13:45 | 1287.
| Visual stimulus-evoked blood velocity responses at far upstream branches of the Posterior Cerebral Artery measured with phase-contrast fMRA Zhangxuan Hu1,2, Sebastien Proulx1,2, Daniel E. P. Gomez1,2, Divya Varadarajan1,2, Saskia Bollmann3, Can Ozan Tan4, Elif Gokcal5,6, M. Edip Gurol5,6, and Jonathan R. Polimeni1,2,7 1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 2Department of Radiology, Harvard Medical School, Boston, MA, United States, 3School of Information Technology and Electrical Engineering, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, Brisbane, Australia, 4Department of Electrical Engineering, Mathematics, and Computer Science, University of Twente, Enschede, Netherlands, 5J. Philip Kistler Stroke Research Center, Massachusetts General Hospital, Boston, MA, United States, 6Department of Neurology, Harvard Medical School, Boston, MA, United States, 7Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States Keywords: fMRI Acquisition, fMRI Motivation: Neuronal activity induces vasodilation in local arterioles that propagates to upstream large arteries, but the furthest detectable arterial dilation from the site of neuronal activity remains unknown. Goal(s): Detecting blood velocity responses at far upstream branches of the Posterior Cerebral Artery induced by a visual stimulus. Approach: In this study, a functional phase-contrast MRA technique was combined with a commonly used block-design stimulation paradigm to detect blood velocity responses. Results: About 10–20% velocity increases at the P2 segments of the Posterior Cerebral Artery were robustly observed. Impact: We demonstrate that neuronal activity-induced velocity response can propagate to large feeding arteries 6–7 cm from the visual cortex. The spatial and temporal properties of this propagation are important for understanding neurovascular coupling, autoregulation, and human fMRI. |
13:57 | 1288.
| DiSpect Consistently and Repeatably Reveals Modulation and Redistribution of Venous Blood Flow Caused by Functional Brain Activation Ekin Karasan1, Chunlei Liu1,2, and Michael Lustig1 1Department of Electrical Engineering and Computer Science, University of California, Berkeley, Berkeley, CA, United States, 2Helen Wills Neuroscience Institute, Berkeley, CA, United States Keywords: fMRI Acquisition, fMRI Motivation: DiSpect can trace blood draining from the capillary bed through the cerebral venous system and map venous territories. Goal(s): Determine whether DiSpect can detect blood flow changes in the veins during neural activation. Approach: DiSpect was performed during a motor cortex task and at baseline for two subjects, each with two repeats to ensure consistency and repeatability. Results: Modulation and redistribution of flow were observed during the task, specifically in veins near the BOLD fMRI activated regions. The measurements showed good repeatability for both subjects. Impact: BOLD contrast is affected by a complex interplay of several physiological processes. DiSpect measures changes in venous blood flow dynamics during neural activation and can potentially help to better understand the venous sources of the BOLD signal. |
14:09 | 1289.
| EPTIMA: Echo Planar Time-resolved Imaging derived Millisecond-scale temporal resolution Acquisition Zijing Dong1,2, Abbas Sohrabpour1,2, Lawrence L. Wald1,2,3, Jonathan R. Polimeni1,2,3, Padmavathi Sundaram1,2, and Fuyixue Wang1,2 1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 2Department of Radiology, Harvard Medical School, Boston, MA, United States, 3Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States Keywords: fMRI Acquisition, Data Acquisition, fMRI Motivation: Achieving millisecond-scale temporal resolution MRI has the potential to provide exciting insights into fast functional/physiological processes of the brain. Goal(s): Develop a new acquisition method, EPTIMA, that can achieve millisecond-scale temporal resolution, while improving efficiency by acquiring a time-series trial of 2D-images in a single excitation for high robustness to physiological-noise/motion. Approach: EPTIMA captures fast temporal dynamics occurring within the readout by measuring the rate at which the baseline signal evolution is changing, and employs spatiotemporal encodings to acquire a complete time-series trial in a single-excitation. Results: EPTIMA can image rapid electric current changes in a phantom and resolve stable phase/magnitude changes in-vivo. Impact: A new acquisition, EPTIMA, was developed to achieve millisecond-scale temporal resolution and to image ultra-fast dynamic processes of human brain. It improves efficiency by acquiring a time-series trial of 2D-images in a single excitation with high robustness to motion/physiological noises. |
14:21 | 1290.
| Chemical Exchange Saturation Transfer-Based Functional Magnetic Resonance Imaging (CEST-fMRI) in the Human Brain at 3T Qicheng Lu1 and Yi Zhang1 1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, HangZhou, China Keywords: fMRI Acquisition, CEST & MT, CEST-fMRI Motivation: Conventional fMRI techniques indirectly map neural activity through the BOLD effect, but there is a need for a methodology to directly detect dynamic changes in neurotransmitter levels. Goal(s): Our goal was to detect the increase in glutamate concentration in the human brain during a visual task based on CEST. Approach: We performed two tailored experiments on a 3T scanner and used a 4-regressor general linear model (GLM) analysis to extract the metabolite effects from CEST-fMRI signals. Results: A ~0.12% metabolite effect was detected at glutamate-proximal frequency offsets, consistent with our simulation under a 3% increase in glutamate concentrations during brain activity. Impact: Our study successfully revealed the mechanism behind CEST-fMRI and demonstrated its ability to detect dynamic changes in glutamate concentrations during visual stimulation. The CEST-fMRI methodology enables the investigation of neurotransmitter changes, potentially becoming an imaging modality that guides neuroscience research. |
14:33 | 1291.
| Simultaneous two-voxel functional magnetic resonance spectroscopy of the motor cortex at 7T Anouk Schrantee1 and Adam Berrington2 1Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands, 2Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom Keywords: Spectroscopy, Spectroscopy, functional MRS Motivation: Functional magnetic resonance spectroscopy (fMRS) shows promise in studying task-related metabolite changes but has been largely confined to single-voxel. Goal(s): To evaluate two-voxel fMRS at 7 T to measure simultaneous bilateral metabolite changes during a unilateral motor task.
Approach: A modified Hadamard-encoded MRS scheme with dynamic fMRS spectral-temporal fitting for analysis was employed. Results: Distinct patterns of BOLD activation in contra- and ipsilateral VOIs were detected with significant increases in Glutamate (Glu) in either VOI during a unilateral task Impact: We demonstrate the feasibility of simultaneous two-voxel MRS to detect bilateral glutamate changes in response to a unilateral motor task. This approach holds promise to increase our understanding of the neurochemical underpinnings of fMRI signals across interconnected brain regions. |
14:45 | 1292.
| Resting-State Functional Quantitative Susceptibility Mapping (rsfQSM) Jannette Nassar1, Oliver C Kiersnowski1, Patrick Fuchs1, Rimona S Weil2, and Karin Shmueli1 1Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Dementia Research Center, Institute of Neurology, University College London, London, United Kingdom Keywords: Functional Connectivity, Quantitative Susceptibility mapping, Brain connectivity, resting-state fQSM Motivation: Task-based functional Quantitative Susceptibility Mapping (fQSM) shows more localized brain activations than fMRI. Resting-state fMRI reveals brain connectivity networks but resting-state analysis of QSM has not yet been performed and may provide complementary information. Goal(s): To perform a resting-state functional analysis using QSM (rsfQSM) and compare it to rsfMRI, focusing on the Default Mode Network (DMN). Approach: We used seed-based and ICA-based analyses for rsfQSM and assessed the similarity of the DMN to that in rsfMRI with quantitative metrics. Results: The DMN was detected in rsfQSM with spatial similarities to the DMN in rsfMRI. rsfQSM showed weaker and less extensive functional connectivity. Impact: We computed resting-state functional connectivity from magnetic susceptibility maps for the
first time, revealing similarities in the default-mode network compared to rsfMRI.
This paves the way for new QSM-based explorations of brain function to
potentially deepen understanding of neurological diseases. |
14:57 | 1293.
| Functional conductivity imaging: quantitative mapping of brain activity Caroline D Rae1, Jun Cao1, Ben Cassidy2, and Iain K Ball3 1Neuroscience Research Australia, UNSW, Randwick, Australia, 24. Pathfinder Exploration LLC, Reno, NV, United States, 3Philips Australia and New Zealand, Sydney, Australia Keywords: Task/Intervention Based fMRI, Brain Motivation: Theory and modelling suggest that detection of neuronal activity may be feasible using phase sensitive MRI methods. Goal(s): To demonstrate successful application of phase-based MREPT to functional tasks in brain Approach: Using bFFE optimised for fast acquisition, data were acquired from 5 participants undertaking visual stimulation or somatosensory stimulation. Electrical conductivity values extracted from phase images were fitted with the measured stimulus response function.
Results: Images showed consistent activation of visual circuitry (~0.1 S/m) in both grey and white matter with similar circuit responses to somatosensory stimulation. Conductivity increased with stimulus duration or increased contrast and was faster, temporally, than BOLD. Impact: Functional conductivity imaging (funCI) reveals activity in both grey and white matter. The
sensitivity, repeatability and time course of funCI shows that MRI can
detect brain activation beyond changes in blood supply. |
15:09 | 1294.
| Functional connectome through the human life span Lianglong Sun1, Tengda Zhao1, Xinyuan Liang1, Mingrui Xia1, Qiongling Li1, Xuhong Liao1, Gaolang Gong1, Qian Wang1, Chenxuan Pang1, Qian Yu1, and Yong He1 1State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China Keywords: Functional Connectivity, Brain Connectivity, brain chart, brain atlas, lifespan, connectomics Motivation: The normative developmental and aging trajectory of the functional connectome in the human brain remains unknown. Goal(s): To establish the normative growth trajectory of functional connectome from the largest, quality-controlled multimodal neuroimaging dataset. Approach: We aggregated 33,809 task-free fMRI scans from 32,328 individuals aged 32 postmenstrual weeks to 80 years from 119 global sites, and quantified lifespan growth charts using generalized additive models for location, scale, and shape (GAMLSS). Results: We uncovered nonlinear connectome growth at the whole cortex, system, and regional levels, identified critical developmental inflection points, and demonstrated substantial individual heterogeneities in patients with ASD and patients with MDD. Impact: Our findings
elucidate for the first time the lifespan evolution of the functional
connectome and serve as a normative reference for quantifying individual
variation in patients with neuropsychiatric disorders. |
15:21 | 1295.
| High-Frequency Oscillation-Based Rotary Saturation: a functional imaging technique for epilepsy lateralization in MRI-negative patients Milena Capiglioni1, Pedro Lima Cardoso2, Simon Daniel Robinson2, Claus Kiefer1, Siegfried Trattnig2, Ekaterina Pataraia3, Roland Beisteiner3, and Roland Wiest1 1Institute for Diagnostic and Interventional Neuroradiology, Support Center for Advanced Neuroimaging (SCAN), University of Bern, Bern, Switzerland, 2High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, 3Department of Neurology, Functional Brain Diagnostics and Therapy, High Field MR Center, Medical University of Vienna, Vienna, Austria Keywords: Epilepsy, Bioeffects & Magnetic Fields, Spin-lock, Novel Contrast Mechanisms Motivation: Delineation of the seizure onset zone (SOZ) in surgical planning for drug-resistant epilepsy requires invasive procedures. The Stimulus-Induced Rotary Saturation (SIRS) sequence targets biomagnetic field associated with epileptic discharges. Goal(s): To evaluate the efficiency of SIRS in epilepsy lateralization using high-frequency oscillations (HFOs) as biomarkers and compare it with EEG and clinical seizure semiology. Approach: We investigated 11 epilepsy patients using SIRS at a 120 Hz spin-lock frequency, assessing the localizing value at hemispheric and lobar levels. Results: SIRS-identified activations were above threshold in 8 of 11 patients, offering potential for improved SOZ localization. Hemispheric concordance was found with EEG in 7 cases. Impact: Spin-lock based
rotary saturation imaging lateralized brain areas in epilepsy patients with
negative MRI findings in concordance with EEG and seizure semiology. Combined
with state-of-the-art non-invasive methods such as EEG, it offers potential for
improved seizure lateralization. |
15:33 | 1296.
| Functional MRI of the nose Sara Ponticorvo1, Jaakko Paasonen2, Petteri Stenroos2, Ekaterina Paasonen2, Pavel Filip1,3, Douglas Rothman4, Edward Auerbach1, Michael Garwood1, Gregory J Metzger1, Olli Gröhn2, Shalom Michaeli1, and Silvia Mangia1 1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, 2A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland, 3Neurology, First Faculty of Medicine and General University Hospital, Charles University, Prague, Czech Republic, 4Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, United States Keywords: Head & Neck/ENT, fMRI (resting state) Motivation: Standard fMRI techniques are unable to image the nasal cavity due to strong susceptibility artefacts. Goal(s): Our goal is to exploit ultrashort or zero echo time imaging to study functional connectivity of the nose. Approach: Resting-state fMRI was performed on 5 humans at 7T and 1 mouse at 9.4T. Independent component analysis (ICA) was performed, and ICA signals were analyzed within the context of other physiological signals. Results: Highly reproducible nose networks were observed in humans. The signal of one network strongly correlated with the autonomic nervous system activity. A pronounced nose network was also observed in the mouse. Impact: Ultrashort and zero echo time fMRI enables
unprecedented performance for detecting functional nose networks providing the
means to study nose activity and system-wide connections between central and
peripheral nervous systems not currently possible with standard fMRI for the
first time. |