Cerebral Blood Flow In Brain Regions Research Articles

Three-dimensional pseudocontinuous arterial spin labeling with dual postlabeling delay for reflecting cerebral blood flow regulation in patients with hydrocephalus: a retrospective cross-sectional study.

Three-dimensional pseudo-continuous arterial spin-labeling (3D pCASL) with dual postlabeling delay (PLD) captures both early and delayed cerebral blood flow (CBF), yet its potential in reflecting blood flow regulation in hydrocephalus patients remains uncertain. This study investigated the hemodynamic characteristics in patients with hydrocephalus and whether the difference in cerebral blood flow using short and long PLDs (ΔCBF = CBFPLD =2.5 s - CBFPLD =1.5 s) could reflect cerebral regulation and further aimed to demonstrate the associations between regional ΔCBF and the degree of ventricular dilatation. This retrospective study included consecutive patients with hydrocephalus and control participants attending The Second Affiliated Hospital of Nanchang University from December 2017 to December 2022. The CBF in 18 brain regions was manually delineated by two radiologists. Regional CBF and ΔCBF were compared via covariance analyses. The associations between ΔCBF and the degree of ventricular dilatation were investigated using linear regression analyses and interaction analysis. In total, 58 patients with communicating hydrocephalus, 57 patients with obstructive hydrocephalus, and 52 controls were analyzed. CBF of the hydrocephalus groups was lower than that of the control group at the shorter PLD. CBF was higher at a longer PLD, with no difference between the hydrocephalus groups and the control group in some regions. The hydrocephalus groups showed a higher ΔCBF compared to the control group. Furthermore, in the left medial watershed (10.6±5.66 vs. 7.01±5.88 mL/100 g/min; P=0.038), communicating hydrocephalus exhibited greater ΔCBF than did obstructive hydrocephalus. ΔCBF of the right posterior external watershed [adjusted β: 0.276; 95% confidence interval (CI): 0.047-0.505; P=0.019] and right parietal cortex (adjusted β: 0.277; 95% CI: 0.056-0.498; P=0.015) in the obstructive hydrocephalus group and ΔCBF of the left internal watershed (adjusted β: 0.274; 95% CI: 0.013-0.536; P=0.040) in the communicating hydrocephalus group were associated with the degree of ventricular dilatation, respectively. Patients with hydrocephalus showed cerebral regulation in maintaining adequate CBF, resulting in longer arterial transit times. The ability to regulate CBF in brain regions represented by the watershed was associated with the degree of ventricular dilation.

Infant brain regional cerebral blood flow increases supporting emergence of the default-mode network.

Human infancy is characterized by most rapid regional cerebral blood flow (rCBF) increases across lifespan and emergence of a fundamental brain system default-mode network (DMN). However, how infant rCBF changes spatiotemporally across the brain and how the rCBF increase supports emergence of functional networks such as DMN remains unknown. Here, by acquiring cutting-edge multi-modal MRI including pseudo-continuous arterial-spin-labeled perfusion MRI and resting-state functional MRI of 48 infants cross-sectionally, we elucidated unprecedented 4D spatiotemporal infant rCBF framework and region-specific physiology-function coupling across infancy. We found that faster rCBF increases in the DMN than visual and sensorimotor networks. We also found strongly coupled increases of rCBF and network strength specifically in the DMN, suggesting faster local blood flow increase to meet extraneuronal metabolic demands in the DMN maturation. These results offer insights into the physiological mechanism of brain functional network emergence and have important implications in altered network maturation in brain disorders.

Dose-dependent association of accelerometer-measured physical activity and sedentary time with brain perfusion in aging.

Age-related decreases in cerebral blood flow (CBF) may lead to cognitive decline, while physical activity (PA) can maintain CBF and cognition in aging. The intensity of PA needed to affect CBF in aging, and the independent effects of sedentary time on CBF are currently unknown. Moreover, research conducted in free-living environments with objective measures of PA (e.g., accelerometry) is lacking. This cross-sectional study used accelerometry to objectively measure sedentary time, all light PA [AllLightPA], moderate-to-vigorous PA [MVPA], and total activity counts [TAC] in 52 cognitively healthy older adults. Robust linear regressions investigated the association of CBF (using arterial spin labeling magnetic resonance imaging) in frontal and medial temporal regions, with each PA intensity and sedentary time. Greater sedentary time was significantly associated with lower CBF in lateral and medial frontal regions after adjusting for MVPA, while higher AllLightPA (adjusted for MVPA), MVPA (adjusted for AllLightPA), and TAC were associated with greater CBF in lateral and medial frontal regions. Lighter activities, as well as MVPA, are beneficial to CBF in brain regions typically affected by the aging process and malleable to exercise interventions (i.e., the frontal lobes), whereas sedentary time is an independent risk factor for neurovascular dysregulation in normal aging.

Nitric oxide: Roles in neurovascular regulation and ischemic brain injury

The brain relies on a continuous delivery of energy substrates through the blood supply, and interruption of cerebral blood flow (CBF) leads to brain damage. Nitric oxide (NO) has been implicated both in the regulation of the cerebral microcirculation and in ischemic brain injury. In the normal brain, neuronal NO is involved in the CBF increases produced by synaptic activity, a vital response that matches CBF delivery to brain activity. The mechanisms of the NO production induced by neural activity involve the NMDA receptor, a subunit of which is tethered to neuronal NO synthase (nNOS) via the adaptor protein PSD-95. The ability of NMDA receptors to trigger NO production depends on tissue plasminogen activator (tPA), which promotes NO production through nNOS phosphorylation. NO is also involved in ischemic brain injury. NO produced by endothelial NOS (eNOS) is protective in the early stages after the arterial occlusion by promoting the maintenance of CBF in brain regions at risk for infarction (ischemic penumbra). However, in the late stages of cerebral ischemia large amounts of NO produced by the “inducible” isoform of NOS (iNOS) in inflammatory cells infiltrating the ischemic tissue is deleterious and contributes to brain injury. Post-ischemic iNOS expression is controlled by the transcription factor NFkb, which is activated through CD36, a scavenger receptor involved in innate immunity. Thus, enhancement of eNOS-derived NO and suppression iNOS-derived NO may have translational potential in cerebrovascular pathologies.

Double-Blind, Placebo-Controlled, Randomized Pilot Study of Cerebral Blood Flow Patterns Employing SPECT Imaging in Dental Postsurgical Pain Patients With and Without Pain Relief

Background Single-photon emission computed tomography (SPECT) has been employed in the study of altered regional cerebral blood flow (CBF) in experimental and chronic pain. CBF patterns have not been evaluated in patients with acute postoperative pain. Objective The purpose of this pilot study was to employ SPECT to measure CBF distribution associated with postoperative dental pain and to compare these CBF patterns to subsequent images in the same patients who were experiencing pain relief versus continued or worsening pain who had received active or placebo analgesic interventions. The primary outcome measure was the percentage change in blood flow in various regions of interest. Methods Twenty-two healthy individuals (10 males and 12 females, age range 20–29 years) who underwent the removal of ≥1 partial or full bony impacted mandibular third molars were evaluated for pain intensity as the local anesthesia dissipated, employing a 0 to10 numeric rating scale (0 = no pain; 10 = worst imaginable). When the subjects' pain level reached ≥4/10, they were injected intravenously with 260 MBq of technetium Tc 99m bicisate (ethyl cysteinate dimer). Under double-blind conditions and 10 minutes before being placed in the SPECT scanner, the first 10 subjects were randomized to receive intravenous ketorolac 15 mg or saline while the remaining 12 subjects were randomized to receive by mouth either ibuprofen 400 mg, ibuprofen 200 mg, acetaminophen 1000 mg, or placebo. One hour after drug administration, subjects were reevaluated for pain, injected with 925 MBq of technetium Tc 99m bicisate, given rescue medication if required, and then rescanned. CBF ratios were obtained for regions of interest and by normalizing to average whole brain activity. Results Subjects generally had a moderate degree (mean [SD], 7.3% [4.0%]) of thalamic asymmetry on initial scans with pain; after treatment, subjects reporting worsening pain regardless of the intervention had higher thalamic asymmetry (8.1% vs 2.8%) than those reporting relief of pain. Subjects who reported reduced pain after the intervention had significantly different ( P < 0.05) mean CBF changes compared with those reporting worsening pain in the left prefrontal cortex, left sensorimotor area, right anterior cingulate, and right caudate. Conclusions Acute postoperative dental pain was associated with moderate thalamic asymmetry that improved following successful pain management. Sustained or worsening pain was associated with increased CBF in brain regions associated with pain pathways, whereas pain relief was associated with decreased activity in the same areas.

Quantification of Cerebral Blood Flow as Biomarker of Drug Effect: Arterial Spin Labeling phMRI After a Single Dose of Oral Citalopram

Arterial spin labeling (ASL) allows noninvasive quantification of cerebral blood flow (CBF), which can be used as a biomarker of drug effects in pharmacological magnetic resonance imaging (phMRI). In a double-blind, placebo-controlled crossover study, we investigated the effects of a single oral dose of citalopram (20 mg) on resting CBF in 12 healthy subjects, using ASL phMRI. Support-vector machine (SVM) analysis detected significant drug-induced reduction in CBF in brain regions including the amygdala, fusiform gyrus, insula, and orbitofrontal cortex. These regions have been shown to have abnormally elevated CBF in patients with major depression, as well as in subjects genetically prone to depression. Mixed-effects analysis on data extracted from selected regions of interest (ROIs) revealed significant drug effect only in serotonergic areas of the brain (z = -4.45, P < 0.005). These results demonstrate the utility of ASL phMRI as a biomarker of pharmacological activity of orally administered drugs in the brain.

P.1.e.02l The effects of cognitive-behavioural therapy on brain regional cerebral blood flow in obsessive compulsive disorder

P.1.e.02l The effects of cognitive-behavioural therapy on brain regional cerebral blood flow in obsessive compulsive disorder

Quantification of pain-induced changes in cerebral blood flow by perfusion MRI

The purpose of this study was to assess if the functional activation caused by painful stimuli could be detected with arterial spin labeling (ASL), which is a non-invasive magnetic resonance imaging (MRI) technique for measuring cerebral blood flow (CBF). Because ASL directly measures blood flow, it is well suited to pain conditions that are difficult to assess with current functional MRI, such as chronic pain. However, the use of ASL in neuroimaging has been hampered by its low sensitivity. Recent improvements in MRI technology, namely increased magnetic field strengths and phased array receiver coils, should enable ASL to measure the small changes in CBF associated with pain. In this study, healthy volunteers underwent two ASL imaging sessions, during which a painful thermal stimulus was applied to the left hand. The results demonstrated that the ASL technique measured changes in regional CBF in brain regions that have been previously identified with pain perception. These included bilateral CBF changes in the insula, secondary somatosensory, and cingulate cortices, as well as the supplementary motor area (SMA). Also observed were contralateral primary somatosensory and ipsilateral thalamic CBF changes. The average change in CBF for all regions of interest was 3.68 ml/100 g/min, ranging from 2.97 ml/100 g/min in ipsilateral thalamus to 4.91 ml/100 g/min in contralateral insula. The average resting global CBF was 54 ± 9.7 ml/100 g/min, and there was no change in global CBF due to the noxious thermal stimulus.

(659): Using perfusion MRI to measure pain-induced changes in cerebral blood flow

Arterial spin labeling (ASL) is a non-invasive magnetic resonance imaging (MRI) technique for measuring cerebral blood flow (CBF). Because ASL directly measures blood flow, it is well suited to pain conditions that are difficult to assess with current functional MRI, such as chronic pain. However, the use of ASL in neuroimaging has been hampered by its low sensitivity. Recent improvements in MRI technology, namely increased magnetic field strengths and phased array receiver coils, should enable ASL to measure the small changes in CBF associated with pain. The purpose of this study was to assess whether the functional activation caused by acute painful stimuli could be detected with an ASL technique. Fourteen healthy volunteers underwent two 11-minute ASL imaging sessions, during which a painful thermal stimulus (mean = 48.9 °C) was applied to the left hand. Functional image analysis software (SPM2) was used for both the fixed effects individual analyses and the random effects group analysis. The results demonstrated that the ASL technique measured changes in regional CBF in brain regions that have been previously identified with pain processing. These included bilateral CBF changes in the insula, secondary somatosensory, and cingulate cortices, as well as the supplementary motor area (SMA). Also observed were contralateral primary somatosensory and ipsilateral thalamic CBF changes. The average change in CBF for all regions of interest was 3.68 ml/100g/min, ranging from 2.97 ml/100g/min in ipsilateral thalamus to 4.91 ml/100g/min in contralateral insula. Although both sessions of data were used to obtain these results, the analysis revealed that data from a single 11-minute session were sufficient to map the pain-related areas of the brain. With its improved sensitivity, ASL will allow for more comprehensive studies of chronic pain conditions, and prolonged pain stimuli, such as tonic pain, particularly with regards to their associated cognitive and emotional components.

Attentional Systems and the Allocation of Cerebral Resources in Reading and Grammatical Tasks

To evaluate the possible role of attentional centers as modulators of neural networks that mediate visual tasks involving reading and grammatical manipulations of verbs, we measured cerebral blood flow (CBF) using positron emission tomography (PET), and reaction times as subjects read verbs, “nonce verbs” such as jelt or brep, and formed past tenses of regular, irregular and nonce verbs after viewing their stems. Statistical parametric maps (SPMs) showed significant activation of the pulvinar in the read verb, generate irregular, and generate nonce past tense tasks, compared to rest. This was confirmed by a post hoc Anova of CBF values from a discrete locus in the pulvinar (p =. 0000417). Functional links between the pulvinar and other brain regions were shown by high correlations of CBF in the pulvinar with CBF in brain regions known to have anatomical connections to the pulvinar, particularly those mediating vision. There was also a significant relationship between task-specific reaction times and rest minus task CBF differences in a multiple regression analysis that included CBF values from the pulvinar, superior colliculus plus reticular formation, and the anterior cingulate, known attentional centers (p =. 021, r2 = 0.99). Regression analyses relating reaction time to the amount of brain activated (pixels in the SPMs) and the degree of activation of the pixels (mean Z score) yielded p values of. 078 and. 074, respectively. Our data provide direct experimental evidence to support the hypothesis that attentional centers are activated in proportion to the complexity of visually mediated language tasks and that the centers that mediate attention modulate the activity of task-specific neural networks.

Local cerebral blood flow in motor neuron disease: correlation with clinical findings

Local cerebral blood flow (CBF) measured by xenon-enhanced CT was correlated with the clinical findings in 21 patients with motor neuron disease (mean ± SD age, 60 ± 10 years). In 11 patients, CBF was also measured after intravenous injection of 2 mg thyrotropin releasing hormone (TRH). There were no significant differences in CBF of the cerebral cortex, basal ganglia, thalamus, and subcortical white matter with respect to age, duration of illness, or presence (n = 9) or absence (n = 12) of bulbar palsy. In patients with upper motor neuron disturbance (n = 10), however, local CBF in the frontal cortex was significantly lower (p < 0.05) than in those without it (n = 11). Within the frontal cortex, CBF reduction was marked in the upper posterolateral part (p < 0.05) that included the motor and premotor areas. Intravenous administration of TRH did not significantly alter the local CBF in any of the brain regions examined. An additional patient with motor neuron disease and severe dementia showed marked CBF reduction in the frontal lobe, which was in common with but much greater than the reduction in those exhibiting subcortical dementia (e.g., progressive supranuclear palsy). We conclude that in motor neuron disease patients with upper motor neuron involvement, the selective reduction of CBF in brain regions that include primary motor and premotor areas may reflect functional disturbance or neuronal degeneration in these regions. The ameliorating effect of TRH in patients with motor neuron disease, if any, appears not to be related to increases in local CBF or activation of brain function.