Lim, Seokbeen

Abstract Introduction Quantitative interpretation of pediatric brain [ 18 F]-FDG PET is limited by the lack of age-matched normative reference databases, despite substantial developmental variation in cerebral glucose metabolism. This study aimed to construct a large-scale normative pediatric [ 18 F]-FDG PET database and develop an age-specific z-score mapping framework for quantitative evaluation of pediatric epilepsy. Method Pediatric brain PET data were retrospectively derived from clinically acquired whole-body or dedicated [ 18 F]-FDG PET examinations in participants 0–19 years of age without neurologic disease or visible brain abnormalities. A total of 417 PET scans from 341 participants were stratified into five developmental age groups: infancy, early childhood, middle childhood/school age, adolescence, and late adolescence. SUVR maps were generated using whole-brain atlas and brainstem reference regions. Voxel-wise t-test analyses were performed to characterize age- and sex-related metabolic differences. Age-specific voxel-wise mean and standard deviation maps were generated from the normative cohort and used to calculate age-matched hypometabolic z-score maps in 14 pediatric patients with epilepsy. The resulting abnormalities were qualitatively evaluated for concordance with epileptogenic findings identified on clinical MRI and/or PET by expert image review. Results Voxel-wise analyses demonstrated prominent age-dependent SUVR differences, particularly between infancy and older age groups. With whole-brain atlas normalization, older children showed progressively higher relative SUVR in cortical and cerebellar gray matter regions, whereas infancy showed relatively higher SUVR in the occipital cortex, white matter, thalamus, and brainstem. Brainstem normalization produced distinct developmental patterns, emphasizing higher white matter SUVR in infancy and broader gray matter differences in older groups. Sex-related differences were limited and regionally specific. Whole-brain atlas normalization showed lower variability than brainstem normalization and was selected for z-score mapping. In representative epilepsy cases, age-matched z-score maps identified focal or regional hypometabolism corresponding to malformations of cortical development, focal cortical dysplasia, mesial temporal sclerosis, nonlesional MRI cases, remote insult, tumor-related abnormalities, and Sturge-Weber syndrome. Discussion A large-scale normative pediatric [18F]-FDG PET database can support developmentally appropriate quantitative interpretation of pediatric brain PET. Age-matched z-score mapping may complement visual assessment by highlighting abnormal cerebral glucose metabolism in pediatric epilepsy, although findings should be interpreted with MRI, EEG, seizure semiology, and other presurgical data.

Abstract INTRODUCTION The tau positron emission tomography (PET) overlap index (OI) has shown promise in maximizing signal‐to‐noise for longitudinal tau PET imaging, particularly for early tau pathology, but requires validation against neuropathology. METHODS Fifty‐seven participants who underwent serial tau PET imaging (flortaucipir) and subsequent autopsy were included. Tau PET OI and standardized uptake value ratios (SUVRs) were compared across neuropathological diagnoses. RESULTS Tau PET OI showed greater concordance with neurofibrillary tangle (NFT) severity in the entorhinal cortex (a key region for Alzheimer's disease [AD] tauopathy) than SUVR, particularly in early Braak tangle stages (positivity: 52.2% for OI vs. 13.0% for SUVR). OI detected overlapping tau voxels that exhibited spatial correspondence with immunohistochemical and autoradiography measures of tau deposition across both AD and non‐AD tauopathies. DISCUSSION These findings demonstrate the enhanced capacity of OI in serial tau PET to robustly detect early and spatially localized tau pathology, supporting its application as a sensitive imaging metric in AD and select non‐AD tauopathies.

Introduction Burnout among healthcare professionals remains a critical public health issue linked to impaired cognition, emotional exhaustion and diminished clinical performance. Structured breathing practices have demonstrated promise in improving autonomic regulation and cerebral oxygenation, yet their feasibility, acceptability and implementation in real-world healthcare settings remain underexplored. Objectives This single-arm pilot feasibility trial aims to evaluate the feasibility, acceptability and implementation appropriateness of a structured breathing-based intervention for healthcare professionals across community-based Mayo Clinic Health System (MCHS) sites. Secondary objectives include assessing usability and engagement with the mobile breathing platform, while exploratory analyses will describe magnitude of variability and feasibility of collecting psychological and cerebral haemodynamic measures. This study will commence in November 2025 and is expected to be completed by June 2026. Methods and analysis A total of 40 clinicians (MD/DO/MBBS/PA) and nurses reporting moderate or greater burnout will be enrolled across four MCHS sites. Participants will complete a 4-month structured breathing programme delivered primarily online, supported by a mobile application for practice tracking. Assessments will occur at baseline, 2 months and 4 months, with functional near-infrared spectroscopy (fNIRS) measures of cerebral oxygenation collected at baseline and 4 months in a population subset. Primary outcomes include (1) recruitment yield, retention and adherence rates; (2) acceptability and participant satisfaction (survey and qualitative feedback); and (3) implementation appropriateness measured by the Acceptability of Intervention Measure (AIM), Intervention Appropriateness Measure (IAM) and Feasibility of Intervention Measure (FIM). Secondary outcomes include digital engagement and usability through mobile analytics and the System Usability Scale. Exploratory outcomes are psychological indicators (burnout, depression, anxiety, perceived stress, sleep, fatigue, professional fulfilment and resilience) and physiological endpoints (fNIRS). Analyses will be descriptive, summarising feasibility metrics with 95% CIs. Progression criteria (recruitment≥75%, retention≥80%, adherence≥70%, AIM/IAM/FIM≥4.0) will determine readiness for a definitive hybrid effectiveness–implementation trial. Ethics and dissemination The study is approved by the Mayo Clinic Institutional Review Board (IRB # 25-009320). All participants will provide informed consent. Study procedures ensure confidentiality, cultural sensitivity and participant safety. Data will be securely stored in REDCap and disseminated through peer-reviewed publications and scientific conference Trial registration number NCT07218458 .

Abstract INTRODUCTION Understanding neuroinflammation across the Alzheimer's disease (AD) spectrum is essential to elucidate disease mechanisms and individualize therapy. METHODS Human microglial translocator protein (TSPO) expression under inflammatory stimuli was assessed by immunoblot experiments. Ninety‐six participants were enrolled across four groups: cognitively unimpaired amyloid (CU A) + and −, mild cognitive impaired (MCI) A+, and Alzheimer's disease dementia (ADD) A+. Neuroinflammation using 11 C‐ER176 TSPO positron emission tomography (PET) was compared to amyloid and tau PET. Correlations between neuroinflammation, amyloid, and tau pathology were examined across disease stages. RESULTS TSPO was upregulated in human microglia under AD‐like inflammatory conditions. Neuroinflammation, defined by PET TSPO, increased in CU A+ participants and became more widespread with increasing disease severity, aligning with worsening amyloid and tau pathology. Associations with tau were particularly extensive in temporal and parietal regions. DISCUSSION These findings suggest probable amyloid association with early microglial activation, while tau pathology is closely tied to wider distribution of neuroinflammation. Highlights TSPO expression increases in human microglia under AD‐like inflammation. 11 C‐ER176 PET shows stage‐dependent neuroinflammation across the AD spectrum. Neuroinflammation overlaps with tau and is more widespread in amyloid‐positive individuals. Activity peaks in MCI, stabilizes later, and relates to vascular and neurodegenerative changes.

Abstract Background The overlap index (OI), previously introduced by Lee et al. (2022), has proven to be a reliable method for detecting tau accumulation via tau‐PET imaging with flortaucipir ([ 18 F]AV‐1451). This technique identifies voxel‐wise increases in standardized uptake value ratio (SUVr) across serial scans. However, the relationship between tau‐PET measurements obtained with [ 18 F]MK‐6240 and [ 18 F]AV‐1451 using the OI remains unclear. This study aims to investigate the relationship between [ 18 F]MK‐6240 and [ 18 F]AV‐1451 tau‐PET using the tau‐PET OI. Method The study included 27 participants from the HEAD project, all of whom underwent two serial tau‐PET scans (each [ 18 F]MK‐6240 and [ 18 F]AV‐1451) along with 3T T1‐weighted MRI, acquired within an average interval of 18 months. SUVr maps for each tau‐PET tracer were normalized to the cerebellar crus grey matter, and MR images were co‐registered to the MCALT T1 template. Tau‐PET images were spatially resampled to the template space, and OI was computed within a predefined META‐ROI using an intensity threshold of 1.3 and a cutoff of 0.5. Clusters containing fewer than 20 contiguous voxels were excluded from analysis. The META‐ROI SUVr was calculated as the average SUVr across the selected region's SUVr. Additionally, a visual comparison was performed to assess the spatial overlap of OI‐identified voxels between the two tau‐PET tracers. Result OI values within the META‐ROI exhibited a broad distribution between [ 18 F]MK‐6240 and [ 18 F]AV‐1451 tau‐PET, particularly in cognitively unimpaired (CU) and younger individuals (Figure 1A). Unlike the OI distribution, the relationship between META‐ROI SUVr values of both tracers followed an exponential trend (Figure 1B). Visual inspection revealed that OI‐detected voxels in [ 18 F]MK‐6240 tau‐PET were frequently localized to the meninges, an established site of off‐target binding, which was not observed in [ 18 F]AV‐1451 tau‐PET (Figure 2). Conclusion The association between [ 18 F]MK‐6240 and [ 18 F]AV‐1451 tau‐PET, as assessed using the OI, exhibited considerable variability in CU and younger participants. Additionally, the presence of overlapping voxels in the meninges in [ 18 F]MK‐6240 tau‐PET highlights the need to account for and potentially exclude off‐target binding effects in these populations. The influence of meningeal signal and other off‐target binding on the OI in the temporal META‐ROI needs to be further evaluated.

Abstract Introduction Burnout among healthcare professionals remains a critical public health issue linked to impaired cognition, emotional exhaustion, and diminished clinical performance. Structured breathing practices have demonstrated promise in improving autonomic regulation and cerebral oxygenation, yet their feasibility and acceptability in real-world healthcare settings remain underexplored. Objectives This single-arm pilot feasibility trial aims to evaluate the feasibility, acceptability, and implementation appropriateness of a structured breathing-based intervention for healthcare professionals across community-based Mayo Clinic Health System (MCHS) sites. Secondary objectives include assessing usability and engagement with the mobile breathing platform, while exploratory analyses will examine preliminary signals of change in psychological well-being and cerebral hemodynamics. Methods and Analysis A total of 40 physicians and nurses reporting moderate or greater burnout will be enrolled across four MCHS sites. Participants will complete a four-month structured breathing program delivered primarily online, supported by a mobile application for practice tracking. Assessments will occur at baseline, 2 months, and 4 months, with optional functional near-infrared spectroscopy (fNIRS) measures of cerebral oxygenation collected at baseline and 4 months in a subset. Primary outcomes include (1) recruitment yield, retention, and adherence rates; (2) acceptability and participant satisfaction (survey and qualitative feedback); and (3) implementation appropriateness measured by the Acceptability of Intervention Measure (AIM), Intervention Appropriateness Measure (IAM), and Feasibility of Intervention Measure (FIM). Secondary outcomes assess digital engagement and usability through mobile analytics and the System Usability Scale (SUS). Exploratory outcomes evaluate psychological indicators—burnout, depression, anxiety, perceived stress, sleep, fatigue, professional fulfillment, and resilience—and physiological endpoints (fNIRS). Analyses will be descriptive, summarizing feasibility metrics with 95% confidence intervals. Progression criteria (recruitment ≥75%, retention ≥80%, adherence ≥70%, AIM/IAM/FIM ≥4.0) will determine readiness for a definitive hybrid effectiveness–implementation trial. Ethics and Dissemination The study is approved by the Mayo Clinic Institutional Review Board (IRB # 25-009320). All participants will provide informed consent. Study procedures ensure confidentiality, cultural sensitivity, and participant safety. Data will be securely stored in REDCap and disseminated through peer-reviewed publications and scientific conference ClinicalTrials.gov ID The study has been prospectively registered at ClinicalTrials.gov (Identifier NCT07218458 ). Strengths and Limitations Evaluates a structured breathing-based intervention using both subjective and objective indicators of feasibility, including recruitment, retention, adherence, and implementation appropriateness. Integrates mobile application analytics with standardized implementation measures (AIM, IAM, FIM) to capture digital engagement and real-world usability. Incorporates functional near-infrared spectroscopy (fNIRS) to explore physiological mechanisms underlying burnout recovery, linking cerebral oxygenation to behavioral outcomes. Conducted across diverse community-based Mayo Clinic Health System sites, enhancing ecological validity and relevance to decentralized clinical settings. Limitations include the single-arm, region-restricted design, modest sample size, and reliance on volunteer participants, which constrain generalizability and preclude causal inference; exploratory outcomes are intended to guide future trial refinement.