Baxter, Leslie C.

Background/Objectives: White matter (WM) tract detection is critical in the presurgical planning of tumor resection. However, standard-of-care imaging techniques including T1-weighted, T2-weighted, and Diffusion Tensor Imaging (DTI) often fail to identify WM tracts within edematous regions. In T1/T2-weighted imaging, edema increases extracellular water and reduces tissue contrast, and in diffusion-weighted imaging, edema elevates isotropic diffusion, reducing sensitivity to anisotropic diffusion along WM tracts. Advanced biophysical diffusion modeling techniques such as Neurite Orientation Dispersion and Density Imaging (NODDI) and the Standard Model (SM) address this limitation by compartmentalizing the diffusion signal into free-water, intra-neurite, and extra-neurite contributions. Here, we test if biophysical multi-compartment models can robustly identify WM tracts and recover tractography streamlines within edematous regions. Methods: In this study, we use multi-shell diffusion-weighted MRI data obtained from patients with meningiomas—a pathology allowing for isolation of the effects of edema without the confounding effects of tumor cell invasion. We compared FA from standard and free-water-corrected DTI, the orientation dispersion index (ODI) from NODDI, and P2 (a scalar descriptor of fiber orientation coherence) from the SM fODF in edematous and unaffected contralateral WM regions. As a proof of concept, we visually evaluated the tractography performance across models. Results: Our results show that (1 − ODI) and P2 values in edema remained close to within-subject contralateral measurements, contrasting with substantial reductions in FA and FW-FA. (1 − ODI) showed a small but statistically significant increase in edema (~8%, p = 0.02), while P2 was unchanged. Conclusions: These results highlight the potential of biophysical diffusion models for preoperative mapping in edema.

ABSTRACT Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) can reduce seizures in patients with drug-resistant epilepsy. However, seizure freedom is rare, and there is no early response biomarker to predict long-term seizure suppression. To evaluate a short-term biomarker of therapeutic response to DBS, we studied 18-minute trials of ANT stimulation in patients with drug-resistant epilepsy undergoing intracranial electroencephalography. We compared a standard high-frequency periodic versus a non-periodic pulse pattern. We found that short-term ANT stimulation within the clinically used amplitude range preferentially altered the first 150 ms of anterograde ANT to anterior cingulate and superior frontal connectivity. Non-periodic ANT stimulation selectively modified early cortico-cortical evoked potentials more than periodic stimulation, and these changes were driven by the response phase. These pattern-specific changes in connectivity between the ANT and spatially restricted cortical areas suggest differing mechanisms and are a promising biomarker for patients being treated with ANT-DBS.

Objective: Age-related hearing loss is prevalent in a large proportion of older adults and is the largest modifiable risk factor of dementia. Previous studies have shown that hearing loss in older adults is associated with reductions in brain volume and alterations in brain connectivity, but there is a gap in our understanding of how hearing loss may impact brain activity, specifically while listening to speech. In this study, we hypothesized that hearing loss would be associated with (1) reduced activation within temporal auditory regions in response to speech presented with and without background noise, and (2) increased activation in the cingulo-opercular network in response to speech in noise. Design: Twenty-seven older adults (mean age = 68 yr, 17 women) recruited from the community completed a clustered sparse-sampling functional magnetic resonance imaging protocol while listening to speech presented with and without multi-talker background noise. Regions of interest–based and exploratory voxel-wise analyses were used to investigate correlations between functional magnetic resonance imaging activation to speech and hearing ability. Hearing was defined as the pure-tone average of hearing thresholds at 0.5, 1, 2, and 4 kHz from the better ear and ranged from normal to a moderate hearing loss. Results: Our results indicate that age-related hearing loss was associated with reduced activation in right Heschl’s gyrus and left middle temporal gyrus in response to speech. Exploratory voxel-wise analyses suggest that hearing loss may be associated with alterations in activation in other sensory cortical regions and portions of the frontal cortex, including left pars opercularis. Activation within the cingulo-opercular network was not associated with hearing loss. Conclusions: These findings suggest that age-related hearing loss in humans is associated with altered brain activity in response to speech, particularly within right Heschl’s gyrus. It further provides hypothesis-generating data for future studies on the effects of hearing loss on brain function.

Introduction Despite growing evidence to characterise cancer-associated cognitive decline (CACD) in women with breast cancer, interventions to mitigate CACD are limited. Emerging evidence suggests aerobic exercise may enhance cognition after breast cancer diagnosis and treatment; yet, CACD remains an understudied outcome of exercise, and few high-quality studies have been conducted. In addition to knowledge gaps in effectiveness, the translation of exercise interventions to community settings remains challenging. The Breast cancer Reasoning and Activity INtervention (BRAIN) investigates the effectiveness of aerobic exercise training, delivered in a community-based setting, for improving cognitive function in women with breast cancer and gathers information on the implementation success of the intervention. Methods and analysis This Hybrid Type I effectiveness–implementation study is conducted at an academic medical centre in the southwestern United States in partnership with a non-profit, community health and wellness organisation. The study enrols 160 women diagnosed with stage I–IIIa breast cancer and within 3–36 months of treatment completion into a 1:1 randomised controlled trial. Individuals randomised to the exercise group receive a 6-month, individually tailored aerobic exercise programme delivered by exercise trainers employed at local community fitness centres. The programme is progressive in nature and designed to help participants achieve aerobic exercise levels consistent with guidelines for cancer survivors. Individuals randomise to the control group receive a 6-month health education control intervention delivered virtually by hospital-based health educators. Cognitive performance (primary), self-reported cognition, patient-reported outcomes, physical activity and cardiorespiratory fitness are measured at baseline, 6 months (postintervention) and 12 months (follow-up). Brain structure and function are measured via magnetic resonance imaging (MRI) at baseline and 6 months. Implementation outcomes are defined by the RE-AIM framework, which includes reach, effectiveness, adoption, implementation and maintenance. RE-AIM outcomes are measured at baseline, 6 months, 12 months and ongoing during the study. Ethics and dissemination This study was approved by the Mayo Clinic Institutional Review Board (#23-000020). All participants provide informed consent prior to participation. Findings will be disseminated to scientific, clinical and community audiences through manuscripts, presentations and newsletters. Trial registration number NCT04816006.

Hippocampal segmentation is essential in neuroimaging for evaluating conditions like Alzheimer’s dementia and mesial temporal sclerosis, where small volume changes can significantly impact normative percentiles. However, inaccurate segmentation is common due to the inclusion of non-hippocampal structures such as choroid plexus and cerebrospinal fluid (CSF), leading to volumetric overestimation and confounding of functional analyses. Current methods of assessment largely rely on virtual or manual ground truth labels, which can fail to capture these inaccuracies. To address this shortcoming, this study introduces a more direct voxel intensity-based method of segmentation assessment. Using paired precontrast and postcontrast T1-weighted MRIs, hippocampal segmentations were refined by adding marginal gray matter and removing marginal CSF and enhancement to determine a total required correction volume. Six segmentation algorithms—e2dhipseg, HippMapp3r, hippodeep, AssemblyNet, FastSurfer, and QuickNat—were implemented and compared. HippMapp3r and e2dhipseg, followed closely by hippodeep, exhibited the least total correction volumes, indicating superior accuracy. Dedicated hippocampal segmentation algorithms outperformed whole-brain methods.

The Program for the Education and Enrichment of Relational Skills (PEERS®) is an evidence-based intervention developed for autistic individuals to support social communication, peer interactions, independence, and interpersonal relationships. Despite a demonstrated effectiveness for young autistic individuals in the US and several other countries, PEERS has yet to be modified to support the needs of autistic adults across the lifespan. The present study describes how our team sought autistic voices to adapt PEERS for adults of any age. Specifically, we aimed to address the needs of middle-aged and older adults and adapt the curriculum to be more neurodiversity-affirming. Between two cohorts that completed the program consecutively, we evaluated the acceptability of the adapted PEERS program and made refinements based on feedback from autistic participants and their study partners. Results indicated that Cohort 2 reported higher satisfaction with the PEERS components and overall program than Cohort 1, suggesting effective refinement. We present a framework of adaptations that more specifically address the needs of middle-aged and older adults in a neurodiverse-affirming way compared to previous iterations. Our approach to implementing an adapted PEERS curriculum across the adult lifespan may serve as a model for improved clinical care and cultivate the acceptance of neurodiversity in the interpersonal domains of autistic adults’ lives.

AbstractThe male preponderance in autism spectrum disorder (ASD) led to the hypothesis that aspects of female biology are protective against ASD. Females with ASD (ASD-F) report more compensatory behaviors (i.e. “camouflaging”) to overcome ASD-related social differences, which may be a mechanism of protection. No studies have examined sex-related brain pathways supporting camouflaging in ASD-F, despite its potential to inform mechanisms underlying the ASD sex bias. We used functional connectivity (FC) to investigate “sex-atypical” and “sex-typical” FC patterns linked to camouflaging in adults with ASD and examined multimodal coherence of findings via structural connectometry. Exploratory associations with cognitive/emotional functioning examined the adaptive nature of FC patterns. We found (i) “sex-atypical” FC patterns linked to camouflaging in the hypothalamus and precuneus and (ii) “sex-typical” patterns in the right anterior cingulate and anterior parahippocampus. Higher hypothalamic FC with a limbic reward cluster also correlated with better cognitive control/emotion recognition. Structural connectometry validated FC results with consistent brain pathways/effect patterns implicated in ASD-F. In summary, “male-typical” and “female-typical” brain connectivity patterns support camouflaging in ASD-F in circuits implicated in reward, emotion, and memory retrieval. “Sex-atypical” results are consistent with fetal steroidogenic/neuroinflammatory hypotheses. However, female genetics/biology may contribute to “female-typical” patterns implicated in camouflaging.

BackgroundAlzheimer's disease (AD) is a progressive neurodegenerative disease that affects aging populations. Current MRI techniques are often limited in their sensitivity to underlying neuropathological changes.PurposeTo characterize differences in voxel‐based morphometry (VBM), apparent diffusion coefficient (ADC), and intravoxel incoherent motion diffusion‐weighted imaging (IVIM‐DWI) metrics in aging populations. Additionally, to investigate the connection between cognitive assessments and neuroimaging metrics.Study TypeProspective/cross‐sectional.PopulationIn all, 49 subjects, including 13 with AD dementia, 12 with mild cognitive impairment (MCI), and 24 healthy controls (HC).Field Strength/Sequence3T/magnetization‐prepared rapid acquisition gradient echo (MP‐RAGE) and IVIM‐DWIAssessmentAll participants completed a cognitive screening battery prior to MRI. IVIM‐DWI maps (pure diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [f]) were generated from a biexponential fit of diffusion MRI data. VBM was performed on the standard T1‐weighted MP‐RAGE structural images. Group‐wise templates were used to compare across groups.Statistical TestsAnalysis of covariance (ANCOVA) with gender and age as covariates (familywise error [FWE] corrected, post‐hoc comparisons using Bonferroni correction) for group comparisons. Partial‐η2 and Hedges' g were used for effect‐size analysis. Spearman's correlations (false discovery rate [FDR]‐corrected) for the relationship between cognitive scores and imaging.ResultsClusters of significant group‐wise differences were found mainly in the temporal lobe, hippocampus, and amygdala using all VBM and IVIM methods (P < 0.05 FWE). While VBM showed significant changes between MCI and AD groups and between HC and AD groups, no significant clusters were observed between HC and MCI using VBM. ADC and IVIM‐D demonstrated significant changes, at P < 0.05 FWE, between HC and MCI, notably in the amygdala and hippocampus. Several voxel‐based correlations were observed between neuroimaging metrics and cognitive tests within the cognitively impaired groups (P < 0.05 FDR).Data ConclusionThese findings suggest that IVIM‐DWI metrics may be earlier biomarkers for AD‐related changes than VBM. The use of these techniques may provide novel insight into subvoxel neurodegenerative processes.Level of Evidence2Technical Efficacy Stage2 J. MAGN. RESON. IMAGING 2020;52:1811–1826.

Fourteen single-sided deaf listeners fit with an MED-EL cochlear implant (CI) judged the similarity of clean signals presented to their CI and modified signals presented to their normal-hearing ear. The signals to the normal-hearing ear were created by (a) filtering, (b) spectral smearing, (c) changing overall fundamental frequency (F0), (d) F0 contour flattening, (e) changing formant frequencies, (f) altering resonances and ring times to create a metallic sound quality, (g) using a noise vocoder, or (h) using a sine vocoder. The operations could be used singly or in any combination. On a scale of 1 to 10 where 10 was a complete match to the sound of the CI, the mean match score was 8.8. Over half of the matches were 9.0 or higher. The most common alterations to a clean signal were band-pass or low-pass filtering, spectral peak smearing, and F0 contour flattening. On average, 3.4 operations were used to create a match. Upshifts in formant frequencies were implemented most often for electrode insertion angles less than approximately 500°. A relatively small set of operations can produce signals that approximate the sound of the MED-EL CI. There are large individual differences in the combination of operations needed. The sound files in Supplemental Material approximate the sound of the MED-EL CI for patients fit with 28-mm electrode arrays.