Technical recommendations for the use of carotid duplex ultrasound for the assessment of extracranial blood flow

2015 ◽  
Vol 309 (7) ◽  
pp. R707-R720 ◽  
Author(s):  
Kate N. Thomas ◽  
Nia C. S. Lewis ◽  
Brigid G. Hill ◽  
Philip N. Ainslie
Keyword(s):  
Blood Flow ◽  
Duplex Ultrasound ◽  
Intensive Training ◽  
Methodological Errors ◽  
Recent Developments ◽  
Within Subjects ◽  
Specialized Technique ◽  
Velocity Information ◽  
Complex Settings ◽  
User Friendly

Duplex ultrasound is an evolving technology that allows the assessment of volumetric blood flow in the carotid and vertebral arteries during a range of interventions along the spectrum of health and chronic disease. Duplex ultrasound can provide high-resolution diameter and velocity information in real-time and is noninvasive with minimal risks or contraindications. However, this ultrasound approach is a specialized technique requiring intensive training and stringent control of multiple complex settings; results are highly operator-dependent, and analysis approaches are inconsistent. Importantly, therefore, methodological differences can invalidate comparisons between different imaging modalities and studies; such methodological errors have potential to discredit study findings completely. The task of this review is to provide the first comprehensive, user-friendly technical guideline for the application of duplex ultrasound in measuring extracranial blood flow in human research. An update on recent developments in the use of edge-detection software for offline analysis is highlighted, and suggestions for future directions in this field are provided. These recommendations are presented in an attempt to standardize measurements across research groups and, hence, ultimately to improve the accuracy and reproducibility of measuring extracranial blood flow both within subjects and between groups.

Assessment of Coronary Microcirculation During Cardiac Catheterization

2018 ◽  
Vol 24 (25) ◽  
pp. 2950-2953
Author(s):  
Sasko Kedev ◽  
Ivan Vasilev
Keyword(s):  
Blood Flow ◽  
Coronary Angiography ◽  
Myocardial Blood Flow ◽  
Functional Tests ◽  
Fractional Flow ◽  
Catheterization Laboratory ◽  
Flow Reserve ◽  
Objective Evidence ◽  
Value Based Care ◽  
User Friendly

Functional tests used in the catheterization laboratory have emerged as a very important adjunctive tool to coronary angiography that can identify patients with myocardial blood flow impairment. Fractional Flow Reserve (FFR) measurement is highly recommended for detection of ischemia-related coronary lesion(s) when objective evidence of vessel-related ischemia is not available. Recently, the much simpler instantaneous wave free ratio (iFR) was proposed as an alternative to FFR without the requirement for administration of vasodilators. More user-friendly techniques like iFR might further contribute to value-based care in coronary interventions.

Objective duplex ultrasound evaluation of the extracranial circulation in multiple sclerosis patients undergoing venoplasty of internal jugular vein stenoses: A pilot study

2013 ◽  
Vol 30 (2) ◽  
pp. 98-104 ◽  
Author(s):  
P Thibault ◽  
W Lewis ◽  
S Niblett
Keyword(s):  
Multiple Sclerosis ◽  
Blood Flow ◽  
Cerebral Perfusion ◽  
Objective Assessment ◽  
Duplex Ultrasound ◽  
Additional Parameter ◽  
Non Invasive ◽  
Venous Circulation ◽  
Ultrasound Evaluation ◽  
Multiple Sclerosis Patients

Objective Chronic cerebrospinal venous insufficiency (CCSVI) is a condition associated with multiple sclerosis (MS) and manifested by stenoses in the extracranial venous circulation. There is a need for an objective non-invasive assessment of CCSVI that is able to accurately identify the location of stenoses and quantify physiological changes in blood flows following treatment. Method A duplex ultrasound method, extracranial duplex ultrasound (ECDU), is described where the internal jugular veins (IJVs) and vertebral veins (VVs) were examined in the supine and sitting position before and after venoplasty in eight patients with clinically diagnosed MS. High-resolution B-mode imaging was used to detect obvious stenoses, intra-luminal membranes, valve abnormalities and vein wall thickening. ECDU was then used to assess blood flow including reflux. To assess obstruction, venous blood volume flows (BVFs) were taken bilaterally from the proximal (J1), mid (J2) and distal (J3) segments of the IJVs and the mid cervical VVs. To assess cerebral perfusion, bilateral BVF measurements were taken, in the supine position only, from the proximal internal carotid arteries (ICA) and mid cervical vertebral arteries (VA). The global arterial cerebral blood flow (GACBF) was then calculated as the sum of the ICA and VA measurements. Results Pre-venography ECDU detected IJV stenoses or obstruction in all patients. Venography findings were consistent with those of the pre-treatment ECDU with the exception of the detection of bilateral IJV stenoses in two patients diagnosed with unilateral IJV stenosis by ECDU. A significant improvement in GACBF was evident following venoplasty ( p < 0.05). A trend to improvement in the post-treatment BVFs of both the IJVs and the mid cervical VVs was also observed. This improvement was most marked in the left VVs ( p = 0.052) and the J2 segment of right IJVs ( p < 0.05). Conclusion The ECDU examination described provides a reliable objective assessment of IJV and VV stenoses and, with the use of BVFs, can quantify the degree of obstruction. These results support the use of ECDU as a non-invasive post-operative assessment of the success of venoplasty. The ability of ECDU to measure GACBF provides an additional parameter to monitor vascular pathophysiology in MS patients. The current findings support the view that the early symptomatic benefits observed after venoplasty for stenoses in the extracranial venous circulation may be the result of increased cerebral perfusion.

scholarly journals Recent developments in theCCP-EMsoftware suite

2017 ◽  
Vol 73 (6) ◽  
pp. 469-477 ◽  
Author(s):  
Tom Burnley ◽  
Colin M. Palmer ◽  
Martyn Winn
Keyword(s):  
Easy Access ◽  
Software Framework ◽  
Command Line ◽  
Command Line Interface ◽  
Software Suite ◽  
Computational Support ◽  
Recent Developments ◽  
User Friendly ◽  
Different Levels ◽  
Friendly Graphical User Interface

As part of its remit to provide computational support to the cryo-EM community, the Collaborative Computational Project for Electron cryo-Microscopy (CCP-EM) has produced a software framework which enables easy access to a range of programs and utilities. The resulting software suite incorporates contributions from different collaborators by encapsulating them in Python task wrappers, which are then made accessibleviaa user-friendly graphical user interface as well as a command-line interface suitable for scripting. The framework includes tools for project and data management. An overview of the design of the framework is given, together with a survey of the functionality at different levels. The currentCCP-EMsuite has particular strength in the building and refinement of atomic models into cryo-EM reconstructions, which is described in detail.

Duplex ultrasound measurement of changes in mesenteric flow velocity with pharmacologic and physiologic alteration of intestinal blood flow in man

1989 ◽  
Vol 9 (1) ◽  
pp. 0018-0025 ◽  
Author(s):  
Michael P. Lilly ◽  
Timothy R. S. Harward ◽  
William R. Flinn ◽  
Donna R. Blackburn ◽  
Patricia M. Astleford ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Duplex Ultrasound ◽  
Intestinal Blood Flow ◽  
Ultrasound Measurement

scholarly journals Predictive modeling and in vivo assessment of cerebral blood flow in the management of complex cerebral aneurysms

2016 ◽  
Vol 36 (6) ◽  
pp. 998-1003 ◽  
Author(s):  
Brian P Walcott ◽  
Clemens Reinshagen ◽  
Christopher J Stapleton ◽  
Omar Choudhri ◽  
Vitaliy Rayz ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysms ◽  
Improve Risk Stratification ◽  
Complex Aneurysms ◽  
Aneurysm Treatment ◽  
Circulation Patterns ◽  
Recent Developments ◽  
Surgical Bypass ◽  
In Vivo Assessment

Cerebral aneurysms are weakened blood vessel dilatations that can result in spontaneous, devastating hemorrhage events. Aneurysm treatment aims to reduce hemorrhage events, and strategies for complex aneurysms often require surgical bypass or endovascular stenting for blood flow diversion. Interventions that divert blood flow from their normal circulation patterns have the potential to result in unintentional ischemia. Recent developments in computational modeling and in vivo assessment of hemodynamics for cerebral aneurysm treatment have entered into clinical practice. Herein, we review how these techniques are currently utilized to improve risk stratification and treatment planning.

scholarly journals The Price of Anarchy in Auctions

2017 ◽  
Vol 59 ◽  
pp. 59-101 ◽  
Author(s):  
Tim Roughgarden ◽  
Vasilis Syrgkanis ◽  
Eva Tardos
Keyword(s):  
Learning Outcomes ◽  
Price Of Anarchy ◽  
Complete Information ◽  
Worst Case ◽  
Extension Theorems ◽  
Complex Settings ◽  
User Friendly ◽  
Auction Formats ◽  
Analytical Tools ◽  
Special Case

This survey outlines a general and modular theory for proving approximation guarantees for equilibria of auctions in complex settings. This theory complements traditional economic techniques, which generally focus on exact and optimal solutions and are accordingly limited to relatively stylized settings. We highlight three user-friendly analytical tools: smoothness-type inequalities, which immediately yield approximation guarantees for many auction formats of interest in the special case of complete information and deterministic strategies; extension theorems, which extend such guarantees to randomized strategies, no-regret learning outcomes, and incomplete-information settings; and composition theorems, which extend such guarantees from simpler to more complex auctions. Combining these tools yields tight worst-case approximation guarantees for the equilibria of many widely-used auction formats.

scholarly journals POTATO: An automated pipeline for batch analysis of optical tweezers data

2021 ◽  
Author(s):  
Stefan Buck ◽  
Lukas Pekarek ◽  
Neva Caliskan
Keyword(s):  
Data Analysis ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Molecular Motors ◽  
Analysis Tool ◽  
Recent Developments ◽  
Protein Nucleic Acid ◽  
Programming Knowledge ◽  
Nucleic Acid Interactions ◽  
User Friendly

Optical tweezers is a single-molecule technique that allows probing of intra- and intermolecular interactions that govern complex biological processes involving molecular motors, protein-nucleic acid interactions and protein/RNA folding. Recent developments in instrumentation eased and accelerated optical tweezers data acquisition, but analysis of the data remains challenging. Here, to enable high-throughput data analysis, we developed an automated python-based analysis pipeline called POTATO (Practical Optical Tweezers Analysis TOol). POTATO automatically processes the high-frequency raw data generated by force-ramp experiments and identifies (un)folding events using predefined parameters. After segmentation of the force-distance trajectories at the identified (un)folding events, sections of the curve can be fitted independently to worm-like chain and freely-jointed chain models, and the work applied on the molecule can be calculated by numerical integration. Furthermore, the tool allows plotting of constant force data and fitting of the Gaussian distance distribution over time. All these features are wrapped in a user-friendly graphical interface (https://github.com/REMI-HIRI/POTATO), which allows researchers without programming knowledge to perform sophisticated data analysis.

Oxidative stress contributes to chronic leg vasoconstriction in estrogen-deficient postmenopausal women

2007 ◽  
Vol 102 (3) ◽  
pp. 890-895 ◽  
Author(s):  
Kerrie L. Moreau ◽  
Ashley R. DePaulis ◽  
Kathleen M. Gavin ◽  
Douglas R. Seals
Keyword(s):  
Oxidative Stress ◽  
Blood Flow ◽  
Ascorbic Acid ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Postmenopausal Women ◽  
Oxidized Ldl ◽  
Duplex Ultrasound ◽  
Vascular Conductance ◽  
Leg Blood Flow

Basal whole leg blood flow and vascular conductance are reduced in estrogen-deficient postmenopausal compared with premenopausal women. The underlying mechanisms are unknown, but oxidative stress could be involved. We studied 9 premenopausal [23 ± 1 yr (mean ± SE)] and 20 estrogen-deficient postmenopausal (55 ± 1 yr) healthy women. During baseline control, oxidized low-density lipoprotein (LDL), a marker of oxidative stress, was 50% greater in the postmenopausal women ( P < 0.001). Basal whole leg blood flow (duplex ultrasound of femoral artery) was 34% lower in the postmenopausal women because of a 38% lower leg vascular conductance ( P < 0.0001); mean arterial pressure was not different. Intravenous administration of a supraphysiological dose of the antioxidant ascorbic acid increased leg blood flow by 15% in the postmenopausal women as a result of an increase in leg vascular conductance (both P < 0.001), but it did not affect leg blood flow in premenopausal controls or mean arterial pressure in either group. In the pooled subjects, the changes in leg blood flow and leg vascular conductance with ascorbic acid were related to baseline plasma oxidized LDL ( r = 0.46 and 0.53, P < 0.01) and waist-to-hip ratio and total body fat ( r = 0.41–0.44, all P < 0.05). Our results are consistent with the hypothesis that oxidative stress contributes to chronic leg vasoconstriction and reduced basal whole leg blood flow in estrogen-deficient postmenopausal women. This oxidative stress-related suppression of leg vascular conductance and blood flow may be linked in part to increased total and abdominal adiposity.

Smart Flow for the evaluation of the hemodialysis arteriovenous fistula

2020 ◽  
Vol 21 (5) ◽  
pp. 652-657
Author(s):  
Marco Colucci ◽  
Massimo Torreggiani ◽  
Irene Bernardi ◽  
Simone Stangalino ◽  
Davide Catucci ◽  
...  
Keyword(s):  
Blood Flow ◽  
Doppler Ultrasound ◽  
Duplex Ultrasound ◽  
Chronic Patients ◽  
Flow Measurements ◽  
Additional Information ◽  
Arteriovenous Fistulas ◽  
Duplex Doppler Ultrasound ◽  
Duplex Doppler ◽  
Flow Turbulence

Background: Smart Flow is an innovative tool available on the Carestream Touch Prime Ultrasound machines, which provides automated blood flow measurement and shows the vectors that form the blood flow in the vessel. We compared the use of Smart Flow with traditional Duplex Doppler Ultrasound to evaluate blood flow of arteriovenous fistulas in prevalent hemodialysis patients. Methods: A total of 31 chronic patients on hemodialysis were enrolled. Blood flow was measured on the brachial artery with Smart Flow and duplex Doppler ultrasound. In a subset of 26 patients, a video of the juxta-anastomotic efferent vein was recorded and analyzed to calculate an index of flow turbulence. Results: We enrolled 21 males and 10 females aged 68.52 ± 11.64 years at the time of evaluation with an average arteriovenous fistulas vintage of 50.23 ± 47.42 months and followed them up for 18.03 ± 5.18 months. Smart Flow and Duplex Doppler Ultrasound blood flow measurements positively correlated (p < 0.0001) in the same patient but Smart Flow gave higher blood flow values (995.0 vs 730.3 mL/min, p < 0.0001), and the Duplex Doppler Ultrasound blood flow standard deviation was similar to Smart Flow (125.4 vs 114.4 mL/min, p < 0.0001). The time needed to evaluate arteriovenous fistulas with Smart Flow was significantly shorter than Duplex Doppler Ultrasound (67.58 ± 19.89 vs 146.3 ± 26.35 s, p < 0.0001). No correlation was found between blood flow turbulence and the subsequent access failure. Conclusion: Smart Flow is reliable, reproducible, and faster than traditional duplex ultrasound. However, the additional information given by the Smart Flow technique does not seem to add any further benefits in terms of prediction of the access failure.

scholarly journals Matched increases in cerebral artery shear stress, irrespective of stimulus, induce similar changes in extra-cranial arterial diameter in humans

2017 ◽  
Vol 39 (5) ◽  
pp. 849-858 ◽  
Author(s):  
Kurt J Smith ◽  
Ryan L Hoiland ◽  
Ryan Grove ◽  
Hamish McKirdy ◽  
Louise Naylor ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Shear Rate ◽  
Duplex Ultrasound ◽  
Arterial Dilation ◽  
Cranial Arteries ◽  
First Time ◽  
Carotid And Vertebral Arteries

The mechanistic role of arterial shear stress in the regulation of cerebrovascular responses to physiological stimuli (exercise and hypercapnia) is poorly understood. We hypothesised that, if shear stress is a key regulator of arterial dilation, then matched increases in shear, induced by distinct physiological stimuli, would trigger similar dilation of the large extra-cranial arteries. Participants ( n = 10) participated in three 30-min experimental interventions, each separated by ≥48 h: (1) mild-hypercapnia (FICO2:∼0.045); (2) submaximal cycling (EX; 60%HRreserve); or (3) resting (time-matched control, CTRL). Blood flow, diameter, and shear rate were assessed (via Duplex ultrasound) in the internal carotid and vertebral arteries (ICA, VA) at baseline, during and following the interventions. Hypercapnia and EX produced similar elevations in blood flow and shear rate through the ICA and VA ( p < 0.001), which were both greater than CTRL. Vasodilation of ICA and VA diameter in response to hypercapnia (5.3 ± 0.8 and 4.4 ± 2.0%) and EX (4.7 ± 0.7 and 4.7 ± 2.2%) were similar, and greater than CTRL ( p < 0.001). Our findings indicate that matched levels of shear, irrespective of their driving stimulus, induce similar extra-cranial artery dilation. We demonstrate, for the first time in humans, an important mechanistic role for the endothelium in regulating cerebrovascular response to common physiological stimuli in vivo.

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