scholarly journals Flow-metabolism uncoupling in patients with asymptomatic unilateral carotid artery stenosis assessed by multi-modal magnetic resonance imaging

2018 ◽  
Vol 39 (11) ◽  
pp. 2132-2143 ◽  
Author(s):  
Jens Göttler ◽  
Stephan Kaczmarz ◽  
Michael Kallmayer ◽  
Isabel Wustrow ◽  
Hans-Henning Eckstein ◽  
...  
Keyword(s):  
Contralateral Side ◽  
Blood Oxygenation ◽  
Carotid Revascularization ◽  
Asymptomatic Patients ◽  
Metabolic States ◽  
Oxygenation Level ◽  
Mri Scans ◽  
Mri Protocol ◽  
Revascularization Therapy ◽  
Continuous Arterial Spin Labeling

Oxygen extraction (OEF), oxidative metabolism (CMRO2), and blood flow (CBF) in the brain, as well as the coupling between CMRO2 and CBF due to cerebral autoregulation are fundamental to brain's health. We used a clinically feasible MRI protocol to assess impairments of these parameters in the perfusion territories of stenosed carotid arteries. Twenty-nine patients with unilateral high-grade carotid stenosis and thirty age-matched healthy controls underwent multi-modal MRI scans. Pseudo-continuous arterial spin labeling (pCASL) yielded absolute CBF, whereas multi-parametric quantitative blood oxygenation level dependent (mqBOLD) modeling allowed imaging of relative OEF and CMRO2. Both CBF and CMRO2 were significantly reduced in the stenosed territory compared to the contralateral side, while OEF was evenly distributed across both hemispheres similarly in patients and controls. The CMRO2-CBF coupling was significantly different between both hemispheres in patients, i.e. significant interhemispheric flow-metabolism uncoupling was observed in patients compared to controls. Given that CBF and CMRO2 are intimately linked to brain function in health and disease, the proposed easily applicable MRI protocol of pCASL and mqBOLD imaging might serve as a valuable tool for early diagnosis of potentially harmful cerebral hemodynamic and metabolic states with the final aim to select clinically asymptomatic patients who would benefit from carotid revascularization therapy.

scholarly journals BOLD MRI to evaluate early development of renal injury in a rat model of diabetes

2018 ◽  
Vol 46 (4) ◽  
pp. 1391-1403 ◽  
Author(s):  
Qidong Wang ◽  
Chuangen Guo ◽  
Lan Zhang ◽  
Rui Zhang ◽  
Zhaoming Wang ◽  
...  
Keyword(s):  
Renal Injury ◽  
Diabetic Rats ◽  
Blood Oxygenation ◽  
Dynamic Changes ◽  
Bold Mri ◽  
Oxygenation Level ◽  
Mri Scans ◽  
Streptozotocin Induced Diabetes ◽  
Magnetic Resonance Imaging Mri ◽  
Diabetes Induction

Objective To investigate changes in renal oxygenation levels by blood-oxygenation-level dependent (BOLD)-magnetic resonance imaging (MRI), and to evaluate BOLD-MRI for detecting early diabetic renal injury. Methods Seventy-five rats, with unilateral nephrectomy, were randomly divided into streptozotocin-induced diabetes mellitus (DM, n = 65) and normal control (NC, n = 10) groups. BOLD-MRI scans were performed at baseline (both groups) and at 3, 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days (DM only). Renal cortical (C) and medullary (M) R2* signals were measured and R2* medulla/cortex ratio (MCR) was calculated. Results DM-group CR2* and MR2* values were significantly higher than NC values following diabetes induction. R2* values increased gradually and peaked at day 35 (CR2*, 33.95 ± 0.34 s–1; MR2*, 43.79 ± 1.46 s–1), then dropped gradually (CR2*, 33.17 ± 0.69 s–1; MR2*, 41.61 ± 0.95 s–1 at day 70). DM-group MCR rose gradually from 1.12 to 1.32 at day 42, then decreased to 1.25 by day 70. Conclusions BOLD-MRI can be used to non-invasively evaluate renal hypoxia and early diabetic renal injury in diabetic rats. MCR may be adopted to reflect dynamic changes in renal hypoxia.

scholarly journals Baseline CBF, and BOLD, CBF, and CMRO2 fMRI of Visual and Vibrotactile Stimulations in Baboons

2010 ◽  
Vol 31 (2) ◽  
pp. 715-724 ◽  
Author(s):  
Hsiao-Ying Wey ◽  
Danny J Wang ◽  
Timothy Q Duong
Keyword(s):  
Gray Matter ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebral Metabolic Rate ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Arterial Transit Time ◽  
Continuous Arterial Spin Labeling ◽  
Calibrated Fmri ◽  
Tesla Scanner

Neurovascular coupling associated with visual and vibrotactile stimulations in baboons anesthetized sequentially with isoflurane and ketamine was evaluated using multimodal functional magnetic resonance imaging (fMRI) on a clinical 3-Tesla scanner. Basal cerebral blood flow ( CBF), and combined blood-oxygenation-level-dependent ( BOLD) and CBF fMRI of visual and somatosensory stimulations were measured using pseudo-continuous arterial spin labeling. Changes in stimulus-evoked cerebral metabolic rate of oxygen ( CMRO2) were estimated using calibrated fMRI. Arterial transit time for vessel, gray matter (GM), and white matter (WM) were 250, 570, and 823 ms, respectively. Gray matter and WM CBF, respectively, were 107.8 ± 7.9 and 47.8 ± 3.8 mL per 100 g per minute under isoflurane, and 108.8 ± 10.3 and 48.7 ± 4.2 mL per 100 g per minute under ketamine (mean ± s.e.m., N = 8 sessions, five baboons). The GM/WM CBF ratio was not statistically different between the two anesthetics, averaging 2.3 ± 0.1. Hypercapnia evoked global BOLD and CBF increases. Blood-oxygenation-level-dependent, CBF, and CMRO2 signal changes by visual and vibrotactile stimulations were 0.19% to 0.22%, 18% to 23%, and 4.9% to 6.7%, respectively. The CBF/CMRO2 ratio was 2.9 to 4.7. Basal CBF and fMRI responses were not statistically different between the two anesthetics. This study establishes a multimodal fMRI protocol to probe clinically relevant functional, physiological and metabolic information in large nonhuman primates.

scholarly journals Reduction of BOLD interference in pseudo-continuous arterial spin labeling: towards quantitative fMRI

2017 ◽  
Vol 38 (5) ◽  
pp. 847-856 ◽  
Author(s):  
Geoffrey Warnock ◽  
Pinar S Özbay ◽  
Felix P Kuhn ◽  
Daniel Nanz ◽  
Alfred Buck ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Time Lag ◽  
Occipital Lobe ◽  
Spin Labeling ◽  
Blood Oxygenation ◽  
Background Suppression ◽  
Oxygenation Level ◽  
Neuronal Stimulation ◽  
Continuous Arterial Spin Labeling ◽  
Stimulation Paradigm

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 15O-water PET. At rest, a good agreement in the CBF values was found between PET and MRI for each of the subtraction methods. Stimulation of the visual system resulted in a regional CBF increase in the occipital lobe, which was detectable in both modalities. Bland–Altman analysis showed a systematic underestimation of the CBF values during activation in MRI. Evaluation of the relative CBF change induced by neuronal stimulation showed good inter-modality agreement for the three subtraction methods. Perfusion data obtained with each subtraction method followed the stimulation paradigm without significant differences in the correlation patterns or in the time lag between stimulation and perfusion response. Comparison to the gold standard confirmed the detectability of a neuronal stimulation pattern by pCASL. The results indicate that the combined use of background suppression and short TE reduces the BOLD-weighting in the pCASL signal.

scholarly journals Validating Linear Systems Analysis for Laminar fMRI: Temporal Additivity for Stimulus Duration Manipulations

2020 ◽  
Author(s):  
Jelle A. van Dijk ◽  
Alessio Fracasso ◽  
Natalia Petridou ◽  
Serge O. Dumoulin
Keyword(s):  
Systems Theory ◽  
Linear Systems ◽  
Blood Oxygenation ◽  
Ultra High Field ◽  
Feedback Information ◽  
Oxygenation Level ◽  
Early Visual Cortex ◽  
Magnetic Resonance Imaging Mri ◽  
And Function ◽  
The Relationship

AbstractAdvancements in ultra-high field (7 T and higher) magnetic resonance imaging (MRI) scanners have made it possible to investigate both the structure and function of the human brain at a sub-millimeter scale. As neuronal feedforward and feedback information arrives in different layers, sub-millimeter functional MRI has the potential to uncover information processing between cortical micro-circuits across cortical depth, i.e. laminar fMRI. For nearly all conventional fMRI analyses, the main assumption is that the relationship between local neuronal activity and the blood oxygenation level dependent (BOLD) signal adheres to the principles of linear systems theory. For laminar fMRI, however, directional blood pooling across cortical depth stemming from the anatomy of the cortical vasculature, potentially violates these linear system assumptions, thereby complicating analysis and interpretation. Here we assess whether the temporal additivity requirement of linear systems theory holds for laminar fMRI. We measured responses elicited by viewing stimuli presented for different durations and evaluated how well the responses to shorter durations predicted those elicited by longer durations. We find that BOLD response predictions are consistently good predictors for observed responses, across all cortical depths, and in all measured visual field maps (V1, V2, and V3). Our results suggest that the temporal additivity assumption for linear systems theory holds for laminar fMRI. We thus show that the temporal additivity assumption holds across cortical depth for sub-millimeter gradient-echo BOLD fMRI in early visual cortex.

Abnormal Emotional Responses to Pleasant and Unpleasant Visual Stimuli in First Episode Schizophrenia: f-MRI Investigation

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
M. Casacchia ◽  
M. Mazza ◽  
A. Catalucci ◽  
R. Pollice ◽  
M. Gallucci ◽  
...  
Keyword(s):  
Negative Symptoms ◽  
Psychiatric Service ◽  
Visual Stimuli ◽  
Chronic Schizophrenia ◽  
Normal Subjects ◽  
Blood Oxygenation ◽  
First Episode ◽  
Affective Deficits ◽  
Oxygenation Level ◽  
Mri Study

Aims:Affective deficits (flat affect, a diminished expression of emotion, anhedonia, and lowered ability to experience pleasure) are very common in schizophrenia. In emotion feeling, the crucial role of the insula, rather than of the primary somatosensory cortices, strongly suggests that the neural substrate for emotions is not merely sensorial. It is more likely that the activation of the insula representation of the viscero-motor activity is responsible for feeling of disgust. A recent MRI study demonstrated specific left anterior insular volume reduction in chronic schizophrenia patients: sustainable is the suggestion that emotion of disgust or of taste may be related to the experience of pleasure, which probably is compromise in schizophrenics.We investigated fMRI brain activations in first episode schizophrenic subjects with negative symptoms and in healthy subjects elicited by pleasant and unpleasant visual stimuli.Method:Ten first-episode schizophrenic subjects with normal IQ were recruited from the psychiatric service “SMILE” of San Salvatore Hospital and 10 healthy volunteers matched for age and education were scanned during observation of pleasant and unpleasant visual stimuli. Functional images were acquired with a 1.5T MRI scanner. Blood oxygenation level dependent (BOLD) contrast was obtained using EPI T2* weighted images.Results:The most important result of the study was the demonstration that anterior insula was activated by the exposure to disgusting stimula in normal subjects but not in schizophrenic subjects.Conclusion:This failure of the neural systems used to support emotional attribution is consistent with pervasive problems in experiencing emotions by schizophrenics.

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