HIFU Treatment of Liver Cancer – Reciprocal Effect of Blood Flow and US Studied from a Patient-Specific Configuration

2014 ◽  
pp. 1-11
Author(s):  
Marc Thiriet ◽  
Maxim Solovchuk ◽  
Tony Wen-Hann Sheu
Keyword(s):  
Blood Flow ◽  
Liver Cancer ◽  
Patient Specific ◽  
Hifu Treatment ◽  
Reciprocal Effect ◽  
Specific Configuration

Numerical Analysis of the VAD Outflow Cannula Positioning on the Blood Flow in the Patient–Specific Brain Supplying Arteries

2020 ◽  
Vol 22 (2) ◽  
pp. 619-636 ◽  
Author(s):  
Zbigniew Tyfa ◽  
Damian Obidowski ◽  
Krzysztof Jóźwik
Keyword(s):  
Blood Flow ◽  
Computer Aided Design ◽  
Volume Flow Rate ◽  
Flow Distribution ◽  
Primary Objective ◽  
Patient Specific ◽  
Blood Flow Distribution ◽  
Reconstruction Process ◽  
Outflow Cannula ◽  
The Brain

AbstractThe primary objective of this research can be divided into two separate aspects. The first one was to verify whether own software can be treated as a viable source of data for the Computer Aided Design (CAD) modelling and Computational Fluid Dynamics CFD analysis. The second aspect was to analyze the influence of the Ventricle Assist Device (VAD) outflow cannula positioning on the blood flow distribution in the brain-supplying arteries. Patient-specific model was reconstructed basing on the DICOM image sets obtained with the angiographic Computed Tomography. The reconstruction process was performed in the custom-created software, whereas the outflow cannulas were added in the SolidWorks software. Volumetric meshes were generated in the Ansys Mesher module. The transient boundary conditions enabled simulating several full cardiac cycles. Performed investigations focused mainly on volume flow rate, shear stress and velocity distribution. It was proven that custom-created software enhances the processes of the anatomical objects reconstruction. Developed geometrical files are compatible with CAD and CFD software – they can be easily manipulated and modified. Concerning the numerical simulations, several cases with varied positioning of the VAD outflow cannula were analyzed. Obtained results revealed that the location of the VAD outflow cannula has a slight impact on the blood flow distribution among the brain supplying arteries.

Blood-flow Restriction Training for a Person With Primary Progressive Multiple Sclerosis: A Case Report

2020 ◽  
Author(s):  
Evan T Cohen ◽  
Nicole Cleffi ◽  
Marianne Ingersoll ◽  
Herb I Karpatkin
Keyword(s):  
Multiple Sclerosis ◽  
Blood Flow ◽  
Case Report ◽  
Physical Therapist ◽  
Blood Flow Restriction ◽  
Patient Specific ◽  
Primary Progressive Multiple Sclerosis ◽  
Primary Progressive ◽  
Flow Restriction ◽  
Strength Tests

Abstract Objective Blood flow restriction (BFR) training, in which an inflatable cuff partially occludes blood flow around the proximal portion of a limb, coupled with low-intensity resistance training (LIRT) has resulted in gains comparable to traditional progressive resistive exercise in healthy populations. The use of BFR with LIRT may enable people with multiple sclerosis (MS) to improve strength without an increase in fatigue. The purpose of this case report is to describe the use of a BFR/LIRT program for a person with MS. Methods (Case Description) The patient was a 54-year-old woman with a 13-year history of primary progressive MS with an Extended Disability Severity Score of 3.0 out of 10. She received a BFR/LIRT program for both lower extremities (LE) biweekly for 12 weeks. Outcomes measured at baseline and at 6 and 12 weeks included the 12-item Multiple Sclerosis Walking Scale (MSWS-12), Fatigue Severity Scale (FSS), Patient-Specific Functional Scale (PSFS) (goals: running for exercise and pleasure for 45 minutes, 100% confidence in negotiating a flight of stairs, confidently and safely drive without restriction), and 14 LE strength tests. Results The intervention was well tolerated without adverse events. After 6 weeks, the MSWS-12 score improved; however, it did not exceed minimum detectable change (MDC). FSS was unchanged. All PSFS goals improved beyond MDC, and improvements in strength exceeded MDC in 2 out of 14 tests. After 12 weeks, MSWS-12 improvements persisted and the FSS score improved, but neither exceeded MDC. The PSFS improvements persisted. There were improvements exceeding MDC for 8 out of 14 strength tests. The remaining 6 strength tests improved but did not exceed MDC. Conclusion The patient had measurable improvements following the use of a BFR/LIRT program. BFR/LIRT may be an option for strength training in people with MS; however, research is needed to determine its safety and effectiveness across the population of people with MS. Impact Traditional physical therapist interventions for people with MS have been shown to be beneficial; however, their usefulness has been limited by fatigue. A growing body of literature has demonstrated the effects of a BFR/LIRT program on strength and other measures of physical function in healthy populations and those with chronic disease. This case report adds missing information to the existing literature and suggests directions for research on the effectiveness of BFR/LIRT in people with primary progressive MS.

Mass transfer and blood flow in a patient-specific three-dimensional Willis circle

2021 ◽  
Vol 126 ◽  
pp. 105369
Author(s):  
Alessio Pignani ◽  
Ivan Di Venuta ◽  
Andrea Boghi ◽  
Fabio Gori
Keyword(s):  
Mass Transfer ◽  
Blood Flow ◽  
Three Dimensional ◽  
Patient Specific

scholarly journals Model Verification and Error Sensitivity of Turbulence-Related Tensor Characteristics in Pulsatile Blood Flow Simulations

Fluids ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 11
Author(s):  
Magnus Andersson ◽  
Matts Karlsson
Keyword(s):  
Blood Flow ◽  
Model Verification ◽  
Patient Specific ◽  
Flow Modeling ◽  
Spatiotemporal Resolution ◽  
Flow Simulations ◽  
Phase Averaging ◽  
Confidence Levels ◽  
Cardiovascular Flow ◽  
Computational Fluid Dynamics Cfd

Model verification, validation, and uncertainty quantification are essential procedures to estimate errors within cardiovascular flow modeling, where acceptable confidence levels are needed for clinical reliability. While more turbulent-like studies are frequently observed within the biofluid community, practical modeling guidelines are scarce. Verification procedures determine the agreement between the conceptual model and its numerical solution by comparing for example, discretization and phase-averaging-related errors of specific output parameters. This computational fluid dynamics (CFD) study presents a comprehensive and practical verification approach for pulsatile turbulent-like blood flow predictions by considering the amplitude and shape of the turbulence-related tensor field using anisotropic invariant mapping. These procedures were demonstrated by investigating the Reynolds stress tensor characteristics in a patient-specific aortic coarctation model, focusing on modeling-related errors associated with the spatiotemporal resolution and phase-averaging sampling size. Findings in this work suggest that attention should also be put on reducing phase-averaging related errors, as these could easily outweigh the errors associated with the spatiotemporal resolution when including too few cardiac cycles. Also, substantially more cycles are likely needed than typically reported for these flow regimes to sufficiently converge the phase-instant tensor characteristics. Here, higher degrees of active fluctuating directions, especially of lower amplitudes, appeared to be the most sensitive turbulence characteristics.

Numerical and experimental study of blood flow through a patient-specific arteriovenous fistula used for hemodialysis

2010 ◽  
Vol 32 (2) ◽  
pp. 111-118 ◽  
Author(s):  
Zaher Kharboutly ◽  
Valerie Deplano ◽  
Eric Bertrand ◽  
Cecile Legallais
Keyword(s):  
Experimental Study ◽  
Blood Flow ◽  
Arteriovenous Fistula ◽  
Patient Specific ◽  
Flow Through

scholarly journals Patient-Specific Detection of Cerebral Blood Flow Alterations as Assessed by Arterial Spin Labeling in Drug-Resistant Epileptic Patients

PLoS ONE ◽  
2015 ◽  
Vol 10 (5) ◽  
pp. e0123975 ◽  
Author(s):  
Ilaria Boscolo Galazzo ◽  
Silvia Francesca Storti ◽  
Alessandra Del Felice ◽  
Francesca Benedetta Pizzini ◽  
Chiara Arcaro ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Patient Specific ◽  
Drug Resistant ◽  
Specific Detection ◽  
Epileptic Patients

scholarly journals Determinants of Cerebrovascular Reserve in Patients with Significant Carotid Stenosis

2020 ◽  
Author(s):  
Joseph P Archie
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Carotid Stenosis ◽  
Vascular Resistance ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Systemic Arterial Pressure ◽  
Patient Specific ◽  
Flow Reserve

AbstractIntroductionIn patients with 70% to 99% diameter carotid artery stenosis cerebral blood flow reserve may be protective of future ischemic cerebral events. Reserve cerebral blood flow is created by brain auto-regulation. Both cerebral blood flow reserve and cerebrovascular reactivity can be measured non-invasively. However, the factors and variables that determine the availability and magnitude and of reserve blood flow remain poorly understood. The availability of reserve cerebral blood flow is a predictor of stroke risk. The aim of this study is to employ a hemodynamic model to predict the variables and functional relationships that determine cerebral blood flow reserve in patients with significant carotid stenosis.MethodsA basic one-dimensional, three-unit (carotid, collateral and brain) energy conservation fluid mechanics blood flow model is employed. It has two distinct but adjacent blood flow components with normal cerebral blood flow at the interface. In the brain auto-regulated blood flow component cerebral blood flow is maintained normal by reserve flow. In the brain pressure dependent blood flow component cerebral blood flow is below normal because cerebral perfusion pressure is below the lower threshold value for auto-regulation. Patient specific values of collateral vascular resistance are determined from a model solution using clinically measured systemic and carotid arterial stump pressures. Collateral vascular resistance curves illustrate the model solutions for reserve and actual cerebral blood flow as a function of percent diameter carotid artery stenosis and mean systemic arterial pressure. The threshold cerebral perfusion pressure value for auto-regulation is assumed to be 50 mmHg. Normal auto-regulated regional cerebral blood flow is assumed to be 50 ml/min/100g. Cerebral blood flow and reserve blood flow solutions are given for systemic arterial pressures of 80, 90, 100, 110 and 120 mmHg and for three patient specific collateral vascular resistance values, Rw = 1.0 (mean patient value), Rw = 0.5 (lower 1 SD) and Rd = 3.0 (upper 1 SD).ResultsReserve cerebral blood flow is only available when a patients cerebral perfusion pressure is in the normal auto-regulatory range. Both actual and reserve cerebral blood flows are primarily from the carotid circulation when carotid stenosis is less than 60% diameter. Between 60% and 75% stenosis the remaining carotid blood flow reserve is utilized and at higher degrees of stenosis all reserve flow is from the collateral circulation. The primary independent variables that determine actual and reserve cerebral blood flow are mean systemic arterial pressure, degree of carotid stenosis and patient specific collateral vascular resistance. Approximate 16% of patients have collateral vascular resistance greater than 5.0 and are predicted to be at high risk of cerebral ischemia or infarction with progression to severe carotid stenosis or occlusion. The approximate 50% of patients with a collateral vascular resistance less than 1.0 are predicted to have adequate cerebral blood flow with progression to carotid occlusion, and most maintain some reserve. Clinically measured values of cerebral blood flow reserve or cerebrovascular reactivity are predicted to be unreliable without consideration of systemic arterial pressure and degree of carotid stenosis. Reserve cerebral blood flow values measured in patients with only moderate 60% to 70% carotid stenosis are in general too high and variable to be of clinical value, but are most reliable when measured near 80% diameter stenosis and considered as percent of the maximum reserve blood flow. Patient specific measured reserve blood flow values can be inserted into the model to calculate the collateral vascular resistance.ConclusionsPredicting cerebral blood flow reserve in patients with significant carotid stenosis is complex and multifactorial. A simple cerebrovascular model predicts that patient specific collateral vascular resistance is an excellent predictor of reserve cerebral blood flow in patients with significant carotid stenosis. Cerebral blood flow reserve measurements are of limited value without accounting for systemic pressure and actual percent carotid stenosis. Asymptomatic patients with severe carotid artery stenosis and a collateral vascular resistance greater than 1.0 are at increased risk of cerebral ischemia and may benefit from carotid endarterectomy.

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