Arterial Spin Labeling Imaging Research Articles

Interictal EEG spikes increase perfusion in low-grade epilepsy-associated tumors: a pediatric arterial spin labeling study.

Arterial spin labeling (ASL), a noninvasive magnetic resonance (MRI) perfusion sequence, holds promise in the presurgical evaluation of pediatric lesional epilepsy patients, including those with low-grade epilepsy-associated tumors (LEATs). The interpretation of ASL-derived perfusion patterns, however, presents challenges. Our study aims to elucidate these perfusion changes in children with LEATs, exploring their correlations with clinical, electroencephalography (EEG), and anatomical MRI findings. Our cohort included 15 children with LEAT-associated focal lesional epilepsy who underwent single-delay pseudo-continuous ASL imaging; eight were imaged under sedation. We assessed perfusion images both qualitatively and quantitatively, focusing on LEAT-related perfusion changes, as indicated by the asymmetry index (AI) and regional cerebral blood flow (rCBF). ASL revealed LEAT-related perfusion changes in all but two patients: 12 LEATs were hypoperfused and one was hyperperfused relative to the contralateral brain parenchyma (CBP). LEATs showed significantly lower perfusion compared to CBP (median: 38.7 vs. 59.1mL/100g/min for LEAT and CBP, respectively; p value = 0.004, Wilcoxon-Mann-Whitney), regardless of sedation. Notably, elevated AI and rCBF values correlated with interictal spikes on EEG (median: -0.008 and 0.84 vs -0.27 and 0.58, respectively), but not to other clinical, EEG, or MRI variables (p value = 0.036, Wilcoxon-Mann-Whitney). By highlighting the connection between LEAT and brain perfusion, and by correlating perfusion characteristics and epileptogenicity, our research enhanced our understanding of pediatric epilepsy associated with LEATs. Also, by proving the robustness of these findings to sedation we confirmed the importance of adding ASL to epilepsy protocols to as a valuable tool to supplement anatomical imaging.

The influence of alterations in the composition of intestinal microbiota on neurovascular coupling and cognitive dysfunction in individuals afflicted with CSVD

IntroductionAn expanding body of research has explored the crucial role of gut microbiota in cerebral small vessel disease (CSVD). The objective of this study is to investigate alterations in the gut microbiota structure among CSVD patients, to explore the correlation between differential taxonomic levels and the neurovascular coupling index as well as cognitive function and to elucidate the imaging and biomarkers of mild cognitive impairment (MCI) in CSVD. MethodsWe enrolled 104 patients with CSVD and 40 healthy controls (HC). Based on cognitive test scores, CSVD patients were categorized into a cognitively normal group (CSVD-NCI, n=61) and a mild cognitive impairment group (CSVD-MCI, n=43). Performing magnetic resonance imaging (MRI) scans, gut microbiota analysis, as well as clinical and neuropsychological assessments for all participants. Based on arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) imaging data, cerebral blood flow (CBF) and neural activity indices are computed. The coupling indices of CBF/mReHo, CBF/mfALFF, CBF/mALFF, and CBF/mDC are calculated to assess the whole-brain neurovascular coupling changes in patients with CSVD. ResultsSpecies annotation revealed differences in the composition at the phylum and genus levels among the HC, CSVD-NCI, and CSVD-MCI groups. Additionally, differential analysis using the Kruskal-Wallis test demonstrated specific dominant microbial communities in all three groups. The relative abundance of certain dominant microbial communities in CSVD patients exhibited correlations with neurovascular coupling and cognitive function. The combined assessment of Bacteroides genus and CBF/mDC proved effective in distinguishing between CSVD-NCI and CSVD-MCI, providing a novel non-invasive approach for the diagnosis of MCI in CSVD.

Pharmacological manipulation of neurotransmitter activity induces disparate effects on cerebral blood flow and resting-state fluctuations

Abstract Functional MRI methods can assess aspects of drug-induced brain response. Resting blood oxygenation level dependent (BOLD) fMRI and arterial spin labeling (ASL) perfusion MRI indirectly measure brain function through the coupling of activity to cerebral blood flow (CBF) and oxygenation but their relative sensitivity has not been directly compared. We assessed changes in resting measures of BOLD and ASL MRI in response to two neurotransmitter modulators: citalopram, a selective serotonin reuptake inhibitor, and alprazolam, a positive allosteric modulator of GABA type A receptor. Thirty healthy subjects were imaged in a placebo-controlled study, with N=20 subjects receiving each treatment as part of an incomplete block design. Time-averaged CBF images from ASL and measures of resting-state fluctuations of BOLD and ASL images were assessed for significant effects. Following acute citalopram administration, analysis of the ASL data showed a reduction in time-averaged regional CBF in regions associated with high levels of 5-HT1A receptor density. In contrast, following alprazolam administration, BOLD amplitude of low frequency fluctuations showed a highly significant and cortically widespread increase, consistent with the distribution of GABA-A receptors. Only a marginal decrease in ASL CBF was detected after alprazolam intake. BOLD and ASL are each sensitive to drugs targeting neurotransmitter systems, but appear to reflect different aspects of neural metabolism and the balance between excitatory and inhibitory activity. Accordingly, their combination may best capture the effects of neurotransmitter modulations, and thus be advantageous for pharmacological MRI studies.

Cerebral perfusion in patients with unilateral internal carotid artery occlusion by dual post-labeling delays arterial spin labeling imaging.

Global and regional cerebral blood flow (CBF) changes in patients with unilateral internal carotid artery occlusion (ICAO) are unclear when the dual post-labeling delays (PLD) arterial spin labeling (ASL) magnetic resonance imaging (MRI) technique is used. Manual delineation of regions of interest for CBF measurement is time-consuming and laborious. To assess global and regional CBF changes in patients with unilateral ICAO with the ASL-MRI perfusion technique. Twenty hospitalized patients with ICAO and sex- and age-matched controls were included in the study. Regional CBF was measured by Dr. Brain's ASL software. The present study evaluated differences in global, middle cerebral artery (MCA) territory, anterior cerebral artery territory, and Alberta Stroke Program Early Computed Tomography Score (ASPECTS) regions (including the caudate nucleus, lentiform nucleus, insula ribbon, internal capsule, and M1-M6) and brain lobes (including frontal, parietal, temporal, and insular lobes) between ICAO patients and controls at PLD 1.5 s and PLD 2.5 s. When comparing CBF between ICAO patients and controls, the global CBF in ICAO patients was lower at both PLD 1.5 s and PLD 2.5 s; the CBF on the occluded side was lower in 15 brain regions at PLD 1.5 s, and it was lower in 9 brain regions at PLD 2.5 s; the CBF in the contralateral hemisphere was lower in the caudate nucleus and internal capsule at PLD 1.5 s and in M6 at PLD 2.5 s. The global CBF in ICAO patients was lower at PLD 1.5 s than at PLD 2.5 s. The ipsilateral CBF at PLD 1.5 s was lower than that at PLD 2.5 s in 15 regions, whereas the contralateral CBF was lower at PLD 1.5 s than at PLD 2.5 s in 12 regions. The ipsilateral CBF was lower than the contralateral CBF in 15 regions at PLD 1.5 s, and in M6 at PLD 2.5 s. Unilateral ICAO results in hypoperfusion in the global and MCA territories, especially in the ASPECTS area. Dual PLD settings prove more suitable for accurate CBF quantification in ICAO.

Arterial spin labeling detects trapped labeled spins in flow-diverted aneurysms and it reflects intra-aneurysmal flow stasis.

This study evaluated arterial spin labeling (ASL) imaging findings in flow-diverted aneurysms (FD-ANs). Twenty-one patients with internal carotid artery aneurysms treated with flow-diverter stent (FDS) were included. Time-of-flight magnetic resonance angiography (TOF-MRA) and ASL were performed before and after follow-up digital subtraction angiography (DSA) on the day, 6 months, and/or 1 year after treatment. Two radiologists rated the clarity of the depiction of FD-ANs for MRA on a 3-point scale and the ASL signal intensity of the aneurysm as negative or positive. A neurosurgeon assessed DSA findings using the O'Kelly-Marotta (OKM) grading scale, categorizing them into filling and stasis grades. The 23 examinations were classified according to the OKM grading scale, and the proportion of ASL-positive cases and the proportion of cases with MRA scores of 1-2 (detectable) were calculated for each grade. The relationship between the OKM grading scale and ASL positivity or MRA detectable was examined using Fisher's exact test. Of seven examinations where the statis grade was 1 or 2, no examinations showed ASL positivity. However, among the 16 examinations in which the stasis grade was 3, 9 examinations showed ASL positivity. A significant association was observed between stasis grade and ASL positivity (p = 0.035). In contrast, no significant relationship was observed between the OKM grading scale and the MRA 3-point scale. High-signal ASL in FD-ANs could reflect stasis within the aneurysm; therefore, noninvasive ASL can indicate reduction in intra-aneurysmal blood flow after treatment and reperfusion during posttreatment observation.

Is initial unilateral revascularization acceptable in pediatric patients with bilateral moyamoya disease with mild contralateral hemodynamic disturbance?

Although asymmetrical vascular involvement between hemispheres is common in pediatric patients with bilateral moyamoya disease, whether hemispheres with mild vascular changes and hemodynamic impairment require immediate surgical revascularization or whether they can be observed until disease progression remains unclear. The authors evaluated the long-term outcomes of their strategy to initially perform unilateral surgery and withhold surgery to the contralateral hemispheres with mild vascular changes and hemodynamic impairment. The authors retrospectively evaluated Japanese pediatric patients (onset age ≤ 15 years) diagnosed with bilateral sporadic moyamoya disease who underwent unilateral revascularization. The authors investigated whether the patient underwent additional collateral surgery and the incidence of ischemic events during follow-up. They also compared visual assessments of arterial spin labeling (ASL) images obtained before initial surgery, before additional contralateral surgery, and at last follow-up. Overall, 30/47 patients (63.8%) experienced progression of hemodynamic impairment in the contralateral hemisphere and underwent additional surgery. The age at initial surgery of the patients who needed additional contralateral surgery was significantly younger than that of the patients who did not require contralateral surgery (mean [SD] 7.0 [3.0] years vs 9.8 [2.6] years, p = 0.002). One patient (age 4 years) developed ischemic stroke before admission for preoperative evaluation 2 months after novel symptom onset, and another patient (age 6 years) experienced ischemic stroke in the contralateral hemisphere while discontinuing antiplatelet agents before surgery; both patients fully recovered from the neurological deficits. In contralateral hemispheres that required additional surgery, the ASL visual assessment scores significantly decreased before the additional contralateral surgery compared to those obtained before the initial surgery (p = 0.008). In pediatric patients with bilateral moyamoya disease, withholding surgery for hemispheres with mild vascular changes and hemodynamic impairment is generally safe. Younger patients were more likely to experience contralateral progression and require additional surgery, so close follow-up is needed. ASL imaging is useful for detecting and following the progression of hemodynamic impairment in conservatively treated hemispheres.

Diagnostic accuracy of arterial spin labeling MR imaging in detecting cerebral arteriovenous malformations: a systematic review and meta-analysis.

Diagnostic accuracy of arteriovenous malformations (AVMs) is imperative for delineating management. The current standard is digital subtraction angiography (DSA). Arterial spin labeling (ASL) is an understudied noninvasive, non-contrast technique that allows angioarchitecture visualization and additionally quantifies cortical and AVM cerebral blood flow and hemodynamics. This meta-analysis aims to compare ASL and DSA imaging in detecting and characterizing cerebral AVMs. EMBASE, Medline, Scopus, and Cochrane databases were queried from inception to July 2022 for reports of AVMs evaluated by DSA and ASL imaging. Fourteen studies with 278 patients evaluated using DSA and ASL imaging prior to intervention were included; pCASL in 11 studies (n = 239, 85.37%) and PASL in three studies (n = 41, 14.64%). The overall AVM detection rate on ASL was 99% (CI 97-100%); subgroup analysis revealed no difference between pCASL vs. PASL (99%; CI 96-100% vs. 100%; CI 95-100% respectively, p = 0.42). The correlation value comparing ASL and DSA nidus size was 0.99. DSA and ASL intermodality agreement Cohen's k factor for Spetzler Martin Grading (SMG) was reported at a median of 0.98 (IQR 0.73-0.1), with a 1.0 agreement on SMG classification. A median of 25 arteries were detected by DSA (IQR 14.5-27), vs. 25 by ASL (IQR 14.5-27.5) at a median 0.92 k factor. ASL provides angioarchitectural visualization noninferior to DSA and additionally quantifies CBF. Our study suggests that ASL should be considered in the detection of AVMs, especially in patients with contrast contraindications or apprehension towards an invasive assessment.

Higher Validity, Lower Radiation: A New Ictal Single-Photon Emission Computed Tomography Framework.

To assess whether arterial spin labeling perfusion images of healthy controls can enhance ictal single-photon emission computed tomography analysis and whether the acquisition of the interictal image can be omitted. We developed 2 pipelines: The first uses ictal and interictal images and compares these to single-photon emission computed tomography and arterial spin labeling of healthy controls. The second pipeline uses only the ictal image and the analogous healthy controls. Both pipelines were compared to the gold standard analysis and evaluated on data of individuals with epilepsy who underwent ictal single-photon emission computed tomography imaging during presurgical evaluation between 2010 and 2022. Fifty healthy controls prospectively underwent arterial spin labeling imaging. The correspondence between the detected hyperperfusion and the postoperative resection cavity or the presumably affected lobe was assessed using Dice score and mean Euclidean distance. Additionally, the outcomes of the pipelines were automatically assigned to 1 of 5 concordance categories. Inclusion criteria were met by 43 individuals who underwent epilepsy surgery and by 73 non-surgical individuals with epilepsy. Compared to the gold standard analysis, both pipelines resulted in significantly higher Dice scores and lower mean distances (p < 0.05). The combination of both provided localizing results in 85/116 cases, compared to 54/116 generated by the current gold standard analysis and the ictal image alone produced localizing results in 60/116 (52%) cases. We propose a new ictal single-photon emission computed tomography protocol; it finds relevantly more ictal hyperperfusion, and halves the radiation dose in about half of the individuals. ANN NEUROL 2024.

Associations of Cerebral Blood Flow Patterns With Gray and White Matter Structure in Patients With Temporal Lobe Epilepsy.

Neuroimaging studies in patients with temporal lobe epilepsy (TLE) show widespread brain network alterations beyond the mesiotemporal lobe. Despite the critical role of the cerebrovascular system in maintaining whole-brain structure and function, changes in cerebral blood flow (CBF) remain incompletely understood in the disease. Here, we studied whole-brain perfusion and vascular network alterations in TLE and assessed its associations with gray and white matter compromises and various clinical variables. We included individuals with and without pharmaco-resistant TLE who underwent multimodal 3T MRI, including arterial spin labelling, structural, and diffusion-weighted imaging. Using surface-based MRI mapping, we generated individualized cortico-subcortical profiles of perfusion, morphology, and microstructure. Linear models compared regional CBF in patients with controls and related alterations to morphological and microstructural metrics. We further probed interregional vascular networks in TLE, using graph theoretical CBF covariance analysis. The effects of disease duration were explored to better understand the progressive changes in perfusion. We assessed the utility of perfusion in separating patients with TLE from controls using supervised machine learning. Compared with control participants (n = 38; mean ± SD age 34.8 ± 9.3 years; 20 females), patients with TLE (n = 24; mean ± SD age 35.8 ± 10.6 years; 12 females) showed widespread CBF reductions predominantly in fronto-temporal regions (Cohen d -0.69, 95% CI -1.21 to -0.16), consistent in a subgroup of patients who remained seizure-free after surgical resection of the seizure focus. Parallel structural profiling and network-based models showed that cerebral hypoperfusion may be partially constrained by gray and white matter changes (8.11% reduction in Cohen d) and topologically segregated from whole-brain perfusion networks (area under the curve -0.17, p < 0.05). Negative effects of progressive disease duration further targeted regional CBF profiles in patients (r = -0.54, 95% CI -0.77 to -0.16). Perfusion-derived classifiers discriminated patients from controls with high accuracy (71% [70%-82%]). Findings were robust when controlling for several methodological confounds. Our multimodal findings provide insights into vascular contributions to TLE pathophysiology affecting and extending beyond mesiotemporal structures and highlight their clinical potential in epilepsy diagnosis. As our work was cross-sectional and based on a single site, it motivates future longitudinal studies to confirm progressive effects, ideally in a multicentric setting.

Cerebral blood flow and structural connectivity after working memory or physical training in paediatric cancer survivors – Exploratory findings

ABSTRACT Paediatric cancer survivors often suffer from cognitive long-term difficulties. Consequently, strengthening cognition is of major clinical relevance. This study investigated cerebral changes in relation to cognition in non-brain tumour paediatric cancer survivors after working memory or physical training compared to a control group. Thirty-four children (≥one-year post-treatment) either underwent eight weeks of working memory training (n = 10), physical training (n = 11), or a waiting period (n = 13). Cognition and MRI, including arterial spin labelling and diffusion tensor imaging, were assessed at three time points (baseline, post-training, and three-month follow-up). Results show lower cerebral blood flow immediately after working memory training (z = −2.073, p = .038) and higher structural connectivity at the three-month follow-up (z = −2.240, p = .025). No cerebral changes occurred after physical training. Short-term changes in cerebral blood flow correlated with short-term changes in cognitive flexibility (r = −.667, p = .049), while long-term changes in structural connectivity correlated with long-term changes in working memory (r = .786, p = .021). Despite the caution given when interpreting data from small samples, this study suggests a link between working memory training and neurophysiological changes. Further research is needed to validate these findings.

Comparison of arterial spin labeling and dynamic susceptibility contrast perfusion MR imaging in pediatric brain tumors: A systematic review and meta-analysis.

Brain tumors are a leading cause of mortality in children. Accurate tumor grading is essential to plan treatment and for prognostication. Perfusion imaging has been shown to correlate well with tumor grade in adults, however there are fewer studies in pediatric patients. Moreover, there is no consensus regarding which MR perfusion technique demonstrates the highest accuracy in the latter population. To compare the diagnostic test accuracy of dynamic-susceptibility contrast and arterial spin-labelling, in their ability to differentiate between low-and high-grade pediatric brain tumors at first presentation. Articles were retrieved from online electronic databases: MEDLINE (Ovid), Web of Science Core Collection and SCOPUS. Studies in pediatric patients with a treatment naïve diagnosed brain tumor and imaging including either ASL or DSC or both, together with a histological diagnosis were included. Studies involving adult patient or mixed age populations, studies with incomplete data and those which used dynamic contrast enhanced perfusion were excluded. The sensitivities and specificities obtained from each study were used to calculate the true-positive, true-negative, false-positive, and false-negative count. A case was defined as a histologically proven high-grade tumor. The random-effect model was used to merge statistics. Significance level was set at p < 0.05. Forest plots showing pairs of sensitivity and specificity, with their 95% confidence intervals, were constructed for each study. The bivariate model was applied in order to account for between-study variability. The SROC plots were constructed from the obtained data-sets. The AUC for the SROC of all studies was estimated to determine the overall diagnostic test accuracy of perfusion MRI, followed by a separate comparison of the SROC of ASL versus DSC studies. Small and heterogenous sample size. The diagnostic accuracy of ASL was found to be comparable and not inferior to DSC, thus its use in the diagnostic assessment of pediatric patients should continue to be supported. ASL = arterial spin labelling, DSC = dynamic susceptibility contrast, DCE = dynamic contrast-enhanced, rCBF = relative cerebral blood flow, rCBV = relative cerebral blood volume, MTT = mean transfer time, TR = repetition time, TE = echo time, SROC = summary receiver operating characteristics, HG= high-grade, LG = low-grade, AUC = area under the curve, PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

CLINICAL APPLICATION STUDY OF 3D-ASL PERFUSION IMAGING AND MAGNETIC RESONANCE DIFFUSION IMAGING IN TRANSIENT ISCHEMIC ATTACK.

Objective: This study aimed to explore the clinical application of three-dimensional arterial spin labeling (3D-ASL) and diffusion-weighted magnetic resonance imaging (DWI) in transient ischemic attacks. Methods: Forty patients with transient cerebral ischemia in our hospital were selected and included from July 2020 to March 2022. All subjects were detected by DWI and 3D-ASL technology. The positive rate, relative cerebral blood flow (rCBF), and the receiver operating characteristic curve of the two methods in the diagnosis of transient cerebral ischemia were compared; the objective was to compare the relationship between the frequency of transient ischemic attack and hypoperfusion, and vascular stenosis. Results: The 3D-ASL examination showed two cases of hypoperfusion in the healthy control group (5.00), and the magnetic resonance imaging examination showed four cases of vascular stenosis in the healthy control group (10.00). The rCBF ratio in the cerebral ischemia group was significantly lower than that in the cerebral ischemia group, which was significantly lower than that in the healthy control group ( P < 0.05). The area under the curve (AUC) of 3D-ASL in the diagnosis of transient cerebral ischemia was 0.800, and the AUC of DWI in the diagnosis of transient cerebral ischemia was 0.725. The AUC of the combination of the two methods in transient cerebral ischemia was 0.850. There was a significant difference in the attack frequency of patients with transient cerebral ischemia with different perfusion ( P < 0.05). There was a significant difference in attack frequency between patients with transient ischemic attack and patients without vascular stenosis ( P < 0.05). Conclusion: 3D-ASL and DWI technology have higher diagnostic efficiency for transient cerebral ischemia.

Changes of cerebral structure and perfusion in subtypes of systemic sclerosis: a brain magnetic resonance imaging study.

The characteristics of brain impairment in different subtypes of systemic sclerosis (SSc) (dcSSc, diffuse cutaneous SSc; lcSSc, limited cutaneous SSc) remain unclear. This study aimed to characterize cerebral structure and perfusion changes in different subtype of SSc patients using magnetic resonance (MR) imaging. Seventy SSc patients (46.0 ± 11.7 years, 62 females) and 30 healthy volunteers (44.8 ± 13.7 years, 24 females) were recruited and underwent brain MR imaging and Montreal Cognitive Assessment (MoCA) test. Gray matter (GM) volumes were measured using voxel-based morphometry analysis on T1-weighted images. Voxel-based and regional cerebral blood flow (CBF) was calculated on arterial spin labelling images. The cerebral structural and perfusion measurements by MR imaging were compared among dcSSc, lcSSc and healthy subjects using one-way ANOVA. The correlations between clinical characteristics and MR imaging measurements were also analyzed. The dcSSc patients exhibited a significant reduction in GM volume in the para-hippocampal region (cluster p < 0.01, FWE corrected) compared with healthy volunteers. Whereas, SSc patients, particularly lcSSc patients, showed elevated CBF in cerebellum, insula, cerebral cortex, and subcortical structures (regional analyses: all p < 0.05; voxel-based analyses: cluster p < 0.01, FWE corrected). Furthermore, clinical characteristics of modified Rodnan skin score (mRSS) (r value ranged from -0.29 to -0.45), MoCA scores (r = 0.40) and antinuclear antibody (ANA) positivity (r=-0.33) were significantly associated with CBF in some regions (all p < 0.05). The manifestations of brain involvement vary among different subtypes of SSc. In addition, severe skin sclerosis may indicate higher risk of brain involvement in SSc patients.

A multi-task generative model for simultaneous post-contrast MR image synthesis and brainstem glioma segmentation

ObjectivesThis study aims to generate post-contrast MR images reducing the exposure of gadolinium-based contrast agents (GBCAs) for brainstem glioma (BSG) detection, simultaneously delineating the BSG lesion, and providing high-resolution contrast information. MethodsA retrospective cohort of 30 patients diagnosed with brainstem glioma was included. Multi-contrast images, including pre-contrast T1 weighted (pre-T1w), T2 weighted (T2w), arterial spin labeling (ASL) and post-contrast T1w images, were collected. A multi-task generative model was developed to synthesize post-contrast T1w images and simultaneously segment BSG masks from the multi-contrast inputs. Performance evaluation was conducted using peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and mean absolute error (MAE) metrics. A perceptual study was also undertaken to assess diagnostic quality. ResultsThe proposed model achieved SSIM of 0.86 ± 0.04, PSNR of 26.33 ± 0.05 and MAE of 57.20 ± 20.50 for post-contrast T1w image synthesis. Automated delineation of the BSG lesions achieved Dice similarity coefficient (DSC) score of 0.88 ± 0.27. ConclusionsThe proposed model can synthesize high-quality post-contrast T1w images and accurately segment the BSG region, yielding satisfactory DSC scores. Clinical relevance statementThe synthesized post-contrast MR image presented in this study has the potential to reduce the usage of gadolinium-based contrast agents, which may pose risks to patients. Moreover, the automated segmentation method proposed in this paper aids radiologists in accurately identifying the brainstem glioma lesion, facilitating the diagnostic process.

The effect of post-labeling delay on cerebral blood flow is influenced by age and sex: a study based on arterial spin-labeling magnetic resonance imaging.

Whether the effect of post-labeling delay (PLD) on cerebral blood flow (CBF) is influenced by age and sex in adults is unknown. In this study, we mainly aimed to explore the potential influence of age and sex on the effect of PLD on CBF. This prospective study enrolled 90 healthy adult volunteers (49.47±15.63 years of age; age range, 20-77 years; 47 female; 43 male). All participants underwent 3-dimensional (3D) pseudo-continuous arterial spin labeling (ASL) imaging with 3 different PLDs (1,525, 2,025, and 2,525 ms). The CBF values for each PLD, the arterial transit time (ATT), and the spatial coefficient of variation (spatial CoV) were computed for 21 regions of interest (ROIs) in every participant. Multivariate regression analysis was conducted to assess the potential influence of age and sex on the effect of PLD on CBF and the relationships among CBF, ATT, PLD, age, sex, and spatial CoV. The CBF increased for 7.32 to 9.87 mL/100 g/min as the PLD increased per 1 second in the global gray matter, bilateral frontal, temporal lobes, the vascular territories of bilateral anterior and middle carotid artery. When the age increased per 1 year, the speed of the changes for CBF decreased for 0.26 to 0.3 mL/100 g/min/s in these regions. However, the CBF decreased for 12 to 17 mL/100 g/min as the PLD increased per 1 second in the bilateral limbic lobes, insula, and deep gray matter. In these regions, the speed of the changes for CBF increased for 0.2 to 0.28 mL/100 g/min/s as the age increased per 1 year. Furthermore, compared to the female, the speed of the changes for CBF decreased for 3.58 to 4.6 mL/100 g/min/s for the male in global gray matter, bilateral frontal, limbic lobes, and the vascular territories of bilateral anterior carotid artery, and the speed increased 4.49 to 5.09 mL/100 g/min/s for the male in the limbic lobes. In addition, the CBF decreased with aging and the CBF tended to be higher in females compared to males. At the same time, we found that the ATT of all ROIs increased with age and manifested higher in males than females. Moreover, we found that CBF decreased with the increase of ATT, and the effect of ATT on CBF was less influenced by PLD. Finally, we found that the spatial CoV of ASL in certain regions increased with the increase of ATT and age, and was greater in males. The effect of PLD on CBF can be influenced by age and sex. The relationships among CBF, ATT, PLD, age, sex, and spatial CoV found in this study may have certain significance for the study of ASL imaging in the future.

Insomnia in patients with MRI-negative epilepsy: The associated factors and 3D-pCASL cerebral blood flow perfusion changes

ObjectiveThis study aimed to identify the factors associated with insomnia in MRI-negative epilepsy and uncover the underlying pathological mechanism driving insomnia within the context of epilepsy. MethodsWe conducted a retrospective study of patients with MRI-negative epilepsy recruited consecutively from December 2021 to December 2022. All subjects completed the Insomnia Severity Index (ISI), Epworth Sleepiness Scale (ESS), Self-rating Anxiety Scale (SAS), and Self-rating Depression Scale (SDS). Additionally, some subjects underwent the three-dimensional pseudo continuous arterial spin labeling(3D-pCASL) imaging examination. Bilateral frontal lobe, temporal lobe, hippocampus, thalamus, amygdala, caudate nucleus and lenticular nucleus were selected as regions of interest(ROI) and cerebral blood flow(CBF) values were measured in these regions. Subjects were classified into insomnia (ISI ≥ 10) or non-insomnia (ISI < 10) groups, and univariate and stepwise logistic regression analyses were employed to identify the factors associated with insomnia. Furthermore, CBF values in each ROI were compared between the two groups to identify the brain regions potentially related to the underlying pathological mechanism of insomnia in epilepsy. ResultsA total of 73 patients with MRI-negative epilepsy were recruited in this study(men, 49.3 %). Among them, 14 patients(19.2 %) had insomnia. Univariate regression revealed that nocturnal seizures, number of anti-seizure medication(ASM), anxiety, use of valproic acid(VPA), depression, and excessive daytime sleepiness(EDS) may be associated with insomnia in MRI-negative epilepsy (all p＜0.05). Stepwise regression demonstrated that nocturnal seizures, anxiety, and EDS were independently associated with insomnia in MRI-negative epilepsy (OR[95 %CI]P: 14.64[2.02–106.27]0.008,49.35[3.06–796.61]0.006, 13.28[1.25–140.66]0.032, respectively). Furthermore, CBF values in the left amygdala were significantly lower in patients with MRI- negative epilepsy who had insomnia. ConclusionThe prevalence of insomnia in MRI-negative epilepsy is 19.2%. Nocturnal seizures, anxiety, and EDS were independently associated with insomnia in MRI-negative epilepsy. The noteworthy decrease in CBF values in the left amygdala might be connected to the underlying pathological mechanism of insomnia in epilepsy.

Amide proton transfer-weighted and arterial spin labeling imaging may improve differentiation between high-grade glioma recurrence and radiation-induced brain injury

Rationale and objectivesThe management of tumor recurrence (TR) and radiation-induced brain injury (RIBI) poses significant challenges, necessitating the development of effective differentiation strategies. In this study, we investigated the potential of amide proton transfer-weighted (APTw) and arterial spin labeling (ASL) imaging for discriminating between TR and RIBI in patients with high-grade glioma (HGG). MethodsA total of 64 HGG patients receiving standard treatment were enrolled in this study. The patients were categorized based on secondary pathology or MRI follow-up results, and the demographic characteristics of each group were presented. The APTw, rAPTw, cerebral blood flow (CBF) and rCBF values were quantified. The differences in various parameters between TR and RIBI were assessed using the independent-samples t-test. The discriminative performance of these MRI parameters in distinguishing between the two conditions was assessed using receiver operating characteristic (ROC) curve analysis. Additionally, the Delong test was employed to further evaluate their discriminatory ability. ResultsThe APTw and CBF values of TR were significantly higher compared to RIBI (P < 0.05). APTw MRI demonstrated superior diagnostic efficiency in distinguishing TR from RIBI (area under the curve [AUC]: 0.864; sensitivity: 75.0 %; specificity: 81.8 %) when compared to ASL imaging. The combined utilization of APTw and CBF value further enhanced the AUC to 0.922. The Delong test demonstrated that the combination of APTw and ASL exhibited superior performance in the identification of TR and RIBI, compared to ASL alone (P = 0.048). ConclusionAPTw exhibited superior diagnostic efficacy compared to ASL in the evaluation of TR and RIBI. Furthermore, the combination of APTw and ASL exhibits greater discriminatory capability and diagnostic performance.

Enhancing the Diagnostic Utility of ASL Imaging in Temporal Lobe Epilepsy through FlowGAN: An ASL to PET Image Translation Framework.

Positron Emission Tomography (PET) using fluorodeoxyglucose (FDG-PET) is a standard imaging modality for detecting areas of hypometabolism associated with the seizure onset zone (SOZ) in temporal lobe epilepsy (TLE). However, FDG-PET is costly and involves the use of a radioactive tracer. Arterial Spin Labeling (ASL) offers an MRI-based quantification of cerebral blood flow (CBF) that could also help localize the SOZ, but its performance in doing so, relative to FDG-PET, is limited. In this study, we seek to improve ASL's diagnostic performance by developing a deep learning framework for synthesizing FDG-PET-like images from ASL and structural MRI inputs. We included 68 epilepsy patients, out of which 36 had well lateralized TLE. We compared the coupling between FDG-PET and ASL CBF values in different brain regions, as well as the asymmetry of these values across the brain. We additionally assessed each modality's ability to lateralize the SOZ across brain regions. Using our paired PET-ASL data, we developed FlowGAN, a generative adversarial neural network (GAN) that synthesizes PET-like images from ASL and T1-weighted MRI inputs. We tested our synthetic PET images against the actual PET images of subjects to assess their ability to reproduce clinically meaningful hypometabolism and asymmetries in TLE. We found variable coupling between PET and ASL CBF values across brain regions. PET and ASL had high coupling in neocortical temporal and frontal brain regions (Spearman's r > 0.30, p < 0.05) but low coupling in mesial temporal structures (Spearman's r < 0.30, p > 0.05). Both whole brain PET and ASL CBF asymmetry values provided good separability between left and right TLE subjects, but PET (AUC = 0.96, 95% CI: [0.88, 1.00]) outperformed ASL (AUC = 0.81; 95% CI: [0.65, 0.96]). FlowGAN-generated images demonstrated high structural similarity to actual PET images (SSIM = 0.85). Globally, asymmetry values were better correlated between synthetic PET and original PET than between ASL CBF and original PET, with a mean correlation increase of 0.15 (95% CI: [0.07, 0.24], p<0.001, Cohen's d = 0.91). Furthermore, regions that had poor ASL-PET correlation (e.g. mesial temporal structures) showed the greatest improvement with synthetic PET images. FlowGAN improves ASL's diagnostic performance, generating synthetic PET images that closely mimic actual FDG-PET in depicting hypometabolism associated with TLE. This approach could improve non-invasive SOZ localization, offering a promising tool for epilepsy presurgical assessment. It potentially broadens the applicability of ASL in clinical practice and could reduce reliance on FDG-PET for epilepsy and other neurological disorders.

Correlations between intravascular pressure gradients and cerebral blood flow in patients with symptomatic, medically refractory, anterior circulation artery stenosis: an exploratory study

BackgroundFractional flow reserve is widely used in coronary disease management, with a threshold of 0.80. However, similar thresholds are unclear in functional assessment of intracranial atherosclerotic stenosis (ICAS).ObjectiveTo investigate the...

Aberrant cerebral blood flow and functional connectivity in patients with vestibular migraine: a resting-state ASL and fMRI study

BackgroundPrior neuroimaging studies on vestibular migraine (VM) have extensively certified the functional and structural alterations in multiple brain regions and networks. However, few studies have assessed the cerebral blood flow (CBF) in VM patients using arterial spin labeling (ASL). The present study aimed to investigate CBF and functional connectivity (FC) alterations in VM patients during interictal periods.MethodsWe evaluated 52 VM patients and 46 healthy controls (HC) who received resting-state pseudo-continuous ASL and functional magnetic resonance imaging (fMRI) scanning. Comparisons of voxel-based CBF and seed-based FC were performed between the two groups. Brain regions showed significant group differences in CBF analyses were chosen as seeds in FC analyses. Additionally, the associations between abnormal imaging results and clinical features were explored.ResultsCompared with HC, VM patients showed higher normalized CBF in the right precentral gyrus (PreCG), left postcentral gyrus (PostCG), left superior frontal gyrus and bilateral insular (p < 0.05, FDR corrected). Furthermore, VM patients exhibited increased FC between the right PreCG and areas of the left PostCG, left cuneus and right lingual gyrus (p < 0.05, FDR corrected). In addition, we observed decreased FC between the left insular and regions of the left thalamus and right anterior cingulate cortex, as well as increased FC between the left insular and right fusiform gyrus in VM patients (p < 0.05, FDR corrected). Moreover, these variations in brain perfusion and FC were significantly correlated with multiple clinical features including frequency of migraine symptoms, frequency of vestibular symptoms and disease duration of VM (all p < 0.05).ConclusionsPatients with VM during interictal period showed hyperperfusion and abnormal resting-state FC in brain regions potentially contributed to disrupted multi-sensory and autonomic processing, as well as impaired ocular motor control, pain modulation and emotional regulation. Our study provided novel insights into the complex neuropathology of VM from a CBF perspective.