scholarly journals Study protocol of validating a numerical model to assess the blood flow in the circle of Willis

BMJ Open ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. e036404
Author(s):  
Yuanyuan Shen ◽  
Yanji Wei ◽  
Reinoud P H Bokkers ◽  
Maarten Uyttenboogaart ◽  
J Marc C van Dijk
Keyword(s):  
Blood Flow ◽  
Numerical Model ◽  
Study Protocol ◽  
Numerical Models ◽  
Medical Center ◽  
Pearson Correlation ◽  
Scientific Journal ◽  
Circle Of Willis ◽  
Patient Specific ◽  
Aneurysmal Subarachnoid Haemorrhage

IntroductionWe developed a zero-dimensional (0D) model to assess the patient-specific haemodynamics in the circle of Willis (CoW). Similar numerical models for simulating the cerebral blood flow (CBF) had only been validated qualitatively in healthy volunteers by magnetic resonance (MR) angiography and transcranial Doppler (TCD). This study aims to validate whether a numerical model can simulate patient-specific blood flow in the CoW under pathological conditions.Methods and analysisThis study is a diagnostic accuracy study. We aim to collect data from a previously performed prospective study that involved patients with aneurysmal subarachnoid haemorrhage (aSAH) receiving both TCD and brain Computerd Tomography angiography (CTA) at the same day. The cerebral flow velocities are calculated by the 0D model, based on the vessel diameters measured on the CTA of each patient. In this study, TCD is considered the gold standard for measuring flow velocity in the CoW. The agreement will be analysed using Pearson correlation coefficients.Ethics and disseminationThis study protocol has been approved by the Medical Ethics Review Board of the University Medical Center Groningen: METc2019/103. The results will be submitted to an international scientific journal for peer-reviewed publication.Trial registration numberNL8114.

scholarly journals Analyzing Circle of Willis blood flow in ischemic stroke patients through 3D Stroke Arterial Flow Estimation

2017 ◽  
Vol 23 (4) ◽  
pp. 427-432 ◽  
Author(s):  
Aichi Chien ◽  
Fernando Viñuela
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Flow Patterns ◽  
Circle Of Willis ◽  
Arterial Flow ◽  
Patient Specific ◽  
Collateral Flow ◽  
Flow Data ◽  
Time Resolved ◽  
Flow Estimation

Background The objective of ischemic stroke (IS) treatment is to achieve revascularization in cerebral arteries to restore blood flow. However, there is no available method to extract arterial flow data from clinical CTA images. We developed 3D Stroke Arterial Flow Estimation (SAFE), which provides blood flow data throughout the Circle of Willis based on 3D CTA and allows comparison of arterial flow distribution in the brain. Methods We implemented a newly developed 3D vascular reconstruction algorithm for clinical stroke CTA images. Based on the patient-specific vascular structure, SAFE calculates time-resolved blood flow information for the entire Circle of Willis and allows quantitative flow study of IS cases. Clinical IS cases are presented to demonstrate the feasibility. Four patients with CTA images and CT perfusion data were studied. To validate the SAFE analysis, correlation analysis comparing blood flow at the MCA, ICA, and BA was performed. Results Different blood flow patterns were found in individual IS patients. Altered flow patterns and high collateral flow rates were found near occlusions in all cases. Quantitative comparison of blood flow data showed that SAFE obtained flow data and CTP were significantly correlated and provide complementary information about cerebral blood flow for individual patients. Conclusions We present SAFE analysis for collecting detailed time-resolved cerebral arterial flow data in the entire Circle of Willis for IS. Further study with more cases may be important to test the clinical utilization of SAFE and helpful to the study of the underlying hemodynamics of stroke.

Blood Flow Dynamic and Fluid-Structure Interaction in Patient-Specific Circle of Willis

2009 ◽  
Author(s):  
Qi Yuan ◽  
Zhen Chen ◽  
Guangyu Zhu
Keyword(s):  
Blood Flow ◽  
Cerebral Arteries ◽  
Fluid Structure Interaction ◽  
3D Models ◽  
Circle Of Willis ◽  
Patient Specific ◽  
Anterior Communicating Artery ◽  
Detailed Knowledge ◽  
Fluid Structure ◽  
Structure Interaction

Over 50% stroke is related to the cerebral artery stenosis. The most common position is in the Circle of Willis (CoW), which is composed of a single anterior communicating artery (ACoA), paired anterior cerebral arteries (ACA), paired middle cerebral arteries (MCA), internal carotid arteries (ICA), posterior communicating arteries (PCoA) and posterior cerebral arteries (PCA). Detailed knowledge of the cerebral hemodynamics is important for a variety of clinical applications [1]. There has been a significant body of research performed on blood flow in the CoW [1,2] treating the cerebral vasculature as a 2D structure. To obtain more accurate hemodynamic results, 3D models should be considered. Studies have been performed on 3D models of the CoW generated from magnetic resonance imaging (MRI) data [3,4]. However, those 3D models neglected the effects of fluid-structure interaction (FSI) between the vessel wall and blood. In this paper, a patient-specific model of CoW from CT scan data was reconstructed and FLUENT 6.1 was used to simulate the blood flow in the CoW. On a special part of CoW, a 3D FSI model for the arteries was introduced to investigate both flow and structure behaviors, as well as their interaction by ADINA 8.3.

scholarly journals Numerical Analysis on the Effects of Saline Injection and Deformation for Radiofrequency Catheter Ablation

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1674
Author(s):  
Jin Woo Ahn ◽  
Young-Jin Kim
Keyword(s):  
Blood Flow ◽  
Catheter Ablation ◽  
Numerical Model ◽  
Radiofrequency Catheter Ablation ◽  
Numerical Models ◽  
Heart Tissue ◽  
Maximum Temperature ◽  
Saline Injection ◽  
Thermal Lesion ◽  
Advection Diffusion Equation

Radiofrequency catheter ablation is an interventional procedure used to treat arrhythmia. An electrode catheter that could inject saline has been developed to prevent steam pop on heart tissue during radiofrequency catheter ablation. Thus, we investigated to numerical model on the effect of saline injection and heart tissue’s deformation. In this study, the hyperelastic model was implemented to analyze heart tissue deformation due to the catheter’s contact force. Besides, the advection–diffusion equation was used to analyze the mixture between saline and blood. We developed the multiphysics model that predicts thermal lesions based on the deformation of the heart and mixing between saline and blood flow. The thermal lesion and the maximum temperature in the numerical model that considered mixing saline and blood were smaller than that of other numerical models that did not consider mixing. Therefore, we observed that the saline injection was affected by thermal lesion due to higher electrical conductivity than blood flow and injection at a lower temperature than the human body. The numerical model was researched that considering the deformation of the heart tissue and saline injection in radiofrequency catheter ablation affects the heart tissue’s thermal lesion and maximum temperature.

scholarly journals IMPROVED NUMERICAL MODEL OF THE ARTERIAL WALL APPLIED FOR SIMULATIONS OF STENT DEPLOYMENT WITHIN PATIENT-SPECIFIC CORONARY ARTERIES

2020 ◽  
pp. 1-5
Author(s):  
Tijana Djukic ◽  
Igor Saveljic ◽  
Gualtiero Pelosi ◽  
Oberdan Parodi ◽  
Nenad Filipovic
Keyword(s):  
Blood Flow ◽  
Numerical Model ◽  
Coronary Arteries ◽  
Arterial Wall ◽  
Arterial Stenosis ◽  
Patient Specific ◽  
Stent Deployment ◽  
Normal Blood Flow ◽  
Experimental Values ◽  
Treatment Procedures

Arterial stenosis is the obstruction of normal blood flow that is caused by atherosclerosis. One of the endovascular treatment procedures in this case is the implantation of a stent to restore the blood flow. This study presented an improved numerical model that can precisely simulate the deformation of human arterial wall in coronary arteries, during the stent deployment process. The new model considered the arterial wall as an incompressible, isotropic and hyperelastic material. The material coefficients were defined according to experimental values presented in literature. The accuracy of the numerical model was investigated by comparing the results with follow up data obtained in clinical examination. The small relative and standard deviation error prove that this numerical model can be used to assist clinicians in decision making and treatment planning with reliable predictions of the outcome of the stent deployment procedure.

scholarly journals Simplifying the Numerical Human Model with k-means Clustering Method

2020 ◽  
pp. 261-270
Author(s):  
Kyoko Fujimoto ◽  
Leonardo M. Angelone ◽  
Sunder S. Rajan ◽  
Maria Ida Iacono
Keyword(s):  
Numerical Model ◽  
Absorption Rate ◽  
Numerical Models ◽  
Human Model ◽  
Patient Specific ◽  
Model Generation ◽  
Rf Heating ◽  
Clustering Method ◽  
Number Of Clusters ◽  
Computational Burden

AbstractCurrently, the safety assessment of radio-frequency (RF) heating using computational modeling is limited by the available numerical models which are not patient specific. However, RF-induced heating depends on the physical characteristics of the patient. The numerical model generation is difficult due to the highly time-consuming segmentation process. Therefore, having fewer types of segmented structures simplifies the generation of numerical models and reduces computational burden as a result. In this study, we used the k-means clustering method to reduce the number of dielectric properties of an existing numerical model and investigated the resulting difference in specific absorption rate (SAR) with respect to the number of clusters.

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.

scholarly journals Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Gianluca Zitti ◽  
Nico Novelli ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Offshore Structures ◽  
Fish Farm ◽  
Maximum Displacement ◽  
Drag Forces ◽  
Real Size ◽  
Lift And Drag ◽  
Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

scholarly journals Patient-Specific Predictive Antibiogram in Decision Support for Empiric Antibiotic Treatment

2020 ◽  
Vol 41 (S1) ◽  
pp. s521-s522
Author(s):  
Debarka Sengupta ◽  
Vaibhav Singh ◽  
Seema Singh ◽  
Dinesh Tewari ◽  
Mudit Kapoor ◽  
...  
Keyword(s):  
Machine Learning ◽  
Antimicrobial Resistance ◽  
Model Building ◽  
Medical Center ◽  
Bacterial Species ◽  
Model Performance ◽  
The United States ◽  
Patient Specific ◽  
Gradient Boosting ◽  
Comparative Performance

Background: The rising trend of antibiotic resistance imposes a heavy burden on healthcare both clinically and economically (US$55 billion), with 23,000 estimated annual deaths in the United States as well as increased length of stay and morbidity. Machine-learning–based methods have, of late, been used for leveraging patient’s clinical history and demographic information to predict antimicrobial resistance. We developed a machine-learning model ensemble that maximizes the accuracy of such a drug-sensitivity versus resistivity classification system compared to the existing best-practice methods. Methods: We first performed a comprehensive analysis of the association between infecting bacterial species and patient factors, including patient demographics, comorbidities, and certain healthcare-specific features. We leveraged the predictable nature of these complex associations to infer patient-specific antibiotic sensitivities. Various base-learners, including k-NN (k-nearest neighbors) and gradient boosting machine (GBM), were used to train an ensemble model for confident prediction of antimicrobial susceptibilities. Base learner selection and model performance evaluation was performed carefully using a variety of standard metrics, namely accuracy, precision, recall, F1 score, and Cohen κ. Results: For validating the performance on MIMIC-III database harboring deidentified clinical data of 53,423 distinct patient admissions between 2001 and 2012, in the intensive care units (ICUs) of the Beth Israel Deaconess Medical Center in Boston, Massachusetts. From ~11,000 positive cultures, we used 4 major specimen types namely urine, sputum, blood, and pus swab for evaluation of the model performance. Figure 1 shows the receiver operating characteristic (ROC) curves obtained for bloodstream infection cases upon model building and prediction on 70:30 split of the data. We received area under the curve (AUC) values of 0.88, 0.92, 0.92, and 0.94 for urine, sputum, blood, and pus swab samples, respectively. Figure 2 shows the comparative performance of our proposed method as well as some off-the-shelf classification algorithms. Conclusions: Highly accurate, patient-specific predictive antibiogram (PSPA) data can aid clinicians significantly in antibiotic recommendation in ICU, thereby accelerating patient recovery and curbing antimicrobial resistance.Funding: This study was supported by Circle of Life Healthcare Pvt. Ltd.Disclosures: None

scholarly journals A Preliminary Analysis of Hearing Loss and Its Association With Mild Cognitive Impairment

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 451-452
Author(s):  
Mary Caroline Yuk ◽  
Rebecca Allen ◽  
Marcia Hay-McCutcheon ◽  
Dana Carroll ◽  
Anne Halli-Tierney
Keyword(s):  
Hearing Loss ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Emotional Health ◽  
Medical Center ◽  
Pearson Correlation ◽  
Well Being ◽  
Hearing Screening ◽  
Community Dwelling ◽  
Age Related

Abstract Age related hearing loss, or presbycusis, is a global condition that is increasing in its prevalence. Despite being one of the most common chronic conditions among the older population, there is much more to understand about its association with other aspects of physical and emotional health and well-being. Current research is suggesting that hearing loss is more prevalent in those with cognitive impairment compared to those without cognitive impairment. This study analyzed the incidence of hearing loss and its linkage to mild cognitive impairment in a community-dwelling geriatric population. With the increasing prevalence of this condition in both rural and urban communities of Alabama, it becomes a more pressing matter to understand comorbidities and risk factors for future decline in functioning. This study was conducted in an interdisciplinary geriatrics primary care outpatient clinic in a Family, Internal, and Rural Medicine department affiliated with a university medical center in the Deep South. Ninety-one participants completed the Montreal Cognitive Assessment (MoCA) and a hearing screening. Hearing screenings were conducted in quiet rooms in the medical center using Phonak hearing screening cards. Detection of 500, 1000, 2000, and 4000 Hz tones was assessed. Pearson correlation analyses demonstrated an association between hearing loss mild cognitive impairment. Poorer hearing was significantly associated with lower scores on the MoCA. Conducting behavioral health screenings like this in other primary geriatrics clinics and community settings could improve care and identification of patient needs by integrating important data regarding comorbidities and independent living.

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.

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