Read by QxMD icon Read

Mri bold

C R Campos Herrera, G C Beltramini, W M Avelar, F O Lima, L M Li
Differently from previous studies that used Transcranial Doppler (TCD) and functional MRI (fMRI) for cerebral vasomotor reactivity (CVR) assessment in patients with carotid stenosis (CS), we assessed CVR using an identical stimulus, the Breath-Holding Test (BHT). We included 15 patients with CS and 7 age-matched controls to verify whether fMRI responded differently to BHT between groups and to calculate the agreement rate between tests. For TCD, impaired CVR was defined when the mean percentage increase on middle cerebral artery velocities was ≤31% on 3 consecutive 30-s apnea intercalated by 4-min normal breathing intervals...
October 24, 2016: Brazilian Journal of Medical and Biological Research, Revista Brasileira de Pesquisas Médicas e Biológicas
Alexander G Huth, Tyler Lee, Shinji Nishimoto, Natalia Y Bilenko, An T Vu, Jack L Gallant
One crucial test for any quantitative model of the brain is to show that the model can be used to accurately decode information from evoked brain activity. Several recent neuroimaging studies have decoded the structure or semantic content of static visual images from human brain activity. Here we present a decoding algorithm that makes it possible to decode detailed information about the object and action categories present in natural movies from human brain activity signals measured by functional MRI. Decoding is accomplished using a hierarchical logistic regression (HLR) model that is based on labels that were manually assigned from the WordNet semantic taxonomy...
2016: Frontiers in Systems Neuroscience
E Castaldi, G M Cicchini, L Cinelli, L Biagi, S Rizzo, M C Morrone
Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them...
October 2016: PLoS Biology
Maryna Lapotka, María Ruz, Alberto Salamanca Ballesteros, Olga Ocón Hernández
PURPOSE: This study describes a new methodology-the cold pressor gel test (CPGT)-for delivering an accessible experimental pain stimulus, which is reproducible and safe for functional MRI (fMRI). METHODS: The cold pressor test was modified to put safety precautions into the CPGT. The material used is cool gelled water with a thickening product, which provides a stable temperature at 0.2 °C. Thirteen women with chronic pelvic pain were scanned using a 3 Tesla (T) MR scanner equipped with a 12-channel head coil...
October 25, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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
Jaakko Paasonen, Raimo A Salo, Joanna K Huttunen, Olli Gröhn
PURPOSE: Anesthesia is a major confounding factor in functional MRI (fMRI) experiments attributed to its effects on brain function. Recent evidence suggests that parameters obtained with resting-state fMRI (rs-fMRI) are coupled with anesthetic depth. Therefore, we investigated whether parameters obtained with rs-fMRI, such as functional connectivity (FC), are also directly related to blood-oxygen-level-dependent (BOLD) responses. METHODS: A simple rs-fMRI protocol was implemented in a pharmacological fMRI study to evaluate the coupling between hemodynamic responses and FC under five anesthetics (α-chloralose, isoflurane, medetomidine, thiobutabarbital, and urethane)...
October 23, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Deven A Karvelas, Sean D Rundell, Janna L Friedly, Alfred C Gellhorn, Laura S Gold, Bryan A Comstock, Patrick J Heagerty, Brian W Bresnahan, David R Nerenz, Jeffrey G Jarvik
BACKGROUND: The association between early physical therapy (PT) and subsequent healthcare utilization following a new visit for low back pain is not clear, particularly in the setting of acute low back pain. PURPOSE: To estimate the association between initiating early physical therapy following a new visit for an episode of low back pain and subsequent back-pain-specific health care utilization in older adults. STUDY DESIGN/SETTING: Prospective cohort study...
October 17, 2016: Spine Journal: Official Journal of the North American Spine Society
Sami Al Kasab, Michael J Lynn, Tanya N Turan, Colin P Derdeyn, David Fiorella, Bethany F Lane, L Scott Janis, Marc I Chimowitz
BACKGROUND: An American Heart Association/American Stroke Association (AHA/ASA) writing committee has recently recommended that tissue evidence of cerebral infarction associated with temporary symptoms (CITS) lasting <24 hours should be considered a stroke. We analyzed the impact of considering CITS as equivalent to stroke on the results of the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial. METHODS: We compared outcomes in the medical (n = 227) and stenting (n = 224) groups in SAMMPRIS using the following primary end point (new components in bold): any stroke, CITS, or death within 30 days after enrollment or within 30 days after a revascularization procedure for the qualifying lesion during follow-up; or ischemic stroke or CITS in the territory of the qualifying artery beyond 30 days...
October 17, 2016: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
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
Chiara Sarappa, Elena Salvatore, Alessandro Filla, Sirio Cocozza, Cinzia Valeria Russo, Francesco Saccà, Arturo Brunetti, Giuseppe De Michele, Mario Quarantelli
The fractional Amplitude of Low Frequency Fluctuations (fALFF) and the degree of local synchronization (Regional Homogeneity - ReHo) of resting-state BOLD signal have been suggested to map spontaneous neuronal activity and local functional connectivity, respectively. We compared voxelwise, independent of atrophy, the fALFF and ReHo patterns of 11 presymptomatic (ps-HD) and 28 symptomatic (sHD) Huntington's disease mutation carriers, with those of 40 normal volunteers, and tested their possible correlations with the motor and cognitive subscores of the Unified Huntington's Disease Rating Scale...
October 12, 2016: Brain Imaging and Behavior
Jackie Leung, James Duffin, Joseph A Fisher, Andrea Kassner
OBJECTIVES: Cerebrovascular reactivity (CVR) measures the ability of cerebral blood vessels to change their diameter and, hence, their capacity to regulate regional blood flow in the brain. High resolution quantitative maps of CVR can be produced using blood-oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) in combination with a carbon dioxide stimulus, and these maps have become a useful tool in the clinical evaluation of cerebrovascular disorders. However, conventional CVR analysis does not fully characterize the BOLD response to a stimulus as certain regions of the brain are slower to react to the stimulus than others, especially in disease...
2016: NeuroImage: Clinical
C S Hakkers, J E Arends, R E Barth, S Du Plessis, A I M Hoepelman, M Vink
HIV-associated neurocognitive disorder (HAND) is a frequently occurring comorbidity of HIV infection. Evidence suggests this condition starts subclinical before a progression to a symptomatic stage. Blood oxygenated level dependent (BOLD) fMRI has shown to be a sensitive tool to detect abnormal brain function in an early stage and might therefore be useful to evaluate the effect of HIV infection on brain function. An extensive literature search was performed in June 2015. Eligibility criteria for included studies were as follows: (1) conducting with HIV-positive patients, (2) using BOLD fMRI, and (3) including a HIV-negative control group...
October 7, 2016: Journal of Neurovirology
Neil P Jerome, Jessica K R Boult, Matthew R Orton, James d'Arcy, David J Collins, Martin O Leach, Dow-Mu Koh, Simon P Robinson
BACKGROUND: To investigate the combined use of intravoxel incoherent motion (IVIM) diffusion-weighted (DW) and blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) to assess rat renal function using a 1.5T clinical platform. METHODS: Multiple b-value DW and BOLD MR images were acquired from adult rats using a parallel clinical coil arrangement, enabling quantitation of the apparent diffusion coefficient (ADC), IVIM-derived diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f), and the transverse relaxation time T2*, for whole kidney, renal cortex, and medulla...
October 3, 2016: BMC Nephrology
J Sherwood, K Lovas, M Rich, Q Yin, K Lackey, M S Bolding, Y Bao
Recent research efforts about iron oxide nanoparticles has focused on the development of iron oxide-based T1 contrast agents for magnetic resonance imaging (MRI), such as ultrasmall iron oxide nanospheres (USNPs <4 nm) and ultrathin nanowires (NW, diameter <4 nm). In this paper, we report the cellular uptake behaviors of these two types of ultrasmall scale nanostructures on HepG2 cells. Both these two nanostructures were functionalized with tannic acid and their physical and chemical properties were carefully analyzed before cellular tests...
October 14, 2016: Nanoscale
Anna I Blazejewska, Sharmishtaa Seshamani, Susan K McKown, Jason S Caucutt, Manjiri Dighe, Christopher Gatenby, Colin Studholme
PURPOSE: Maximization of the blood oxygen level-dependent (BOLD) functional MRI (fMRI) contrast requires the echo time of the MR sequence to match the T2* value of the tissue of interest, which is expected to be higher in the fetal brain compared with the brain of a child or an adult. METHODS: T2* values of the cortical plate/cortical gray matter tissue in utero in healthy fetuses from mid-gestation onward (20-36 gestational weeks) were measured using 3D T2* maps calculated from 2D dual-echo T2*-weighted data corrected for between-slice motion and reconstructed in 1...
October 3, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Peiying Liu, Babu G Welch, Yang Li, Hong Gu, Darlene King, Yihong Yang, Marco Pinho, Hanzhang Lu
Diagnosis and treatment monitoring of cerebrovascular diseases routinely require hemodynamic imaging of the brain. Current methods either only provide part of the desired information or require the injection of multiple exogenous agents. In this study, we developed a multiparametric imaging scheme for the imaging of brain hemodynamics and function using gas-inhalation MRI. The proposed technique uses a single MRI scan to provide simultaneous measurements of baseline venous cerebral blood volume (vCBV), cerebrovascular reactivity (CVR), bolus arrival time (BAT), and resting-state functional connectivity (fcMRI)...
September 28, 2016: NeuroImage
Leila M Soravia, Ariane Orosz, Simon Schwab, Masahito Nakataki, Roland Wiest, Andrea Federspiel
BACKGROUND: Imaging studies have provided evidence that cognitive-behavioral therapy (CBT) is able to change brain activation in phobic patients in response to threatening stimuli. The changes occurred in both emotion-generating and modulatory regions. In this study, we use a data-driven approach to explore resting state cerebral blood flow (CBF) measured by arterial spin labeling (ASL), before and after CBT. METHODS: Eight female patients with spider phobia were scanned before and 1 month after an exposure-based group therapy for spider phobia...
September 2016: Brain and Behavior
Miriam C Klein-Flügge, Steven W Kennerley, Karl Friston, Sven Bestmann
UNLABELLED: Integrating costs and benefits is crucial for optimal decision-making. Although much is known about decisions that involve outcome-related costs (e.g., delay, risk), many of our choices are attached to actions and require an evaluation of the associated motor costs. Yet how the brain incorporates motor costs into choices remains largely unclear. We used human fMRI during choices involving monetary reward and physical effort to identify brain regions that serve as a choice comparator for effort-reward trade-offs...
September 28, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Jordan E Pierce, Jennifer E McDowell
Cognitive control is engaged to facilitate stimulus-response mappings for novel, complex tasks and supervise performance in unfamiliar, challenging contexts-processes supported by pFC, ACC, and posterior parietal cortex. With repeated task practice, however, the appropriate task set can be selected in a more automatic fashion with less need for top-down cognitive control and weaker activation in these brain regions. One model system for investigating cognitive control is the ocular motor circuitry underlying saccade production, with basic prosaccade trials (look toward a stimulus) and complex antisaccade trials (look to the mirror image location) representing low and high levels of cognitive control, respectively...
September 27, 2016: Journal of Cognitive Neuroscience
Gabriëlla A M Blokland, Angus K Wallace, Narelle K Hansell, Paul M Thompson, Ian B Hickie, Grant W Montgomery, Nicholas G Martin, Katie L McMahon, Greig I de Zubicaray, Margaret J Wright
In a population-based genome-wide association (GWA) study of n-back working memory task-related brain activation, we extracted the average percent BOLD signal change (2-back minus 0-back) from 46 regions-of-interest (ROIs) in functional MRI scans from 863 healthy twins and siblings. ROIs were obtained by creating spheres around group random effects analysis local maxima, and by thresholding a voxel-based heritability map of working memory brain activation at 50%. Quality control for test-retest reliability and heritability of ROI measures yielded 20 reliable (r>0...
September 23, 2016: International Journal of Psychophysiology
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"