50% diameter reduction and the difference was statistically significant. Conclusion The study indicates that VFI is a potential future tool for the evaluation of arterial stenoses.

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Brandt, Andreas Hjelm, Tin-Quoc Nguyen, Henrik Gutte, Jonathan Frederik Carlsen, Ramin Moshavegh, Jørgen Arendt Jensen, Michael Bachmann Nielsen, and Kristoffer Lindskov Hansen. "Carotid Stenosis Assessment with Vector Concentration before and after Stenting." Diagnostics 10, no. 6 (June 20, 2020): 420. http://dx.doi.org/10.3390/diagnostics10060420.

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Digital subtraction angiography (DSA) is considered the reference method for the assessment of carotid artery stenosis; however, the procedure is invasive and accompanied by ionizing radiation. Velocity estimation with duplex ultrasound (DUS) is widely used for carotid artery stenosis assessment since no radiation or intravenous contrast is required; however, the method is angle-dependent. Vector concentration (VC) is a parameter for flow complexity assessment derived from the angle independent ultrasound method vector flow imaging (VFI), and VC has shown to correlate strongly with stenosis degree. The aim of this study was to compare VC estimates and DUS estimated peak-systolic (PSV) and end-diastolic velocities (EDV) for carotid artery stenosis patients, with the stenosis degree obtained with DSA. Eleven patients with symptomatic carotid artery stenosis were examined with DUS, VFI, and DSA before and after stent treatment. Compared to DSA, VC showed a strong correlation (r = −0.79, p < 0.001), while PSV (r = 0.68, p = 0.002) and EDV (r = 0.51, p = 0.048) obtained with DUS showed a moderate correlation. VFI using VC calculations may be a useful ultrasound method for carotid artery stenosis and stent patency assessment.

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Forcada, Pedro J. "Study of Arterial Function and Remodelling by Using Radiofrequency and a New Multidirectional Doppler Technology." Angiology and Vascular Surgery 6, no. 1 (May 7, 2021): 1–8. http://dx.doi.org/10.24966/avs-7397/100056.

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Introduction: Atherosclerosis is the underlying cause of a cardiovascular disease epidemic worldwide. The understanding of normal artery structure and function and the initial disarrangements conducting to atherosclerosis is of key relevance to develop preventive interventions based on a rational study of arterial structural and functional parameters, their pathologic behaviour and response to therapeutic interventions. New US approaches enable a precise evaluation of the forces and stimuli acting on the arterial wall and measure its responses precisely in different clinical stages of the arterial atherosclerotic disease and a better assessment of the efficacy or not of different therapeutic interventions. The ability to analyse WSS hemodynamically and to measure it accurately is an essential basis for the assessment of the atherosclerotic risk in the general population. A new angle-independent technique, measuring and visualizing blood flow velocities in all directions, called Vector Flow Imaging (VFI), has been proposed. Systems are equipped with VFI based on a multi-angle transmission plane waves method, which allows a very high frame rate and a detailed visualization of complex flow.

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9

Gould, Sara, Chase Cawyer, Louis Dell’Italia, Lorie Harper, Gerald McGwin, and Marcas Bamman. "Resistance Training Does Not Decrease Placental Blood Flow During Valsalva Maneuver: A Novel Use of 3D Doppler Power Flow Ultrasonography." Sports Health: A Multidisciplinary Approach 13, no. 5 (March 12, 2021): 476–81. http://dx.doi.org/10.1177/19417381211000717.

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Background: The Valsalva maneuver may increase maternal blood pressure and intra-abdominal pressure, resulting in decreased blood flow to the fetus during resistance training. Hypothesis: There is no significant reduction in placental blood flow in pregnancy during resistance training in recreational athletes, as documented by a 3-dimensional power flow Doppler ultrasonography. Study Design: Cohort. Level of Evidence: Level 3. Methods: A cohort of healthy women who participated in recreational athletics was enrolled in a prospective study to assess placental blood flow during a resistance exercise. A 1 repetition maximum (1RM, up to 50 lb) was determined through a modified chest press as a marker of heavy resistance training. Three-dimensional volume measurements and power Doppler flow were determined at the rest phase and during the 1RM lift phase. The vascular flow index (VFI) was calculated to determine placental perfusion during each phase. Results: A total of 22 women participated. The mean age of participants was 31 years. Gestational age ranged from 13 to 28 weeks. Average 1RM weight lifted was 30 lb. Four women (18%) were able to lift 50 lb, the maximum weight that the study allowed. The remaining 18 women (82%) lifted their true 1RM. Mean VFI during lift phase was 2.185 compared with 2.071 at rest ( P = 0.03). There was a slight mean increase in VFI during lift phase, 0.114 (95% CI 0.009-0.182) from 2.071 to 2.185 with lifting ( P = 0.03). The 15 women who participated in structured exercise had a mean VFI at rest and during the lift phase of 2.031 and 2.203, respectively ( P = 0.01). Conclusion: Three-dimensional power flow Doppler imaging can guide resistance training during pregnancy to prevent fetal injury due to hypoperfusion. Resistance training up to an RM1 of 50 lb did not result in a significant reduction of placental blood flow from resting state in the study population. Clinical Relevance: This technique may be used to guide training parameters among pregnant athletes.

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Choudhary, Sumesh, Vineet Mishra, Rohina Aggarwal, and Kavita Mistry. "Evaluation and correlation of placental vasculature by three-dimensional power Doppler ultrasonography with umbilical Doppler in normal and IUGR pregnancies." International Journal of Reproduction, Contraception, Obstetrics and Gynecology 7, no. 9 (August 27, 2018): 3818. http://dx.doi.org/10.18203/2320-1770.ijrcog20183801.

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Background: In recent years there have been significant developments in the use of 3D Power Doppler (3DPD) imaging and quantitative 3DPD histogram analysis to estimate both placental volume and intraplacental vasculature. This study is to evaluate the distribution and variation of placental vascular indices according to gestational age and placental volume and position. Co relate the umbilical Doppler indices with placental vascular indices.Methods: From September 2016 to October 2017, three-dimensional (3D)-power Doppler ultrasound was performed in 200 singalton pregnancies from 20 to 40 weeks of gestation. Using the same pre-established settings for all patients, power Doppler was applied to the placenta and placental volume was obtained by the rotational technique (VOCAL). The 3D-power histogram was used to determine the placental vascular indices: vascularization index (VI), flow index (FI) and vascularization-flow index (VFI). Umbilical Doppler was measured on the free loop of umbilical cord. The placental vascular indices were then plotted against gestational age placental volume, position and umbilical Doppler SD ratio, PI and RI. These values were evaluated in IUGR fetus.Results: Analysis of the results showed that the placental vascular indices estimated by 3D-power Doppler ultrasonography presented constant distribution throughout gestation despite the significant increase in placental volume. Placental position at fundal region shows higher value of VI, FI, and VFI. Placental position with relation to VI, FI, and VFI shows statistically significant with p value <0.01. Placental vascular indices VI, FI and VFI when corelated with systolic/ diastolic ratio, pulsatility index and resistive resistance index of umbilical artery shows poor negative correlation, only VI and FI shows statistically significant with SD ratio as p value is <0.01and <0.04. VFI did not show statistically significant as p value is 0.10(NS). With pulsatility index p value is statistically significant is less than<0.01 with vascular indices. Resistive index p value is statistically significant is less than <0.01 for VI and VFI but not significant with FI as p value is 0.06.Conclusions: Doppler ultrasound assists in the evaluation of placental vascularization in normal and IUGR pregnancies, may play an important role in future research on fetoplacental insufficiency.

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11

Jensen, Jorgen Arendt, Svetoslav Ivanov Nikolov, Alfred C. H. Yu, and Damien Garcia. "Ultrasound Vector Flow Imaging—Part II: Parallel Systems." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 63, no. 11 (November 2016): 1722–32. http://dx.doi.org/10.1109/tuffc.2016.2598180.

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12

Li, You L., Jessica Ducey-Wysling, Aurélie D’Hondt, Dongwoon Hyun, Bhavik Patel, and Jeremy J. Dahl. "Vector flow imaging using a deep neural network." Journal of the Acoustical Society of America 146, no. 4 (October 2019): 2901–2. http://dx.doi.org/10.1121/1.5137068.

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13

Hansen, Kristoffer Lindskov, Mads Møller Pedersen, Hasse Møller-Sørensen, Jesper Kjaergaard, Jens Christian Nilsson, Jens Teglgaard Lund, Jørgen Arendt Jensen, and Michael Bachmann Nielsen. "Intraoperative Cardiac Ultrasound Examination Using Vector Flow Imaging." Ultrasonic Imaging 35, no. 4 (September 30, 2013): 318–32. http://dx.doi.org/10.1177/0161734613505552.

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14

Okada, Takashi, Yoshinori Seki, Akimitsu Harada, Shigeo Ohtsuki, and Motonao Tanaka. "1507: A New Measurement Method of Blood Flow Vector: Vector Flow Mapping." Ultrasound in Medicine & Biology 35, no. 8 (August 2009): S237. http://dx.doi.org/10.1016/j.ultrasmedbio.2009.06.894.

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15

Nguyen, Tin-Quoc, Marie Sand Traberg, Jacob Bjerring Olesen, Søren Thorup Heerwagen, Andreas Hjelm Brandt, Thor Bechsgaard, Brian Lindegaard Pedersen, et al. "Flow Complexity Estimation in Dysfunctional Arteriovenous Dialysis Fistulas using Vector Flow Imaging." Ultrasound in Medicine & Biology 46, no. 9 (September 2020): 2493–504. http://dx.doi.org/10.1016/j.ultrasmedbio.2020.05.021.

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16

Westerdale, John, Marek Belohlavek, Eileen M. McMahon, Panupong Jiamsripong, Jeffrey J. Heys, and Michele Milano. "Flow Velocity Vector Fields by Ultrasound Particle Imaging Velocimetry." Journal of Ultrasound in Medicine 30, no. 2 (February 2011): 187–95. http://dx.doi.org/10.7863/jum.2011.30.2.187.

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17

Ketterling, Jeffrey A., Akshay Shekhar, Orlando Aristizabal, Anthony Podkowa, Billy Y. Yiu, and Alfred Yu. "Plane-wave vector-flow imaging of adult mouse heart." Journal of the Acoustical Society of America 143, no. 3 (March 2018): 1930. http://dx.doi.org/10.1121/1.5036306.

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18

Holbek, Simon, Kristoffer Lindskov Hansen, Nikolaj Fogh, Ramin Moshavegh, Jacob Bjerring Olesen, Michael Bachmann Nielsen, and Jorgen Arendt Jensen. "Real-Time 2-D Phased Array Vector Flow Imaging." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 65, no. 7 (July 2018): 1205–13. http://dx.doi.org/10.1109/tuffc.2018.2838518.

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19

Di Ianni, Tommaso, Kristoffer Lindskov Hansen, Carlos Armando Villagomez Hoyos, Ramin Moshavegh, Michael Bachmann Nielsen, and Jorgen Arendt Jensen. "Portable Vector Flow Imaging Compared With Spectral Doppler Ultrasonography." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 66, no. 3 (March 2019): 453–62. http://dx.doi.org/10.1109/tuffc.2018.2872508.

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20

Oddershede, Niels, and Jorgen Jensen. "Effects Influencing Focusing in Synthetic Aperture Vector Flow Imaging." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 54, no. 9 (September 2007): 1811–25. http://dx.doi.org/10.1109/tuffc.2007.465.

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21

Goddi, Alfredo, Chandra Bortolotto, Ilaria Fiorina, Maria Vittoria Raciti, Marianna Fanizza, Elena Turpini, Giulia Boffelli, and Fabrizio Calliada. "High-frame rate vector flow imaging of the carotid bifurcation." Insights into Imaging 8, no. 3 (May 12, 2017): 319–28. http://dx.doi.org/10.1007/s13244-017-0554-5.

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22

Feinberg, David A., Lawrence E. Crooks, Phillip Sheldon, John Hoenninger Iii, Jeffrey Watts, and Mitsuaki Arakawa. "Magnetic Resonance Imaging the Velocity Vector Components of Fluid Flow." Magnetic Resonance in Medicine 2, no. 6 (December 1985): 555–66. http://dx.doi.org/10.1002/mrm.1910020606.

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23

Du, Yigang, Alfredo Goddi, Chandra Bortolotto, Yingying Shen, Alex Dell'Era, Fabrizio Calliada, and Lei Zhu. "Wall Shear Stress Measurements Based on Ultrasound Vector Flow Imaging." Journal of Ultrasound in Medicine 39, no. 8 (March 3, 2020): 1649–64. http://dx.doi.org/10.1002/jum.15253.

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24

Goddi, Alfredo, Marianna Fanizza, Chandra Bortolotto, Maria Vittoria Raciti, Ilaria Fiorina, Xujin He, Yigang Du, and Fabrizio Calliada. "Vector flow imaging techniques: An innovative ultrasonographic technique for the study of blood flow." Journal of Clinical Ultrasound 45, no. 9 (July 21, 2017): 582–88. http://dx.doi.org/10.1002/jcu.22519.

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Holbek, Simon, Kristoffer Lindskov Hansen, Hamed Bouzari, Caroline Ewertsen, Matthias Bo Stuart, Carsten Thomsen, Michael Bachmann Nielsen, and Jørgen Arendt Jensen. "Common Carotid Artery Flow Measured by 3-D Ultrasonic Vector Flow Imaging and Validated with Magnetic Resonance Imaging." Ultrasound in Medicine & Biology 43, no. 10 (October 2017): 2213–20. http://dx.doi.org/10.1016/j.ultrasmedbio.2017.06.007.

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Tanaka, Tomohiko, Takashi Okada, Tomohide Nishiyama, and Yoshinori Seki. "Relative pressure imaging in left ventricle using ultrasonic vector flow mapping." Japanese Journal of Applied Physics 56, no. 7S1 (June 28, 2017): 07JF26. http://dx.doi.org/10.7567/jjap.56.07jf26.

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Shahriari, Shahrokh, and Damien Garcia. "Meshfree simulations of ultrasound vector flow imaging using smoothed particle hydrodynamics." Physics in Medicine & Biology 63, no. 20 (October 17, 2018): 205011. http://dx.doi.org/10.1088/1361-6560/aae3c3.

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Norton, Stephen J. "Tomographic Reconstruction of 2-D Vector Fields: Application to Flow Imaging." Geophysical Journal International 97, no. 1 (April 1989): 161–68. http://dx.doi.org/10.1111/j.1365-246x.1989.tb00491.x.

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Ohtsuki, Shigeo, Motonao Tanaka, and Motoyoshi Okujima. "Flow vector mapping through stream function from two‐dimensional Doppler imaging." Journal of the Acoustical Society of America 84, S1 (November 1988): S138. http://dx.doi.org/10.1121/1.2025802.

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Kokkalis, Efstratios, Peter R. Hoskins, George A. Corner, Peter A. Stonebridge, Anthony J. Doull, and J. Graeme Houston. "Secondary Flow in Peripheral Vascular Prosthetic Grafts Using Vector Doppler Imaging." Ultrasound in Medicine & Biology 39, no. 12 (December 2013): 2295–307. http://dx.doi.org/10.1016/j.ultrasmedbio.2013.07.014.

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Yiu, Billy Y. S., Simon S. M. Lai, and Alfred C. H. Yu. "Vector Projectile Imaging: Time-Resolved Dynamic Visualization of Complex Flow Patterns." Ultrasound in Medicine & Biology 40, no. 9 (September 2014): 2295–309. http://dx.doi.org/10.1016/j.ultrasmedbio.2014.03.014.

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Zhang, Haibin, Xiaofeng Ren, Jin Song, Xinyu Cao, Benna Wang, Ying Liu, Zhiguo Li, and Na Ma. "Intraventricular Isovolumic Relaxation Flow Patterns Studied by Using Vector Flow Mapping." Echocardiography 33, no. 6 (February 1, 2016): 902–9. http://dx.doi.org/10.1111/echo.13192.

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Kupsch, Christian, David Weik, Lukas Feierabend, Richard Nauber, Lars Buttner, and Jurgen Czarske. "Vector Flow Imaging of a Highly Laden Suspension in a Zinc-Air Flow Battery Model." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 66, no. 4 (April 2019): 761–71. http://dx.doi.org/10.1109/tuffc.2019.2891514.

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Goddi, A. Alfredo, L. Luca Aiani, Y. Yigang Du, X. Xujin He, Y. Yingying Shen, and L. Lei Zhu. "P84 HIGH-FRAME RATE VECTOR FLOW IMAGING: RELATIONSHIP BETWEEN CAROTID BIFURCATION GEOMETRY AND FLOW PATTERNS." Artery Research 20, no. C (2017): 76. http://dx.doi.org/10.1016/j.artres.2017.10.100.

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Asami, Rei, Tomohiko Tanaka, Motochika Shimizu, Yoshinori Seki, Tomohide Nishiyama, Hajime Sakashita, and Takashi Okada. "Ultrasonic Vascular Vector Flow Mapping for 2-D Flow Estimation." Ultrasound in Medicine & Biology 45, no. 7 (July 2019): 1663–74. http://dx.doi.org/10.1016/j.ultrasmedbio.2019.02.014.

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Boonnuk, Tanunchai, Sanun Srisuk, and Thanwa Sripramong. "Active Contour Model with Edge Flow Vector for Texture Segmentation." Applied Mechanics and Materials 781 (August 2015): 511–14. http://dx.doi.org/10.4028/www.scientific.net/amm.781.511.

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In this paper, we propose effective method for texture segmentation using active contour model with edge flow vector. This technique was applied from previous active contour model that uses gradient vector flow as external force. It was observed that our method provided better results for texture segmentation while a traditional active contour model and active contour model with gradient vector flow were not capable to be used with texture image. Thus, texture image such as medical imaging can be identified using active contour model with edge flow vector.

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Hansen, Kristoffer Lindskov, Hasse Møller-Sørensen, Jesper Kjaergaard, Maiken Brit Jensen, Jørgen Arendt Jensen, and Michael Bachmann Nielsen. "Aortic Valve Stenosis Increases Helical Flow and Flow Complexity: A Study of Intra-Operative Cardiac Vector Flow Imaging." Ultrasound in Medicine & Biology 43, no. 8 (August 2017): 1607–17. http://dx.doi.org/10.1016/j.ultrasmedbio.2017.03.018.

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Qiu, Yi-Jie, Juan Cheng, Qi Zhang, Dao-Hui Yang, Dan Zuo, Feng Mao, Ling-Xiao Liu, Yi Dong, Si-Qi Cao, and Wen-Ping Wang. "Clinical Application of High-Frame-Rate Vector Flow Imaging in Evaluation of Carotid Atherosclerotic Stenosis." Diagnostics 13, no. 3 (January 31, 2023): 519. http://dx.doi.org/10.3390/diagnostics13030519.

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Objective: This study seeks to evaluate the value of the high-frame-rate vector flow imaging technique in assessing the hemodynamic changes of carotid atherosclerotic stenosis in aging people (>60 years old). Methods: Aging patients diagnosed with carotid atherosclerotic stenosis who underwent carotid high-frame-rate vector flow imaging examination were prospectively enrolled. A Mindray Resona7s ultrasound machine equipped with high-frame-rate vector flow function was used for ultrasound evaluation. First, B mode ultrasound and color Doppler flow imaging were used to evaluate carotid stenosis. Then, the vector arrows and flow streamline detected by V Flow were analyzed and the wall shear stress values (Pa) at the carotid stenosis site were measured. All patients were divided into symptomatic and asymptomatic groups according to whether they had acute/subacute stroke or other clinical symptoms within 2 weeks before ultrasound examination. The results of digital subtraction angiography or computed tomography angiography were used as the gold standard. The stenosis rate was calcified, according to North American Symptomatic Carotid Endarterectomy Trial criteria. The diagnostic values of wall shear stress, conventional ultrasound, and the combined diagnosis in carotid atherosclerotic stenosis were compared. Results: Finally, 88 patients with carotid atherosclerotic plaque were enrolled (71 males (80.7%), mean age 67.6 ± 5.4 years). The success rate of high-frame-rate vector flow imaging was 96.7% (88/91). The WSS value of symptomatic carotid stenosis (1.4 ± 0.15 Pa) was significantly higher than that of asymptomatic carotid stenosis (0.80 ± 0.08 Pa) (p < 0.05). Taking the wall shear stress value > 0.78 Pa as the diagnostic criteria for symptomatic carotid atherosclerotic plaque, the area under receiver operating characteristic curves was 0.79 with 87.1% sensitivity and 69.6% specificity. The area under receiver operating characteristic curves of the combined diagnosis (0.966) for differentiating severe carotid atherosclerotic stenosis was significantly higher than that of conventional ultrasound and WSS value, with 89.7% sensitivity and 93.2% specificity (p < 0.05). Conclusion: As a non-invasive imaging method, the high-frame-rate vector flow imaging technique showed potential value in the preoperative assessment of the symptomatic carotid atherosclerotic stenosis and diagnosing carotid atherosclerotic stenosis in aging patients.

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Rossi, Stefano, Alessandro Ramalli, Fabian Fool, and Piero Tortoli. "High-Frame-Rate 3-D Vector Flow Imaging in the Frequency Domain." Applied Sciences 10, no. 15 (August 3, 2020): 5365. http://dx.doi.org/10.3390/app10155365.

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Ultrasound vector Doppler techniques for three-dimensional (3-D) blood velocity measurements are currently limited by low temporal resolution and high computational cost. In this paper, an efficient 3-D high-frame-rate vector Doppler method, which estimates the displacements in the frequency domain, is proposed. The novel method extends to 3-D an approach so far proposed for two-dimensional (2-D) velocity measurements by approximating the (x, y, z) displacement of a small volume through the displacements estimated for the 2-D regions parallel to the y and x directions, respectively. The new method was tested by simulation and experiments for a 3.7 MHz, 256-element, 2-D piezoelectric sparse spiral array. Simulations were also performed for an equivalent 7 MHz Capacitive Micromachined Ultrasonic Transducer spiral array. The results indicate performance (bias ± standard deviation: 6.5 ± 8.0) comparable to the performance obtained by using a linear array for 2-D velocity measurements. These results are particularly encouraging when considering that sparse arrays were used, which involve a lower signal-to-noise ratio and worse beam characteristics with respect to full 2-D arrays.

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Villagomez Hoyos, Carlos Armando, Matthias Bo Stuart, Kristoffer Lindskov Hansen, Michael Bachmann Nielsen, and Jorgen Arendt Jensen. "Accurate Angle Estimator for High-Frame-Rate 2-D Vector Flow Imaging." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 63, no. 6 (June 2016): 842–53. http://dx.doi.org/10.1109/tuffc.2016.2551689.

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Yiu, Billy Y. S., and Alfred C. H. Yu. "Least-Squares Multi-Angle Doppler Estimators for Plane-Wave Vector Flow Imaging." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 63, no. 11 (November 2016): 1733–44. http://dx.doi.org/10.1109/tuffc.2016.2582514.

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Madiena, Craig, Julia Faurie, Jonathan Poree, and Damien Garcia. "Color and Vector Flow Imaging in Parallel Ultrasound With Sub-Nyquist Sampling." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 65, no. 5 (May 2018): 795–802. http://dx.doi.org/10.1109/tuffc.2018.2817885.

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Collins II, R. Thomas, Megan E. Laughlin, Sean M. Lang, Elijah H. Bolin, Joshua A. Daily, Hanna A. Jensen, and Morten O. Jensen. "Real-time transthoracic vector flow imaging of the heart in pediatric patients." Progress in Pediatric Cardiology 53 (June 2019): 28–36. http://dx.doi.org/10.1016/j.ppedcard.2019.02.003.

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Mozumi, Michiya, Ryo Nagaoka, and Hideyuki Hasegawa. "Singular value decomposition filtering in high-frame-rate cardiac vector flow imaging." Bulletin of Electrical Engineering and Informatics 9, no. 1 (February 1, 2020): 171–79. http://dx.doi.org/10.11591/eei.v9i1.1858.

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Dysfunction of the left ventricle (LV) weakens the cardiac function and affects the physical activity. Echocardiagraphy has been used to visualize the blood flow dynamics and to evaluate the cardiac function. However, the signal processing to suppress the clutter signals should be employed. In this study, we employed the singular value decomposition (SVD) clutter filtering to obtain the cardiac blood speckle images. We also employed the adaptive thresholding metric to determine the proper cutoff values at each phase during the cardiac cycle. Moreover, we employed a depth-dependent SVD clutter filter for more accurate estimation of the cardiac blood echo signals. The 2D blood flow velocity vectors were estimated by applying the block matching method to obtained blood speckle images. The obtained results show that the proposed filter suppressed the clutter signals from left ventricular wall significantly, and the contrast-to-noise ratio (CNR) was improved from -0.5 dB to 13.8 dB by the proposed SVD clutter filtering.

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Zhou, Xinhuan, Peter Vincent, Xiaowei Zhou, Chee Hau Leow, and Meng-Xing Tang. "Optimization of 3-D Divergence-Free Flow Field Reconstruction Using 2-D Ultrasound Vector Flow Imaging." Ultrasound in Medicine & Biology 45, no. 11 (November 2019): 3042–55. http://dx.doi.org/10.1016/j.ultrasmedbio.2019.06.402.

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Au, Jason S., Billy Y. S. Yiu, and Alfred C. H. Yu. "Case Studies in Physiology: Visualization of blood recirculation in a femoral artery “trifurcation” using ultrasound vector flow imaging." Journal of Applied Physiology 127, no. 6 (December 1, 2019): 1809–13. http://dx.doi.org/10.1152/japplphysiol.00451.2019.

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The femoral bifurcation is typically composed of a common femoral artery that bifurcates into the superficial (SFA) and deep (DFA) femoral arteries, with the lateral circumflex femoral artery (LCFA) branching distal to the origin of the DFA. We report a unique case of a 22-yr-old woman with a femoral “trifurcation,” where the origin of the LCFA coincides with the origin of the DFA, resulting in a true three-way branching of the common femoral artery. We characterized the complex hemodynamics of the trifurcation region with ultrasound vector flow imaging at rest, and during 80 mmHg cuff compression of the calf to induce greater oscillatory blood flow. At rest, a clear trifurcation is observed with color Doppler imaging, while vector flow imaging further revealed a large area of flow circulation proximal to the LCFA and DFA. Cuff compression reduced SFA blood flow to 0 cm3/min, characterized by almost constant retrograde blood flow throughout diastole. When visualized with vector flow imaging, diastolic retrograde blood flow from the SFA appeared to reperfuse the DFA and LCFA during late systole, eliminating the retrograde flow component and providing a secondary source of anterograde blood flow to the thigh. In a rare case of a femoral trifurcation, we demonstrate blood recirculation patterns at rest, as well as collateral retrograde blood flow redistribution during lower limb compression. While it is unknown whether these trifurcation findings extend to typical bifurcations, it is evident that advanced methods of blood flow characterization are necessary to visualize and study complex vascular regions. NEW & NOTEWORTHY A femoral “trifurcation” is observed when the lateral circumflex femoral artery has an atypical proximal origin, branching at the same level as the superficial and deep femoral arteries. Ultrasound vector flow imaging at 750 fps was able to reveal substantial blood recirculation within the trifurcation at rest, as well as unique redistribution of blood flow between downstream branches during external cuff manipulation of retrograde flow, indicating novel ways in which diastolic blood flow is controlled.

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Wen, Han. "Mapping the velocity vector onto the spin vector: Two-dimensional velocity-selective spin excitation for MR flow imaging." Magnetic Resonance in Medicine 46, no. 4 (October 2001): 767–72. http://dx.doi.org/10.1002/mrm.1255.

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Evans, David H., Jørgen Arendt Jensen, and Michael Bachmann Nielsen. "Ultrasonic colour Doppler imaging." Interface Focus 1, no. 4 (May 6, 2011): 490–502. http://dx.doi.org/10.1098/rsfs.2011.0017.

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Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been found to be of great value in assessing blood flow in many clinical conditions. Although the method for obtaining the velocity information is in many ways similar to the method for obtaining the anatomical information, it is technically more demanding for a number of reasons. It also has a number of weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new techniques that seek to overcome the vector problem mentioned above are described. Finally, some examples of vector velocity images are presented.

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Hansen, Kristoffer Lindskov, Michael Bachmann Nielsen, and Jørgen Arendt Jensen. "Vector velocity estimation of blood flow – A new application in medical ultrasound." Ultrasound 25, no. 4 (June 5, 2017): 189–99. http://dx.doi.org/10.1177/1742271x17713353.

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Vector flow techniques in the field of ultrasound encompass different pulse emission and estimation strategies. Numerous techniques have been introduced over the years, and recently commercial implementations usable in the clinic have been made. A number of clinical papers using different vector velocity approaches have been published. This review will give an overview of the most significant in vivo results achieved with ultrasound vector flow techniques, and will outline some of the possible clinical applications for vector velocity estimation in the future.

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Hansen, Kristoffer Lindskov, Hasse Møller-Sørensen, Jesper Kjaergaard, Maiken Brit Jensen, Jens Teglgaard Lund, Mads Møller Pedersen, Theis Lange, Jørgen Arendt Jensen, and Michael Bachmann Nielsen. "Analysis of Systolic Backflow and Secondary Helical Blood Flow in the Ascending Aorta Using Vector Flow Imaging." Ultrasound in Medicine & Biology 42, no. 4 (April 2016): 899–908. http://dx.doi.org/10.1016/j.ultrasmedbio.2015.11.029.

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