Spin Labeling Research Articles

A novel method for functional brain networks based on static cerebral blood flow.

Cerebral blood flow (CBF) offers a quantitative and reliable measurement for brain activity and is increasingly used to study functional networks. However, current methods evaluate inter-regional relations mainly based on CBF temporal dynamics, which suffers from low signal-to-noise ratio and poor temporal resolution. Here we proposed a method to construct functional brain networks by estimating shape similarity (index by Jensen-Shannon divergence) in probability distributions of regional static CBF measured by arterial spin labeling perfusion imaging over a scanning period. Based on CBF data of 30 healthy participants from 10 visits, we found that the CBF networks exhibited non-trivial topological features (e.g., small-world organization, modular architecture, and hubs) and showed low-to-fair test-retest reliability and high between-subject consistency. We further found that interregional CBF similarities were depended on anatomical distance and differed between high- and lower-order subnetworks. Moreover, interregional CBF similarities within high-order subnetworks showed significantly lower reliability than those within low-order subnetworks. Finally, we showed that nodal degree of the CBF networks were related to regional sizes and CBF levels and spatially aligned with maps of the dopamine transporter and metabolic glutamate receptor 5 intensities, expression levels of genes primarily enriched in cholesterol-related pathways and endothelial cells, and meta-analytic activations related to memory, language, and executive function. Altogether, our proposed method provide a novel, relatively reliable, and neurobiologically meaningful means to study functional network organization of the human brain.

Blood-brain barrier water permeability across the adult lifespan: A multi-echo ASL study.

An emerging biomarker of blood-brain barrier (BBB) permeability is the time of exchange (Tex) of water from the blood to tissue, as measured by multi-echo arterial spin labeling (ASL) MRI. This new non-invasive sequence, already tested in mice, has recently been adapted to humans and optimized for clinical scanning time. In this study, we studied the normal variability of Tex over age and sex, which needs to be established as a reference for studying changes in neurological disease. We evaluated Tex, cerebral blood flow (CBF) and arterial transit time (ATT) in 209 healthy adults between 26 and 87 years, over age and sex, using general linear models in gray matter, white matter, and regionally in cerebral lobes. After QC, 194 participants were included in the main analysis, and the results demonstrated that both gray matter (GM) and white matter (WM) BBB permeability was higher with higher age (Tex lower by 0.47 ms per year in GM [p < 0.05], and by 0.49 ms in WM, for females; no significant for males), with the largest Tex difference in the frontal lobes (0.64 ms decrease per year, p = 0.011, population average). CBF was lower with higher age in the GM (-0.71 mL/min/100g per year, p < 0.001, for females; -0.31 mL/min/100g per year, p < 0.05, for males). When correcting Tex models for CBF and ATT, effect of age on Tex disappears in the GM, but not in the WM (β=-0.28, p = 0.08). The CBF findings of this study are in line with previous studies, demonstrating the validity of the new sequence. The BBB water permeability variation over age and sex described in this study provides a reference for future BBB research.

Advantages and challenges of using arterial spin labelling MRI to monitor cerebral blood flow in multi-centre clinical trials of neurodegenerative disease: Experience from the RADAR study.

Arterial spin labelling (ASL) enables non-invasive quantification of regional brain perfusion using MRI. ASL was used in the Reducing Pathology in Alzheimer's Disease through Angiotensin TaRgeting (RADAR) multi-centre trial to pilot the assessment of the effects of the anti-hypertension drug losartan on cerebral blood flow (CBF). In the multi-centre setting, disparities in ASL implementation on scanners from different manufacturers lead to inherent differences in measured CBF and its associated parameters (e.g. spatial coefficient of variation (sCoV) of CBF, a proxy of arterial arrival times). In addition, differences in ASL acquisition parameter settings can also affect the measured quantitative perfusion values. In this study, we used data from the RADAR cohort as a case study to evaluate the site-dependent systematic differences of CBF and sCoV, and show that variations in the readout module (2D or 3D) and the post-labelling delay acquisition parameter introduced artifactual group differences. When accounting for this effect in data analysis, we show that it is still possible to combine ASL data across sites to observe the expected relationships between grey matter CBF and cognitive scores. In summary, ASL can provide useful information relating to CBF difference in multi-centre therapeutic trials, but care must be taken in data analysis to account for the inevitable inter-site differences in scanner type and acquisition protocol.

Multimodal magnetic resonance imaging studies on non-motor symptoms of Parkinson's disease.

This study aims to investigate the diagnostic value of multi-modal magnetic resonance imaging (MRI) utilizing arterial spin labeling (ASL), quantitative susceptibility mapping (QSM), and 3D T1-weighted imaging (3DT1WI) in patients with Parkinson's disease (PD). Additionally, it evaluates the relationship between MRI findings and non-motor symptoms associated with PD. ASL, QSM, and 3DT1WI scans were performed on 48 PD patients and 46 healthy controls (HC). We extracted and analyzed differences in regional cerebral blood flow (rCBF), magnetic susceptibility, and gray matter density parameters between the two groups. These MRI parameters were correlated with clinical scale scores assessing non-motor symptoms, including cognitive function, sleep quality, olfaction, autonomic function, anxiety, depression, and fatigue. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic accuracy of each imaging modality in distinguishing PD from HC. The areas under the ROC curve (AUC) for rCBF, magnetic susceptibility, and gray matter density were 0.941, 0.979, and 0.624, respectively. In PD patients, a negative correlation was found between Unified Parkinson's Disease Rating Scale Part II (UPDRS II) scores and rCBF in the bilateral precuneus. The Pittsburgh Sleep Quality Index (PSQI) scores negatively correlated with rCBF in the left middle temporal gyrus and right middle occipital gyrus. Hamilton Depression Rating Scale (HAMD) scores positively correlated with QSM values in the right supplementary motor area, while scores on the Argentine Smell Identification Test (AHRS) negatively correlated with QSM values in the same area. Disease duration showed a positive correlation with QSM values in the right middle cingulate gyrus. Additionally, PSQI scores positively correlated with QSM values in the left middle cingulate gyrus, and fatigue severity scale (FSS) scores also positively correlated with QSM values in the left middle cingulate gyrus. Gray matter atrophy in the left inferior temporal gyrus was associated with cognitive impairment in PD. Occipital hypoperfusion and cortical atrophy in the left inferior temporal gyrus may serve as novel imaging biomarkers for PD and are associated with sleep disturbances and cognitive impairment in PD patients. Extensive iron deposition in the bilateral cerebral cortex of PD patients may be a contributing factor to non-motor symptoms such as sleep disturbances and fatigue. Multimodal imaging techniques, including ASL, QSM, and 3DT1WI, can enhance the diagnostic accuracy for PD.

Double inversion recovery for mitigating the impact of heart rate variability in myocardial arterial spin labeling

Double inversion recovery for mitigating the impact of heart rate variability in myocardial arterial spin labeling

Ictal 1.5-Tesla MR imaging with arterial spin labeling perfusion imaging in three patients with electrographic seizures diagnosed with routine electroencephalography based on the ACNS Critical Care EEG Terminology 2021

Ictal 1.5-Tesla MR imaging with arterial spin labeling perfusion imaging in three patients with electrographic seizures diagnosed with routine electroencephalography based on the ACNS Critical Care EEG Terminology 2021

A Test-Retest Study of Single- and Multi-Delay pCASL for Choroid Plexus Perfusion Imaging in Healthy Subjects Aged 19 to 87 Years.

There is a growing interest in the choroid plexus (ChP) due to its critical role in cerebrospinal fluid (CSF) production and its involvement in neurodegenerative and cerebrovascular diseases. However, comprehensive studies comparing the accuracy and reliability of single- and multi-PLD (post-labeling delay) arterial spin labeling (ASL) techniques, specifically in relation to the ChP, remain limited. This study systematically evaluated the test-retest reliability and quantification accuracy of cerebral blood flow (CBF) measurements, focusing on the ChP, using single-delay and multi-delay 3D gradient-and-spin echo (GRASE) pseudo-continuous ASL (pCASL) on 28 subjects (aged 19 to 87 years, 14 males/14 females) at 3.0 tesla. Both single-delay (2 sec) and 5-PLD (0.5 - 2.5 sec) pCASL scans were repeated approximately one week apart with a spatial resolution of 2.5×2.5×3 mm³. Voxel-wise and regional CBF and arterial transit time (ATT) measurements were compared to assess test-retest reliability, with a particular focus on ChP perfusion changes with age. In this study, 12.15% of ChP voxels exhibited ATTs longer than 2 sec, potentially leading to a significant underestimation of CBF using single-delay ASL. Multi-delay ASL showed improved accuracy in estimating CBF values for the ChP compared to single-delay ASL when ATT > PLD. Additionally, ChP volume (mean ± std = 1.72± 0.85 ml) increased (p < 0.01) and ChP perfusion (43.07±14.18 mL/100 g/min) decreased (p = 0.04) with age. These findings underscore the robustness of multi-delay ASL with model-fitting quantification in assessing ChP perfusion, making it the preferred method for accurate CBF and ATT estimation, particularly in regions with prolonged transit time such as ChP.

Utilizing arterial spin labeling MRI for serial monitoring in pediatric patients with pulmonary embolisms

Utilizing arterial spin labeling MRI for serial monitoring in pediatric patients with pulmonary embolisms

Enhanced Benefit of STA-MCA Bypass Surgery in Chronic Terminal Internal Carotid and/or Middle Cerebral Artery Occlusion Patients With Impaired Collateral Circulation: Introducing a Novel Assessment Approach for Collateral Compensation.

Background: Ischemic stroke is one of the major emergency diseases leading to death and disability worldwide, characterized by its acute onset and the urgent need for prompt medical intervention to reduce mortality and long-term disability. Chronic terminal internal carotid artery and/or middle cerebral artery occlusion (CTI/MCAO) is an important subtype of intracranial artery occlusive disease. The superficial temporal artery-to-MCA (STA-MCA) bypass has been proposed to improve cerebral blood flow (CBF) and cerebrovascular reserve (CVR), potentially enhancing neurological outcomes. However, its safety and efficacy in CTI/MCAO patients remain controversial. Methods: A total of 107 CTI/MCAO patients from Nanjing Brain Hospital, enrolled between July 2019 and June 2022, were divided into surgical and medical treatment groups. Cerebral perfusion and collateral formation were evaluated using pseudocontinuous arterial spin labeling (pCASL) and digital subtraction angiography (DSA). Modified Rankin scale (mRS) score and complication rates were compared between the two groups. In addition, correlations between Matsushima grades, early-arriving flow proportion (EFP), and lesion-side cerebrovascular (LCBV) scores were analyzed. Results: The surgical group showed significantly lower mRS scores than the medical group (p=0.018), with no significant differences in complication rates at the 6-month follow-up (p=0.861). CBF differed significantly among affected MCA segments (p < 0.001), particularly in the insular and opercular regions (M2-M3) (p=0.006). Matsushima grades in unilateral CTI/MCAO patients were negatively correlated with preoperative LCBV scores (γ s = -0.468, p=0.005) and EFP (γ s = -0.648, p=0.007). EFP demonstrated high accuracy in predicting LCBV scores in CTI/MCAO patients (AUC = 0.902, p=0.004). Conclusion: STA-MCA bypass surgery improved neurological outcomes in CTI/MCAO patients, particularly those with poor preoperative collateral compensation. EFP may serve as a reliable, noninvasive tool for assessing collateral circulation status in this population.

Pretreatment arterial spin labeling combined with radiological depth of invasion predicts treatment outcome in nonmetastatic NPC.

To investigate the value of arterial spin labeling (ASL) and radiological depth of invasion (rDOI) in predicting long-term treatment outcomes in nonmetastatic nasopharyngeal carcinoma (NPC). A total of 113 patients with NPC were included and randomly divided into training (n = 81) and validation (n = 32) cohorts. Tumor blood flow (TBF) parameters derived from the ASL (TBFMean, TBFSD, and nTBF) were obtained. Two radiologists independently measured the rDOI in both axial (rDOI_a) and coronal (rDOI_c) planes, subsequently categorizing patients into low-risk and high-risk groups. Spearman analysis was used to explore the correlation. In the training cohort, ASL-based, ASL+rDOI, and TNM models were constructed using univariate and multivariate Cox regression analyses. Model performance, including calibration, robustness, discrimination, and clinical utility, was assessed in both training and validation cohorts. The net classification index (NRI) and integrated discrimination improvement (IDI) were calculated. The median follow-up duration was 63.4 (56.2, 100.1) months. Disease progression and death occurred in 45 (39.8%) and 32 (28.3%) patients, respectively. TBFMean and rDOI were independent predictors of overall survival (OS) (hazard ratios [HR], 0.973 and 2.975, respectively) and progression-free survival (PFS) (HR, 0.985 and 2.207, respectively). rDOI_a and rDOI_c were significantly correlated with T stage (r = 0.538-0.738, P ≤ 0.002). The ASL+rDOI model demonstrated good robustness and clinical utility in both training and validation cohorts. Post-hoc subgroup analysis showed favorable results. TBFMean and rDOI can predict survival outcomes in patients with NPC. Adding rDOI further improved the prediction performance.

Quantitative imaging for early detection and risk stratification of cardiovascular disease using 4D flow MRI and arterial spin labelling

Heart failure (HF) significantly burdens global healthcare, necessitating early detection and precise risk stratification. Advanced imaging techniques like 4D flow Magnetic resonance imaging (MRI) and arterial spin labelling (ASL) provide crucial insights into cardiac function by capturing complex flow patterns and measuring myocardial blood flow. Hence, this study explores how these modalities can enhance early detection and risk assessment of cardiovascular diseases, aiming to improve patient outcomes. Ten patients aged ≤ 65 with clinically compensated cardiomyopathy were recruited. MRI examinations included 4D flow MRI using a 1.5 T Philips Achieva Scanner and ASL imaging on a 3 Tesla scanner. Data analysis for 4D flow MRI involved segmenting the left ventricle and categorizing pathlines into flow components, while ASL data were analyzed using Buxton’s model to quantify myocardial blood flow (MBF). The study population had a mean age of 49 ± 14 years, predominantly female (6:4). Average heart rate was 61 ± 11 bpm and blood pressures averaged 122/77 mmHg. Left ventricular end-diastolic volume was 179 ± 33 mL with an ejection fraction of 42 ± 5%. Patients showed lower direct flow volume and kinetic energy in early diastolic phases compared to healthy individuals. In conclusion, 4D flows MRI and accelerated ASL are effective for early detection and risk stratification in cardiovascular disease, offering enhanced cardiovascular assessment and potential improvements in patient care.

MVP-VSASL: measuring MicroVascular Pulsatility using velocity-selective arterial spin labeling.

By leveraging the small-vessel specificity of velocity-selective arterial spin labeling (VSASL), we present a novel technique for measuring cerebral MicroVascular Pulsatility named MVP-VSASL. We present a theoretical model relating the pulsatile, cerebral blood flow-driven VSASL signal to the microvascular pulsatility index ( ), a widely used metric for quantifying cardiac-dependent fluctuations. The model describes the dependence of the of VSASL signal (denoted ) on bolus duration (an adjustable VSASL sequence parameter) and provides guidance for selecting a value of that maximizes the SNR of the measurement. The model predictions were assessed in humans using data acquired with retrospectively cardiac-gated VSASL sequences over a broad range of values. In vivo measurements were also used to demonstrate the feasibility of whole-brain voxel-wise pulsatility mapping, assess intrasession repeatability of , and illustrate the potential of this method to explore an association with age. The theoretical model showed excellent agreement to the empirical data in a gray matter region of interest (average value of 0.898 0.107 across six subjects). We further showed excellent intrasession repeatability of the pulsatility measurement ( , ) and the potential to characterize associations with age ( , ). We have introduced a novel, VSASL-based cerebral microvascular pulsatility technique, which may facilitate investigation of cognitive disorders where damage to the microvasculature has been implicated.

Ultra‐high temporal resolution 4D angiography using arterial spin labeling with subspace reconstruction

AbstractPurposeTo achieve ultra‐high temporal resolution non‐contrast 4D angiography with improved spatiotemporal fidelity.MethodsContinuous data acquisition using 3D golden‐angle sampling following an arterial spin labeling preparation allows for flexibly reconstructing 4D dynamic angiograms at arbitrary temporal resolutions. However, k‐space data is often temporally “binned” before image reconstruction, negatively affecting spatiotemporal fidelity and limiting temporal resolution. In this work, a subspace was extracted by linearly compressing a dictionary constructed from simulated curves of an angiographic kinetic model. The subspace was used to represent and reconstruct the voxelwise signal timecourse at the same temporal resolution as the data acquisition without temporal binning. Physiological parameters were estimated from the resulting images using a Bayesian fitting approach. A group of eight healthy subjects were scanned and the in vivo results reconstructed by different methods were compared. Because of the difficulty of obtaining ground truth 4D angiograms with ultra‐high temporal resolution, the in vivo results were cross‐validated with numerical simulations.ResultsThe proposed method enables 4D time‐resolved angiography with much higher temporal resolution (14.7 ms) than previously reported (˜50 ms) while maintaining high spatial resolution (1.1 mm isotropic). Blood flow dynamics were depicted in greater detail, thin vessel visibility was improved, and the estimated physiological parameters also exhibited more realistic spatial patterns with the proposed method.ConclusionIncorporating a subspace compressed kinetic model into the reconstruction of 4D ASL angiograms notably improved the temporal resolution and spatiotemporal fidelity, which was subsequently beneficial for accurate physiological modeling.

Efficient Orthogonal Spin Labeling of Proteins via Aldehyde Cyclization for Pulsed Dipolar EPR Distance Measurements.

Pulsed dipolar electron paramagnetic resonance (PD-EPR) measurement is a powerful technique for characterizing the interactions and conformational changes of biomolecules. The extraction of these distance restraints from PD-EPR experiments relies on manipulation of spin-spin pairs. The orthogonal spin labeling approach offers unique advantages by providing multiple distances between different spin-spin pairs. Here, we report an efficient orthogonal labeling approach based on exploiting the cyclization between the 1,2-aminothiol moiety in a protein (e.g., the N-terminal cysteine) with the aldehyde group in a spin label and a thiol substitution (or addition) reaction with a different spin label. We demonstrated that this orthogonal spin labeling method enables high accuracy and precision of multiple protein distance constraints through the PD-EPR measurement from a single sample. This spin labeling approach was applied to characterize the oligomeric state of the trigger factor (TF) protein of Escherichia coli, an important protein chaperone, in solution and cell lysates by distance measurements between different spin-spin pairs. Contrary to popular belief, TF exists mainly in the monomeric state and not as a dimer in the cell lysate.

Altered neurovascular coupling and structure-function coupling in Moyamoya disease affect postoperative collateral formation

Chronic ischemia in moyamoya disease (MMD) impaired white matter microstructure and neural functional network. However, the coupling between cerebral blood flow (CBF) and functional connectivity and the association between structural and functional network are largely unknown. 38 MMD patients and 20 sex/age-matched healthy controls (HC) were included for T1-weighted imaging, arterial spin labeling imaging, resting-state functional MRI and diffusion tensor imaging. All patients had preoperative and postoperative digital subtraction angiography. Upon constructing the structural connectivity (SC) and functional connectivity (FC) networks, the SC-FC coupling was calculated. After obtaining the graph theoretical parameters, neurovascular coupling represented the spatial correlation between node degree centrality (DC) of functional networks and CBF. The CBF-DC coupling and SC-FC coupling were compared between MMD and HC groups. We further analyzed the correlation between coupling indexes and cognitive scores, as well as postoperative collateral formation. Compared with HC, CBF-DC coupling was decreased in MMD (p = 0.021), especially in the parietal lobe (p = 0.047). SC-FC coupling in MMD decreased in frontal, occipital, and subcortical regions. Cognitive scores were correlated with the CBF-DC coupling in frontal lobes (r = 0.394, p = 0.029) and SC-FC coupling (r = 0.397, p = 0.027). The CBF-DC coupling of patients with good postoperative collateral formation was higher (p = 0.041). Overall, neurovascular decoupling and structure-functional decoupling at the cortical level may be the underlying neuropathological mechanisms of MMD.

Evaluating Vascular Hemodynamics in Cerebral Proliferative Angiopathy Using Advanced Arterial Spin Labeling MRI

Cerebral proliferative angiopathy (CPA) is a rare vascular disorder that affects normal blood circulation in the brain. Although the structural changes in CPA can be characterized using standard radiologic modalities, assessing the vascular hemodynamics in patients with CPA remains challenging due to inadequate imaging technologies. Arterial spin labeling (ASL) is a noninvasive magnetic resonance technique that allows quantitative assessments of cerebral blood flow. ASL with multiple labeling delays (multidelay ASL) also enables the quantification of arterial transit time. Here, we report the first application of multidelay ASL in a patient with CPA before and after bypass surgery. Our study demonstrated that ASL can be effectively applied to evaluating hemodynamic changes in patients with CPA. Our quantitative results indicated that, in regions affected by CPA, cerebral blood flow increased by at least 14% and arterial transit time decreased by 9.4% after bypass surgery.

Response to clozapine in treatment resistant schizophrenia is related to alterations in regional cerebral blood flow

AbstractPET and SPECT studies in treatment-resistant schizophrenia (TRS) have revealed significant alterations in regional cerebral blood flow (CBF) during clozapine treatment, which may vary according to the clinical response. Here, we used the more recent MRI approach of arterial spin labelling (ASL) to evaluate regional CBF in participants with TRS (N = 36) before starting treatment with clozapine compared to in healthy volunteers (N = 16). We then compared CBF in the TRS group, before and after 12 weeks of treatment with clozapine (N = 24); and examined the relationship of those differences against changes in Positive and Negative Syndrome Scale for Schizophrenia (PANSS) scores over the treatment period. We observed widespread reductions in CBF in TRS compared to in healthy volunteers (p &lt; 0.05). After covarying for global CBF and age, lower CBF in frontal and parietal regions was still evident (p &lt; 0.05, FWE corrected). Clozapine treatment was associated with longitudinal decreases in CBF in the anterior cingulate cortex (ACC) (p &lt; 0.05). Higher striatal CBF at baseline was associated with greater improvement in total and general symptoms following clozapine, and higher hippocampal CBF was associated with greater improvement in total and positive symptoms. Longitudinal reductions in CBF in the ACC and thalamus were associated with less improvement in negative (ACC), positive (thalamus), and total (thalamus) symptoms. These findings suggest that changes in CBF on clozapine administration in TRS may accompany symptomatic improvement, and that CBF prior to clozapine initiation may determine the degree of clinical response.

Analysis of the MODIST Sequence for Selective Proton-Proton Recoupling.

Theoretical and simulated analyses of selective homonuclear dipolar recoupling sequences serve as primary tools for understanding and determining the robustness of these sequences under various conditions. In this article, we investigate the recently proposed first-order dipolar recoupling sequence known as MODIST (Modest Offset Difference Internuclear Selective Transfer). We evaluate the MODIST transfer efficiency, assessing its dependence on rf-field strengths and the number of simulated spins, extending up to 10 spins. This helps to identify conditions that enhance polarization transfer among spins that are nearby in frequency, particularly among aliphatic protons. The exploration uncovers a novel effect for first-order selective recoupling sequences that we term "facilitated dipolar recoupling". This effect amplifies the recoupled dipolar interaction between distant spins due to the presence of additional strongly dipolar-coupled spins. Unlike the third spin-assisted recoupling mechanism, facilitated dipolar recoupling only requires a coupling to one of the two distant spins of interest. Experimental demonstration of MODIST, including at different rf-field strengths, was carried out with the membrane protein influenza A M2 in lipid bilayers using 55 kHz magic-angle spinning (MAS). Reducing MODIST rf-field strength by a factor of 2 unveils possibilities for detecting Hα-Hα and HMeth-HMeth correlations with a 3D (H)C(H)(H)CH experiment under fast MAS rates, all achievable without specific spin labeling.

Enabling structural biological electron paramagnetic resonance spectroscopy in membrane proteins through spin labelling.

Pulsed dipolar electron paramagnetic resonancespectroscopy (PDS), combined with site-directed spin-labelling, represents a powerful tool for the investigation of biomacromolecules, emerging as a keystone approach in structural biology. Increasingly, PDS is applied to study highly complex integral membrane protein systems, such as mechanosensitive ion channels, transporters, G-protein coupled receptors, ion pumps, and outer membrane proteins elucidating their dynamics and revealing conformational ensembles. Indeed, PDS offers a platform to study intermediate or lowly-populated states that are otherwise invisible to other modern methods, such as X-ray crystallography, cryo-EM, and hydrogen-deuterium exchange-mass spectrometry. Importantly, advances in spin labelling strategies welcome a new era of membrane protein investigation under near-native or in-cell conditions. Here, we review recent integral membrane protein PDS applications, and highlight well-suited, emerging spin labelling strategies that show promise for future studies.

Effect of carotid artery stenting on cognitive function in patients with asymptomatic carotid artery stenosis, a multimodal magnetic resonance study.

More and more evidence suggesting that internal carotid artery stenosis is not only a risk factor for ischemic stroke but also for cognitive impairments. Hypoperfusion and silent micro emboli have been reported as the pathophysiological mechanisms causing cognitive impairment. The effect of carotid artery stenting (CAS) on cognitive function varied from study to study. This study aims to explore the effect of CAS on cognition and exam the changes in cerebral perfusion and brain connectivity with pulsed arterial spin labeling (pASL) and resting-state functional MRI (R-fMRI). We conducted a controlled trial to assess alterations in cognitive performance among patients with "asymptomatic" carotid artery stenosis prior to and 3 months post-CAS intervention. Cognitive function including the Montreal Cognitive Assessment (MoCA) Beijing Version, the Minimum Mental State Examination (MMSE), the Digit Symbol Test, the Rey Auditory Verbal Learning Test (RAVLT), and the Verbal Memory Test. pASL perfusion MRI and R-fMRI were also performed prior to and 3 months post-CAS intervention. 13 patients completed all the follow-up. We observed increased perfusion in the right parietal lobe and right occipital lobe, increased amplitude of low-frequency fluctuation (ALFF) in the right precentral gyrus, increased connectivity to the posterior cingulate cortex (PCC) in the right frontal gyrus and right precuneus, and increased voxel-wise mirrored homotopic connectivity (VMHC) in the right precuneus 3 months after CAS when compared with prior to CAS. Cognitive test results showed significant improvement in the scores on the MMSE, the Verbal Memory test, and the delayed recall. CAS can partly improve the cognitive function in patients with "asymptomatic" carotid artery stenosis, and the improvement may be attributable to the increased perfusion in the right parietal lobe and right occipital lobe, increased ALFF in the right precentral gyrus, increased connectivity to the PCC in the right frontal gyrus and right precuneus, and increased VMHC in the right precuneus.