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Purpose: To 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. Methods: Developers 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. Results: The 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. Conclusion: Although 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. [ABSTRACT FROM AUTHOR]

Background: 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. Method: 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. Result: 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). Conclusion: 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. [ABSTRACT FROM AUTHOR]

Background: Amide 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. Purpose: To investigate whether cerebral APT‐CEST with clinically feasible scan time is reproducible in healthy tissue and glioma for clinical use at 3 T. Study Type: Prospective, longitudinal. Subjects: Twenty‐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/Sequence: 3 T, Turbo Spin Echo ‐ ampling perfection with application optimized contrasts using different flip angle evolution ‐ chemical exchange saturation transfer (TSE SPACE‐CEST). Assessment: APT‐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 Tests: Brown‐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. Results: Intratumoral 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 Conclusion: Cerebral 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 Evidence: 2 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

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., (© 2024 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)