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https://www.readbyqxmd.com/read/28441420/mapping-of-the-brain-hemodynamic-responses-to-sensorimotor-stimulation-in-a-rodent-model-a-bold-fmri-study
#1
Salem Boussida, Amidou S Traoré, Franck Durif
Blood Oxygenation Level Dependent functional MRI (BOLD fMRI) during electrical paw stimulation has been widely used in studies aimed at the understanding of the somatosensory network in rats. However, despite the well-established anatomical connections between cortical and subcortical structures of the sensorimotor system, most of these functional studies have been concentrated on the cortical effects of sensory electrical stimulation. BOLD fMRI study of the integration of a sensorimotor input across the sensorimotor network requires an appropriate methodology to elicit functional activation in cortical and subcortical areas owing to the regional differences in both neuronal and vascular architectures between these brain regions...
2017: PloS One
https://www.readbyqxmd.com/read/28437782/detection-of-renal-hypoxia-in-lupus-nephritis-using-blood-oxygen-level-dependent-mr-imaging-a-multiple-correspondence-analysis
#2
Huilan Shi, Tiekun Yan, Dong Li, Junya Jia, Wenya Shang, Li Wei, Zhenfeng Zheng
BACKGROUND/AIMS: Nephrologists have pursued ideal, dynamic and noninvasive methods for assessing renal function and disease progression. Blood oxygen level dependent (BOLD) imaging is a useful technique for assessing renal disease. This current study was performed to explore the correlation between the hypoxia iconographical index and renal pathological features in lupus nephritis. METHODS: Adult patients with lupus nephritis (LN) and healthy volunteers were recruited for this study...
April 5, 2017: Kidney & Blood Pressure Research
https://www.readbyqxmd.com/read/28424572/functional-sensitivity-of-2d-simultaneous-multi-slice-echo-planar-imaging-effects-of-acceleration-on-g-factor-and-physiological-noise
#3
Nick Todd, Oliver Josephs, Peter Zeidman, Guillaume Flandin, Steen Moeller, Nikolaus Weiskopf
Accelerated data acquisition with simultaneous multi-slice (SMS) imaging for functional MRI studies leads to interacting and opposing effects that influence the sensitivity to blood oxygen level-dependent (BOLD) signal changes. Image signal to noise ratio (SNR) is decreased with higher SMS acceleration factors and shorter repetition times (TR) due to g-factor noise penalties and saturation of longitudinal magnetization. However, the lower image SNR is counteracted by greater statistical power from more samples per unit time and a higher temporal Nyquist frequency that allows for better removal of spurious non-BOLD high frequency signal content...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28421854/reduction-of-bold-interference-in-pseudo-continuous-arterial-spin-labeling-towards-quantitative-fmri
#4
Geoffrey Warnock, Pinar S Özbay, Felix P Kuhn, Daniel Nanz, Alfred Buck, Andreas Boss, Cristina Rossi
Fluctuations in blood-oxygenation level dependent (BOLD) signal and perfusion affect the quantification of changes in cerebral blood flow (CBF), coupled to neuronal activity, in arterial spin labeling (ASL). Subtraction methods for control and labeled MR images (i.e. pair-wise, surround subtraction, and subtraction of sinc-interpolated images), postulated to mitigate this interference in pseudo-continuous ASL (pCASL), were evaluated by comparison with quantitative (15)O-water PET. At rest, a good agreement in the CBF values was found between PET and MRI for each of the subtraction methods...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28415581/tumor-physiological-changes-during-hypofractionated-stereotactic-body-radiation-therapy-assessed-using-multi-parametric-magnetic-resonance-imaging
#5
Heling Zhou, Zhang Zhang, Rebecca Denney, Jessica S Williams, Jeni Gerberich, Strahinja Stojadinovic, Debabrata Saha, John M Shelton, Ralph P Mason
Radiation therapy is a primary treatment for non-resectable lung cancer and hypoxia is thought to influence tumor response. Hypoxia is expected to be particularly relevant to the evolving new radiation treatment scheme of hypofractionated stereotactic body radiation therapy (SBRT). As such, we sought to develop non-invasive tools to assess tumor pathophysiology and response to irradiation. We applied blood oxygen level dependent (BOLD) and tissue oxygen level dependent (TOLD) MRI, together with dynamic contrast enhanced (DCE) MRI to explore the longitudinal effects of SBRT on tumor oxygenation and vascular perfusion using A549 human lung cancer xenografts in a subcutaneous rat model...
March 21, 2017: Oncotarget
https://www.readbyqxmd.com/read/28406906/water-diffusion-closely-reveals-neural-activity-status-in-rat-brain-loci-affected-by-anesthesia
#6
Yoshifumi Abe, Tomokazu Tsurugizawa, Denis Le Bihan
Diffusion functional MRI (DfMRI) reveals neuronal activation even when neurovascular coupling is abolished, contrary to blood oxygenation level-dependent (BOLD) functional MRI (fMRI). Here, we show that the water apparent diffusion coefficient (ADC) derived from DfMRI increased in specific rat brain regions under anesthetic conditions, reflecting the decreased neuronal activity observed with local field potentials (LFPs), especially in regions involved in wakefulness. In contrast, BOLD signals showed nonspecific changes, reflecting systemic effects of the anesthesia on overall brain hemodynamics status...
April 2017: PLoS Biology
https://www.readbyqxmd.com/read/28396293/the-impact-of-ultra-high-field-mri-on-cognitive-and-computational-neuroimaging
#7
Federico De Martino, Essa Yacoub, Valentin Kemper, Michelle Moerel, Kamil Uludag, Peter De Weerd, Kamil Ugurbil, Rainer Goebel, Elia Formisano
The ability to measure functional brain responses non-invasively with ultra high field MRI (7 T and above) represents a unique opportunity in advancing our understanding of the human brain. Compared to lower fields (3 T and below), ultra high field MRI has an increased sensitivity, which can be used to acquire functional images with greater spatial resolution, and greater specificity of the blood oxygen level dependent (BOLD) signal to the underlying neuronal responses. Together, increased resolution and specificity enable investigating brain functions at a submillimeter scale, which so far could only be done with invasive techniques...
April 7, 2017: NeuroImage
https://www.readbyqxmd.com/read/28374506/g-csf-and-cognitive-dysfunction-in-elderly-diabetic-mice-with-cerebral-small-vessel-disease-preventive-intervention-effects-and-underlying-mechanisms
#8
Zhu-Fei Guan, Ying-Hong Tao, Xiao-Ming Zhang, Qi-Lin Guo, Ying-Chao Liu, Yu Zhang, Yan-Mei Wang, Gang Ji, Guo-Feng Wu, Na-Na Wang, Hao Yang, Zhong-Yu Yu, Jing-Chun Guo, Hou-Guang Zhou
AIMS: Although cognitive dysfunction is a common neurological complication in elderly patients with diabetes, the mechanisms underlying this relationship remain unclear, and effective preventive interventions have yet to be developed. Thus, this study investigated the preventive effects and mechanisms of action associated with granulocyte colony-stimulating factor (G-CSF) on cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease. METHODS: This study included 40 male db/db diabetic and wild-type (WT) mice that were categorized into the following four groups at the age of 3 weeks: db/db group (DG), db/db+G-CSF group (DGG), WT group (WG), and WT+G-CSF group (WGG)...
April 4, 2017: CNS Neuroscience & Therapeutics
https://www.readbyqxmd.com/read/28374010/following-eye-gaze-activates-a-patch-in-the-posterior-temporal-cortex-that-is-not-part-of-the-human-face-patch-system
#9
Kira Marquardt, Hamidreza Ramezanpour, Peter W Dicke, Peter Thier
Humans follow another person's eye gaze to objects of interest to the other, thereby establishing joint attention, a first step toward developing a theory of the other's mind. Previous functional MRI studies agree that a "gaze-following patch" (GFP) of cortex close to the posterior superior temporal sulcus (STS) is specifically implicated in eye gaze-following. The location of the GFP is in the vicinity of the posterior members of the core face-processing system that consists of distinct patches in ventral visual cortex, the STS, and frontal cortex, also involved in processing information on the eyes...
March 2017: ENeuro
https://www.readbyqxmd.com/read/28373123/sensitivity-and-specificity-considerations-for-fmri-encoding-decoding-and-mapping-of-auditory-cortex-at-ultra-high-field
#10
Michelle Moerel, Federico De Martino, Valentin G Kemper, Sebastian Schmitter, An T Vu, Kâmil Uğurbil, Elia Formisano, Essa Yacoub
Following rapid technological advances, ultra-high field functional MRI (fMRI) enables exploring correlates of neuronal population activity at an increasing spatial resolution. However, as the fMRI blood-oxygenation-level-dependent (BOLD) contrast is a vascular signal, the spatial specificity of fMRI data is ultimately determined by the characteristics of the underlying vasculature. At 7T, fMRI measurement parameters determine the relative contribution of the macro- and microvasculature to the acquired signal...
March 31, 2017: NeuroImage
https://www.readbyqxmd.com/read/28365848/attenuation-of-cortical-activity-triggering-descending-pain-inhibition-in-chronic-low-back-pain-patients-a-functional-magnetic-resonance-imaging-study
#11
Yohei Matsuo, Jiro Kurata, Miho Sekiguchi, Katsuhiro Yoshida, Takuya Nikaido, Shin-Ichi Konno
PURPOSE: A considerable portion of chronic low back pain (cLBP) patients lack anatomical abnormality, resist conventional therapeutic interventions, and their symptoms are often complicated with psychological and social factors. Such patients have been reported to show cerebral abnormalities both in anatomy and function by neuroimaging studies. Here we examined differences in cerebral reactivity to a simulated low back pain stimulus between cLBP patients and healthy controls by functional magnetic resonance imaging (fMRI), and their behavioral correlates from a psychophysical questionnaire...
April 1, 2017: Journal of Anesthesia
https://www.readbyqxmd.com/read/28363836/multi-echo-fmri-a-review-of-applications-in-fmri-denoising-and-analysis-of-bold-signals
#12
Prantik Kundu, Valerie Voon, Priti Balchandani, Michael V Lombardo, Benedikt A Poser, Peter Bandettini
In recent years the field of fMRI research has enjoyed expanded technical abilities related to resolution, as well as use across many fields of brain research. At the same time, the field has also dealt with uncertainty related to many known and unknown effects of artifact in fMRI data. In this review we discuss an emerging fMRI technology, called multi-echo (ME)-fMRI, which focuses on improving the fidelity and interpretability of fMRI. Where the essential problem of standard single-echo fMRI is the indeterminacy of sources of signals, whether BOLD or artifact, this is not the case for ME-fMRI...
March 28, 2017: NeuroImage
https://www.readbyqxmd.com/read/28362834/the-impact-of-inspired-oxygen-levels-on-calibrated-fmri-measurements-of-m-oef-and-resting-cmro2-using-combined-hypercapnia-and-hyperoxia
#13
Isabelle Lajoie, Felipe B Tancredi, Richard D Hoge
Recent calibrated fMRI techniques using combined hypercapnia and hyperoxia allow the mapping of resting cerebral metabolic rate of oxygen (CMRO2) in absolute units, oxygen extraction fraction (OEF) and calibration parameter M (maximum BOLD). The adoption of such technique necessitates knowledge about the precision and accuracy of the model-derived parameters. One of the factors that may impact the precision and accuracy is the level of oxygen provided during periods of hyperoxia (HO). A high level of oxygen may bring the BOLD responses closer to the maximum M value, and hence reduce the error associated with the M interpolation...
2017: PloS One
https://www.readbyqxmd.com/read/28355354/cerebral-blood-flow-and-vasoreactivity-in-aging-an-arterial-spin-labeling-study
#14
R F Leoni, I A F Oliveira, O M Pontes-Neto, A C Santos, J P Leite
Regional cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) in young and elderly participants were assessed using pulsed arterial spin labeling (ASL) and blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) techniques in combination with inhalation of CO2. Pulsed ASL and BOLD-MRI were acquired in seventeen asymptomatic volunteers (10 young adults, age: 30±7 years; 7 elderly adults, age: 64±8 years) with no history of diabetes, hypertension, and neurological diseases. Data from one elderly participant was excluded due to the incorrigible head motion...
March 23, 2017: Brazilian Journal of Medical and Biological Research, Revista Brasileira de Pesquisas Médicas e Biológicas
https://www.readbyqxmd.com/read/28345164/comparing-functional-mri-protocols-for-small-iron-rich-basal-ganglia-nuclei-such-as-the-subthalamic-nucleus-at-7-t-and-3-t
#15
Gilles de Hollander, Max C Keuken, Wietske van der Zwaag, Birte U Forstmann, Robert Trampel
The basal ganglia (BG) form a network of subcortical nuclei. Functional magnetic resonance imaging (fMRI) in the BG could provide insight in its functioning and the underlying mechanisms of Deep Brain Stimulation (DBS). However, fMRI of the BG with high specificity is challenging, because the nuclei are small and variable in their anatomical location. High resolution fMRI at field strengths of 7 Tesla (T) could help resolve these challenges to some extent. A set of MR protocols was developed for functional imaging of the BG nuclei at 3 T and 7 T...
March 27, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28320141/functional-magnetic-resonance-imaging-responses-in-cadasil
#16
Ikreet Cheema, Aaron R Switzer, Cheryl R McCreary, Michael D Hill, Richard Frayne, Bradley G Goodyear, Eric E Smith
OBJECTIVES: The magnitude of the blood oxygen dependent level (BOLD) functional MRI (fMRI) response to visual stimulation is reduced in the small vessel disease cerebral amyloid angiopathy (CAA), reflecting impaired vascular reactivity. We determined whether BOLD responses were reduced in another small vessel disease, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). METHODS: BOLD fMRI data were collected using a visual stimulus (contrast-reversing checkerboard) and motor task (finger-tapping)...
April 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28293468/a-method-for-independent-component-graph-analysis-of-resting-state-fmri
#17
Demetrius Ribeiro de Paula, Erik Ziegler, Pubuditha M Abeyasinghe, Tushar K Das, Carlo Cavaliere, Marco Aiello, Lizette Heine, Carol di Perri, Athena Demertzi, Quentin Noirhomme, Vanessa Charland-Verville, Audrey Vanhaudenhuyse, Johan Stender, Francisco Gomez, Jean-Flory L Tshibanda, Steven Laureys, Adrian M Owen, Andrea Soddu
INTRODUCTION: Independent component analysis (ICA) has been extensively used for reducing task-free BOLD fMRI recordings into spatial maps and their associated time-courses. The spatially identified independent components can be considered as intrinsic connectivity networks (ICNs) of non-contiguous regions. To date, the spatial patterns of the networks have been analyzed with techniques developed for volumetric data. OBJECTIVE: Here, we detail a graph building technique that allows these ICNs to be analyzed with graph theory...
March 2017: Brain and Behavior
https://www.readbyqxmd.com/read/28284801/functional-connectivity-and-activity-of-white-matter-in-somatosensory-pathways-under-tactile-stimulations
#18
Xi Wu, Zhipeng Yang, Stephen K Bailey, Jiliu Zhou, Laurie E Cutting, John C Gore, Zhaohua Ding
Functional MRI has proven to be effective in detecting neural activity in brain cortices on the basis of blood oxygenation level dependent (BOLD) contrast, but has relatively poor sensitivity for detecting neural activity in white matter. To demonstrate that BOLD signals in white matter are detectable and contain information on neural activity, we stimulated the somatosensory system and examined distributions of BOLD signals in related white matter pathways. The temporal correlation profiles and frequency contents of BOLD signals were compared between stimulation and resting conditions, and between relevant white matter fibers and background regions, as well as between left and right side stimulations...
March 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/28277456/resting-state-bold-mri-for-perfusion-and-ischemia
#19
Hannes Kroll, Greg Zaharchuk, Thomas Christen, Jeremy J Heit, Michael Iv
Advanced imaging techniques including computed tomography (CT) angiography, CT perfusion, magnetic resonance (MR) angiography, MR with diffusion- and perfusion-weighted imaging, and, more recently, resting-state BOLD (Blood Oxygen Level Dependent) functional MRI (rs-fMRI) are increasingly used to evaluate patients with acute ischemic stroke. Advanced imaging allows for identification of patients with ischemic stroke and determination of the size of infarcted and potentially salvageable tissue, all of which yield crucial information for proper stroke management...
April 2017: Topics in Magnetic Resonance Imaging: TMRI
https://www.readbyqxmd.com/read/28275197/relationship-between-changes-in-the-temporal-dynamics-of-the-blood-oxygen-level-dependent-signal-and-hypoperfusion-in-acute-ischemic-stroke
#20
Ahmed A Khalil, Ann-Christin Ostwaldt, Till Nierhaus, Ramanan Ganeshan, Heinrich J Audebert, Kersten Villringer, Arno Villringer, Jochen B Fiebach
BACKGROUND AND PURPOSE: Changes in the blood-oxygen-level-dependent (BOLD) signal provide a noninvasive measure of blood flow, but a detailed comparison with established perfusion parameters in acute stroke is lacking. We investigated the relationship between BOLD signal temporal delay and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) in stroke patients. METHODS: In 30 patients with acute (<24 hours) ischemic stroke, we performed Pearson correlation and multiple linear regression between DSC-MRI parameters (time to maximum [Tmax], mean transit time, cerebral blood flow, and cerebral blood volume) and BOLD-based parameters (BOLD delay and coefficient of BOLD variation)...
March 8, 2017: Stroke; a Journal of Cerebral Circulation
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