Imaging neuroscience (Cambridge, Mass.)最新文献

{"title":"Dynamic 18F-FDG PET characterizes age-related changes in fitted ventricular FDG kinetics in humans.","authors":"Zeyu Zhou, Tianyun Zhao, He Wang, Aaron Carretero Benites, John Gardus, Qiuting Wen, Yang Feng, Christine DeLorenzo, Ramin Parsey, Chuan Huang","doi":"10.1162/IMAG.a.1395","DOIUrl":"10.1162/IMAG.a.1395","url":null,"abstract":"<p><p>Ventricular cerebrospinal fluid (CSF) transport is an important component of intracranial solute movement and may contribute to glymphatic-associated transport pathways. However, clinically accessible methods for quantifying ventricular CSF tracer dynamics in humans remain limited. This study examined the potential of dynamic 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) for quantifying ventricular CSF tracer kinetics as an indirect measure of CSF transport by evaluating its association with age and clinical factors. We analyzed baseline dynamic 18F-FDG PET data from participants with major depressive disorder enrolled in a prior clinical trial. Time-activity curves extracted from the lateral ventricles were modeled using a variant of the single-tissue compartment kinetic model to estimate kinetic parameters describing effective tracer entry into (<i>K₁</i> ) and net removal (<i>k₂</i> ) from the ventricular compartment. Associations with age and clinical factors were assessed using correlation and multiple linear regression analyses. Both <i>K₁</i> (r = -0.700, p < 0.001) and <i>k₂</i> (r = -0.712, p < 0.001) demonstrated strong negative correlations with age. In multivariable models adjusting for sex, ventricular volume, and depression severity, age remained a significant predictor of both parameters. Ventricular volume was also a significant predictor of both <i>K₁</i> and <i>k₂</i> , while <i>k₂</i> additionally showed a significant association with depression severity. These findings suggest that dynamic 18F-FDG PET can characterize ventricular tracer kinetics without intrathecal contrast administration, revealing a robust age-dependent decline in both tracer entry and removal processes and supporting its potential utility for studying ventricular CSF transport dynamics in aging and disease.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13662652/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149198246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduced NEXI protocol for the quantification of human gray matter microstructure on the Connectome 2.0 scanner.","authors":"Quentin Uhl, Tommaso Pavan, Julianna Gerold, Kwok-Shing Chan, Yohan Jun, Shohei Fujita, Aneri Bhatt, Yixin Ma, Qiaochu Wang, Hong-Hsi Lee, Susie Y Huang, Berkin Bilgic, Ileana Jelescu","doi":"10.1162/IMAG.a.1380","DOIUrl":"10.1162/IMAG.a.1380","url":null,"abstract":"<p><p>Biophysical diffusion MRI models such as Neurite Exchange Imaging (NEXI) are essential for probing gray matter microstructure, estimating compartment diffusivities (<i>D_i</i> , <i>D_e</i> ), neurite fraction (<i>f</i>), and exchange time (<i>t_ex</i> ). However, NEXI multi-shell, multi-diffusion-time requirements lead to prohibitively long acquisitions. Leveraging the Connectome 2.0 ultra-high gradient scanner, we developed a time-efficient protocol using an Explainable AI (XAI) framework. Combining XGBoost, SHAP, and Recursive Feature Elimination trained on synthetic signals, XAI identified an optimal 8-feature subset, halving scan time from 27 to 14 minutes. Validated in vivo in 7 healthy participants, the XAI protocol was benchmarked against the full 15-feature acquisition, a Cramér-Rao Lower Bound (CRLB) theoretical optimum, and 2 expert-designed heuristics (\"Mid-Range\" and \"Corner\"). The XAI protocol robustly reproduced parameter estimates and maintained full protocol test-retest reproducibility. Remarkably, the data-driven XAI selection converged to the theoretical CRLB optimum. This validates XAI mathematical optimality while highlighting its primary advantage: achieving gold-standard optimization without requiring complex analytical Jacobians, making it effortlessly adaptable to numerically defined models or complex noise distributions where CRLB becomes intractable. Furthermore, XAI demonstrated superior in vivo robustness compared with heuristics: \"Mid-Range\" sampling yielded biased <i>t_ex</i> estimates due to insufficient temporal diversity, while \"Corner\" sampling yielded unstable <i>D_i</i> estimates (fivefold higher coefficient of variation) due to noise sensitivity. Ultimately, this robust 14-minute NEXI protocol accelerates exchange-sensitive microstructural mapping, establishing a generalizable, model-agnostic optimization framework adaptable to future ultra-high gradient systems (e.g., Siemens Cima.X or GE MAGNUS) and existing clinical scanners.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13657203/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149186678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multimodal MRI insights into glymphatic clearance and blood-brain barrier integrity in healthy aging.","authors":"Anjan Bhattarai, Yufei D Zhu, Barah Albuhwailah, Pauline Maillard, Charles DeCarli, Audrey P Fan","doi":"10.1162/IMAG.a.1391","DOIUrl":"https://doi.org/10.1162/IMAG.a.1391","url":null,"abstract":"<p><p>Aging is associated with impaired CSF clearance in preclinical models, but its impact on blood-brain barrier (BBB) health and glymphatic function in humans remains unclear. The BBB and glymphatic functions are complementary and may partially overlap, yet their interaction is yet to be fully elucidated. In this study, we aimed to compare BBB integrity, extracellular free water, and glymphatic function between healthy young and older adults, and to examine mechanistic relationships among these measures using multimodal MRI techniques. 30 healthy participants with no known neurological or psychiatric disorders, including 12 younger (26 ± 3 years) and 18 older individuals (75 ± 7 years), underwent MRI scans on a 3T Siemens Prisma scanner. Multimodal MRI techniques were used, including diffusion-prepared arterial spin labeling to measure the water exchange rate (Kw) across the blood-brain barrier (BBB); free water (FW) imaging to quantify extracellular free water in white matter; and diffusion tensor imaging along perivascular spaces (DTI-ALPS) to assess glymphatic function. These measures were compared between younger and older individuals. Mediation analysis was performed to assess the mechanistic relationship between BBB integrity and glymphatic function and to test whether this relationship was mediated by free water. Older individuals showed reduced whole-brain Kw (p = 0.021), increased white matter FW (p = 0.002), and reduced DTI-ALPS (p < 0.001) compared to younger adults. Kw was positively associated with DTI-ALPS (β = 0.402 × 10^-2, p = 0.022) and negatively associated with FW (β = -0.676 × 10^-3, p = 0.008). DTI-ALPS was negatively associated with FW (β = -3.487, p = 0.001). Significantly reduced Kw was also observed in the cortical grey matter of older adults. Reduced Kw may reflect impaired BBB function, while reduced DTI-ALPS and increased FW indicate impaired glymphatic clearance. FW mediated the relationship between Kw and DTI-ALPS (95% CI [0.00014, 0.00404], p = 0.035), suggesting a potential mechanistic link between BBB function, extracellular water content, and glymphatic clearance efficiency. Overall, this study provides novel multimodal MRI insights into BBB and glymphatic alterations in healthy aging and may inform the development of MRI biomarkers to preserve cognitive health.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13651135/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149170569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Imaging Neuroscience: The First Three Years-Editorial.","authors":"Stephen M Smith","doi":"10.1162/IMAG.a.1392","DOIUrl":"https://doi.org/10.1162/IMAG.a.1392","url":null,"abstract":"<p><p>In April 2023, the editors of <i>NeuroImage</i> and <i>NeuroImage:Reports</i> resigned, and a month later launched <i>Imaging Neuroscience</i>. <i>NeuroImage</i> had been the leading journal in our field, but its publication fee had reached a level that many considered unethical and unsustainable. We therefore launched <i>Imaging Neuroscience</i> with MIT Press, with the goal of replacing <i>NeuroImage</i> as our field's leading journal, and with greater control by the academic community over publication fees and adoption of modern and ethical publishing practices. Three-and-a-half years later, as I step down as Editor-in-Chief, this editorial gives a brief summary of how things are going. The bottom line is: very well indeed!</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13651134/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149169193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validating the neurite exchange imaging (NEXI) model of gray matter using Monte Carlo simulations in numerical substrates.","authors":"Rita Oliveira, Jasmine Nguyen-Duc, Malte Brammerloh, Ileana Jelescu","doi":"10.1162/IMAG.a.1381","DOIUrl":"10.1162/IMAG.a.1381","url":null,"abstract":"<p><p>NEXI is a gray matter (GM) microstructural model designed to probe brain tissue microstructure <i>in vivo</i> using diffusion MRI. NEXI describes GM as two exchanging Gaussian compartments-neurites, modeled as randomly oriented, infinitely long sticks, and the extracellular space-allowing the estimation of biophysically interpretable parameters related to neurite microstructure and intercompartmental exchange. While modeling cell processes as sticks and each compartment as Gaussian are common assumptions for brain biophysical models of diffusion, neurite structural irregularities and the presence of somas, particularly in GM, may violate them and bias NEXI parameter estimates. Furthermore, the barrier-limited exchange assumed in the Kärger model that underlies NEXI may also be violated in realistic conditions. Therefore, in this work, we evaluate NEXI's accuracy in numerical substrates that contain GM features such as neurite beading, undulation, orientation dispersion, and the presence of somas across a range of membrane permeabilities. Diffusion signals were generated with Monte Carlo simulations of water diffusion and subsequently fitted with NEXI. Overall, NEXI captured trends of exchange time across permeability levels and showed good ability to disentangle exchange effects from other microstructural features. The largest bias in <i>t_ex</i> was introduced by somas, and in <i>D_i</i> by permeability, somas and beading. Otherwise, the structural irregularities evaluated in this study had a relatively modest impact on NEXI estimates. Most bias in NEXI estimates comes from finite SNR. Future work should aim to further improve substrate realism to better represent the complexity of GM morphology.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13644052/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149139719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Head-to-head comparison of diffusion imaging markers for cognitive decline and risk of dementia: The population-based Rotterdam Study.","authors":"Mathijs T Rosbergen, Frank J Wolters, M Arfan Ikram, Meike W Vernooij","doi":"10.1162/IMAG.a.1382","DOIUrl":"10.1162/IMAG.a.1382","url":null,"abstract":"<p><p>Diffusion tensor imaging (DTI) is a promising tool for early detection of white matter deterioration, but the optimal DTI marker for assessing risk of cognitive decline and dementia is undetermined. The aim of this study was to compare the predictive value of multiple diffusion measures for cognitive decline and dementia risk in a population-based study. We measured peak-width skeletonized mean diffusivity (PSMD), normal-appearing white matter mean diffusivity (MD), and fractional anisotropy (FA) in participants aged 45 years and older who underwent 1.5T MRI between 2006-2015 as part of the ongoing prospective population-based Rotterdam Study. In a head-to-head comparison between DTI markers, we determined risk of cognitive decline and dementia during follow-up, using linear regression and Cox proportional hazard models, respectively, that also include age, sex, education, and presence of lacunes or microbleeds. Of 5230 participants (mean age: 65.0 years +/-10.9 [standard deviation], 55.8% women), 286 developed dementia during a median follow-up of 9.8 years. For dementia risk, PSMD and global MD were superior regarding model fit, with the highest hazard ratio for global MD (HR: 1.74 [95%CI: 1.53-1.98])<i>.</i> Similarly, PSMD and MD had the highest discriminatory value (C-statistic, for PSMD: 0.886, and for MD: 0.882), albeit differences with other measures were small. Of all participants, 4433 (84.3%) had complete data on all cognitive tests at baseline, of whom 2800 (63.2%) completed their follow-up visit after on average 5.6 years. For global cognition both at time of MRI and at follow-up, PSMD was superior in terms of model fit and showed the highest regression coefficients, followed by tract-specific measures of MD and FA. In conclusion, when directly comparing structural connectivity measures, PSMD is superior to MD and FA for prediction of cognition and cognitive decline, while PSMD and MD perform best with respect to dementia risk.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13644046/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149139746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Philadelphia Theta Burst Project: A novel fMRI-guided electric field modeling dataset with reliability metrics.","authors":"David F Gregory, Ivy Sun, Marta Teferi, Hannah Gura, Milan Patel, Abigail Casalvera, Sneha Chandrashekar, Kevin G Lynch, Douglas H Schultz, Ashish Jeyapratap, Quinn Tate, Walid Makhoul, Zhi-De Deng, Desmond J Oathes, Yvette I Sheline, Nicholas L Balderston","doi":"10.1162/IMAG.a.1314","DOIUrl":"10.1162/IMAG.a.1314","url":null,"abstract":"<p><p>Recent neuromodulation studies suggest that theta burst stimulation (TBS) applied to the dorsolateral prefrontal cortex (dlPFC) can influence neural circuits involved in cognitive control and emotion-related processing, with relevance for psychiatric disorders. However, large-scale datasets characterizing variability, reliability, and multimodal neural responses to TBS remain limited. To address this gap, we established the Philadelphia Theta Burst Project, a dataset of 100 healthy participants who completed 4 fMRI sessions following cumulatively increasing doses of intermittent or continuous TBS, with participants randomized to one protocol or the other. Each session includes multiband, multi-echo resting-state (16 minutes) and task-based fMRI (16 minutes) during a Sternberg working memory paradigm. TMS targeting was guided by task-evoked activation in the left dlPFC. Structural T1-weighted, T2-weighted, and diffusion-weighted imaging were also acquired. Here, we describe the dataset design, acquisition protocol, and data characteristics, and report initial measures of data quality and reliability. The completed dataset can be accessed at https://openneuro.org/datasets/ds008893, providing an open resource for future investigations of TBS mechanisms and individualized neuromodulation strategies.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13641012/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149119564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial distribution of spinal cord fMRI activity with electrocutaneous stimulation.","authors":"Sandrine Bédard, Merve Kaptan, Teresa Indriolo, Christine S W Law, Dario Pfyffer, Lindsay Lee, John Ratliff, Serena Hu, Suzanne Tharin, Zachary A Smith, Gary H Glover, Sean Mackey, Julien Cohen-Adad, Kenneth A Weber Ii","doi":"10.1162/IMAG.a.1383","DOIUrl":"10.1162/IMAG.a.1383","url":null,"abstract":"<p><p>Sensory organization at the spinal segment level is commonly inferred from dermatomal maps that assume a fixed correspondence between cutaneous regions and spinal segments. However, based on the complexities of spinal neuroanatomy and neurophysiology, the distribution of sensory signals within the cord may be broader and less segment-specific than dermatomal maps suggest, leaving the segment-level localization of sensory-evoked activity in humans uncertain. Spinal cord functional magnetic resonance imaging (fMRI) is currently the only technique capable of noninvasively mapping sensory activity with high spatial resolution in the human spinal cord. However, its application remains technically challenging and is limited by the uncertainty in segmental localization. In this study, we leveraged recent advancements in spinal cord fMRI, including spinal nerve rootlet-based spatial normalization, to investigate how sensory information is represented and distributed within the human spinal cord during electrocutaneous stimulation of the third digit of the right hand (i.e., C7 dermatome). Forty healthy adults were scanned with electrocutaneous stimulation at four individualized intensities across multiple runs to quantify (i) the rostrocaudal distribution of sensory-evoked activity, (ii) intensity-dependent changes in detectability and localization, and (iii) the effect of normalization strategy on segmental localization. Across participants, stimulation produced activation localized in the lower cervical cord (e.g., C6-C8), with the most consistent segmental localization near C7. Stronger stimulation increased detectability and produced more consistent segmental localization across participants. Importantly, normalization that incorporated nerve rootlet landmarks sharpened localization and improved sensitivity relative to conventional intervertebral disc-based alignment. This highlights the value of functionally relevant anatomical landmarks for group inference in the spinal cord. Responses were strongest in the initial run and attenuated with repetition, suggesting habituation or adaptation that can bias multi-run paradigms if unmodeled. Together, our results define practical acquisition and analysis conditions (e.g., stimulation strength, anatomical alignment strategy, and run structure) under which segment-level spinal sensory responses can be detected, thereby supporting more reliable studies of human spinal cord future basic and translational studies, including pain mechanisms, sensory function, and spinal injury.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13636297/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149119578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expanding the toolkit: OPMs for studying the developing brain.","authors":"Margot J Taylor, Natalie Rhodes","doi":"10.1162/IMAG.a.1387","DOIUrl":"https://doi.org/10.1162/IMAG.a.1387","url":null,"abstract":"<p><p>Tremendous maturation in brain structure and function, underlying very rapid cognitive development, occurs in the early years of life, yet it has been difficult to obtain reliable measures of brain function over this period. A major challenge has been the difficulty of acquiring reliable neuroimaging data from awake young children, who often struggle to tolerate conventional imaging environments or remain still during scanning. Existing approaches each involves important compromises between spatial and temporal resolution, movement tolerance and practicality for use in early childhood. Optically pumped magnetometers (OPMs), a recent advance in magnetoencephalography (MEG) technology, are expanding the developmental neuroimaging toolkit. By enabling adaptable, wearable, and movement-tolerant MEG systems, OPMs retain the excellent spatial and temporal resolution of conventional cryogenic MEG technology while improving suitability for infants, toddlers, and young children. In this commentary, we briefly review the current functional neuroimaging toolkit used across development and discuss how OPMs are transforming the study of the developing brain. We highlight recent applications of OPMs to study early life, their potential for investigating brain-behaviour relationships and social interaction, and their promise for improving inclusion of clinical populations traditionally underrepresented in neuroimaging research. We also outline remaining technical and methodological challenges that should be addressed as the field continues to grow.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13636295/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149119527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Iterative delay correction improves breath-hold cerebrovascular reactivity mapping in clinical populations.","authors":"Rebecca G Clements, Fatemeh Geranmayeh, Niamh V Parkinson, Molly G Bright","doi":"10.1162/IMAG.a.1386","DOIUrl":"10.1162/IMAG.a.1386","url":null,"abstract":"<p><p>Cerebrovascular reactivity (CVR), the ability of cerebral blood vessels to dilate or constrict in response to a vasoactive stimulus, is an important measure of cerebrovascular health. Accurate CVR estimation requires accounting for the time required for the vasoactive stimulus to reach each brain region and the time it takes for local arterioles to modulate cerebral blood flow. The temporal search range used to calculate this spatially varying offset can substantially impact CVR estimates, and the appropriate search range may vary across populations, acquisition protocols, and even brain regions. Here, we present an iterative approach for automatically determining the appropriate maximum shift, using breath-hold fMRI data acquired in a cohort of stroke survivors. This approach selectively expands the delay search range only for voxels with estimated delays at the boundary (i.e., near the minimum or maximum shift) until the estimated delay is no longer at the boundary or a predefined value is reached. In the context of stroke, among voxels initially at the boundary, this approach significantly increased the number of voxels with statistically significant CVR (i.e., having a relationship between end-tidal CO₂ and the BOLD signal that is unlikely to be due to random chance). It also resulted in CVR polarity reversals in voxels originally at the early-response boundary and amplified negative CVR values in voxels originally at the late-response boundary, suggesting that using an iterative maximum shift can critically impact CVR interpretation. This approach is broadly applicable beyond stroke, but careful parameter tuning is required, as illustrated by our demonstration of the parameter tuning process for a participant with Moyamoya disease. Together, these findings suggest that iterative delay correction allows for improved CVR assessments in clinical populations.</p>","PeriodicalId":73341,"journal":{"name":"Imaging neuroscience (Cambridge, Mass.)","volume":"4 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13636296/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149119540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}