Arterial spin labeling in pediatric epilepsy in the emergency setting: clinical predictors of diagnostic yield and optimal acquisition time.

To develop and evaluate a motion-compensated diffusion imaging with phase-contrast (MC-DIP) technique for mitigating errors in regional cerebral blood flow (rCBF) quantification caused by physiological brain motion. Diffusion-weighted images were acquired in 11 healthy volunteers on a 3.0 T MRI system using three gradient schemes: second-order motion-compensated (2nd-MC), first-order motion-compensated (1st-MC), and non-compensated (non-MC) diffusion gradients. Absolute rCBF maps were generated for each scheme by calibrating intravoxel incoherent motion-derived relative perfusion maps with total cerebral blood flow measured by phase-contrast MRI. The rCBF values from the DIP methods were compared in gray and white matter with a reference arterial spin labeling (ASL) measurement. Both motion-compensated schemes (2nd-MC and 1st-MC) provided significantly better biexponential fitting accuracy in gray matter compared with the non-MC scheme (p < 0.05). In white matter, however, only the 2nd-MC scheme resulted in a significant improvement over the other methods (p < 0.05). While rCBF values from all three DIP methods showed a strong positive correlation with ASL in gray matter (ρ ≥ 0.82, p < 0.05), only the 2nd-MC-DIP method demonstrated a significant positive correlation in white matter (ρ = 0.69, p < 0.05). The implementation of second-order motion compensation within the DIP framework improves fitting accuracy, enabling robust rCBF quantification.

We aim to assess the reliability of cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) obtained simultaneously from a novel multi-band pseudo-continuous arterial spin labeling (M2-PCASL) sequence and hypercapnic gas challenge, to examine factors influencing CBF variability, and to evaluate the impact of carbon dioxide (CO2) concentration on CVR estimates. Nine participants underwent test-retest M2-PCASL scans at 3T with hypercapnia to quantify CBF and CVR. Reliability was assessed using the intraclass correlation coefficient (ICC) at whole brain, region of interest (ROI), and voxel levels. Linear mixed-effect models were used to investigate factors contributing to CBF variability. Independent samples t-tests were used to compare BOLD CVR and temporal contrast to noise ratio (tCNR) from different CO2 concentrations. With smoothing, the M2-PCASL sequence estimated baseline CBF and BOLD CVR with good to excellent reliability (ICC > 0.81) in the whole brain, gray matter (GM), and white matter (WM). Average ICCs across the Automated Anatomical Labeling atlas ROIs were between 0.50 ± 0.30 and 0.69 ± 0.19. CBF CVR achieved fair to moderate reliability in GM (ICCs between 0.42 and 0.55). Head motion was significantly associated with CBF temporal SNR (p ≤ 0.002). 5% and 8% CO2 yielded similar BOLD CVR estimates, but the BOLD tCNR using 5% CO2 was lower, although not statistically significant. The M2-PCASL sequence with hypercapnia reliably estimates baseline CBF and BOLD CVR at improved spatial and temporal resolutions relative to existing methods, enabling us to noninvasively and comprehensively assess cerebrovascular health.

Cerebrovascular dysfunction, including reduced cerebral blood flow (CBF) and cerebrovascular reactivity (CVR), contributes to Alzheimer's disease (AD). Caloric restriction (CR) and resveratrol (Rsv) benefit vascular health, yet their impact on CBF and CVR in AD remains unclear. Here, we investigated the cerebrovascular effects of 40% CR or Rsv supplementation in WT and TgF344-AD rats. Using pseudo-continuous arterial spin labelling (pCASL) MRI, we observed that male Tg control (Ctrl) rats exhibited reduced relative CBF (rCBF) and absolute CBF (aCBF) in the caudate-putamen at baseline compared to WT Ctrl and Tg Rsv rats, while Rsv restored CBF to WT levels. Male Rsv rats also showed higher rCBF than CR rats in the somatosensory cortex, irrespective of genotype. In the cingulate cortex, male Tg rats had lower rCBF than WT, irrespective of treatment. During hypercapnia, Tg males displayed lower rCBF and aCBF across multiple regions, while Rsv increased rCBF in cingulate cortex and somatosensory cortex, regardless of genotype. In females, treatments did not affect baseline or hypercapnic CBF, although CR and Rsv reduced CVR compared to Ctrl. In summary, these findings suggest Rsv reverses AD-related hypoperfusion in males, whereas CR may impair cerebrovascular responsiveness in females, highlighting the need for sex-specific therapeutic strategies.

Coronary microvascular dysfunction (CMD) is a major contributor to cardiovascular complications in diabetes. Although noninvasive techniques such as arterial spin labeling cardiac MRI (ASL-MRI) and transthoracic echocardiography (TTE) are available, their comparative performance for CMD remains unclear. To compare ASL-MRI and TTE for CMD assessment in type 1 and type 2 (T1DM, T2DM) mouse models and relate functional indices to histological microvascular and myocardial remodeling, including early-stage T2DM (8w-T2DM). Prospective. Forty 8-week-old male C57BL/6J mice allocated to five groups: control, T1DM, and T2DM (n = 10 per group, imaged 16 weeks postinduction), and early-stage T2DM (8w-T2DM) and age-matched controls (n = 5 per group, imaged 8 weeks post-induction). Segmented FLASH cine, steady-pulsed labeling ASL, and inversion-recovery segmented FLASH (T1 mapping) sequences at 9.4 T. Rest/stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) were derived from ASL data using a model-based approach incorporating native T1 (from segmented FLASH data). Coronary flow velocity (CFV) and reserve (CFVR) were measured by TTE at rest (1.5% isoflurane) and stress (2.5% isoflurane). Histology included assessment of hematoxylin-eosin (myocyte area), Masson (collagen), and IB4 (capillary density). Group comparisons used t-tests, Mann-Whitney U tests, and one-/two-way ANOVA with Bonferroni correction; correlations were assessed with Pearson or Spearman coefficients (r). p < 0.05 was considered significant. 38 animals completed MR and TTE imaging. At 16 weeks, stress diastolic MBF was significantly lower in T1DM (14.67 ± 1.62 mL/g/min) and T2DM (13.42 ± 2.44 mL/g/min) vs. controls (22.19 ± 0.25 mL/g/min), with significantly reduced MPR in T2DM (1.53 ± 0.17 vs. 2.27 ± 0.15). TTE showed significantly reduced CFVR only in T2DM (2.16 ± 0.24 vs. 2.75 ± 0.24). In 8w-T2DM, ASL-MRI detected significantly reduced MPR (1.87 ± 0.16 vs. 2.26 ± 0.13), whereas TTE showed no significant CFVR change (p = 0.900). Capillary density significantly decreased in 16-week and 8-week T2DM. IB4-positive area correlated with CFVR (r = 0.673) and more strongly with MPR (r = 0.810). ASL-MRI detected CMD in diabetic mice, outperforming TTE in early-stage disease and showing a strong association with microvascular injury. 1. Stage 2.

We investigate whether common circle of Willis (CoW) variants relate to cerebral blood flow (CBF) characteristics among aging adults. Vanderbilt Memory and Aging Project participants free of clinical stroke (n = 390, 71 ± 8 years, 55% male) completed magnetic resonance angiography to assess cerebral artery variants and pseudocontinuous arterial spin labeling to quantify resting CBF and spatial coefficient of variation (sCoV), a marker of perfusion heterogeneity or stability. Linear regression models related categorical variants to regional CBF and sCoV, adjusting for age, sex, race/ethnicity, education, cognitive status, Framingham Stroke Risk Profile, and APOE-ε4 status. Absence of at least one posterior communicating artery (PcoA) related to lower occipital lobe CBF (p = 0.001) and higher global (p = 0.003), temporal (p = 0.001), and occipital lobe sCoV (p = 0.01). Bilateral PcoA absence related to lower global (p = 0.01), parietal (p = 0.01), and occipital lobe CBF (p = 0.0001) and higher global (p < 0.0001), temporal (p < 0.0001), and occipital lobe sCoV (p = 0.0003). Hypoplastic and fetal-type variants did not relate to outcomes (p > 0.22). Findings demonstrate that missing PcoAs influence both perfusion magnitude and efficiency, suggesting that common CoW variants may produce regionally coherent hemodynamic effects in heart-healthy aging adults and represent markers of early cerebrovascular vulnerability.

Arterial Spin Labeling MRI Denoising via Locally Adaptive Regularization with Structure-Guided Collaborative Data Selection.

To compare the radiomics features of pseudocontinuous arterial spin labeling (ASL) and dynamic susceptibility contrast (DSC) perfusion-weighted imaging in distinguishing radiation-induced brain injury (RIBI) from tumor recurrence (TR) in patients with diffuse gliomas. A total of 131 patients with pathologically confirmed adult-type diffuse gliomas, presenting with newly developed abnormal enhancing lesions after standard radiotherapy, were included for model development. Lesion segmentation was performed manually by two raters using ITK-SNAP and the segmentation consistency was assessed by intraclass correlation coefficient (ICC). A total of 1015 radiomics features were extracted from the segmented areas of T2WI, T1WI, contrast-enhanced T1WI (CE-T1WI), cerebral blood flow (CBF) maps from ASL, and relative cerebral blood flow (rCBF) maps from DSC, respectively. Feature selection was conducted via t-tests, and an elastic net regression (ENR) algorithm combined with recursive feature elimination (RFE) with cross-validation was used to identify the important features. Four machine learning classifiers were employed to establish radiomics models. Diagnostic performance was assessed using the area under the curve (AUC) in conventional (T2WI+T1WI + CE-T1WI), ASL-CBF, DSC-rCBF, conventional + ASL-CBF, and conventional + DSC-rCBF radiomics models, respectively. The optimal models were further validated in an independent validation set (n = 37). Six features from ASL-CBF, five from DSC-rCBF, one from T1WI, one from T2WI, and four from CE-T1WI were identified as the most significant features. The K-nearest neighbor (KNN) classifier was selected as the optimal classifier. In the training set, both ASL-CBF (AUC = 0.962) and DSC-rCBF (AUC = 0.946) radiomics models demonstrated satisfactory diagnostic performance, surpassing that of conventional MRI radiomics model (AUC = 0.844). The diagnostic accuracy was further improved when integrating DSC-rCBF features into conventional MRI models (AUC = 0.971). In the independent validation set, the ASL-CBF, conventional + ASL-CBF and conventional + DSC-rCBF models achieved satisfactory performance, with AUC of 0.955, 0.968 and 0.960. While the DSC-rCBF model alone showed an AUC of 0.887 and decreased specificity (58.3%), and the conventional model demonstrated decreased AUC of 0.720 and specificity (33.3%). In this exploratory study, radiomics features derived from both ASL-CBF and DSC-rCBF showed promise in distinguishing RIBI from TR. Integrating perfusion features into conventional MRI enhanced model accuracy. These preliminary findings suggest ASL-based radiomics as a viable, non-contrast alternative; however, these results should be interpreted with caution due to the modest validation sample size and single-center design. They require validation in larger, prospective, multi-center cohorts before clinical implementation.

Kidney transplantation is the gold-standard renal-replacement therapy for end-stage kidney disease, yet delayed graft function affects 5-50% of recipients and predicts chronic allograft dysfunction. Functional magnetic resonance imaging (fMRI) offers a non-invasive means to simultaneously assess allograft perfusion, oxygenation, and microstructure. We systematically searched PubMed, Web of Science, Cochrane Library, Embase, and MEDLINE for studies evaluating arterial spin labeling (ASL), blood oxygen level-dependent (BOLD), diffusion-weighted imaging (DWI), and intravoxel incoherent motion (IVIM) MRI in kidney transplant recipients. Study quality was appraised with QUADAS-2. Data were pooled using random-effects models, with subgroup analyses by magnetic field strength, post-transplant time, and baseline creatinine. Twenty-eight studies comprising 1,956 recipients were included. ASL-derived cortical renal blood flow (RBF) discriminated normal from impaired renal function (estimated glomerular filtration rate (eGFR) ≥ 60 vs. <60 mL/min/1.73m²; mean difference (MD) 98.48mL·min⁻¹·100g⁻¹, 95% confidence interval (CI) 68.66-128.31; P < 0.00001; I²=57%) and correlated with eGFR (r = 0.58). BOLD identified acute rejection (lower R2*; I²=77-86%) but not acute tubular necrosis. IVIM-derived D values showed the strongest discriminatory power (MD 0.14-0.16 × 10⁻³ mm²/s; P < 0.00001; I²=0%). Substantial heterogeneity (I²=18-98%) limited conclusions for some parameters. Multiparametric fMRI, particularly ASL and IVIM shows promise for detecting early allograft dysfunction. However, marked inter-study heterogeneity underscores the need for standardized protocols before clinical implementation.

Treatment for hyperglycemic hyperosmolar syndrome (HHS) was initiated for a transferred unconscious patient. Aphasia and agnosia remained even after metabolic improvement. Arterial spin labeling (ASL) indicated increased blood flow in the left temporal and parietal lobes. ASL may provide useful information regarding cerebral perfusion abnormalities in patients with HHS.

Atrial fibrillation (AF) is associated with a high risk of stroke, as well as cognitive decline and dementia. Advanced imaging techniques were employed to test the hypothesis that AF worsens cerebrovascular function as evaluated using neurovascular coupling (NVC) and cerebrovascular carbon dioxide reactivity (CVRCO2) tests. Twenty healthy controls (HC; 63.4±9.5 years) and nineteen AF patients (66.6±12.0 years) completed NVC (visual stimulation with a flickering checkerboard) and CVRCO2 (5%CO2) assessments during functional (blood oxygen level-dependent [BOLD]) and perfusion (arterial spin labelling) magnetic resonance imaging. Additionally, brain volumes and cognition were assessed. During CVRCO2 assessment, neither %∆ in BOLD signal (HC: 3.09±0.50; AF: 3.23±0.70%; p=0.513) nor %∆ in cerebral blood flow (CBF) (HC: 36.6±18.8; AF: 43.6±20.6%; p=0.319) were different between groups. During NVC assessment, CMRO2 (HC: 5.25±1.84; AF: 4.36±2.50%, p=0.285), %∆BOLD (HC: 1.60±0.38; AF: 1.66±0.79%; p=0.762) and %∆CBF (HC: 49.4 [20.1-71.9]; AF: 51.7 [38.3-66.9]%; p=0.850) all increased similarly in HC and AF. AF patients had lower hippocampal volume relative to total intracranial volume than HC (0.50±0.06 vs. 0.55±0.06%; p=0.020). There were no differences between HC and AF in cognitive performance across multiple domains (all p>0.05). These results suggest that NVC and CVRCO2 responses are preserved in AF.

To evaluate markers of cerebral small vessel disease (SVD), cerebral blood flow (CBF), and white matter integrity in patients with subcortical ischemic vascular dementia (SIVD) using multimodal magnetic resonance imaging (MRI), and to analyze the impact of total SVD load on cerebral perfusion and white matter injury. Fifty SIVD patients who visited the Cognitive Disorders Clinic of Tianjin Medical University General Hospital between October 2017 and October 2022 were enrolled and underwent 3.0 T multimodal MRI examination. A total SVD load score was calculated based on the severity of white matter hyperintensities (WMH), lacunes, enlarged perivascular space (EPVS), and cerebral microbleeds (CMB). The patients were divided into a low total SVD load group (0-4 points, n=32) and a high total SVD load group (5-6 points, n=18). CBF and white matter integrity were assessed using arterial spin labeling (ASL) and diffusion tensor imaging (DTI), respectively. Independent-sample t-test and χ2 test were used for intergroup comparison. Binary logistic regression model was adopted to analyze the correlation of various imaging markers with CBF and DTI parameters in all subjects. Compared with the low total SVD load group, the high total SVD load group exhibited reduced CBF in the right cerebellar posterior lobe and tonsil [(45.7±14.9) vs (59.6±12.5) ml·(100 g)-1·min-1, t=3.52, P<0.01], left superior frontal gyrus [(22.2±6.3) vs (26.8±6.0) ml·(100 g)-1·min-1, t=2.55, P=0.01], left middle frontal gyrus [(50.6±15.8) vs (60.5±14.8) ml·(100 g)-1·min-1, t=2.22, P=0.03], and right middle frontal gyrus [(58.7±16.1) vs (67.7±12.7) ml·(100 g)-1·min-1, t=2.18, P=0.04]. Decreased fractional anisotropy values (all P<0.05) and increased mean diffusivity values (all P<0.05) were observed in multiple white matter regions, including the corpus callosum, right cerebral peduncle, bilateral internal capsules, bilateral anterior corona radiata, bilateral posterior corona radiata, bilateral posterior thalamic radiation, bilateral cingulate gyri, and bilateral frontoparietal superior fasciculi. Meanshile, reduced CBF and impaired white matter integrity in these brain regions were correlated with scores of individual SVD markers and the total SVD load score (all P<0.05). The total SVD load is closely associated with decreased cerebral perfusion and impaired white matter integrity in SIVD patients, which is an important pathological mechanism underlying brain dysfunction.

Differentiating true progression (TP) from pseudoprogression (PsP) after chemoradiotherapy in gliomas remains challenging because conventional MRI findings overlap. To assess whether voxel-level radiomics habitat metrics improve TP/PsP classification and complement clinical and molecular features. Retrospective, multi-center. 193 glioma patients after treatment: 121 in the training set (54.2 ± 11.3 years; 74 men; 85 TP/36 PsP) and 72 in the external testing set (51.4 ± 10.4 years; 44 men; 52 TP/20 PsP). 3 and 1.5 T; contrast-enhanced T1-weighted spin-echo imaging (T1CE), T2-weighted fast/turbo spin-echo imaging (T2WI), T2-weighted fluid-attenuated inversion recovery fast/turbo spin-echo imaging (T2-FLAIR), diffusion-weighted echo-planar imaging (DWI), and arterial spin labeling (ASL). Voxel-wise radiomics features were extracted from contrast-enhancing tumor ROIs. Gaussian mixture models generated soft habitats, from which voxel-level metrics were calculated. Three models were constructed. The Clinical Model included tumor grade, isocitrate dehydrogenase (IDH) status, O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, and time interval. Feature selection used least absolute shrinkage and selection operator (LASSO); classifier optimization employed Optuna-based Bayesian methods. Receiver operating characteristic (ROC) curve analysis, calibration curves, decision curve analysis (DCA), and SHAP were used. p < 0.05 indicated significance. In the testing set, the Clinical, Voxel-wise Habitat, and Combined Models achieved areas under the curve (AUCs) of 0.701 (95% confidence interval [CI]: 0.597-0.806), 0.832 (95% CI: 0.736-0.917), and 0.890 (95% CI: 0.819-0.958), respectively. The Combined Model significantly outperformed the clinical model (difference, 0.189). Voxel-wise Habitat versus Clinical (difference, 0.131; p = 0.164) and Combined versus Voxel-wise Habitat comparisons (difference, 0.058; p = 0.105) were not significant. SHAP ranked CBF_habitat_edge_standard_deviation, CBF_habitat_entropy_mean, and T1CE_habitat_edge_standard_deviation as leading contributors. Voxel-wise habitat analysis, combined with clinical and molecular features, improved TP/PsP discrimination with interpretable heterogeneity metrics. 3. Stage 3.

Brain and physiological responses to flavored waters with different sweeteners: a randomized cross-over study in healthy young adults.

Acute focal neurological deficits require rapid differentiation between ischemic stroke and stroke mimics to avoid treatment delays and inappropriate therapy. Seizures, including ictal deficits, status epilepticus, and post-ictal/Todd's phenomena, are among the most challenging mimics. This review summarizes the role of multimodal neuroimaging in distinguishing acute ischemic stroke from seizure-related deficits. We performed a focused narrative review of neuroimaging findings in acute stroke mimics, emphasizing non-contrast computed tomography (CT), CT angiography, CT perfusion, magnetic resonance imaging (MRI), including diffusion weighted imaging (DWI), apparent diffusion coefficient (ADC), fluid attenuated inversion recovery (FLAIR), and arterial spin labeling (ASL) sequences. Imaging patterns, diagnostic pitfalls, and practical clues for hyperacute stroke pathways were synthesized. Acute ischemic stroke is typically suggested by vascular-territorial abnormalities, including arterial occlusion or stenosis, territorial hypoperfusion, and congruent DWI/ADC restriction. Seizure-related deficits more often show non-territorial cortical perfusion changes, ictal or status-related hyperperfusion, reversible MRI abnormalities, and absence of arterial occlusion. However, post-ictal hypoperfusion, peri-ictal diffusion restriction, and reperfusion-related hyperperfusion may overlap with ischemic patterns. A multimodal approach integrating vascular imaging, perfusion distribution, DWI/ADC, ASL, clinical timing, and EEG findings can improve diagnostic accuracy in the stroke-seizure differential without delaying treatment in true acute ischemic stroke.

Neurofibromatosis type1 (NF1) is amultisystem disorder with wide-ranging clinical presentations. Patients with NF1 may manifest with macrocephaly, strokes, and cognitive deficits, abnormal neural development, and other neurologic symptoms. This study used an atlas-based approach to quantitatively examine structural and physiologic changes of the brain in children with NF1. Children evaluated for NF1 over a9-year period at achildren's hospital were retrospectively reviewed (n = 34). Children with intracranial tumors or prior strokes were excluded. Patients received diffusion-weighted imaging (DWI) and arterial spin labeling (ASL) perfusion imaging on a3T MRI scanner. Using an atlas-based approach, quantitative assessment of regional brain volumes, median apparent diffusion coefficient (ADC), and cerebral blood flow (CBF) was performed for the cerebral cortex, thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens, brainstem, and cerebral white matter. Differences were tested between NF1 patients and 100 typically developing controls. Compared to controls, children with NF1 demonstrated significantly increased volume measurements in all brain regions (p < 0.001), significantly higher median ADC values in all structures except for the putamen and nucleus accumbens (p < 0.001), and significantly lower median CBF most notable in the cerebral white matter (p < 0.001), globus pallidus (p < 0.001), hippocampus (p < 0.001), amygdala (p < 0.001), and brainstem (p = 0.001). This study measured microstructural and physiologic brain changes in children with NF1 compared to typically developing children. Further studies are needed to elucidate the cellular and molecular basis for these differences. With further refinement, atlas-based quantitative MRI brain signatures may serve as useful biomarkers of neural development, cognitive dysfunction, and risks for vasculopathy-related strokes in children with NF1.

The susceptibility of athletes to long-term adverse outcomes following recurrent concussion remains controversial. Acute concussion precipitates a transient reduction in cerebral blood flow (CBF) that typically returns to pre-injury levels. Recent work suggests that long-term CBF alterations may be sex-specific. We assessed whether concussion history was associated with chronic CBF alterations and whether sex moderated this relationship in otherwise healthy, active collegiate-aged athletes. Collegiate-aged athletes from the community (N = 204, 37.8% female, Mage = 21.0 ± 1.7) underwent magnetic resonance imaging with pseudo-continuous arterial spin labeling to quantify global and regional CBF and spatial coefficient of variation. Participants also completed measures of depression, anxiety, and cognition. Multiple linear regressions incorporating prior concussion-by-sex interaction terms adjusted for relevant covariates were fit to estimate the extent to which sex moderated the concussion history-CBF relationship. Exploratory analyses further assessed whether oral contraceptive use or pill formulation moderated this association in females. The number of prior concussions was negatively associated with global and regional gray-matter CBF in female but not male athletes, with the strongest associations localizing to frontotemporal regions. CBF metrics were not related to cognitive performance or affective symptom burden. Contraceptive use did not appear to substantially moderate the concussion history-CBF association in female athletes. Female-specific associations between concussion history and cerebral hypoperfusion in early adulthood suggest potential sex differences in pathways and trajectories of adverse long-term outcomes. Early chronic CBF alterations may represent one vulnerability to future risk in a sex-specific manner.

Nonconvulsive seizures are clinically important in severe traumatic brain injury but are difficult to detect when continuous electroencephalography (EEG) is not feasible in the intensive care unit. We conducted a prospective observational study to evaluate a nurse-led patch-type EEG protocol, with arterial spin labeling (ASL) magnetic resonance imaging as an exploratory comparator. Patch-type EEG monitoring was feasible in 21 of 24 enrolled patients (87.5%), and both EEG and ASL assessments were evaluable in 16 patients. Electrographic seizures were detected in four patients (25%), with all of them showing corresponding focal hyperperfusion on imaging. These findings suggest that simplified patch-type EEG monitoring is feasible in this setting; however, further studies are warranted to determine the clinical relevance of nurse-led patch-type EEG monitoring.

To develop an effective deep learning (DL)-based method to denoise arterial spin labeling (ASL) data. Conventional DL-based ASL denoising methods often suffer from overfitting and poor generalization when training data are limited. The proposed method overcame this problem using two strategies: (i) perform data augmentation to create large training data and (ii) denoise in-distribution and out-of-distribution components of the target perfusion-weighted image separately. Specifically, Image-to-Image Schrödinger Bridge (I2SB)-based distribution remapping transforms were applied to the large public ASL datasets so that their intensity distribution matched that of the data to be denoised. U-Net-based DL denoisers were trained on the remapped data to capture in-distribution features. High-SNR outputs from the DL-denoiser were incorporated into a Bayesian model to reconstruct the out-of-distribution features with sparsity constraints, generating denoised images for cerebral blood flow (CBF) quantification. Simulation studies highlighted the importance of distribution remapping for effective data augmentation in limited-data scenarios. Both simulation and in vivo experiments showed that the proposed method outperformed state-of-the-art approaches, achieving an average SNR improvement of approximately 7 dB. Evaluations on multiple datasets confirmed robust and generalizable performance across different ASL sequences and imaging protocols. To demonstrate clinical potential, our method was applied to denoising stroke patient data (using only one-sixth of total averages with ˜83% reduction in scan time) and produced comparable CBF maps to the conventional ASL method. The proposed method enables effective ASL denoising with limited training data. It has the potential to accelerate ASL acquisition, enhance image quality, and improve clinical utility.

The effects of acute ketone monoester supplementation on brain insulin responsiveness and cognitive performance: Results of a randomized, double-blind, placebo-controlled crossover trial in older men with overweight.