Background Anabolic-androgenic steroids (AAS) are commonly used by recreational weightlifters for performance enhancement, despite associated health risks, including cardiovascular and brain effects. This study investigates the cerebrovascular effects of prolonged AAS use in male weightlifters, focusing on cerebral blood flow (CBF) and other indicators of cerebrovascular health. Methods Eighty-six males were included, with 41 current consumers of AAS and 45 non-using weightlifting controls. Cerebrovascular health was evaluated using magnetic resonance imaging (MRI) pseudo-continuous arterial spin labeling (PCASL) derivatives to measure CBF and spatial coefficient of variation (sCoV) of CBF in gray matter. Additionally, MRI T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences were used to analyze white matter hyperintensities as a marker of small-vessel disease. Results AAS consumers had significantly higher sCoV than weightlifting controls (p = 0.001). Further, sCoV in total gray matter correlated with testosterone/epitestosterone ratio and total years of AAS use. No significant differences were found in CBF or white matter hyperintensity volume. Conclusion These findings indicate that long-term AAS use may impact cerebrovascular health, evidenced by increased sCoV. Although cerebral perfusion was unaffected, elevated sCoV suggest that AAS use may pose a risk for cerebrovascular pathology later in life.

Background: Blood-brain barrier (BBB) dysfunction is suggested to be a potential mediator between vascular risk factors and cognitive impairment, leading to vascular cognitive impairment. Objective: To investigate the relationships between age, sex, and vascular risk factors and BBB water permeability as well as their relationship with cognition. Methods: To measure BBB permeability, a novel arterial spin labelling MRI technique (ME-ASL) was applied to derive the time of exchange (Tex), arterial time transit (ATT), and cerebral blood flow (CBF). The association of potential risk factors, such as age, sex, body mass index (BMI), blood pressure (BP), and medical history, with these BBB parameters were assessed in 144 community-dwelling adults (median age 59 years, 57% females). The relationship between BBB permeability and cognitive performance measured by the Montreal Cognitive Assessment (MoCA) was also assessed. Results: We found that increased BMI was significantly associated with decreased CBF (β = −0.06). Systolic BP and diastolic BP showed significant associations with all ASL parameters; systolic BP was negatively correlated with Tex (β = −0.02) and CBF (β = −0.01) but positively with ATT (β = 0.02). Diastolic BP was negatively associated with Tex (β = −0.03) and CBF (β = −0.03) but positively with ATT (β = 0.03). MoCA scores had a borderline significant association with Tex (OR = 1.51) and a significant association with CBF (OR = 1.84), which became non-significant after adjusting for confounders. Conclusions: These outcomes underscore the potential of using ME-ASL, warranting further research to strengthen these findings.

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.

The Amyloid Imaging to Prevent Alzheimer’s Disease (AMYPAD) Prognostic & Natural History Study (PNHS) is a prospective longitudinal PET cohort of over 1,500 non-demented individuals from 10 parent cohorts across Europe. We provide an overview of ongoing efforts to curate and integrate magnetic resonance imaging (MRI) multimodal images across sites and to extract biologically meaningful information ( i.e. , image-derived phenotypes; IDPs) in this early AD population. Data will be made available on the ADDI platform ( fair.addi.ad-datainitiative.org ). Imaging protocols included core (T1w, T2w, T2*, FLAIR) and advanced (rs-fMRI, SWI, DWI, and ASL) MRI sequences. Figure 1 provides an overview of the different acquisitions, their corresponding pipelines, and the obtained IDPs. For T1w images, we computed regional volumes and thickness values using FreeSurfer v7.1.1 ( surfer.nmr.mgh.harvard.edu/ ). Morphometric similarity networks were computed using MIND ( github.com/isebenius/MIND ). White matter hyperintensity volumes were obtained from FLAIR images using Bayesian Model Selection (BaMoS). With rs-fMRI, mean functional connectivity of canonical networks were extracted using FSL MELODIC and dual-regression analyses after preprocessing with fMRIPrep v23.0.1 ( fmriprep.org ). Diffusion MRI scans were processed with QSIprep v0.16 ( qsiprep.readthedocs.io ) to compute tract-based spatial statistics and tractograms to build structural connectivity matrices. Finally, cerebral blood flow and the spatial coefficient of variation were computed from ASL images using ExploreASL ( github.com/ExploreASL ). Statistical harmonization was performed using RELIEF ( github.com/junjypark/RELIEF ). Baseline and follow-up characteristics of the 1537 subjects with available T1w are described in Table 1. Raw and statistically harmonized variants of 380 core and 298 advanced IDPs were calculated. Figure 2 shows the distribution of hippocampal volumes per site before and after statistical harmonization, and their relation with participants' age (R 2 raw =0.179, R 2 harmonized =0.422). Considering recent developments in the field, the AMYPAD PNHS aims to include additional IDPs associated with vascular health, such as perivascular spaces and other glymphatic system-related markers. We present the pipeline built for MRI harmonization and feature extraction of the AMYPAD PNHS dataset. The extracted IDPs can help identify novel imaging outcomes, support the development of disease progression models for the preclinical stages of AD, and provide a reference point for future studies to promote replicability and robustness of findings.

Introduction Arterial spin labeling (ASL) MRI, a non-invasive technique for imaging perfusion, now allows studying BBB permeability. The DEveloping BBB-ASL as a non-Invasive Early biomarker of Alzheimer's Disease (DEBBIE-AD) multi-cohort study integrates this modified BBB-ASL technique in several healthy and diseased populations (Table 1) to study methodological and clinical research questions (Table 2) on the ability of BBB-ASL as an early AD biomarker. Methods DEBBIE-AD will enroll various cohorts with subjective cognitive decline, mild cognitive impairment, and AD dementia, as well as age-matched healthy controls, at seven sites (Table 1). Our newly developed BBB-ASL sequence — implemented with the vendor-independent MRI framework gammaSTAR — will be added to multiple MRI protocols. The BBB-ASL sequence combines time-encoded multi-post labeling delay pseudo-continuous ASL with a multi-echo 3D GRASE readout, allowing estimating CBF, ATT, and the BBB time of exchange (Tex). Data analyses will be conducted using ExploreASL. Beyond MRI standard sequences, including T1w, T2w, FLAIR, DWI, the DEBBIE clinical outcomes include amyloid-PET and blood and CSF fluid biomarkers (Table 1). Expected Results Preliminary testing of the BBB-ASL has been conducted on 3T systems (different Siemens Heathineers scanners) in different cohorts at multiple sites. Data processing with ExploreASL includes FSL-FABBER4 for quantification, allowing harmonized image processing. An example of the mean and standard deviation Tex maps of two DEBBIE cohorts is shown in Figure 1 to illustrate the similarities of the Tex patterns from two cohorts of similar-aged healthy adults from different sites. Discussion The DEBBIE-AD study aims to provide evidence on the ability of BBB-ASL to measure BBB permeability and demonstrate its utility in AD-related pathologies. The presented sequence may provide novel and unique insights into the staging of BBB permeability changes in groups at greater risk of developing AD, which may, in turn, provide new targets for treatment.

PURPOSE:Arterial spin labeling (ASL) is a widely used contrast-free MRI method for assessing cerebral blood flow (CBF). Despite the generally adopted ASL acquisition guidelines, there is still wide variability in ASL analysis. We explored this variability through the ISMRM-OSIPI ASL-MRI Challenge, aiming to establish best practices for more reproducible ASL analysis. METHODS:Eight teams analyzed the challenge data, which included a high-resolution T1-weighted anatomical image and 10 pseudo-continuous ASL datasets simulated using a digital reference object to generate ground-truth CBF values in normal and pathological states. We compared the accuracy of CBF quantification from each team's analysis to the ground truth across all voxels and within predefined brain regions. Reproducibility of CBF across analysis pipelines was assessed using the intra-class correlation coefficient (ICC), limits of agreement (LOA), and replicability of generating similar CBF estimates from different processing approaches. RESULTS:Absolute errors in CBF estimates compared to ground-truth synthetic data ranged from 18.36 to 48.12 mL/100 g/min. Realistic motion incorporated into three datasets produced the largest absolute error and variability between teams, with the least agreement (ICC and LOA) with ground-truth results. Fifty percent of the submissions were replicated, and one produced three times larger CBF errors (46.59 mL/100 g/min) compared to submitted results. CONCLUSIONS:Variability in CBF measurements, influenced by differences in image processing, especially to compensate for motion, highlights the significance of standardizing ASL analysis workflows. We provide a recommendation for ASL processing based on top-performing approaches as a step toward ASL standardization.

INTRODUCTION:Loss of blood-brain barrier (BBB) integrity is hypothesised to be one of the earliest microvascular signs of Alzheimer's disease (AD). Existing BBB integrity imaging methods involve contrast agents or ionising radiation, and pose limitations in terms of cost and logistics. Arterial spin labelling (ASL) perfusion MRI has been recently adapted to map the BBB permeability non-invasively. The DEveloping BBB-ASL as a non-Invasive Early biomarker (DEBBIE) consortium aims to develop this modified ASL-MRI technique for patient-specific and robust BBB permeability assessments. This article outlines the study design of the DEBBIE cohorts focused on investigating the potential of BBB-ASL as an early biomarker for AD (DEBBIE-AD). METHODS AND ANALYSIS:DEBBIE-AD consists of a multicohort study enrolling participants with subjective cognitive decline, mild cognitive impairment and AD, as well as age-matched healthy controls, from 13 cohorts. The precision and accuracy of BBB-ASL will be evaluated in healthy participants. The clinical value of BBB-ASL will be evaluated by comparing results with both established and novel AD biomarkers. The DEBBIE-AD study aims to provide evidence of the ability of BBB-ASL to measure BBB permeability and demonstrate its utility in AD and AD-related pathologies. ETHICS AND DISSEMINATION:Ethics approval was obtained for 10 cohorts, and is pending for 3 cohorts. The results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.

The blood-brain barrier (BBB) consists of specialized cells that tightly regulate the in- and outflow of molecules from the blood to brain parenchyma, protecting the brain's microenvironment. If one of the BBB components starts to fail, its dysfunction can lead to a cascade of neuroinflammatory events leading to neuronal dysfunction and degeneration. Preliminary imaging findings suggest that BBB dysfunction could serve as an early diagnostic and prognostic biomarker for a number of neurological diseases. This review aims to provide clinicians with an overview of the emerging field of BBB imaging in humans by answering three key questions: (1. Disease) In which diseases could BBB imaging be useful? (2. Device) What are currently available imaging methods for evaluating BBB integrity? And (3. Distribution) what is the potential of BBB imaging in different environments, particularly in resource limited settings? We conclude that further advances are needed, such as the validation, standardization and implementation of readily available, low-cost and non-contrast BBB imaging techniques, for BBB imaging to be a useful clinical biomarker in both resource-limited and well-resourced settings.

Decreased cerebral blood flow (CBF) and deterioration of blood-brain barrier (BBB) are suggested to be precursor conditions of cognitive impairment. Using a novel multi-echo-time arterial spin labelling (ASL) protocol, we examined the time of exchange (Tex) of water across the BBB as a measurement of BBB permeability. We further examined the association of cardiovascular risk factors with Tex in an ongoing cohort study. Data (n = 29, mean age: 55.9±6.1years, 69% women) were drawn from Neurological biomarkers of Blood, MRI and Cognition (NEURO-BMC) study performed at National University of Singapore. NEURO-BMC is an ongoing prospective cohort study (age: 45-65 years) on brain changes in a subclinical phase of cognitive impairment. A multi-echo, Hadamard-encoded multi-post-labelling-delay pseudo-continuous ASL (PCASL) protocol was used on a 3T scanner. ExploreASL was used with a modified version of FSL FABBER(4) to quantify cerebral blood flow (CBF), arterial transit time (ATT), and Tex. ASL-extracted parameters were compared with cardiovascular risk parameters such as blood pressure (BP), BMI and smoking status. High systolic and diastolic BP were associated with significantly reduced Tex (Fig 1). Additionally, higher systolic and diastolic BP showed a trend of increased ATT and reduced CBF, though the associations were not statistically significant (Table 1). High BMI had a significant association with increased ATT and reduced CBF. However, no trend was observed between BMI and Tex. Participants who ever smoked were observed to have a reduced Tex and CBF and increased ATT, but statistical significance was only found for CBF (Fig 1). In this pilot study, we showed that BBB-ASL-derived parameters - ATT, CBF, and Tex - were associated with BP, BMI, and smoking status. While the sample size for this preliminary analysis was too small to make a definitive conclusion as not all associations were statistically significant, all studied cardiovascular risk factors showed their potential in increasing the risk of BBB deterioration. Further investigation with a larger sample size and other health risk factors to assess these observations is warranted.

PURPOSETo create an inventory of image processing pipelines of arterial spin labeling (ASL) and list their main features, and to evaluate the capability, flexibility, and ease of use of publicly available pipelines to guide novice ASL users in selecting their optimal pipeline.METHODSDevelopers self-assessed their pipelines using a questionnaire developed by the Task Force 1.1 of the ISMRM Open Science Initiative for Perfusion Imaging. Additionally, each publicly available pipeline was evaluated by two independent testers with basic ASL experience using a scoring system created for this purpose.RESULTSThe developers of 21 pipelines filled the questionnaire. Most pipelines are free for noncommercial use (n = 18) and work with the standard NIfTI (Neuroimaging Informatics Technology Initiative) data format (n = 15). All pipelines can process standard 3D single postlabeling delay pseudo-continuous ASL images and primarily differ in their support of advanced sequences and features. The publicly available pipelines (n = 9) were included in the independent testing, all of them being free for noncommercial use. The pipelines, in general, provided a trade-off between ease of use and flexibility for configuring advanced processing options.CONCLUSIONAlthough most ASL pipelines can process the common ASL data types, only some (namely, ASLPrep, ASLtbx, BASIL/Quantiphyse, ExploreASL, and MRICloud) are well-documented, publicly available, support multiple ASL types, have a user-friendly interface, and can provide a useful starting point for ASL processing. The choice of an optimal pipeline should be driven by specific data to be processed and user experience, and can be guided by the information provided in this ASL inventory.

Aging-related cognitive decline can be accelerated by a combination of genetic factors, cardiovascular and cerebrovascular dysfunction, and amyloid-β burden. Whereas cerebral blood flow (CBF) has been studied as a potential early biomarker of cognitive decline, its normal variability in healthy elderly is less known. In this study, we investigated the contribution of genetic, vascular, and amyloid-β components of CBF in a cognitively unimpaired (CU) population of monozygotic older twins. We included 134 participants who underwent arterial spin labeling (ASL) MRI and [18F]flutemetamol amyloid-PET imaging at baseline and after a four-year follow-up. Generalized estimating equations were used to investigate the associations of amyloid burden and white matter hyperintensities with CBF. We showed that, in CU individuals, CBF: 1) has a genetic component, as within-pair similarities in CBF values were moderate and significant (ICC > 0.40); 2) is negatively associated with cerebrovascular damage; and 3) is positively associated with the interaction between cardiovascular risk scores and early amyloid-β burden, which may reflect a vascular compensatory response of CBF to early amyloid-β accumulation. These findings encourage future studies to account for multiple interactions with CBF in disease trajectory analyses.

Blood-brain barrier (BBB) dysfunction is considered a hallmark of Alzheimer’s disease (AD), making non-invasive imaging of BBB with arterial spin labeling (ASL) MRI a potential imaging biomarker (BBB-ASL). However, the normal BBB development over the lifespan is unknown. Here, we created population-based BBB-ASL permeability reference maps, and aimed to investigate associations between BBB-ASL, chronological age, and biological cerebrovascular age – expressed as white matter hyperintensities (WMH) volume. Cognitively-unimpaired (CU) participants were included from Center for Lifespan Changes in Brain and Cognition (LCBC) (n = 28, age 58.9±16.1y) and University of Singapore (n = 30, age 55.8±6.1y). The Singapore cohort is known to be vascularly compromised and thus expected to have early cerebrovascular pathology in the form of WMH. Multi-echo, multi-post-labeling-delay pseudo-continuous ASL images were acquired at two identical Siemens 3T scanners and analyzed with ExploreASL. Gray matter (GM) BBB water time-of-exchange (Tex) was quantified with and without partial-volume correction (PVC). For Singapore data, WMH were segmented on 3D FLAIR. Linear regression models were used to investigate associations of Tex with age and WMH volume, with and without covarying for sex and site. Both site population-averages (Figure 1) show similar Tex patterns, with slightly higher posterior variability in the Singapore data. GM Tex was negatively associated with age (Figure 2A) irrespective of PVC, and after covarying for sex and site (Table 1). GM Tex was also negatively associated with WMH volume (ß = -0.005, p = 0.012), although the association became non-significant if both PVC and sex and site corrections were applied (ß = -0.005, p = 0.068). Our findings support the hypothesis of increased BBB permeability with aging and there are signs of association with increased cerebrovascular age assessed with WMH volume. We aim to further increase our sample size and also investigate associations with other AD biomarkers.

BackgroundAmide proton transfer (APT) imaging is a chemical exchange saturation transfer (CEST) technique offering potential clinical applications such as diagnosis, characterization, and treatment planning and monitoring in glioma patients. While APT‐CEST has demonstrated high potential, reproducibility remains underexplored.PurposeTo investigate whether cerebral APT‐CEST with clinically feasible scan time is reproducible in healthy tissue and glioma for clinical use at 3 T.Study TypeProspective, longitudinal.SubjectsTwenty‐one healthy volunteers (11 females; mean age ± SD: 39 ± 11 years) and 6 glioma patients (3 females; 50 ± 17 years: 4 glioblastomas, 1 oligodendroglioma, 1 radiologically suspected low‐grade glioma).Field Strength/Sequence3 T, Turbo Spin Echo ‐ ampling perfection with application optimized contrasts using different flip angle evolution ‐ chemical exchange saturation transfer (TSE SPACE‐CEST).AssessmentAPT‐CEST measurement reproducibility was assessed within‐session (glioma patients, scan session 1; healthy volunteers scan sessions 1, 2, and 3), between‐sessions (healthy volunteers scan sessions 1 and 2), and between‐days (healthy volunteers, scan sessions 1 and 3). The mean APTCEST values and standard deviation of the within‐subject difference (SDdiff) were calculated in whole tumor enclosed by regions of interest (ROIs) in patients, and eight ROIs in healthy volunteers—whole‐brain, cortical gray matter, putamen, thalami, orbitofrontal gyri, occipital lobes, central brain—and compared.Statistical TestsBrown‐Forsythe tests and variance component analysis (VCA) were used to assess the reproducibility of ROIs for the three time intervals. Significance was set at P < 0.003 after Bonferroni correction.ResultsIntratumoral mean APTCEST was significantly higher than APTCEST in healthy‐appearing tissue in patients (0.5 ± 0.46%). The average within‐session, between‐sessions, and between‐days SDdiff of healthy control brains was 0.2% and did not differ significantly with each other (0.76 > P > 0.22). The within‐session SDdiff of whole‐brain was 0.2% in both healthy volunteers and patients, and 0.21% in the segmented tumor. VCA showed that within‐session factors were the most important (60%) for scanning variance.Data ConclusionCerebral APT‐CEST imaging may show good scan–rescan reproducibility in healthy tissue and tumors with clinically feasible scan times at 3 T. Short‐term measurement effects may be the dominant components for reproducibility.Level of Evidence2Technical EfficacyStage 2

As cerebrovascular and Alzheimer’s proteinopathy have previously shown to affect cerebral blood flow (CBF) as well as cognition, CBF could be a potential early hemodynamic biomarker of cognitive decline. Here, we investigated to what extent cardiovascular risk factors and amyloid burden affect CBF in an elderly cognitively unimpaired (CU) population. We included 153 CU participants (minimal MMSE = 28) from the EMIF-AD PreclinAD Twin60++ cohort ( Table 1) , who underwent [18F]flutemetamol PET and arterial spin labeling (ASL) MRI. Amyloid-PET scans were visually assessed as negative or positive, upon which participants were grouped based on their longitudinal changes in amyloid positivity (visual read groups). Cortical amyloid burden was quantified with the Centiloid method globally and for 4 early amyloid accumulation regions of interest (ROIs). ASL scans were processed and quantified with ExploreASL for total gray matter (GM), and for vascular territories overlapping with the amyloid ROIs (Figure 1). Longitudinal analysis including baseline Centiloid values and yearly CBF change rates (Delta CBF) was performed for 98 participants with longitudinal imaging data available (4.23 years ± 0.43 follow-up time). Associations between CBF and amyloid — with and without the interaction of vascular risk factors (i.e., Framingham score) — were assessed using generalized estimating equations (GEEs), both for baseline and rates of change measurements. Models were adjusted for age, sex, and twin dependency. While no association between amyloid burden and CBF was observed across the cohort, in participants with a high Framingham vascular risk score, higher amyloid was associated with increased CBF, for most ROIs ( Table 2 , Figure 2 ). Additionally, precuneus amyloid burden was predictive of CBF change in the corresponding vascular territory ( Figure 3 ). Visual reading shows that subjects with high amyloid burden at baseline had a higher increase of CBF at follow-up (Stable AB+, Figure 4 ). We found that the combination of cardiovascular risk and amyloid burden in AD signature regions was associated with increased CBF in CU individuals, which may reflect a vascular or inflammatory compensatory response to early Alzheimer pathology. Future studies may help understanding how these mechanisms affect cognition.

While arterial spin labeling (ASL) has developed from a preclinical research sequence to a standardized clinical sequence, acquisition techniques still differ between MRI scanners, vendors, and laboratories to accommodate ASL's intrinsically low SNR. Although ASL's image processing essentially revolves around a control-label image subtraction, proper quantification and interpretation of ASL CBF images require knowledge of the interaction of brain physiology with acquisition and image processing methods. This chapter provides an overview of the acquisition and image processing basics of clinical ASL to measure cerebral blood flow (CBF). We specifically discuss cerebrovascular, oncology, neurodegenerative, epilepsy, and pediatric applications. We end this chapter by describing novel ASL research that we believe is promising for future clinical use.

Arterial spin labeling (ASL) is a non-invasive and cost-effective MRI technique for brain perfusion measurements. While it has developed into a robust technique for scientific and clinical use, its image processing can still be daunting. The 2019 Ann Arbor ISMRM ASL working group established that education is one of the main areas that can accelerate the use of ASL in research and clinical practice. Specifically, the post-acquisition processing of ASL images and their preparation for region-of-interest or voxel-wise statistical analyses is a topic that has not yet received much educational attention. This educational review is aimed at those with an interest in ASL image processing and analysis. We provide summaries of all typical ASL processing steps on both single-subject and group levels. The readers are assumed to have a basic understanding of cerebral perfusion (patho) physiology; a basic level of programming or image analysis is not required. Starting with an introduction of the physiology and MRI technique behind ASL, and how they interact with the image processing, we present an overview of processing pipelines and explain the specific ASL processing steps. Example video and image illustrations of ASL studies of different cases, as well as model calculations, help the reader develop an understanding of which processing steps to check for their own analyses. Some of the educational content can be extrapolated to the processing of other MRI data. We anticipate that this educational review will help accelerate the application of ASL MRI for clinical brain research.