Cerebral Blood Flow Measurements Research Articles

Impaired Iron Metabolism and Cerebral Perfusion Patterns in Unilateral Middle Cerebral Artery Stenosis or Occlusion: Insights from Quantitative Susceptibility mapping.

Cerebral hypoperfusion caused by stenosis or occlusion of the middle cerebral artery (MCA) may be followed by impaired iron metabolism. We explored the association between iron changes of gray matter (GM) nuclei subregions and different cerebral perfusion patterns in patients with chronic unilateral middle cerebral artery (MCA) stenosis or occlusion using quantitative susceptibility imaging (QSM). Sixty-one patients with unilateral MCA stenosis or occlusion were recruited and scored with Alberta-Stroke-Program-Early-CT-Score (ASPECTS) based on relative cerebral blood flow (rCBF) measurements to calculate the number of corresponding hypoperfusion subregions, and then divided into an extensive-hypoperfusion group (EH group), regional-hypoperfusion group (RH group), and normal-perfusion group (Control group) accordingly. The measured magnetic susceptibility of GM nuclei subregions was compared between the lesion and contralateral side for each group and among the three groups. Correlation analysis was performed to assess the relationships of magnetic susceptibility of GM nuclei with mean rCBF, National-Institutes-of-Health-stroke-scale (NIHSS) and modified-Rankin-scale (mRS) scores. Magnetic susceptibility in the putamen (PU) and globus pallidus (GP) at the lesion side was higher in the EH and RH groups compared with the contralateral side (all P < 0.05). Susceptibility in the lesion side PU and GP showed negative correlations with mean rCBF and positive correlations with NIHSS and mRS scores (all P < 0.05). Our findings demonstrate that chronic cerebral hypoperfusion might be one cause of cerebral abnormal iron metabolism. In addition, magnetic susceptibility of PU and GP seems to be correlated with stroke scale scores, suggesting that iron deposition may play an important role in neurologic deficits after ischemic stroke.

Acorus tatarinowii alleviates D-galactose-induced Alzheimer’s-like disease cognitive impairment and Aβ-induced pericytes dysfunction in mice

Pericytes regulate cerebral blood flow (CBF) and excess amyloid in the brain. Pericyte dysfunction may contribute to the pathology of Alzheimer’s disease (AD). Acorus tatarinowii (AT), a Chinese medicine commonly used to treat AD, protects the central nervous system. However, whether AT can regulate pericyte function and ameliorate cognitive dysfunction remains unclear. We employed a novel target recognition assay, quantitative measurement of CBF, hematoxylin and eosin staining, immunofluorescence staining, and Western blot to investigate the role of AT in improving cognitive function in patients with AD. Additionally, we investigated the therapeutic potential of β-Asarone, the primary active compound in AT, for treating AD by modulating pericyte function using transmission electron microscopy, silver staining, electrical impedance, and other methodologies. The results revealed that administration of AT effectively alleviated the cognitive impairments induced by D-galactose in mice, as evidenced by enhanced CBF, improved histological characteristics of damaged brain tissue cells, increased expression of platelet-derived growth factor-β (PDGF-β), decreased Aβ accumulation via enhanced lipoprotein receptor-related protein 1 (LRP1), and reduced beta-site APP-cleaving enzyme 1 (BACE1). β-Asarone treatment mitigated ROS release and BACE1 expression while elevating the cell index in Aβ1-40 injured mouse brain vascular pericytes (MBVP). These findings suggest that AT has the potential to enhance CBF and mitigate pericellular dysfunction, thereby ameliorating Aβ deposition in the brain and improving cognitive impairment in patients with AD

Catheter ablation increases cerebral blood flow and cognitive function in elderly patients with atrial fibrillation

Abstract Background Atrial fibrillation (AF) has been considered to have an increased risk for cognitive impairment independent of a stroke and a silent micro-infarction. The mechanism of this interaction is unclear. One of the potential explanations is brain hypoperfusion due to a reduced cardiac output. To date, there are no reports focusing on the cerebral blood flow and cognitive impairment in patients undergoing AF ablation. Purpose The purpose of this study was to investigate whether catheter ablation of AF would increase cerebral blood flow and restore cognitive impairment. Methods AF patients aged 75 years or older with mild or more cognitive impairment were selected. The assessment of cognitive function using Mini-Mental State Examination (MMSE) and Hasegawa's Dementia Scale-Revised (HDS-R), and measurement of cerebral blood flow using 99mTc-ECD SPECT imaging were examined before and 3 months after ablation. Results A total of 25 elderly patients (mean age 83, 14 males and 11 females) were included in this study. Of them, 23 patients had persistent AF. Twenty-three patients (92%) maintained sinus rhythm after ablation. There was a significant improvement in MMSE score (from 24.6±4.5 to 25.9±4.0, p&amp;lt;0.05) and HDS-R (from 23.2±5.5 to 24.8±5.1, p&amp;lt;0.05) after ablation. Cerebral blood flow also significantly increased after ablation (right lobe: from 34.4±4.6 to 38.5±4.4 ml/100g/min, p&amp;lt;0.01, left lobe: from 35.3±9.7 to 38.8±3.7 ml/100g/min, p&amp;lt;0.01). Overall average cerebral blood flow increased by 10.1±9.4% after ablation. There was a positive correlation between the changes in MMSE score and the changes in cerebral blood flow (r=0.65, p&amp;lt;0.05). Conclusion AF ablation in elderly patients increased cerebral blood flow and cognitive function. AF ablation would be one of the therapeutic options to improve cognitive function in elderly patients with cognitive impairment.

Intraoperative transfontanelle ultrasonography for pediatric patients.

Cerebral blood flow (CBF) plays a vital role in delivering cerebral oxygen, and the accurate assessment of CBF is crucial for the intraoperative management of critically ill infants. Although the direct measurement of CBF is challenging, CBF velocity (CBFV) can be assessed using transcranial Doppler. Recent advances in point-of-care ultrasound have introduced brain ultrasound as a feasible intraoperative option, in which transfontanelle ultrasonography (TFU) has been applied to measure the CBFV through the anterior fontanelle. However, the intraoperative application of TFU in pediatric patients remains limited. The present review highlights the procedural aspects and clinical applications of TFU for anesthetic and intensive care management in pediatric patients. TFU facilitates the visualization of cerebral vessels and allows a noninvasive assessment of cerebral hemodynamics. The clinical significance of TFU involves its usefulness in various clinical scenarios, including monitoring CBF during cardiac surgery, assessing fluid responsiveness, and estimating intracranial pressure. TFU also enables the detection of cerebral emboli and the evaluation of anatomical abnormalities such as hydrocephalus or intracranial hemorrhage. TFU has demonstrated potential as an invaluable tool in pediatric care, despite limited familiarity among anesthesiologists. Additional research is needed to explore the associations between CBF and clinical outcomes, focusing on autoregulation, the impact of physiological changes, the associations of TFU findings with other brain monitoring tools such as electroencephalography, cerebral oximetry, and the implications of microemboli. TFU is a significant advancement and valuable tool for noninvasively assessing cerebral hemodynamics and CBF in pediatric patients with open fontanelles.

I feel your pain: higher empathy is associated with higher posterior default mode network activity

Abstract Empathy is characterized as the ability to share one's experience and is associated with altruism. Previous work using blood oxygen level–dependent (BOLD) functional MRI (fMRI) has found that empathy is associated with greater activation in brain mechanisms supporting mentalizing (temporoparietal junction), salience (anterior cingulate cortex; insula), and self-reference (medial prefrontal cortex; precuneus). However, BOLD fMRI has some limitations that may not reliably capture the tonic experience of empathy. To address this, the present study used a perfusion-based arterial spin labeling fMRI approach that provides direct a quantifiable measurement of cerebral blood flow (1 mL/100 g tissue/min) and is less susceptible to low-frequency fluctuations and empathy-based “carry-over” effects that may be introduced by BOLD fMRI–based block designs. Twenty-nine healthy females (mean age = 29 years) were administered noxious heat (48°C; left forearm) during arterial spin labeling fMRI. In the next 2 fMRI scans, female volunteers viewed a stranger (laboratory technician) and their romantic partner, respectively, receive pain-evoking heat (48°C; left forearm) in real-time and positioned proximal to the scanner during fMRI acquisition. Visual analog scale (0 = “not unpleasant”; 10 = “most unpleasant sensation imaginable”) empathy ratings were collected after each condition. There was significantly (P = 0.01) higher empathy while viewing a romantic partner in pain and greater cerebral blood flow in the right temporoparietal junction, amygdala, anterior insula, orbitofrontal cortex, and precuneus when compared with the stranger. Higher empathy was associated with greater precuneus and primary visual cortical activation. The present findings indicate that brain mechanisms supporting the embodiment of another's experience is associated with higher empathy.

Measurement of Cerebral Blood Flow Using Transcranial Doppler Ultrasonography: Comparison of Two Populations of Patients on Chronic Hemodialysis

Measurement of Cerebral Blood Flow Using Transcranial Doppler Ultrasonography: Comparison of Two Populations of Patients on Chronic Hemodialysis

All-optics technique for monitoring absolute cerebral blood flow: validation against magnetic resonance imaging perfusion.

The ability to monitor cerebral blood flow (CBF) at the bedside is essential to managing critical-care patients with neurological emergencies. Diffuse correlation spectroscopy (DCS) is ideal because it is non-invasive, portable, and inexpensive. We investigated a near-infrared spectroscopy (NIRS) approach for converting DCS measurements into physiological units of blood flow. Using magnetic resonance imaging perfusion as a reference, we investigated the accuracy of absolute CBF measurements from a bolus-tracking NIRS method that used transient hypoxia as a flow tracer and hypercapnia-induced increases in CBF measured by DCS. Twelve participants (7 female, years) completed a hypercapnia protocol with simultaneous CBF recordings from DCS and arterial spin labeling (ASL). Nine participants completed the transient hypoxia protocol while instrumented with time-resolved NIRS. The estimate of baseline CBF was subsequently used to calibrate hypercapnic DCS data. Moderately strong correlations at baseline ( and ) and during hypercapnia ( and ) were found between CBF values from calibrated DCS and ASL (range 34 to ). Results demonstrated the feasibility of an all-optics approach that can both quantify CBF and perform continuous perfusion monitoring.

Brain perfusion alterations in patients and survivors of COVID‐19 infection using arterial spin labeling: A systematic review

AbstractCoronavirus disease (COVID‐19) has been shown to impact the central nervous system, leading to various neurological complications. Arterial spin labeling (ASL), a non‐invasive magnetic resonance imaging technique, enables the measurement of cerebral blood flow and perfusion abnormalities. This systematic review aims to synthesize ASL findings in patients with COVID‐19 and assess the potential role of ASL in diagnosing and managing neurological complications. A comprehensive search was conducted on PubMed and Scopus for studies related to ASL in individuals with COVID‐19 or post‐COVID‐19 syndrome published between December 2019 and August 2024. Extracted data encompassed study characteristics, ASL protocols, cognitive assessments, and principal findings. The most consistent observation across studies was hypoperfusion detected in various brain regions, particularly within the frontal lobes, which may correlate with cognitive impairment and olfactory dysfunction. Additionally, some investigations reported hyperperfusion localized to the leptomeninges. These results may reflect underlying mechanisms such as hypoxic–ischemic injury, inflammation, vascular dysfunction, and neuronal damage attributable to COVID‐19. In conclusion, ASL has emerged as a valuable tool for evaluating brain perfusion among patients affected by or recovering from COVID‐19 since it offers critical insights into cerebral hemodynamics and metabolism. Further research is warranted to validate these ASL findings and elucidate whether post‐COVID‐19 syndrome contributes to persistent brain perfusion issues.

Sex Disparities in Mortality After Endovascular Therapy in Large Core Infarcts

Background In recent large core endovascular therapy (EVT) trials of large vessel occlusion acute ischemic stroke (AIS), treatment was associated with reduced rates of mortality. Because post‐AIS mortality can be influenced by societal and biological factors that differ between women and men, we investigate sex‐based differences in mortality outcomes following EVT in large core AIS. Methods From our prospectively collected multicenter registry across 4 comprehensive stroke centers in the Greater Houston area, we identified patients from 2017 to 2022 with large vessel occlusion AIS and large infarct core. Large infarct core was defined by computed tomography perfusion exceeding 70 mL (by regional cerebral blood flow measurements using automated postprocessing) or computed tomography Alberta Stroke Program Early CT [Computed Tomography] Score&lt;6. The primary outcome of this study was the likelihood of mortality at 90 days, determined through multivariable logistic regression adjusted for EVT, sex, and EVT/sex interaction term. Secondary outcomes included 90‐day disability outcomes and intracerebral hemorrhage. Results Among 190 patients who met inclusion criteria, 50% were female and 45.3% received EVT. Demographic differences between the sexes were largely balanced apart from the older age of presentation for women compared with men (75 versus 67, women versus men; P &lt;0.01). In univariable analysis, women who did not receive EVT had greater mortality (27.4% difference; P &lt;0.001) compared with men, with comparable rates in EVT‐treated cohorts. In multivariable analysis, non‐EVT management was strongly associated with mortality in women compared with men at discharge (odds ratio [OR] 5.81, 95% CI [1.96–17.23]) and 90‐days (OR 6.77, 95% CI [2.09–21.94]). In the secondary analysis, which additionally adjusted the model for age and National Institutes of Health Stroke Scale score, these findings were unchanged. The sex/EVT interaction term showed significant interaction for mortality both at discharge and 90 days ( P &lt;0.01). Conclusion EVT in large core AIS populations may disparately reduce mortality in women compared to men.

Noninvasive Monitoring of Changes in Cerebral Hemodynamics During Prolonged Field Care for Hemorrhagic Shock and Hypoxia-Induced Injuries With Portable Diffuse Optical Sensors.

Achieving simultaneous cerebral blood flow (CBF) and oxygenation measures, specifically for point-of-care injury monitoring in prolonged field care, requires the implementation of appropriate methodologies and advanced medical device design, development, and evaluation. The near-infrared spectroscopy (NIRS) method measures the absorbance of light whose attenuation is related to cerebral blood volume and oxygenation. By contrast, diffuse correlation spectroscopy (DCS) allows continuous noninvasive monitoring of microvascular blood flow by directly measuring the degree of light scattering because of red blood cell (RBC) movement in tissue capillaries. Hence, this study utilizes these two optical approaches (DCS-NIRS) to obtain a more complete hemodynamic monitoring by providing cerebral microvascular blood flow, hemoglobin oxygenation and deoxygenation in hemorrhage, and hypoxia-induced injuries. Piglet models of hemorrhage and hypoxia-induced brain injury were used with DCS and NIRS sensors placed over the preorbital to temporal skull regions. To induce hemorrhagic shock, up to 70% of the animal's total blood volume was withdrawn through graded hemorrhage serially via a syringe from a femoral artery cannula in 10 mL/kg aliquots over 1 minute every 10 minutes. A second group of animals was subjected to hypoxia for ∼1 hour through graded hypoxia by serial titration from normoxic fraction inspired oxygen of 21% to hypoxic fraction inspired oxygen of 6%. A subset of animals served as sham-controls undergoing anesthesia, instrumentation, and ventilation as the injury groups, yet experiencing no blood loss or hypoxia. We first investigated the relationship between hemorrhagic shock and no shock by using measured biomarkers, including blood flow index from DCS associated with CBF and oxygenated (HbO) and de-oxygenated hemoglobin from NIRS. The statistical analysis revealed a significant difference between no shock and hemorrhagic shock (P < .01). The HbO decreased with each blood loss as expected, yet the de-oxygenated hemoglobin was slightly changed. During hypoxia-induced global hypoxic-ischemic injury tests, the CBF results from graded hypoxia were consistent with the response previously measured during hemorrhagic shock. Moreover, HbO decreased when the animal was hypoxic, as expected. A statistical analysis was also conducted to compare the results with those of the sham controls. There is a consistency in blood flow measures in both injury mechanisms (hemorrhagic shock and hypoxia), which is significant as the new prototype system provides similar measures and trends for each brain injury type, suggesting that the optical system can be used in response to different injury mechanisms. Notably, the results support the idea that this optical system can probe the hemodynamic status of local cerebral cortical tissue and provide insight into the underlying changes of cerebral tissue perfusion at the microvascular level. These measurement capabilities can improve shock identification and monitoring of medical management of injuries, particularly hemorrhagic shock, in prolonged field care.

A generalized signal model for dual-module velocity-selective arterial spin labeling.

To develop a generalized signal model for dual-module velocity-selective arterial spin labeling (dm-VSASL) that can integrate arbitrary saturation and inversion profiles. A recently developed mathematical framework for single-module VSASL is extended to address the increased complexity of dm-VSASL and to model the use of realistic velocity-selective profiles in the label-control and vascular crushing modules. Expressions for magnetization difference, arterial delivery functions, labeling efficiency, and cerebral blood flow (CBF) estimation error are presented. Sources of error are examined and timing requirements to minimize quantification errors are derived. For ideal velocity-selective profiles, the predicted signals match those of prior work. With realistic profiles, a CBF-dependent estimation error can occur when velocity-selective inversion (VSI) is used for the labeling modules and velocity-selective saturation (VSS) is used for the vascular crushing module. The error reflects a mismatch between the leading and trailing edges of the delivery function for the second bolus and can be minimized by choosing a nominal labeling cutoff velocity that is lower than the nominal saturation cutoff velocity. In the presence of and inhomogeneities, the labeling efficiency of dual-module VSI is more attenuated than that of dual-module VSS. The proposed signal model will enable researchers to more accurately assess and compare the performance of realistic dm-VSASL implementations and improve the quantification of dm-VSASL CBF measures.

Shifting concepts of autoregulation: Commentary to ‘Static autoregulation in humans'

Advances in imaging techniques have transformed our understanding of cerebral autoregulation. Older imaging techniques provided measurements of cerebral blood flow (CBF) that reflected the average CBF over a window of 10–20 minutes. A key finding, dating back to 1959, was that CBF remained more or less stable over a remarkably wide range of changes in blood pressure. Modern techniques can measure changes in CBF within the time frame of a heartbeat. They have revealed, paradoxically, a remarkable instability of CBF. This commentary attempts to reconcile these seemingly contradictory observations.

Simultaneous and cumulative effects of tDCS on cerebral metabolic rate of oxygen in multiple sclerosis.

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique with simultaneous (during stimulation) and cumulative effects (after repeated sessions) on blood flow and neuronal metabolism. These effects remain mostly unclear especially in multiple sclerosis (MS). This work aims to elucidate brain metabolic and hemodynamic underpinnings of tDCS and its potential therapeutic impact in MS patients using quantitative tDCS-MRI. MS participants (n = 20; age = 45.4 ± 12.3 years, 7 males) underwent 3 T MRI scans before and after 20 daily sessions of dorsolateral prefrontal cortex (DLFPC) tDCS (2.0 mA, left anodal) paired with adaptive cognitive training (aCT). During both visits, imaging measurements of cerebral blood flow (CBF), cerebral venous blood oxygenation (Yv) and calculated cerebral metabolic rate of oxygen (CMRO2) were obtained at pre-tDCS, during-tDCS and post-tDCS. At baseline, significant increase from pre- to during-tDCS was observed in CMRO2 (7.6%; p = 0.002), CBF (11.0%; p < 0.0001) and Yv (1.9%; p = 0.006). At follow up, we observed an increase in pre-tDCS CMRO2 (140.59 ± 13.83 μmol/100 g/min) compared to baseline pre-tDCS levels (128.30 ± 14.00 μmol/100 g/min; p = 0.006). Sustained elevations in CMRO2 and CBF into post-tDCS were also observed (tDCS lingering effects). Cumulative tDCS effects were observed in the form of sustained elevations in CMRO2 and CBF in pre-tDCS follow up, reaching the magnitudes measured at baseline during-tDCS. TDCS induces an acute surge in metabolic activity persisting immediately after the stimulation is removed. Moreover, treatment composed of repeated tDCS-aCT paired sessions contributes to establishing long-lasting increases in neuronal activity.

Arterial Spin Labeling Magnetic Resonance Imaging for Acute Disorders of Consciousness in the Intensive Care Unit.

To investigate patients with disorders of consciousness (DoC) for residual awareness, guidelines recommend quantifying glucose brain metabolism using positron emission tomography. However, this is not feasible in the intensive care unit (ICU). Cerebral blood flow (CBF) assessed by arterial spin labeling magnetic resonance imaging (ASL-MRI) could serve as a proxy for brain metabolism and reflect consciousness levels in acute DoC. We hypothesized that ASL-MRI would show compromised CBF in coma and unresponsive wakefulness states (UWS) but relatively preserved CBF in minimally conscious states (MCS) or better. We consecutively enrolled ICU patients with acute DoC and categorized them as being clinically unresponsive (i.e., coma or UWS [≤ UWS]) or low responsive (i.e., MCS or better [≥ MCS]). ASL-MRI was then acquired on 1.5T or 3T. Healthy controls were investigated with both 1.5T and 3T ASL-MRI. We obtained 84 ASL-MRI scans from 59 participants, comprising 36 scans from 35 patients (11 women [31.4%]; median age 56years, range 18-82years; 24 ≤ UWS patients, 12 ≥ MCS patients; 32 nontraumatic brain injuries) and 48 scans from 24 healthy controls (12 women [50%]; median age 50years, range 21-77years). In linear mixed-effects models of whole-brain cortical CBF, patients had 16.2mL/100g/min lower CBF than healthy controls (p = 0.0041). However, ASL-MRI was unable to discriminate between ≤ UWS and ≥ MCS patients (whole-brain cortical CBF: p = 0.33; best hemisphere cortical CBF: p = 0.41). Numerical differences of regional CBF in the thalamus, amygdala, and brainstem in the two patient groups were statistically nonsignificant. CBF measurement in ICU patients using ASL-MRI is feasible but cannot distinguish between the lower and the upper ends of the acute DoC spectrum. We suggest that pilot testing of diagnostic interventions at the extremes of this spectrum is a time-efficient approach in the continued quest to develop DoC neuroimaging markers in the ICU.

Differentiation Between High-Grade Glioma and Brain Metastasis Using Cerebral Perfusion-Related Parameters (Cerebral Blood Volume and Cerebral Blood Flow): A Systematic Review and Meta-Analysis of Perfusion-weighted MRI Techniques.

Distinguishing high-grade gliomas (HGGs) from brain metastases (BMs) using perfusion-weighted imaging (PWI) remains challenging. PWI offers quantitative measurements of cerebral blood flow (CBF) and cerebral blood volume (CBV), but optimal PWI parameters for differentiation are unclear. To compare CBF and CBV derived from PWIs in HGGs and BMs, and to identify the most effective PWI parameters and techniques for differentiation. Systematic review and meta-analysis. Twenty-four studies compared CBF and CBV between HGGs (n = 704) and BMs (n = 488). Arterial spin labeling (ASL), dynamic susceptibility contrast (DSC), dynamic contrast-enhanced (DCE), and dynamic susceptibility contrast-enhanced (DSCE) sequences at 1.5 T and 3.0 T. Following the PRISMA guidelines, four major databases were searched from 2000 to 2024 for studies evaluating CBF or CBV using PWI in HGGs and BMs. Standardized mean difference (SMD) with 95% CIs was used. Risk of bias (ROB) and publication bias were assessed, and I2 statistic was used to assess statistical heterogeneity. A P-value<0.05 was considered significant. HGGs showed a significant modest increase in CBF (SMD = 0.37, 95% CI: 0.05-0.69) and CBV (SMD = 0.26, 95% CI: 0.01-0.51) compared with BMs. Subgroup analysis based on region, sequence, ROB, and field strength for CBF (HGGs: 375 and BMs: 222) and CBV (HGGs: 493 and BMs: 378) values were conducted. ASL showed a considerable moderate increase (50% overlapping CI) in CBF for HGGs compared with BMs. However, no significant difference was found between ASL and DSC (P = 0.08). ASL-derived CBF may be more useful than DSC-derived CBF in differentiating HGGs from BMs. This suggests that ASL may be used as an alternative to DSC when contrast medium is contraindicated or when intravenous injection is not feasible. Stage 2.

Identification of toll-like receptor 2 as a key regulator of neuronal apoptosis in vascular dementia by bioinformatics analysis and experimental validation

BackgroundVascular dementia (VaD), the second most prevalent type of dementia, lacks a well-defined cause and effective treatment. Our objective was to utilize bioinformatics analysis to discover the fundamental disease-causing genes and pathological mechanisms in individuals diagnosed with VaD. MethodsTo identify potential pathogenic genes associated with VaD, we conducted weighted gene co-expression network analysis (WGCNA), differential expression analysis, and protein–protein interaction (PPI) analysis. The exploration of potential biological mechanisms involved the utilization of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis. Moreover, a bilateral common carotid artery stenosis (BCAS) mouse model of VaD was established, and the expression of the hub gene, its relationship with cognitive function and its potential pathogenic mechanism were verified by cognitive behavior tests, cerebral blood flow measurement, Western blotting, and immunofluorescence experiments. ResultsThis study identified 293 DEGs from the brain cortex of VaD patients and healthy controls, among these genes, the Toll-like receptor 2 (TLR2) gene was identified as hub gene, and it was associated with the apoptosis-related pathway PI3K/AKT.The BCAS model demonstrated that the use of TLR2 inhibitors greatly enhanced the cognitive function of the mice (p < 0.05). Additionally, there was a notable decrease in the number of apoptotic cells in the brain cortex of the mice (p < 0.01). Moreover, significant alterations in the levels of proteins related to the PI3K/AKT pathway and cleaved-caspase3 proteins were detected (p < 0.05). ConclusionsTLR2 plays a role in the pathophysiology of VaD by enhancing the neuronal apoptotic pathway, suggesting it could be a promising therapeutic target.

Multi-Tracer Studies of Brain Oxygen and Glucose Metabolism Using a Time-of-Flight Positron Emission Tomography - Computed Tomography Scanner.

The authors have developed a paradigm using positron emission tomography (PET) with multiple radiopharmaceutical tracers that combines measurements of cerebral metabolic rate of glucose (CMRGlc), cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF), and cerebral blood volume (CBV), culminating in estimates of brain aerobic glycolysis (AG). These in vivo estimates of oxidative and non-oxidative glucose metabolism are pertinent to the study of the human brain in health and disease. The latest positron emission tomography-computed tomography (PET-CT) scanners provide time-of-flight (TOF) imaging and critical improvements in spatial resolution and reduction of artifacts. This has led to significantly improved imaging with lower radiotracer doses. Optimized methods for the latest PET-CT scanners involve administering a sequence of inhaled 15O-labeled carbon monoxide (CO) and oxygen (O2), intravenous 15O-labeled water (H2O), and 18F-deoxyglucose (FDG)-all within 2-h or 3-h scan sessions that yield high-resolution, quantitative measurements of CMRGlc, CMRO2, CBF, CBV, and AG. This methods paper describes practical aspects of scanning designed for quantifying brain metabolism with tracer kinetic models and arterial blood samples and provides examples of imaging measurements of human brain metabolism.

Study of Time-Resolved Dynamics in Turbid Medium Using a Single-Cavity Dual-Comb Laser.

In measuring cerebral blood flow (CBF) noninvasively using optical techniques, diffusing-wave spectroscopy is often combined with near-infrared spectroscopy to obtain a reliable blood flow index. Measuring the blood flow index at a determined depth remains the ultimate goal. In this study, we present a simple approach using dual-comb lasers where we simultaneously measure the absorption coefficient (μa), the reduced scattering coefficient (μs '), and dynamic properties. This system can also effectively differentiate dynamics from various depths, which is crucial for analyzing multilayer dynamics. For CBF measurements, this capability is particularly valuable as it helps mitigate the influence of the scalp and skull, thereby enhancing the specificity of deep tissue.

Compact and cost-effective laser-powered speckle contrast optical spectroscopy fiber-free device for measuring cerebral blood flow.

In the realm of cerebrovascular monitoring, primary metrics typically include blood pressure, which influences cerebral blood flow (CBF) and is contingent upon vessel radius. Measuring CBF noninvasively poses a persistent challenge, primarily attributed to the difficulty of accessing and obtaining signal from the brain. Our study aims to introduce a compact speckle contrast optical spectroscopy device for noninvasive CBF measurements at long source-to-detector distances, offering cost-effectiveness, and scalability while tracking blood flow (BF) with remarkable sensitivity and temporal resolution. The wearable sensor module consists solely of a laser diode and a board camera. It can be easily placed on a subject's head to measure BF at a sampling rate of 80Hz. Compared to the single-fiber-based version, the proposed device achieved a signal gain of about 70 times, showed superior stability, reproducibility, and signal-to-noise ratio for measuring BF at long source-to-detector distances. The device can be distributed in multiple configurations around the head. Given its cost-effectiveness, scalability, and simplicity, this laser-centric tool offers significant potential in advancing noninvasive cerebral monitoring technologies.

Simultaneous assessment of blood flow and myelin content in the brain white matter with dynamic [11C]PiB PET: a test-retest study in healthy controls.

Exploring the relationship between oxygen supply and myelin damage would benefit from a simultaneous quantification of myelin and cerebral blood flow (CBF) in the brain's white matter (WM). To validate an analytical method for quantifying both CBF and myelin content in the WM using dynamic [11C]PiB positron emission tomography (PET). A test-retest study was performed on eight healthy subjects who underwent two consecutive dynamic [11C]PiB-PET scans. Three quantitative approaches were compared: simplified reference tissue model 2 (SRTM2), LOGAN graphical model, and standardized uptake value ratio (SUVR). The sensitivity of methods to the size of the region of interest was explored by simulating lesion masks obtained from 36 subjects with multiple sclerosis. Reproducibility was assessed using the relative difference and interclass correlation coefficient. Repeated measures correlations were used to test for cross-correlations between metrics. Among the CBF measures, the relative delivery (R1) of the simplified reference tissue model 2 (SRTM2) displayed the best reproducibility in the white matter, with a strong influence of the size of regions analyzed, the test-retest variability being below 10% for regions above 68 mm3 in the supratentorial white matter. [11C]PiB PET-derived proxies of CBF demonstrated lower perfusion of white matter compared to grey matter with an overall ratio equal to 1.71 ± 0.09 when the SRTM2-R1 was employed. Tissue binding in the white matter was well estimated by the Logan graphical model through estimation of the distribution volume ratio (LOGAN-DVR) and SRTM2 distribution volume ratio (SRTM2-DVR), with test-retest variability being below 10% for regions exceeding 106 mm3 for LOGAN-DVR and 300 mm3 for SRTM2-DVR. SRTM2-DVR provided a better contrast between white matter and grey matter. The interhemispheric variability was also dependent on the size of the region analyzed, being below 10% for regions above 103 mm3 for SRTM2-R1 and above 110 mm3 for LOGAN-DVR. Whereas the 1 to 8-minute standardized uptake value ratio (SUVR1-8) showed an intermediary reproducibility for CBF assessment, SUVR0-2 for perfusion or SUVR50-70 for tissue binding showed poor reproducibility and correlated only mildly with SRTM2-R1 and LOGAN-DVR estimations respectively. [11C]PiB PET imaging can simultaneously quantify perfusion and myelin content in WM diseases associated with focal lesions. For longitudinal studies, SRTM2-R1 and DVR should be preferred over SUVR for the assessment of regional CBF and myelin content, respectively. European Union Clinical Trials Register EUDRACT; EudraCT Number: 2008-004174-40; Date: 2009-03-06; https//www.clinicaltrialsregister.eu ; number 2008-004174-40.