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https://www.readbyqxmd.com/read/28074541/comparison-of-respiratory-motion-suppression-techniques-for-4d-flow-mri
#1
Petter Dyverfeldt, Tino Ebbers
PURPOSE: The purpose of this work was to assess the impact of respiratory motion and to compare methods for suppression of respiratory motion artifacts in 4D Flow MRI. METHODS: A numerical 3D aorta phantom was designed based on an aorta velocity field obtained by computational fluid mechanics. Motion-distorted 4D Flow MRI measurements were simulated and several different motion-suppression techniques were evaluated: Gating with fixed acceptance window size, gating with different window sizes in inner and outer k-space, and k-space reordering...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28057635/in-vivo-assessment-of-the-impact-of-regional-intracranial-atherosclerotic-lesions-on-brain-arterial-3d-hemodynamics
#2
C Wu, S Schnell, P Vakil, A R Honarmand, S A Ansari, J Carr, M Markl, S Prabhakaran
BACKGROUND AND PURPOSE: Intracranial atherosclerosis induces hemodynamic disturbance, which is not well-characterized, particularly in cerebral flow redistribution. We aimed to characterize the impact of regional stenotic lesions on intracranial hemodynamics by using 4D flow MR imaging. MATERIALS AND METHODS: 4D flow MR imaging was performed in 22 symptomatic patients (mean age, 68.4 ± 14.2 years) with intracranial stenosis (ICA, n = 7; MCA, n = 9; basilar artery, n = 6) and 10 age-appropriate healthy volunteers (mean age, 60...
January 5, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28048777/mo-e-brb-00-panel-discussion-sbrt-srs-case-studies-lung
#3
Stanley Benedict
: In this interactive session, lung SBRT patient cases will be presented to highlight real-world considerations for ensuring safe and accurate treatment delivery. An expert panel of speakers will discuss challenges specific to lung SBRT including patient selection, patient immobilization techniques, 4D CT simulation and respiratory motion management, target delineation for treatment planning, online treatment alignment, and established prescription regimens and OAR dose limits. Practical examples of cases, including the patient flow thought the clinical process are presented and audience participation will be encouraged...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048757/mo-e-brb-01-panel-member
#4
S Benedict
: In this interactive session, lung SBRT patient cases will be presented to highlight real-world considerations for ensuring safe and accurate treatment delivery. An expert panel of speakers will discuss challenges specific to lung SBRT including patient selection, patient immobilization techniques, 4D CT simulation and respiratory motion management, target delineation for treatment planning, online treatment alignment, and established prescription regimens and OAR dose limits. Practical examples of cases, including the patient flow thought the clinical process are presented and audience participation will be encouraged...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048100/su-f-t-91-development-of-real-time-abdominal-compression-force-acf-monitoring-system
#5
T Kim, S Kim, D Kim, S Kang, M Cho, K Kim, D Shin, Y Noh, T Suh
PURPOSE: Hard-plate based abdominal compression is known to be effective, but no explicit method exists to quantify abdominal compression force (ACF) and maintain the proper ACF through the whole procedure. In addition, even with compression, it is necessary to do 4D CT to manage residual motion but, 4D CT is often not possible due to reduced surrogating sensitivity. In this study, we developed and evaluated a system that both monitors ACF in real time and provides surrogating signal even under compression...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048099/mo-e-brb-02-panel-member
#6
J Larner
: In this interactive session, lung SBRT patient cases will be presented to highlight real-world considerations for ensuring safe and accurate treatment delivery. An expert panel of speakers will discuss challenges specific to lung SBRT including patient selection, patient immobilization techniques, 4D CT simulation and respiratory motion management, target delineation for treatment planning, online treatment alignment, and established prescription regimens and OAR dose limits. Practical examples of cases, including the patient flow thought the clinical process are presented and audience participation will be encouraged...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048061/mo-fg-campus-jep2-01-4d-mri-with-3d-radial-sampling-and-self-gating-based-k-space-sorting-image-quality-improvement-by-slab-selective-excitation
#7
Z Deng, W Yang, J Pang, R Tuli, X Bi, B Hakimian, B Fraass, D Li, Z Fan
PURPOSE: A recent 4D MRI technique based on 3D radial sampling and self-gating-based K-space sorting has shown promising results in characterizing respiratory motion. However due to continuous acquisition and potentially drastic k-space undersampling resultant images could suffer from low blood-to-tissue contrast and streaking artifacts. In this study 3D radial sampling with slab-selective excitation (SS) was proposed in attempt to enhance blood-to-tissue contrast by exploiting the in-flow effect and to suppress the excess signal from the peripheral structures particularly in the superior-inferior direction...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047932/tu-h-campus-iep3-02-neurovascular-4d-parametric-imaging-using-co-registration-of-biplane-dsa-sequences-with-3d-vascular-geometry-obtained-from-cone-beam-ct
#8
A Balasubramoniam, D Bednarek, S Rudin, C Ionita
PURPOSE: To create 4D parametric images using biplane Digital Subtraction Angiography (DSA) sequences co-registered with the 3D vascular geometry obtained from Cone Beam-CT (CBCT). METHODS: We investigated a method to derive multiple 4D Parametric Imaging (PI) maps using only one CBCT acquisition. During this procedure a 3D-DSA geometry is stored and used subsequently for all 4D images. Each time a biplane DSA is acquired, we calculate 2D parametric maps of Bolus Arrival Time (BAT), Mean Transit Time (MTT) and Time to Peak (TTP)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047708/th-cd-207a-05-lung-surface-deformation-vector-fields-prediction-by-monitoring-respiratory-surrogate-signals
#9
J Nasehi Tehrani, A McEwan, J Wang
PURPOSE: In this study, we developed and evaluated a method for predicting lung surface deformation vector fields (SDVFs) based on surrogate signals such as chest and abdomen motion at selected locations and spirometry measurements. METHODS: A Patient-specific 3D triangular surface mesh of the lung region at end-expiration (EE) phase was obtained by threshold-based segmentation method. For each patient, a spirometer recorded the flow volume changes of the lungs; and 192 selected points at a regular spacing of 2cm X 2cm matrix points over a total area of 34cm X 24cm on the surface of chest and abdomen was used to detect chest wall motions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047441/mo-e-brb-03-panel-member
#10
B Salter
: In this interactive session, lung SBRT patient cases will be presented to highlight real-world considerations for ensuring safe and accurate treatment delivery. An expert panel of speakers will discuss challenges specific to lung SBRT including patient selection, patient immobilization techniques, 4D CT simulation and respiratory motion management, target delineation for treatment planning, online treatment alignment, and established prescription regimens and OAR dose limits. Practical examples of cases, including the patient flow thought the clinical process are presented and audience participation will be encouraged...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28046971/th-cd-206-01-expectation-maximization-algorithm-based-tissue-mixture-quantification-for-perfusion-mri
#11
H Han, Z Liang, L Li, L Xing
PURPOSE: To investigate the feasibility of estimating the tissue mixture perfusions and quantifying cerebral blood flow change in arterial spin labeled (ASL) perfusion MR images. METHODS: The proposed perfusion MR image analysis framework consists of 5 steps: (1) Inhomogeneity correction was performed on the T1- and T2-weighted images, which are available for each studied perfusion MR dataset. (2) We used the publicly available FSL toolbox to strip off the non-brain structures from the T1- and T2-weighted MR images...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28018823/3d-heart-model-and-4d-flow-mri-20-years-after-spiral-arterial-switch-operation
#12
Hans-Hinrich Sievers, Arash Kheradvar, Hans-Heiner Kramer, Carsten Rickers
Case of a patient is presented here 20 years after spiral direct anastomosis of the great arteries in an arterial switch operation. Three-dimensional model of the heart combined with four-dimensional flow magnetic resonance imaging presents a novel comprehensive way to assess surgical results.
December 2016: Thoracic and Cardiovascular Surgeon Reports
https://www.readbyqxmd.com/read/28004789/assessment-of-turbulent-viscous-stress-using-icosa-4d-flow-mri-for-prediction-of-hemodynamic-blood-damage
#13
Hojin Ha, Jonas Lantz, Henrik Haraldsson, Belen Casas, Magnus Ziegler, Matts Karlsson, David Saloner, Petter Dyverfeldt, Tino Ebbers
Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal blood flow, but quantifying of these effects, which are dominated by shear stresses in highly fluctuating turbulent flow, has not been feasible. This study evaluated the novel application of turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing hemodynamic stresses and corresponding blood damage index (BDI) in stenotic turbulent blood flow. The results showed that 4D Flow MRI underestimates the maximum principal shear stress of laminar viscous stress (PLVS), and overestimates the maximum principal shear stress of Reynolds stress (PRSS) with increasing voxel size...
December 22, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27989994/functional-assessment-of-thoracic-aortic-aneurysms-the-future-of-risk-prediction
#14
REVIEW
Pouya Youssefi, Rajan Sharma, C Alberto Figueroa, Marjan Jahangiri
INTRODUCTION: Treatment guidelines for the thoracic aorta concentrate on size, yet acute aortic dissection or rupture can occur when aortic size is below intervention criteria. Functional imaging and computational techniques are a means of assessing haemodynamic parameters involved in aortic pathology. SOURCES OF DATA: Original articles, reviews, international guidelines. AREAS OF AGREEMENT: Computational fluid dynamics and 4D flow MRI allow non-invasive assessment of blood flow parameters and aortic wall biomechanics...
December 17, 2016: British Medical Bulletin
https://www.readbyqxmd.com/read/27940231/superior-abdominal-4d-flow-mri-data-consistency-with-adjusted-preprocessing-workflow-and-noncontrast-acquisitions
#15
Eric J Keller, Jeremy D Collins, Cynthia Rigsby, James C Carr, Michael Markl, Susanne Schnell
RATIONALE AND OBJECTIVES: To assess the impact of an alternative preprocessing workflow on noncontrast- and contrast-enhanced abdominal four-dimensional flow magnetic resonance imaging (4D flow MRI) data consistency. MATERIALS AND METHODS: Twenty patients with cirrhosis and portal hypertension (5 women; 53 ± 10 years old) underwent 4D flow MRI at 3.0T before and after administration of 0.03 mmol/kg of gadofosveset trisodium with velocity sensitivities of 100 and 50 cm/s for arterial and venous flow quantifications, respectively...
December 8, 2016: Academic Radiology
https://www.readbyqxmd.com/read/27918636/4d-printing-of-shape-memory-based-personalized-endoluminal-medical-devices
#16
Matt Zarek, Nicola Mansour, Shir Shapira, Daniel Cohn
The convergence of additive manufacturing and shape-morphing materials is promising for the advancement of personalized medical devices. The capability to transform 3D objects from one shape to another, right off the print bed, is known as 4D printing. Shape memory thermosets can be tailored to have a range of thermomechanical properties favorable to medical devices, but processing them is a challenge because they are insoluble and do not flow at any temperature. This study presents here a strategy to capitalize on a series of medical imaging modalities to construct a printable shape memory endoluminal device, exemplified by a tracheal stent...
December 5, 2016: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/27894675/the-manifestation-of-vortical-and-secondary-flow-in-the-cerebral-venous-outflow-tract-an-in-vivo-mr-velocimetry-study
#17
Sarah Kefayati, Matthew Amans, Farshid Faraji, Megan Ballweber, Evan Kao, Sinyeob Ahn, Karl Meisel, Van Halbach, David Saloner
Aberrations in flow in the cerebral venous outflow tract (CVOT) have been implicated as the cause of several pathologic conditions including idiopathic intracranial hypertension (IIH), multiple sclerosis (MS), and pulsatile tinnitus (PT). The advent of 4D flow magnetic resonance imaging (4D-flow MRI) has recently allowed researchers to evaluate blood flow patterns in the arterial structures with great success. We utilized similar imaging techniques and found several distinct flow characteristics in the CVOT of subjects with and without lumenal irregularities...
January 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/27891248/synchrotron-4-dimensional-imaging-of-two-phase-flow-through-porous-media
#18
F H Kim, D Penumadu, P Patel, X Xiao, E J Garboczi, S P Moylan, M A Donmez
Near real-time visualization of complex two-phase flow in a porous medium was demonstrated with dynamic 4-dimensional (4D) (3D + time) imaging at the 2-BM beam line of the Advanced Photon Source (APS) at Argonne National Laboratory. Advancing fluid fronts through tortuous flow paths and their interactions with sand grains were clearly captured, and formations of air bubbles and capillary bridges were visualized. The intense X-ray photon flux of the synchrotron facility made 4D imaging possible, capturing the dynamic evolution of both solid and fluid phases...
2016: MRS Adv
https://www.readbyqxmd.com/read/27888419/unravelling-cardiovascular-disease-using-four-dimensional-flow-cardiovascular-magnetic-resonance
#19
Vivian P Kamphuis, Jos J M Westenberg, Roel L F van der Palen, Nico A Blom, Albert de Roos, Rob van der Geest, Mohammed S M Elbaz, Arno A W Roest
Knowledge of normal and abnormal flow patterns in the human cardiovascular system increases our understanding of normal physiology and may help unravel the complex pathophysiological mechanisms leading to cardiovascular disease. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has emerged as a suitable technique that enables visualization of in vivo blood flow patterns and quantification of parameters that could potentially be of prognostic value in the disease process. In this review, current image processing tools that are used for comprehensive visualization and quantification of blood flow and energy distribution in the heart and great vessels will be discussed...
November 25, 2016: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/27885707/spatial-resolution-and-velocity-field-improvement-of-4d-flow-mri
#20
Fraser M Callaghan, Stuart M Grieve
PURPOSE: 4D-flow MRI obtains a time-dependent 3D velocity field; however, its use for the calculation of higher-order parameters is limited by noise. We present an algorithm for denoising 4D-flow data. THEORY AND METHODS: By integrating a velocity field and eliminating streamlines in noisy flow, depicted by high curvature, a denoised dataset may be extracted. This method, defined as the velocity field improvement (VFIT) algorithm, was validated in an analytical dataset and using in vivo data in comparison with a computation fluid dynamics (CFD) simulation...
November 24, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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