Allison Shields
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View article: Analysis of quantitative angiography in intracranial aneurysm using projection foreshortening correction and injection bias removal
Analysis of quantitative angiography in intracranial aneurysm using projection foreshortening correction and injection bias removal Open
Background In neurovascular disease applications, 2D quantitative angiography (QA) based on digital subtraction angiography (DSA), is an intraoperative methodology used to assess disease severity and guide treatment. However, despite DSA's…
View article: Leveraging Convolutional Neural Networks for 3D Quantitative Angiography Reconstructions from Sparse Cone Beam CT Projections Utilizing CFD Data
Leveraging Convolutional Neural Networks for 3D Quantitative Angiography Reconstructions from Sparse Cone Beam CT Projections Utilizing CFD Data Open
This study leverages convolutional neural networks to enhance the temporal resolution of 3D angiography in intracranial aneurysms focusing on the reconstruction of volumetric contrast data from sparse and limited projections. Three patient…
View article: Analysis of Quantitative Angiography using Projection Foreshortening Correction and Injection Bias Removal
Analysis of Quantitative Angiography using Projection Foreshortening Correction and Injection Bias Removal Open
This study aims to mitigate these biases and enhance QA analysis by applying a path-length correction (PLC) correction, followed by singular value decomposition (SVD)-based deconvolution, to angiograms obtained through both in-silico and i…
View article: Effect of Singular Value Decomposition Algorithms on Removing Injection Variability in 2D Quantitative Angiography of Intracranial Aneurysms
Effect of Singular Value Decomposition Algorithms on Removing Injection Variability in 2D Quantitative Angiography of Intracranial Aneurysms Open
Intraoperative 2D quantitative angiography (QA) for intracranial aneurysms (IAs) has accuracy challenges due to the variability of hand injections. Despite the success of singular value decomposition (SVD) algorithms in reducing biases in …
View article: Effect of singular value decomposition on removing injection variability in 2D quantitative angiography: An in silico and in vitro phantoms study
Effect of singular value decomposition on removing injection variability in 2D quantitative angiography: An in silico and in vitro phantoms study Open
Background Intraoperative 2D quantitative angiography (QA) for intracranial aneurysms (IAs) has accuracy challenges due to the variability of hand injections. Despite the success of singular value decomposition (SVD) algorithms in reducing…
View article: In-silico analysis of curve fitting in angiographic parametric imaging in intracranial aneurysms to reduce patient and interventionalist-induced errors
In-silico analysis of curve fitting in angiographic parametric imaging in intracranial aneurysms to reduce patient and interventionalist-induced errors Open
In Angiographic Parametric Imaging (API), accurate estimation of parameters\nfrom Time Density Curves (TDC) is crucial. However, these estimations are often\nmarred by errors arising from factors such as patient motion, procedural\nprefere…
View article: Personal values and psychopathology in a diverse youth sample
Personal values and psychopathology in a diverse youth sample Open
Substantial research has examined the associations between youth personality traits and psychopathology, with little attention to the role that personal values might play. Previous work has indicated that youth’s personal values are relate…
View article: Angiographic velocimetry analysis using contrast dilution gradient method with a 1000 frames per second photon-counting detector
Angiographic velocimetry analysis using contrast dilution gradient method with a 1000 frames per second photon-counting detector Open
Using 1000 fps HSA, CDG-based extraction of velocities across large arteries is possible. The method is sensitive to noise; however, image processing techniques and a contrast injection, which adequately fills the vessel assist algorithm a…
View article: Application of 1,000 fps High-Speed Angiography to In-Vitro Hemodynamic Evaluation of Left Ventricular Assist Device Outflow Graft Configurations
Application of 1,000 fps High-Speed Angiography to In-Vitro Hemodynamic Evaluation of Left Ventricular Assist Device Outflow Graft Configurations Open
Left ventricular assist device (LVAD)–induced hemodynamics are characterized by fast-moving flow with large variations in velocity, making quantitative assessments difficult with existing imaging methods. This study demonstrates the abilit…
View article: Multi-angled simultaneous biplane High-Speed Angiography (HSA) of patient-specific 3D-printed aneurysm phantoms using 1000 fps CdTe Photon-Counting Detectors (PCD’s )
Multi-angled simultaneous biplane High-Speed Angiography (HSA) of patient-specific 3D-printed aneurysm phantoms using 1000 fps CdTe Photon-Counting Detectors (PCD’s ) Open
1000 fps HSA enables visualization of flow details, which may be important in accurately guiding interventional procedures; however, single-plane imaging may lack clear visualization of vessel geometry and flow detail. The previously prese…
View article: Comparison of pulsatile flow dynamics before and after endovascular intervention in 3D-printed patient-specific internal carotid artery aneurysm models using 1000 fps photon-counting detectors for Simultaneous Biplane High Speed Angiography (SB-HSA)
Comparison of pulsatile flow dynamics before and after endovascular intervention in 3D-printed patient-specific internal carotid artery aneurysm models using 1000 fps photon-counting detectors for Simultaneous Biplane High Speed Angiography (SB-HSA) Open
A significant challenge regarding the treatment of aneurysms is the variability in morphology and analysis of abnormal flow. With conventional DSA, low frame rates limit the flow information available to clinicians at the time of the vascu…
View article: Geometrically-independent contrast dilution gradient (CDG) velocimetry using photon-counting 1000 fps high speed angiography (HSA) for 2D velocity distribution estimation
Geometrically-independent contrast dilution gradient (CDG) velocimetry using photon-counting 1000 fps high speed angiography (HSA) for 2D velocity distribution estimation Open
CDG may be used to obtain velocity distributions in and surrounding vascular pathologies provided the contrast injection is sufficient to provide a gradient, and diffusion of contrast through the system is negligible.
View article: Investigating angiographic injection parameters for cerebral aneurysm hemodynamic characterization using patient-specific simulated angiograms
Investigating angiographic injection parameters for cerebral aneurysm hemodynamic characterization using patient-specific simulated angiograms Open
Cerebral aneurysm (CA) rupture is one of the major causes of hemorrhagic stroke. During endovascular therapy (ET), neurointerventionalists rely on qualitative image sequences and do not have access to crucial quantitative hemodynamic infor…
View article: Determining 3D distributions of pulsatile blood flow using orthogonal Simultaneous Biplane High-Speed Angiography (SB-HSA) with 1000 fps CdTe photon counting detectors for 3D X-ray Particle Image Velocimetry (3D-XPIV) compared to results using Computational Fluid Dynamics (CFD)
Determining 3D distributions of pulsatile blood flow using orthogonal Simultaneous Biplane High-Speed Angiography (SB-HSA) with 1000 fps CdTe photon counting detectors for 3D X-ray Particle Image Velocimetry (3D-XPIV) compared to results using Computational Fluid Dynamics (CFD) Open
3D hemodynamic distributions are useful for the diagnosis and treatment of aneurysms. Detailed blood-flow patterns and derived velocity maps can be obtained using 1000 fps High Speed Angiography (HSA). The novel orthogonal Simultaneous Bip…
View article: Use of high-speed angiography HSA-derived boundary conditions and Physics Informed Neural Networks (PINNs) for comprehensive estimation of neurovascular hemodynamics
Use of high-speed angiography HSA-derived boundary conditions and Physics Informed Neural Networks (PINNs) for comprehensive estimation of neurovascular hemodynamics Open
The study shows the feasibility of obtaining patient-specific velocity and pressure fields using an assumption-free data driven approach based purely on governing physical equations and imaging data.
View article: 2D versus 3D comparison of angiographic imaging biomarkers using computational fluid dynamics simulations of contrast injections
2D versus 3D comparison of angiographic imaging biomarkers using computational fluid dynamics simulations of contrast injections Open
Quantitative angiography (QAngio) may provide hemodynamic information during neurointerventional procedures through imaging biomarkers related to contrast flow. The standard clinical implementation of QAngio is limited by projection imagin…
View article: Initial investigations of scatter cross-talk in simultaneous biplane high-speed 1000 frames per second neuro-angiography using Monte Carlo simulations
Initial investigations of scatter cross-talk in simultaneous biplane high-speed 1000 frames per second neuro-angiography using Monte Carlo simulations Open
The Aries photon counting detector (PCD) by Direct Conversion Inc. can image up to 1000 frames per second and is used to track contrast bolus in neuro-vasculature for hemodynamic calculations. For 3D tracking, synchronized biplane imaging …
View article: Comparison of quantitative imaging characteristics between a new, larger-FOV 1000 fps high-speed angiographic (HSA) photon-counting detector (Aries) with a smaller HSA detector (Actaeon)
Comparison of quantitative imaging characteristics between a new, larger-FOV 1000 fps high-speed angiographic (HSA) photon-counting detector (Aries) with a smaller HSA detector (Actaeon) Open
High Speed Angiography (HSA) requires imaging detectors with both high-temporal and high-spatial resolution. Both the Aries and Acteon detectors by Direct Conversion (Stockholm, Sweden) are CdTe direct photon-counting detectors (PCD) that …
View article: 2D vessel contrast dilution gradient (CDG) analysis using 1000 fps high speed angiography (HSA) for velocity distribution estimation
2D vessel contrast dilution gradient (CDG) analysis using 1000 fps high speed angiography (HSA) for velocity distribution estimation Open
CDG may be used to obtain velocity distributions in and surrounding vascular pathologies provided diffusion is negligible relative to convection in the flow, given a continuous gradient of contrast.
View article: Initial evaluation of 2D and 3D simulated high-speed 1000 fps vascular contrast-flow image sequences using computational fluid dynamics (CFD)
Initial evaluation of 2D and 3D simulated high-speed 1000 fps vascular contrast-flow image sequences using computational fluid dynamics (CFD) Open
Digital subtraction angiography (DSA) remains the clinical standard for detailed visualization of the neurovasculature due to its high-spatial resolution; however, detailed blood-flow quantification is impaired by its low-temporal resoluti…
View article: Derivation of vascular wall shear stress from 1000 fps high-speed angiography (HSA) velocity distributions
Derivation of vascular wall shear stress from 1000 fps high-speed angiography (HSA) velocity distributions Open
Pathological changes in blood flow lead to altered hemodynamic forces, which are responsible for a number of conditions related to the remodeling and regeneration of the vasculature. More specifically, wall shear stress (WSS) has been show…
View article: Leveraging patient-specific simulated angiograms to characterize cerebral aneurysm hemodynamics using computational fluid dynamics
Leveraging patient-specific simulated angiograms to characterize cerebral aneurysm hemodynamics using computational fluid dynamics Open
Cerebral aneurysms (CA) affect nearly 6% of the US population and its rupture is one of the major causes of hemorrhagic stroke. Neurointerventionalists performing endovascular therapy (ET) to treat CA rely on qualitative image sequences ob…
View article: Use of 1000fps high speed x-ray angiography (HSAngio) to quantify differences in flow diversion effects of three stents with different coverage densities in a cerebral aneurysm invitro model
Use of 1000fps high speed x-ray angiography (HSAngio) to quantify differences in flow diversion effects of three stents with different coverage densities in a cerebral aneurysm invitro model Open
High temporal resolution images acquired using 1000fps HSAngio can be used to visualize blood flow patterns and derive flow velocities during neurointerventional procedures. In this work we use this technology to quantify the changes in th…
View article: Simultaneous biplane high speed 1000 fps x-ray angiography (HSAngio)
Simultaneous biplane high speed 1000 fps x-ray angiography (HSAngio) Open
High-speed 1000-fps x-ray Angiography (HSAngio) images can be used to visualize blood-flow patterns and derive flow velocities during neurointerventional procedures. In this work, we present for the very first-time, orthogonal views of con…
View article: Semi-automatic co-registration of 3D CFD vascular geometry to 1000 fps high-speed angiographic (HSA) projection images for flow determination comparisons
Semi-automatic co-registration of 3D CFD vascular geometry to 1000 fps high-speed angiographic (HSA) projection images for flow determination comparisons Open
Image co-registration is an important tool that is commonly used to quantitatively or qualitatively compare information from images or data sets that vary in time, origin, etc. This research proposes a method for the semi-automatic co-regi…
View article: Evaluation of methods to derive blood flow velocity from 1000 fps high-speed angiographic sequences (HSA) using optical flow (OF) and computational fluid dynamics (CFD)
Evaluation of methods to derive blood flow velocity from 1000 fps high-speed angiographic sequences (HSA) using optical flow (OF) and computational fluid dynamics (CFD) Open
Digital Subtraction Angiography (DSA) is considered the gold standard for imaging and guiding treatment of neurovascular lesions, such as cerebral aneurysms and carotid stenoses. Though DSA can show high-resolution morphology, it remains d…
View article: Characterization of velocity patterns produced by pulsatile and constant flows using 1000 fps high-speed angiography (HSA)
Characterization of velocity patterns produced by pulsatile and constant flows using 1000 fps high-speed angiography (HSA) Open
In order to accurately quantify rapidly changing blood flow velocities, as typically seen in the neurovasculature, high temporal resolution is necessary. Current methods to extract velocity data from angiographic image sequences are genera…