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https://www.readbyqxmd.com/read/27902858/reliable-estimation-of-microvascular-flow-patterns-in-patients-with-disrupted-blood-brain-barrier-using-dynamic-susceptibility-contrast-mri
#1
Mikkel Bo Hansen, Anna Tietze, Jayashree Kalpathy-Cramer, Elizabeth R Gerstner, Tracy T Batchelor, Leif Østergaard, Kim Mouridsen
PURPOSE: To present and quantify the performance of a method to compute tissue hemodynamic parameters from dynamic susceptibility contrast (DSC) MRI data in brain tissue with possible nonintact blood-brain barrier. THEORY AND MATERIALS AND METHODS: We propose a Bayesian scheme to obtain perfusion metrics, including capillary transit-time heterogeneity (CTH), from DSC-MRI data in the presence of contrast agent extravasation. Initial performance assessment is performed through simulations...
November 30, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27867088/techniques-for-blood-volume-fmri-with-vaso-from-low-resolution-mapping-towards-sub-millimeter-layer-dependent-applications
#2
Laurentius Huber, Dimo Ivanov, Daniel A Handwerker, Sean Marrett, Maria Guidi, Kâmil Uludağ, Peter A Bandettini, Benedikt A Poser
Quantitative cerebral blood volume (CBV) fMRI has the potential to overcome several specific limitations of BOLD fMRI. It provides direct physiological interpretability and promises superior localization specificity in applications of sub-millimeter resolution fMRI applications at ultra-high magnetic fields (7T and higher). Non-invasive CBV fMRI using VASO (vascular space occupancy), however, is inherently limited with respect to its data acquisition efficiency, restricting its imaging coverage and achievable spatial and temporal resolution...
November 17, 2016: NeuroImage
https://www.readbyqxmd.com/read/27864578/mesoscopic-imaging-of-glioblastomas-are-diffusion-perfusion-and-spectroscopic-measures-influenced-by-the-radiogenetic-phenotype
#3
Theo Demerath, Carl Philipp Simon-Gabriel, Elias Kellner, Ralf Schwarzwald, Thomas Lange, Dieter Henrik Heiland, Peter Reinacher, Ori Staszewski, Hansjörg Mast, Valerij G Kiselev, Karl Egger, Horst Urbach, Astrid Weyerbrock, Irina Mader
The purpose of this study was to identify markers from perfusion, diffusion, and chemical shift imaging in glioblastomas (GBMs) and to correlate them with genetically determined and previously published patterns of structural magnetic resonance (MR) imaging. Twenty-six patients (mean age 60 years, 13 female) with GBM were investigated. Imaging consisted of native and contrast-enhanced 3D data, perfusion, diffusion, and spectroscopic imaging. In the presence of minor necrosis, cerebral blood volume (CBV) was higher (median ± SD, 2...
November 18, 2016: Neuroradiology Journal
https://www.readbyqxmd.com/read/27856222/negative-hemodynamic-response-without-neuronal-inhibition-investigated-by-combining-optical-imaging-and-electrophysiological-recording
#4
Zengguang Ma, Pengjia Cao, Pengcheng Sun, Zhuofan Lu, Liming Li, Yao Chen, Xinyu Chai
Understanding the mechanisms underlying negative hemodynamic responses is critical for the interpretation of functional brain imaging signals. Negative imaging signals have been found in the visual, somatosensory and motor cortices in functional magnetic resonance imaging (fMRI) and intrinsic signal optical imaging (ISOI) studies. However, the origin of negative imaging signals is still controversial. The present study investigated the visual cortical responses to peripheral grating stimuli using multi-wavelength ISOI and electrophysiological recording...
November 14, 2016: Neuroscience Letters
https://www.readbyqxmd.com/read/27825979/functional-circuit-mapping-of-striatal-output-nuclei-using-simultaneous-deep-brain-stimulation-and-fmri
#5
Nathalie Van Den Berge, Daniel L Albaugh, Andrew Salzwedel, Christian Vanhove, Roel Van Holen, Wei Gao, Garret D Stuber, Yen-Yu Ian Shih
The substantia nigra pars reticulata (SNr) and external globus pallidus (GPe) constitute the two major output targets of the rodent striatum. Both the SNr and GPe converge upon thalamic relay nuclei (directly or indirectly, respectively), and are traditionally modeled as functionally antagonistic relay inputs. However, recent anatomical and functional studies have identified unanticipated circuit connectivity in both the SNr and GPe, demonstrating their potential as far more than relay nuclei. In the present study, we employed simultaneous deep brain stimulation and functional magnetic resonance imaging (DBS-fMRI) with cerebral blood volume (CBV) measurements to functionally and unbiasedly map the circuit- and network level connectivity of the SNr and GPe...
November 5, 2016: NeuroImage
https://www.readbyqxmd.com/read/27823971/combined-use-of-susceptibility-weighted-magnetic-resonance-imaging-sequences-and-dynamic-susceptibility-contrast-perfusion-weighted-imaging-to-improve-the-accuracy-of-the-differential-diagnosis-of-recurrence-and-radionecrosis-in-high-grade-glioma-patients
#6
Tae-Hyung Kim, Tae Jin Yun, Chul-Kee Park, Tae Min Kim, Ji-Hoon Kim, Chul-Ho Sohn, Jae Kyung Won, Sung-Hye Park, Il Han Kim, Seung Hong Choi
Purpose was to assess predictive power for overall survival (OS) and diagnostic performance of combination of susceptibility-weighted MRI sequences (SWMRI) and dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWI) for differentiation of recurrence and radionecrosis in high-grade glioma (HGG). We enrolled 51 patients who underwent radiation therapy or gamma knife surgeryfollowed by resection for HGG and who developed new measurable enhancement more than six months after complete response. The lesions were confirmed as recurrence (n = 32) or radionecrosis (n = 19)...
November 3, 2016: Oncotarget
https://www.readbyqxmd.com/read/27807911/effects-of-reduced-oxygen-availability-on-the-vascular-response-and-oxygen-consumption-of-the-activated-human-visual-cortex
#7
Felipe Rodrigues Barreto, Silvia Mangia, Carlos Ernesto Garrido Salmon
PURPOSE: To identify the impact of reduced oxygen availability on the evoked vascular response upon visual stimulation in the healthy human brain by magnetic resonance imaging (MRI). MATERIALS AND METHODS: Functional MRI techniques based on arterial spin labeling (ASL), blood oxygenation level-dependent (BOLD), and vascular space occupancy (VASO)-dependent contrasts were utilized to quantify the BOLD signal, cerebral blood flow (CBF), and volume (CBV) from nine subjects at 3T (7M/2F, 27...
November 3, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27807663/effect-of-posture-and-extracranial-contamination-on-results-of-cerebral-oximetry-by-near-infrared-spectroscopy
#8
Shinya Kato, Kenji Yoshitani, Yosuke Kubota, Yuzuru Inatomi, Yoshihiko Ohnishi
BACKGROUND: Near-infrared spectroscopy (NIRS)-based cerebral oximetry is a noninvasive technology used to estimate regional cerebral oxygen saturation (rSO2). Extracranial blood flow is known to substantially affect rSO2 values measured by most clinically available devices. Several studies have also reported that the Trendelenburg position and upright position have a larger effect on rSO2 measurements than the supine position. Therefore, we investigated the effect of these two positions (the Trendelenburg position versus the upright position) and extracranial contamination on rSO2 measurements obtained using two commercially available devices and one prototype device...
November 2, 2016: Journal of Anesthesia
https://www.readbyqxmd.com/read/27801401/-perfusion-criteria-of-the-eicma-efficacy-in-patients-with-symptomatic-occlusion-of-the-internal-carotid-artery
#9
V A Lukshin, D Yu Usachev, I N Pronin, A D Akhmedov, E I Shul'ts
AIM: To investigate changes in cerebral perfusion in patients with unilateral internal carotid artery occlusion before and after surgical revascularization of the brain, depending on the clinical efficacy of surgical treatment. MATERIAL AND METHODS: The study included 60 patients with unilateral ICA occlusions who underwent placement of an extra-intracranial microvascular anastomosis (EICMA). All patients underwent a CT perfusion study before and after cerebral revascularization...
2016: Zhurnal Voprosy Neĭrokhirurgii Imeni N. N. Burdenko
https://www.readbyqxmd.com/read/27797101/quantitative-measurement-of-cerebral-blood-volume-using-velocity-selective-pulse-trains
#10
Dexiang Liu, Feng Xu, Doris D Lin, Peter C M van Zijl, Qin Qin
PURPOSE: To develop a non-contrast-enhanced MRI method for cerebral blood volume (CBV) mapping using velocity-selective (VS) pulse trains. METHODS: The new pulse sequence applied velocity-sensitive gradient waveforms in the VS label modules and velocity-compensated ones in the control scans. Sensitivities to the gradient imperfections (e.g., eddy currents) were evaluated through phantom studies. CBV quantification procedures based on simulated labeling efficiencies for arteriolar, capillary, and venular blood as a function of cutoff velocity (Vc) are presented...
October 31, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27789149/noncontrast-computed-tomography-versus-computed-tomography-angiography-source-images-for-predicting-final-infarct-size-in-anterior-circulation-acute-ischemic-stroke-a-prospective-cohort-study
#11
Amritendu Mukherjee, Prakash Muthusami, Aneesh Mohimen, Srinivasan K, Babunath B, Sylaja Pn, Chandrasekharan Kesavadas
BACKGROUND: There has been a recent debate regarding the superiority of computed tomography angiography source images (CTASIs) over noncontrast computed tomography (NCCT) to predict the final infarct size in acute ischemic stroke (AIS). We hypothesized that the parenchymal abnormality on CTASI in faster scanners would overestimate ischemic core. METHODS: This prospective study assessed the correlation of Alberta Stroke Program Early CT Score (ASPECTS) on NCCT, CTASI, and computed tomography perfusion (CTP) with final infarct size in patients within 8 hours of AIS...
October 24, 2016: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/27781042/cbv_aspects-improvement-over-ct_aspects-on-determining-irreversible-ischemic-lesion-decreases-over-time
#12
Marina Padroni, Sandra Boned, Marc Ribó, Marian Muchada, David Rodriguez-Luna, Pilar Coscojuela, Alejandro Tomasello, Jordi Cabero, Jorge Pagola, Noelia Rodriguez-Villatoro, Jesus M Juega, Estela Sanjuan, Carlos A Molina, Marta Rubiera
: The Alberta Stroke Program Early CT Score (ASPECTS) is a useful scoring system for assessing early ischemic signs on noncontrast computed tomography (CT). Cerebral blood volume (CBV) on CT perfusion defines the core lesion assumed to be irreversibly damaged. We aim to explore the advantages of CBV_ASPECTS over CT_ASPECTS in the prediction of final infarct volume according to time. METHODS: Consecutive patients with anterior circulation stroke who underwent endovascular reperfusion according to initial CT_ASPECTS ≥7 were studied...
September 2016: Interventional Neurology
https://www.readbyqxmd.com/read/27775841/evaluation-of-an-fmri-uspio-based-assay-in-healthy-human-volunteers
#13
Richard Baumgartner, William Cho, Alexandre Coimbra, Christopher Chen, Zaiqi Wang, Arie Struyk, Narayanaswamy Venketasubramanian, May Low, Cindy Gargano, Fuqiang Zhao, Donald Williams, Torsten Reese, Stephanie Seah, Dai Feng, Sonya Apreleva, Esben Petersen, Jeffrey L Evelhoch
PURPOSE: To present the testretest and contrast dose effect results of cerebral blood volume (CBV) functional MRI (fMRI) in healthy human volunteers using ferumoxytol (Feraheme), an ultrasmall-superparamagnetic iron oxide (USPIO) nanoparticle. MATERIALS AND METHODS: This was an open-label, two-period, fixed-sequence study in healthy young volunteers. In eight subjects, using a 3 Tesla field strength system, blood oxygen level dependent (BOLD) and CBV fMRI were acquired in response to a visual black-and-white checkboard stimulation paradigm using an escalating ferumoxytol dose design (250, 350, and 510 mg iron)...
October 24, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27753725/shortened-mean-transit-time-in-ct-perfusion-with-singular-value-decomposition-analysis-in-acute-cerebral-infarction-quantitative-evaluation-and-comparison-with-various-ct-perfusion-parameters
#14
Kazuhiro Murayama, Kazuhiro Katada, Motoharu Hayakawa, Hiroshi Toyama
OBJECTIVE: We aimed to clarify the cause of shortened mean transit time (MTT) in acute ischemic cerebrovascular disease and examined its relationship with reperfusion. METHODS: Twenty-three patients with acute ischemic cerebrovascular disease underwent whole-brain computed tomography perfusion (CTP). The maximum MTT (MTTmax), minimum MTT (MTTmin), ratio of maximum and minimum MTT (MTTmin/max), and minimum cerebral blood volume (CBV) (CBVmin) were measured by automatic region of interest analysis...
October 7, 2016: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/27753225/photoacoustic-microscopy-of-electronic-acupuncture-ea-effect-in-small-animals
#15
Jinge Yang, Dan Wu, Yong Tang, Huabei Jiang
Acupuncture has been an effective treatment for various pain in China for several thousand years. However, the mechanisms underlying this mysterious ancient healing are still largely unknown. Here we applied photoacoustic microscopy (PAM) to investigate brain hemodynamic changes in response to electronic acupuncture (EA) at ST36 (Zusanli). Due to the high optical absorption of blood at 532 nm, PAM could sensitively probe changes in hemoglobin concentration (HbT, i.e., cerebral blood volume [CBV]) of cortical regions in high resolution...
October 18, 2016: Journal of Biophotonics
https://www.readbyqxmd.com/read/27739434/multiparametric-mri-based-differentiation-of-who-grade-ii-iii-glioma-and-who-grade-iv-glioblastoma
#16
Benedikt Wiestler, Anne Kluge, Mathias Lukas, Jens Gempt, Florian Ringel, Jürgen Schlegel, Bernhard Meyer, Claus Zimmer, Stefan Förster, Thomas Pyka, Christine Preibisch
Non-invasive, imaging-based examination of glioma biology has received increasing attention in the past couple of years. To this end, the development and refinement of novel MRI techniques, reflecting underlying oncogenic processes such as hypoxia or angiogenesis, has greatly benefitted this research area. We have recently established a novel BOLD (blood oxygenation level dependent) based MRI method for the measurement of relative oxygen extraction fraction (rOEF) in glioma patients. In a set of 37 patients with newly diagnosed glioma, we assessed the performance of a machine learning model based on multiple MRI modalities including rOEF and perfusion imaging to predict WHO grade...
October 14, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27731907/brain-capillary-transit-time-heterogeneity-in-healthy-volunteers-measured-by-dynamic-contrast-enhanced-t1-weighted-perfusion-mri
#17
Henrik B W Larsson, Mark B Vestergaard, Ulrich Lindberg, Helle K Iversen, Stig P Cramer
PURPOSE: Capillary transit time heterogeneity, measured as CTH, may set the upper limit for extraction of substances in brain tissue, e.g., oxygen. The purpose of this study was to investigate the feasibility of dynamic contrast-enhanced T1 weighted MRI (DCE-MRI) at 3 Tesla (T), in estimating CTH based on a gamma-variate model of the capillary transit time distribution. In addition, we wanted to investigate if a subtle increase of the blood-brain barrier permeability can be incorporated into the model, still allowing estimation of CTH...
October 12, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27720821/field-strength-dependence-of-grey-matter-r2-on-venous-oxygenation
#18
Paula L Croal, Ian D Driver, Susan T Francis, Penny A Gowland
The relationship between venous blood oxygenation and change in transverse relaxation rate (ΔR2(⁎)) plays a key role in calibrated BOLD fMRI. This relationship, defined by the parameter β, has previously been determined using theoretical simulations and experimental measures. However, these earlier studies have been confounded by the change in venous cerebral blood volume (CBV) in response to functional tasks. This study used a double-echo gradient echo EPI scheme in conjunction with a graded isocapnic hyperoxic sequence to assess quantitatively the relationship between the fractional venous blood oxygenation (1-Yv) and transverse relaxation rate of grey matter (ΔR2(⁎)GM), without inducing a change in vCBV...
October 5, 2016: NeuroImage
https://www.readbyqxmd.com/read/27718078/interleaving-cerebral-ct-perfusion-with-neck-ct-angiography-part-i-proof-of-concept-and-accuracy-of-cerebral-perfusion-values
#19
Marcel T H Oei, Frederick J A Meijer, Willem-Jan van der Woude, Ewoud J Smit, Bram van Ginneken, Mathias Prokop, Rashindra Manniesing
OBJECTIVES: We present a novel One-Step-Stroke protocol for wide-detector CT scanners that interleaves cerebral CTP with volumetric neck CTA (vCTA). We evaluate whether the resulting time gap in CTP affects the accuracy of CTP values. METHODS: Cerebral CTP maps were retrospectively obtained from 20 patients with suspicion of acute ischemic stroke and served as the reference standard. To simulate a 4 s gap for interleaving CTP with vCTA, we eliminated one acquisition at various time points of CTP starting from the bolus-arrival-time(BAT)...
October 7, 2016: European Radiology
https://www.readbyqxmd.com/read/27686551/-preliminary-study-on-assessment-of-lexiscan-induced-blood-brain-barrier-opening-and-its-level-by-ct-perfusion-imaging
#20
Y Duan, B Q Yang, C C Chang, J Zhou, H Y Li, Z H Xu, Z W Wang, D Y Li
Objective: To evaluate the level of lexiscan-induced blood-brain barrier opening of healthy rabbits via CT perfusion weighted imaging (PWI) scan. Methods: Between November 2014 and May 2015, thirty New Zealand white rabbits were randomly assigned into three groups: the experimental group A1 which received one injection of lexiscan(1 ml/kg); the experimental group A2 which received three times injection of lexiscan(total dose: 1.5 ml/kg), finished within 15 minutes; the control group B which was injected the same volume normal saline(1 ml/kg), after 30 minutes, CT PWI scan was performed...
September 20, 2016: Zhonghua Yi Xue za Zhi [Chinese medical journal]
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