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Divya Varadarajan^1,2, Paul Wighton^1,2, Jingyuan Chen^1,2, Sebastien Proulx^1,2, Robert Frost^1,2, Andre van der Kouwe^1,2, Avery Berman³, and Jonathan R. Polimeni^1,2
1Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, ²Harvard Medical School, Boston, MA, United States, ³Carleton University, Ottawa, ON, Canada

Keywords: fMRI, Blood vessels

Here we apply single-vessel fMRI techniques to evaluate BOLD and non-BOLD contributions within individual arteries and veins. First we identified individual vessels from inflow effects in a small set of slices, and distinguished arteries and veins on the basis of their T2* decay. Then we applied a high-inplane-resolution multi-echo single-vessel fMRI approach to examine fMRI responses within these vessels. We find evidence for both BOLD and potentially non-BOLD responses within arteries, suggesting that in some cases BOLD may capture arterial responses BOLD which may be more neuronally specific (in space and time) than effects from downstream veins.

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Brett Liem^1,2, Atena Akbari^1,2, Joseph S Gati¹, Peter Zeman¹, and Ravi S Menon^1,2
1Centre for Functional and Metabolic Mapping, Robarts Research Institute, London, ON, Canada, ²Medical Biophysics, The University of Western Ontario, London, ON, Canada

Keywords: fMRI (task based), High-Field MRI, Phase Regression

We investigated the signal spatial specificity of the GRE-BOLD contrast with and without phase regression in ocular dominance columns and layers of human V1. Phase regression is a post-processing technique that uses phase data to suppress the large vein signal, thus improving the GRE signal spatial specificity. Our results showed that the phase regressed laminar BOLD signal profile peaks towards the middle cortical depth, while that of GRE-BOLD was biased towards the cortical surface. Phase regression did not improve the contrast between columns, suggesting that the phase is not sensitive to intracortical veins running parallel to the cortical surface.

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Dana Ramadan^1,2, Jonas Bause¹, Rüdiger Stirnberg³, Philipp Ehses³, and Klaus Scheffler^1,4
1Department for High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics Tübingen, Tübingen, Germany, ²Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Germany, ³German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ⁴Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany

Keywords: fMRI, High-Field MRI, Blood Vessels, Brain

The spatial specificity of fMRI with GRE-EPI is significantly affected by large draining veins on the cortical surface. They cause susceptibility changes that are strongest when the veins are oriented perpendicular to B₀. Since they follow the cortical curvature, their orientation to B₀ can be approximated by the cortical orientation. Previous studies have shown a high dependence of the GRE-EPI signal on the cortical orientation, reflecting its disadvantage of being sensitive to these veins. In this preliminary two-subject study, this phenomenon is investigated with GRE-EPI and bSSFP in different cortical depths to experimentally explore the sensitivity of bSSFP to microvasculature.

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Mukund Balasubramanian^1,2, Avery J. L. Berman^3,4, Robert V. Mulkern^1,2, Lawrence L. Wald^1,5, William A. Grissom⁶, and Jonathan R. Polimeni^1,5,7
1Harvard Medical School, Boston, MA, United States, ²Boston Children's Hospital, Boston, MA, United States, ³Carleton University, Ottawa, ON, Canada, ⁴University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada, ⁵Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ⁶Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ⁷Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Keywords: fMRI, RF Pulse Design & Fields, Ultra-High-Field MRI

We show that SLR pulses provide much better slice profiles (and thus much higher SNR) than standard sinc pulses for short-TR spin-echo (SE) acquisitions, even when there is substantial B₁⁺ inhomogeneity. As one application, we used SLR pulses and a TR of 300 ms in SE-EPI acquisitions at 7T, enabling the “direct” measurement of cardiac frequencies at ~1 Hz without aliasing. Far less cardiac fluctuation was seen in SE- versus GE-EPI data. While SE-fMRI is known to have reduced macrovascular weighting and thus improved spatial specificity relative to GE-fMRI, our results suggest that it may also have better temporal specificity.

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Jiawen Dakota Fan^1,2, Javier Gonzalez-Castillo³, Peter A. Bandettini^3,4, Jonathan R. Polimeni^2,5,6, and Jingyuan E. Chen^2,5
1Center for Data Science, New York University, New York City, NY, United States, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ³Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Health, Bethesda, MD, United States, ⁴Functional MRI Core, National Institute of Health, Bethesda, MD, United States, ⁵Department of Radiology, Harvard Medical School, Boston, MA, United States, ⁶Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Keywords: fMRI, White Matter

In this study, by integrating 7T high-resolution imaging and massive data averaging, we show that white matter fMRI activations can be detected at a single-voxel level. Hemodynamic changes evoked by the flickering checkerboard stimuli were not homogenous within the optic radiation, and the averaged pattern exhibited a delayed time to peak longer than V1, consistent with previous literature. The current datasets also revealed stimulus-locked changes in certain white-matter tracts beyond the visual pathway.

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Samuel Bianchi¹, Jakob Heinzle², Maria Engel¹, Stefan Frässle², Klaas Enno Stephan^2,3, and Klaas Paul Pruessmann^1
1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland, ²Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland, ³Max Planck Institute for Metabolism Research, Cologne, Germany

Keywords: fMRI (task based), Modelling, Hemdoynamic response, HRF, Activation, BOLD

Characterizing hemodynamic responses with great temporal precision is crucial for the interpretation of fMRI data with respect to the underlying neuronal activity. Recent literature highlights that analyses based on a canonical hemodynamic response function (HRF) may fail to capture relevant aspects of neuronal activity in certain conditions¹. Ultra-fast fMRI enables precise temporally precise characterizations of hemodynamic responses and their trial-by-trial variation. Here, we analyzed fMRI timeseries sampled at  which allowed us to model hemodynamic responses for individual trials during a visuo-motor task. Trial-by-trial variability of hemodynamic responses are analyzed by principal components analysis (PCA) and related to trial-specific conditions.

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Alejandro Monreal-Madrigal¹, Denizhan Kurban¹, Zoia Laraib^1,2, Renzo Huber¹, Dimo Ivanov¹, Nicolas Boulant³, and Benedikt A Poser^1
1Maastricht University, Maastricht, Netherlands, ²Polytechnic University of Turin, Turin, Italy, ³University-Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France

Keywords: fMRI, High-Field MRI, Pulse Sequence Design

VASO fMRI can provide beneficial localization specificity and quantifiability compared to the commonly used BOLD contrast. Previous work has also shown the benefits of using spiral readouts compared to Cartesian EPI. In this work, we employ 3D stack-of-spirals readouts and compare it with the current state of the art 3D EPI readouts for VASO fMRI. The sequence implementation is done using Pulseq, images were reconstructed with MRIReco.jl; functional analysis with an openly available pipeline. We find that a VASO tSNR improvement of a factor of 2 over EPI is achieved using the proposed spiral implementation.

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Alexander JS Beckett^1,2, Samantha J Ma³, An T Vu^4,5, and David A Feinberg^1,2
1Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States, ²Advanced MRI Technologies, Sebastopol, CA, United States, ³Siemens Medical Solutions USA, Inc., Malvern, PA, United States, ⁴Radiology, University of California, San Francisco, CA, United States, ⁵San Francisco Veteran Affairs Health Care System, San Francisco, CA, United States

Keywords: fMRI, Neuroscience

Resolution in functional imaging can be increased by limiting the Field of View (FOV) for the image, increased acceleration and faster imaging using specialized gradient systems. Here we combine the high performance gradients of the NexGen 7T scanner with limited FOV imaging to collect ultra-high resolution fMRI in the occipital pole. Isotropic resolutions of 0.35mm are demonstrated using 3D EPI.

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Hsin-Ju Lee^1,2, Hankyeol Lee³, Kamil Uludag⁴, and Fa-Hsuan Lin^1,2
1Physical Sciences Platform, Sunnybrook Research institute, Toronto, ON, Canada, ²Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ³Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea, Republic of, ⁴Techna Institute & Koerner Scientist in MR Imaging, University Health Network, Toronto, ON, Canada

Keywords: fMRI (task based), fMRI (task based)

We use cortical-depth dependent fMRI to study the correlation between neural oscillations and fMRI signals across cortical depths in the auditory cortex during music listening. The correlation between fMRI signals and acoustic stimuli was the strongest at the primary auditory cortex in the intermediate cortical depths during the first listening, matching the hypothesis of feedforward signal supported by the connectivity. The correlation was suppressed in the repeated listening, superficial as well as deep depths, and at the secondary auditory cortex.

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Shota Hodono¹, Reuben Rideaux², Timo van Kerkoerle³, and Martijn A. Cloos^1
1Centre for Advanced Imaging, University of Queensland, St Lucia, Australia, ²Queensland Brain Institute, University of Queensland, St Lucia, Australia, ³NeuroSpin, The French Alternative Energies and Atomic Energy Commission (CEA), Gif-Sur-Yvette, France

Keywords: fMRI, Contrast Mechanisms, DIANA

Here we describe our initial results attempting to observe neuronal activation in humans using the Direct Imaging of Neuronal Activity (DIANA) method. Both visual and auditory paradigms were explored. BOLD and anatomical ROI were tested and dedicated single slice control experiments were performed, but clear DIANA signals remained elusive. The translation of DIANA from animals to humans appears to be non-trivial. Nevertheless, considering the potential payoff continued effort towards this goal may be well worth it. To aid in this quest, parallel studies focused on DIANA’s ability to detect spiking and hyperpolarisation in controlled settings may be of great value.

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Lonike Faes¹, Isma Zulfiqar¹, Luca Vizioli², Zidan Yu³, Yuan-Hao Wu⁴, Jiyun Shin⁴, Ryszard Auksztulewicz⁵, Lucia Melloni^6,7, Kamil Uludag⁸, Essa Yacoub², and Federico De Martino^1,2
1Deparment of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, ²Center for Magnetic Resonance Research, Minneapolis, MN, United States, ³University of Hawaii, Honolulu, HI, United States, ⁴New York University Grossman School of Medicine, New York University, New York, NY, United States, ⁵Center for Cognitive Neuroscience Berlin, Free University Berlin, Berlin, Germany, ⁶Department of Neurology, New York University, New York, NY, United States, ⁷Department of Neurophysiology, Max-Planck Institute for Brain Research, Frankfurt am Main, Germany, ⁸Joint Department of Medical Imaging and Krembil Brain Institute, Techna Institute & Koerner Scientist in MR Imaging, Toronto, ON, Canada

Keywords: fMRI (task based), High-Field MRI

We use ultra-high field fMRI to explore the differential role of cortical layers in the information flow between top-down predictions and bottom up sensory evidence in a predictive coding (PC) framework. As the measured BOLD signal is affected by vascular draining, we use a computational model that combines neuronal dynamics with laminar vascular physiology to help us understand prediction signals at cortical depths and underlying neuronal responses. We show that a violation in prediction caused response modulation in superficial and deep layers in the primary auditory cortex, which is in line with the PC framework. 

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Viktor Pfaffenrot¹, David Leitao^2,3, Annika Verheyen¹, Markus May^1,4, Raphael Tomi-Tricot⁵, Shaihan Malik^2,6, and David Norris^1,7
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany, ²Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ³London Collaborative Ultra high field System (LoCUS), London, United Kingdom, ⁴High Field and Hybrid MR Imaging, University Duisburg-Essen, University Hospital Essen, Essen, Germany, ⁵MR Research Collaborations, Siemens Healthcare Limited, Frimley, United Kingdom, ⁶Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ⁷Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, Netherlands

Keywords: fMRI, Magnetization transfer, laminar fMRI

The GRE-BOLD contrast used in laminar fMRI suffers from suboptimal specificity due to unwanted extravascular effects. Recently, efforts were made to increase specificity of GRE-BOLD by means of CBV-weighting using the magnetization transfer contrast. The specificity improvement depends on the amount of selective GM signal reduction. We investigate whether PUSH pTx pulses, designed to maximize MT contrast in a given area, can achieve a higher functional contrast. Our results suggest that when opting for high-power, off-resonant MT pulses, both PUSH and a CP²⁺ mode perform equally well in increasing the functional contrast at short TE compared to GRE-BOLD in V1.

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SoHyun Han^1,2, Dongho Kim^1,2, and Seong-Gi Kim^1,2
1Center for Neuroscience Imaging Research, Suwon, Korea, Republic of, ²Sungkyunkwan University, Suwon, Korea, Republic of

Keywords: fMRI, Brain

High spatial resolution laminar specific fMRI has a potential to separate between top-down and bottom-up signals. In this study, we investigated the effect of attention across cortical layers in the human S1 using SAGE-EPI sequence. fMRI experiments during vibrotactile stimulation with passive and attention tasks with 0.8mm isotropic resolution at 7T were performed. We demonstrated that the SE-BOLD can identify laminar profiles of bottom-up and top-down processes: the laminar profile of passive task showed the peak at layer 4, but that of attention task showed the peak at the superficial layers.

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Nikos Priovoulos^1,2, Icaro Agenor Ferreira de Oliveira^1,2,3, Benedikt Poser⁴, David G Norris^5,6, and Wietske van der Zwaag^1,2
1Spinoza Center for Neuroimaging, Amsterdam, Netherlands, ²Computational Cognitive Neuroscience and Neuroimaging, Netherlands Institute for Neuroscience, Amsterdam, Netherlands, ³Techna Institute, University Health Network, Amsterdam, Netherlands, ⁴MR-Methods group, MBIC, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, ⁵Donders Institute for Brain, Cognition and Behaviour, Donders Centre for Cognitive Neuroimaging, Radboud University Nijmegen, Nijmegen, Netherlands, ⁶Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany

Keywords: fMRI, fMRI, high field, cerebral blood volume

BOLD fMRI is widely used in neuroscience, but has limited spatial specificity while alternative approaches based on tissue cerebral blood volume (CBV) change have limited sensitivity. Recently, arterial CBV change (Arterial Blood Contrast; tracked through magnetization-transfer) was suggested as an fMRI mechanism, but its localization and sensitivity remain unexplored, since efficiently isolating the arterial CBV is challenging. Here, we combine temporally-efficient saturation with center-slice-out readouts and BOLD-correction to isolate arterial CBV for high-resolution 7T human fMRI. Our novel sequence shows much-improved specificity compared to BOLD and similar sensitivity to VASO, suggesting Arterial Blood Contrast to be a promising fMRI approach.

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Jasmine Khedidja Nguyen-Duc¹, Wiktor Olszowy², Jonathan Patino Lopez ³, and Ileana Jelescu^1
1Department of Radiology, CHUV, Lausanne, Switzerland, ²CIBM Center for Biomedical Imaging, Lausanne, Switzerland, ³Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Keywords: fMRI (task based), Diffusion/other diffusion imaging techniques, simulations, diffusion fMRI

Diffusion functional Magnetic Resonance Imaging (dFMRI) may be used to study the white matter activation in a more direct way than BOLD. The aim of this work is to extract the decrease in apparent diffusion coefficient (ADC) in the white matter observed in real data, and compare to that in a simulation of realistic axon swelling. Results suggest that the decrease is of low amplitude (<0.5%) but nonetheless detectable.

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Emma Brouwer ^1,2, Julie Hashimoto ^1,3, Nikos Priovoulos^1,2, and Wietske van der Zwaag^1,2
1Spinoza Centre for Neuroimaging, Amsterdam, Netherlands, ²Computational Cognitive Neuroscience and Neuroimaging, Netherlands Institute for Neuroscience, Amsterdam, Netherlands, ³Vrije Universiteit Amsterdam, Amsterdam, Netherlands

Keywords: fMRI (task based), Brain, cerebellum

The human cerebellum forms an important part of the sensory and motor networks. Specifically, cerebellar damage has been shown to result in difficulty to perform proprioceptive tasks. Hence, studying the functional cerebellar organisation can be of great neuroscientific and clinical interest. This requires high-resolution images due to the thin, highly-foliated cortex of the cerebellum. We investigated the difference between a simultaneous-unilateral-finger-flex (SUFF) and midline-contralateral-finger-touch (MCFT) using B₁-shimmed fMRI at 7T. Movements with higher proprioceptive engagement (MCFT) resulted in stronger, more medially located activations on the cerebellar surface compared to movements which are less reliant on proprioception (SUFF). 

 

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Guy Shlomo Baz^1,2, Edna Furman-Haran ^2,3, and Rita Shmidt^1,2
1Department of brain sciences, Weizmann Institute, Rehovot, Israel, ²The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute, Rehovot, Israel, ³Life Sciences Core Facilities, Weizmann Institute, Rehovot, Israel

Keywords: fMRI (task based), High-Field MRI

Ultra-high field MRI provides increased sensitivity, which we aim to utilize for improving the temporal resolution in functional studies. To investigate the achievable resolution at 7T MRI, a dynamic phantom that can generate an fMRI-like time-series was used. A dataset based on block-design with defined time shifts and a range of contrast-to-noise values was used to characterize the effective temporal resolution. Estimated temporal resolution was x1.7 times better for multi-echo compared to single-echo EPI, estimated as 146ms for a scan with TR of 600ms. This study offers a novel approach of optimizing protocols and new insights into fMRI temporal resolution.

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Arjama Halder¹, Chad T. Harris², Curtis N. Wiens², Andrew T. Curtis², William B. Handler³, Andrea Soddu³, and Blaine A Chronik^1,3
1Medical Biophysics, Western University, London, ON, Canada, ²Research and Development, Synaptive Medical, Toronto, ON, Canada, ³Physics and Astronomy, Western University, London, ON, Canada

Keywords: fMRI, fMRI (task based)

fMRI is typically not performed at field strengths < 1.5T due to low magnetic susceptibility contrast and inadequate gradient performance.  Leveraging the high-performance gradient set of a head-only 0.5T MRI, the feasibility of motor task based fMRI was evaluated using a 4mm isotropic GRE-EPI acquisition. Activated regions within the PMC were consistent with expected behaviour.  Furthermore, a significant change in signal during activation of 1.8+/-0.4% was measured within an ROI of activated voxels.  These results suggest that motor task based BOLD fMRI is possible at 0.5T.