scholarly journals Computational Hemodynamic Analysis for the Diagnosis of Atherosclerotic Changes in Intracranial Aneurysms: A Proof-of-Concept Study Using 3 Cases Harboring Atherosclerotic and Nonatherosclerotic Aneurysms Simultaneously

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Shin-ichiro Sugiyama ◽  
Hidenori Endo ◽  
Kuniyasu Niizuma ◽  
Toshiki Endo ◽  
Kenichi Funamoto ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Aneurysms ◽  
Patient Specific ◽  
Proof Of Concept ◽  
Inlet Flow ◽  
Flow Rates ◽  
Concept Study ◽  
Relative Residence Time ◽  
The Mean ◽  
Atherosclerotic Changes

This was a proof-of-concept computational fluid dynamics (CFD) study designed to identify atherosclerotic changes in intracranial aneurysms. We selected 3 patients with multiple unruptured aneurysms including at least one with atherosclerotic changes and investigated whether an image-based CFD study could provide useful information for discriminating the atherosclerotic aneurysms. Patient-specific geometries were constructed from three-dimensional data obtained using rotational angiography. Transient simulations were conducted under patient-specific inlet flow rates measured by phase-contrast magnetic resonance velocimetry. In the postanalyses, we calculated time-averaged wall shear stress (WSS), oscillatory shear index, and relative residence time (RRT). The volume of blood flow entering aneurysms through the neck and the mean velocity of blood flow inside aneurysms were examined. We applied the age-of-fluid method to quantitatively assess the residence of blood inside aneurysms. Atherosclerotic changes coincided with regions exposed to disturbed blood flow, as indicated by low WSS and long RRT. Blood entered aneurysms in phase with inlet flow rates. The mean velocities of blood inside atherosclerotic aneurysms were lower than those inside nonatherosclerotic aneurysms. Blood in atherosclerotic aneurysms was older than that in nonatherosclerotic aneurysms, especially near the wall. This proof-of-concept study demonstrated that CFD analysis provided detailed information on the exchange and residence of blood that is useful for the diagnosis of atherosclerotic changes in intracranial aneurysms.

scholarly journals 403 Simulation of Altered Blood Flow in Bicuspid Aortic Valve Disease: A Proof of Concept Study

2020 ◽  
Vol 29 ◽  
pp. S219
Author(s):  
L. Holmes ◽  
G. Black ◽  
R. Jeremy ◽  
R. Cordina ◽  
D. Celermajer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Bicuspid Aortic Valve ◽  
Aortic Valve Disease ◽  
Valve Disease ◽  
Proof Of Concept ◽  
Concept Study ◽  
Altered Blood

Does the DSA reconstruction kernel affect hemodynamic predictions in intracranial aneurysms? An analysis of geometry and blood flow variations

2017 ◽  
Vol 10 (3) ◽  
pp. 290-296 ◽  
Author(s):  
P Berg ◽  
S Saalfeld ◽  
S Voß ◽  
T Redel ◽  
B Preim ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Aneurysms ◽  
Three Dimensional ◽  
Patient Specific ◽  
Parent Artery ◽  
Imaging Data ◽  
Specific Flow ◽  
Aneurysm Neck ◽  
Velocity Magnitude ◽  
Reconstruction Kernel

BackgroundComputational fluid dynamics (CFD) blood flow predictions in intracranial aneurysms promise great potential to reveal patient-specific flow structures. Since the workflow from image acquisition to the final result includes various processing steps, quantifications of the individual introduced potential error sources are required.MethodsThree-dimensional (3D) reconstruction of the acquired imaging data as input to 3D model generation was evaluated. Six different reconstruction modes for 3D digital subtraction angiography (DSA) acquisitions were applied to eight patient-specific aneurysms. Segmentations were extracted to compare the 3D luminal surfaces. Time-dependent CFD simulations were carried out in all 48 configurations to assess the velocity and wall shear stress (WSS) variability due to the choice of reconstruction kernel.ResultsAll kernels yielded good segmentation agreement in the parent artery; deviations of the luminal surface were present at the aneurysm neck (up to 34.18%) and in distal or perforating arteries. Observations included pseudostenoses as well as noisy surfaces, depending on the selected reconstruction kernel. Consequently, the hemodynamic predictions show a mean SD of 11.09% for the aneurysm neck inflow rate, 5.07% for the centerline-based velocity magnitude, and 17.83%/9.53% for the mean/max aneurysmal WSS, respectively. In particular, vessel sections distal to the aneurysms yielded stronger variations of the CFD values.ConclusionsThe choice of reconstruction kernel for DSA data influences the segmentation result, especially for small arteries. Therefore, if precise morphology measurements or blood flow descriptions are desired, a specific reconstruction setting is required. Furthermore, research groups should be encouraged to denominate the kernel types used in future hemodynamic studies.

scholarly journals Changes in the microcirculation of the oral mucosa in post-COVID-19 patients not receiving anti-coagulant therapy

2022 ◽  
Vol 20 (4) ◽  
pp. 95-100
Author(s):  
M. V. Chubarnova ◽  
A. B. Davydov ◽  
V. A. Esin ◽  
O. B. Davydova ◽  
I. O. Kostin
Keyword(s):  
Blood Flow ◽  
Oral Mucosa ◽  
High Frequency ◽  
Control Group ◽  
High Frequency Ultrasound ◽  
Flow Rates ◽  
Mean Values ◽  
Coronavirus Infection ◽  
The Mean ◽  
Frequency Ultrasound

Introduction. The outbreak of a new coronavirus infection has become a challenge for the global health system. The COVID-19 infection is directly related to various disorders of the cardiovascular system, including the microcirculatory bed, caused by thrombotic events and deteriorations of blood rheology. Aims. The paper reports on the results of a study of Doppler sonographic parameters changes in patients with a novel coronavirus infection over the past 6 months. Materials and methods. We assessed the oral mucosa microcirculation in three segments using the high-frequency ultrasound dopple-rography. Results. We recorded the linear and volumetric blood flow rates and the Gosling and Purselo indexes in the course of our work. When comparing the obtained average statistical parameters of blood flow velocity, the linear and volumetric blood flow rates in patients of both groups were found to be lain in the same range and the mean values of Vas, Vam, Qas were equal. The mean values of the Purselo resistance index were closer to 1,0 in patients with COVID-19, and the values of the Gosling pulsation index (PI) were on average 53.3 % higher than in the control group. Conclusion. We evaluated the screening capabilities and potential of high-frequency ultrasound dopplerography for use in patients of different age groups and different somatic status.

scholarly journals Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

2021 ◽  
Author(s):  
Barry Vuong
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Intracranial Aneurysm ◽  
Intracranial Aneurysms ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Optical Coherence ◽  
Specific Flow ◽  
Arterial Lumen ◽  
Risk Of Rupture

The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

scholarly journals Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

2021 ◽  
Author(s):  
Barry Vuong
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Intracranial Aneurysm ◽  
Intracranial Aneurysms ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Optical Coherence ◽  
Specific Flow ◽  
Arterial Lumen ◽  
Risk Of Rupture

The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

scholarly journals From imaging to hemodynamics – how reconstruction kernels influence the blood flow predictions in intracranial aneurysms

2016 ◽  
Vol 2 (1) ◽  
pp. 679-683 ◽  
Author(s):  
Sylvia Glaßer ◽  
Philipp Berg ◽  
Samuel Voß ◽  
Steffen Serowy ◽  
Gabor Janiga ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Aneurysms ◽  
Medical Community ◽  
Patient Specific ◽  
Therapy Planning ◽  
Rotational Angiography ◽  
Mean Velocity ◽  
3D Images ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

AbstractComputational fluid dynamics (CFD) is increasingly used by biomedical engineering groups to understand and predict the blood flow within intracranial aneurysms and support the physician during therapy planning. However, due to various simplifications, its acceptance remains limited within the medical community. To quantify the influence of the reconstruction kernels employed for reconstructing 3D images from rotational angiography data, different kernels are applied to four datasets with patient-specific intracranial aneurysms. Sharp, normal and smooth reconstructions were evaluated. Differences of the resulting 24 segmentations and the impact on the hemodynamic predictions are quantified to provide insights into the expected error ranges. A comparison of the segmentations yields strong differences regarding vessel branches and diameters. Further, sharp kernels lead to smaller ostium areas than smooth ones. Analyses of hemodynamic predictions reveal a clear time and space dependency, while mean velocity deviations range from 3.9 to 8%. The results reveal a strong influence of reconstruction kernels on geometrical aneurysm models and the subsequent hemodynamic parameters. Thus, patient-specific blood flow predictions require a carefully selected reconstruction kernel and appropriate recommendations need to be formulated.

scholarly journals Proof of Concept Study for the Design, Manufacturing, and Testing of a Patient-Specific Shape Memory Device for Treatment of Unicoronal Craniosynostosis

2018 ◽  
Vol 29 (1) ◽  
pp. 45-48 ◽  
Author(s):  
Alessandro Borghi ◽  
Will Rodgers ◽  
Silvia Schievano ◽  
Allan Ponniah ◽  
Owase Jeelani ◽  
...  
Keyword(s):  
Shape Memory ◽  
Memory Device ◽  
Patient Specific ◽  
Proof Of Concept ◽  
Concept Study ◽  
Specific Shape

Sensitivity of patient-specific numerical simulation of cerebal aneurysm hemodynamics to inflow boundary conditions

2007 ◽  
Vol 106 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Prem Venugopal ◽  
Daniel Valentino ◽  
Holger Schmitt ◽  
J. Pablo Villablanca ◽  
Fernando Viñuela ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Flow Rate ◽  
Artery Aneurysm ◽  
Blood Flow Rate ◽  
Patient Specific ◽  
Stress Distributions ◽  
Flow Rates

Object Due to the difficulty of obtaining patient-specific velocity measurements during imaging, many assumptions have to be made while imposing inflow boundary conditions in numerical simulations conducted using patient-specific, imaging-based cerebral aneurysm models. These assumptions can introduce errors, resulting in lack of agreement between the computed flow fields and the true blood flow in the patient. The purpose of this study is to evaluate the effect of the assumptions made while imposing inflow boundary conditions on aneurysmal hemodynamics. Methods A patient-based anterior communicating artery aneurysm model was selected for this study. The effects of various inflow parameters on numerical simulations conducted using this model were then investigated by varying these parameters over ranges reported in the literature. Specifically, we investigated the effects of heart and blood flow rates as well as the distribution of flow rates in the A1 segments of the anterior cerebral artery. The simulations revealed that the shear stress distributions on the aneurysm surface were largely unaffected by changes in heart rate except at locations where the shear stress magnitudes were small. On the other hand, the shear stress distributions were found to be sensitive to the ratio of the flow rates in the feeding arteries as well as to variations in the blood flow rate. Conclusions Measurement of the blood flow rate as well as the distribution of the flow rates in the patient's feeding arteries may be needed for numerical simulations to accurately reproduce the intraaneurysmal hemodynamics in a specific aneurysm in the clinical setting.

Mesenteric venous blood flow and the net absorption of glucose in sheep fed dried grass or ground maize-based diets

1984 ◽  
Vol 103 (3) ◽  
pp. 549-553 ◽  
Author(s):  
A. N. Janes ◽  
D. S. Parker ◽  
T. E. C. Weekes ◽  
D. G. Armstrong
Keyword(s):  
Blood Flow ◽  
Venous Blood ◽  
Live Weight ◽  
Glucose Absorption ◽  
Venous Blood Flow ◽  
Post Mortem ◽  
Mesenteric Blood Flow ◽  
Flow Rates ◽  
Mesenteric Vein ◽  
The Mean

SummaryA surgical procedure is described for placing a catheter in the mesenteric vein of sheep, such that blood draining the reticulo-rumen is not sampled. This catheter, together withothers in the mesenteric vein and carotid artery, was used to determine mesenteric blood flow and the net absorption of glucose in five sheep fed both dried grass and ground maize-based diets. The mean (± S.E.) mesenteric blood flow rates were 33 ±0·9 and 37 ± 5·7ml/min/kg live weight when fed the dried grass and maize-based diets respectively. These flow rates, together with the small venousarterial differences in plasma volatile fattyacid concentrations observed, indicated that the mesenteric catheter did not sample blood draining the reticulo-rumen in the conscious, fed animal. Further confirmation was provided by subsequent post-mortem examinations of the catheters. When fed the dried-grass diet, a significant net absorption of glucose could not be detected. However, when fed the maize-based diet a net glucose absorption of 19·3 ± 0·75 mmol/h was observed.

Sign in / Sign up

Export Citation Format

Share Document