Maria Guadalupe Garcia Gomar^1,2, Kavita Singh¹, Simone Cauzzo^1,3,4, and Marta Bianciardi^1
1Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Escuela Nacional de Estudios Superiores, Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Mexico, ³Sant'Anna School of Advanced Studies, Institute of Life Sciences, Pisa, Italy, ⁴Research Center E. Piaggi, University of Pisa, Pisa, Italy

The subthalamic nucleus (STh) plays a crucial role in the basal ganglia movement-related circuit and it is involved in movement disorders such as Parkinson’s disease, dystonia, and chorea, among others. Its study in living humans is challenging due to limited resolution and contrast in conventional MRI. Previous work developed an in-vivo atlas of two STh subregions based on their fractional anisotropy properties. With the goal of characterizing their function and connectivity, in the present study, we evaluated the functional and structural connectivity of these STh subregions using 7 Tesla MRI and tested their preferential connectivity towards associative or motor regions. 

Zhongliang Zu¹, Yu Zhao¹, Yurui Gao¹, Muwei Li¹, Zhaohua Ding¹, and John C Gore^1
1Vanderbilt University Medical Center, Nashville, TN, United States

We describe a novel graph analysis that includes a multigraph with multiple edges between a pair of nodes to model brain functional networks, and introduce a three-way correlation between BOLD signals from a pair of gray matter volumes (nodes) and one white matter bundle to define functional connectivity. Characteristics of inter-nodal communication may be derived from this analysis. By examining selected databases, we show inter-nodal communications vary with ages. By integrating fMRI signals from white matter as a third component in network analysis, more comprehensive descriptions of brain function may be obtained.

Alexander D. Cohen¹, Michael D. McCrea^2,3, and Yang Wang^1
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, ²Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States, ³Neurology, Medical College of Wisconsin, Milwaukee, WI, United States

Repetitive head impact exposure (RHIE) during contact sports may have damaging neurocognitive effects. In this study, we investigated longitudinal changes in dynamic functional connectivity (dFNC) using multiband multi-echo (MBME) fMRI in high school football players over the course of two seasons. Four recurring connectivity states were identified. A greater total number of dFNC changes were observed over two seasons compared to over the course of one season. Changes across all four states were only observed in the two-season comparison. These preliminary results suggest that RHIE may lead to accumulated effects in functional connectivity patterns.

Benjamin Sipes¹, Angela Jakary¹, Melanie Morrison¹, Tony T Yang², and Olga Tymofiyeva^1
1Radiology, University of California, San Francisco, San Francisco, CA, United States, ²Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, United States

In this study, we found that adolescent resting state functional brain networks contains a subnetwork significantly related to self-reported prosocial behavior and compassion. The subnetwork regions indicated connects many previously identified brain regions associated with prosocial behavioral tasks in adolescents, including the bilateral precuneus, left lateral prefrontal cortex, medial prefrontal cortex, inferior frontal gyri, temporal poles, left amygdala, right posterior cingulate cortex, occipital cortex, left supplementary motor area, and cerebellum.

Daehun Kang¹, Myung-Ho In¹, Maria A Halverson¹, Nolan K Meyer¹, Erin M Gray¹, Thomas K Foo², Radhika Madhavan², Zaki Ahmed¹, Hang Joon Jo³, Brice Fernandez⁴, David F Black¹, Kirk M Welker¹, Joshua D Trzasko¹, John Huston, III¹, Matt A Bernstein¹, and Yunhong Shu^1
1Department of Radiology, Mayo Clinic, Rochester, MN, United States, ²GE Global Research, Niskayuna, NY, United States, ³Department of Physiology, Hanyang University, Seoul, Korea, Republic of, ⁴GE Healthcare, Buc, France

Through echo-combination, multi-echo echo-planar-imaging (ME-EPI) has shown improved performance for fMRI over single-echo (SE)-EPI. The high-performance gradients on a compact 3T scanner enable whole-brain high-spatial-resolution ME-EPI with reasonable echo times and comparable TR to SE-EPI. To evaluate the fidelity of the ME-EPI sequence in resting state fMRI and compare with that of SE-EPI sequence, seed-based and ICA-based functional connectivity (FC) analyses were applied to evaluate scan-time-dependency and accuracy improvement. ME-EPI extracted more and stronger FCs in seed-based connectivity analysis and produced higher sensitivity and accuracy in ICA-based method, compared to SE-EPI.

Emily L. Tse¹, Russell W. Chan^1,2, Sarah Y. Wu¹, Yixi Xue¹, Peiying Liu³, Steen Moeller⁴, and Kevin C. Chan^1,5
1Department of Ophthalmology, New York University Grossman School of Medicine, New York, NY, United States, ²Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, United States, ³Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States, ⁴Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, United States, ⁵Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States

Cerebrovascular reactivity (CVR) reflects the response of cerebral blood vessels to vasoactive stimuli. Whole-brain relative CVR (rCVR) mapping is achieved using task-free resting-state fMRI, which resembles conventional CVR mapping using hypercapnia challenge. To optimize rCVR mapping, we apply NOise Reduction with DIstribution Corrected (NORDIC) PCA which removes thermal noise originating from the scanner and/or the subject. Results show that NORDIC-correction increases the temporal signal-to-noise ratio in both humans and mice, lowers mouse rCVR variance, and potentially improves mouse rCVR along cortical layers. Future rCVR studies investigating cerebrovascular diseases may incorporate NORDIC-correction for higher sensitivity.

Daehun Kang¹, Myung-Ho In¹, Maria A Halverson¹, Nolan K Meyer¹, Erin M Gray¹, Thomas K Foo², Radhika Madhavan², Zaki Ahmed¹, Hang Joon Jo³, Brice Fernandez⁴, David F Black¹, Kirk M Welker¹, Joshua D Trzasko¹, John Huston, III¹, Matt A Bernstein¹, and Yunhong Shu^1
1Department of Radiology, Mayo Clinic, Rochester, MN, United States, ²GE Global Research, Niskayuna, NY, United States, ³Department of Physiology, Hanyang University, Seoul, Korea, Republic of, ⁴GE Healthcare, Buc, France

For multi-echo EPI, the T₂^*-weighted echo combination (T2EC) is a commonly used pre-processing step to boost the data quality. We assessed the benefit of T2EC in high-spatial-resolution multi-echo fMRI with explained variances and functional connectivity detectability. The performance was evaluated and compared with single-echo EPI for resting state fMRI on a compact 3T scanner with high-performance gradients. It was shown that a large portion of unwanted signal variance was globally suppressed through T2EC. Multi-echo acquisition shows improved image intensity and enhanced functional sensitivity in brain regions affected by signal-dropout.

Qingfei Luo¹, Kaibao Sun¹, Alessandro Scotti¹, Guangyu Dan^1,2, Muge Karaman^1,2, and Xiaohong Joe Zhou^1,2,3
1Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States, ²Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States, ³Departments of Radiology and Neurosurgery, University of Illinois at Chicago, Chicago, IL, United States

The simultaneous multi-slice EPI (SMS-EPI) technique is widely used in fast fMRI studies to achieve a short TR (e.g., < 1 s), but its image quality can be degraded when the slices span only a small brain area. In this study we develop a fast fMRI acquisition technique for imaging a small area by employing (k, t)-space undersampling and three-dimension reduced field-of-view imaging (k-t 3D-rFOVI). Our human fMRI experiments covering the visual cortex demonstrate that k-t 3D-rFOVI can provide higher detection sensitivity of brain activations than SMS-EPI.

Kaibao Sun¹, Guangyu Dan^1,2, Alessandro Scotti¹, Muge Karaman^1,2, Qingfei Luo¹, and Xiaohong Joe Zhou^1,2,3
1Center for MR Research, University of Illinois at Chicago, Chicago, IL, United States, ²Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States, ³Departments of Radiology and Neurosurgery, University of Illinois at Chicago, Chicago, IL, United States

Functional MRI (fMRI) is typically performed with whole brain coverage, even when only a small brain area is of interest. Although zoomed fMRI has been demonstrated using 2D multi-slice acquisitions, extending this capability to 3D focused volume has not been well explored. We have implemented a 3D reduced field-of-view technique for fMRI by using a 2D RF pulse and applied this technique to a visual fMRI study on ten subjects. Compared to a conventional fMRI sequence with a full field-of-view, our technique produced high isotropic spatial resolution and reduced image distortion, despite a moderate reduction in temporal signal-to-noise ratio.

Fuyixue Wang^1,2, Zijing Dong^1,2, Jingyuan Chen^1,2, Kawin Setsompop^3,4, Jonathan R. Polimeni^1,2, and Lawrence L. Wald^1,2
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Department of Radiology, Stanford University, Stanford, CA, United States, ⁴Department of Electrical Engineering, Stanford University, Stanford, CA, United States

This work aims to address the limitations of EPI and improve fMRI acquisition by developing a single-shot EPTI method, to provide fast distortion-free imaging, with significantly improved tSNR, CNR, robustness to motion, reduced signal dropout, and multi-echo capability for denoising/analysis. The single-shot acquisition is enabled by the newly-designed k-t encoding to provide stronger correlation for improved reconstruction. Results show ss-EPTI achieves: i) 30% higher tSNR efficiency than EPI and 70% higher than 3-shot EPTI; ii) 50% higher CNR than EPI (visual-task); iii) distortion-free fMRI with improved robustness to motion; iv) effective signal dropout reduction; and v) effective non-BOLD variation separation.

Wen-Ju Pan¹, Yunmiao Wang², Harrison Watters¹, Lisa Meyer-Baese¹, Alaina Corrie Smith¹, Dieter Jaeger², and Shella Keilholz^1
1Biomedical Engineering, Emory University/Georgia Institute of Technology, Atlanta, GA, United States, ²Biology, Emory University, Atlanta, GA, United States

We present an optimized wide-field optical imaging method with GEVI in mice to probe the relationship between slow changes in neuronal membrane potential and the BOLD signal in hindpaw stimulation, demonstrate neuronal sub-threshold activity of slow fluctuations could be possibly isolated from hemodynamic signals.

Fuyixue Wang^1,2, Zijing Dong^1,2, Lawrence L. Wald^1,2, Jonathan R. Polimeni^1,2, and Kawin Setsompop^3,4
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Department of Radiology, Stanford University, Stanford, CA, United States, ⁴Department of Electrical Engineering, Stanford University, Stanford, CA, United States

This work utilizes our recently developed spin-echo EPTI technique with minimal T2’-contamination and high specificity to map the layer-dependent responses in primary motor cortex at 7T and further investigate the impact of large vessel bias from T2’ contamination. EPTI resolves multi-contrast images across the readout that are free from distortion and blurring, and simultaneously obtains a SE image with pure T2-weighting and multiple asymmetric SE images with various T2’-weightings. The activation of finger-tapping task was studied using SE-EPTI at 0.9-mm isotropic resolution. Improved specificity of layer-dependent responses was observed using pure SE images. 

Wei D Zhang¹, Peter T Fox ¹, Hillary F Huber², Peter William Nathanielsz³, and Geoffrey D Clarke^4
1Research Imaging Institute, UT Health San Antonio, San Antonio, TX, United States, ²Texas Pregnancy & Life-Course Health Research Center, Texas Biomedical Research Institute, San Antonio, TX, United States, ³Animal Science, University of Wyoming, Laramie, WY, United States, ⁴Research Imaging Insitute, UT Health San Antonio, San Antonio, TX, United States

Maternal obesity status was found to affect neural functional connectivity of adult offspring in in a baboon model. Significant differences in connectivity between offspring of obese mothers and age/sex matched controls were found in  regions of the left temporal lobe and frontal lobe using rs-fMRI.

Ali Golestani¹ and Jean Chen^2,3
1University of Toronto, Toronto, ON, Canada, ²Rotman Research Institute at Baycrest, Toronto, ON, Canada, ³Department of Biophysics, University of Toronto, Toronto, ON, Canada

Data-driven methods have been suggested to remove heartbeat and respiration noises from fMRI signals. We compared the effectiveness of these methods (global-signal regression (GS), white matter and CSF (cerebrospinal fluid) regression, anatomical and temporal CompCor, ICA AROMA) in removing the noise. GS, AROMA, and aCompCor removed the most physiological fluctuation, but GS and AROMA also removed most signals under 0.1 Hz. We also observed that all methods removed less noise power and more low-frequency power from young adult data compared to older adults. 

Wei Zhu¹, Corey Cruttenden¹, Shinho Cho¹, Xiao-Hong Zhu¹, Kamil Ugurbil¹, and Wei Chen^1
1University of Minnesota, Minneapolis, MN, United States

The specificity of hemodynamic signals detected by functional magnetic resonance imaging (fMRI) to neuronal activity is complicated by the neurovascular coupling. To investigate the fidelity of fMRI in differentiating the neuronal activity across cortical layers, we mapped the laminar orientation preference maps in the cat visual cortex by using high-resolution cerebral blood volume weighted (wCBV) fMRI and single-unit neuronal action potential recording, respectively. The strong correlation between wCBV percent change and spike firing rate indicates that wCBV fMRI with sufficient spatial resolution could distinguish the differences of neural activities across layers but with a reduced sharpness.

Hanne D Hansen^1,2, Martin Schain², Helen P Deng¹, Joseph B Mandeville^1,3, Bruce R Rosen^1,3, and Christin Y Sander^1,3
1A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, ²Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark, ³Harvard Medical School, Boston, MA, United States

In this study, we imaged the effect of repeated amphetamine injections over >24h using simultaneous PET/fMRI in non-human primates and demonstrate that both internalization and recycling of receptors take place during this timeframe. We provide novel insight into D₁ vs. D₂ receptor contributions by using a D₁ blocking agent in combination with amphetamine injections. These results shed a new light into the timelines of dopamine receptor subtype adaptations and not only provide a link to existing in vitro results but also a foundation for linking receptor-specific mechanisms to initial stages of psychostimulant drug use and abuse.

Anna Izabella Blazejewska^1,2, Daniel Gomez^1,2,3, and Jonathan R Polimeni^1,2,4
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Charlestown, MA, United States, ³Department of Biomedical Engineering, Boston University, Boston, MA, United States, ⁴Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

The gradient-echo BOLD fMRI signal demonstrates greatest changes with activation near large draining veins which results in cortical-depth activation profiles that increase linearly with depth from the white to pial surface. However, due to the sparsity of pial vessels these profiles are likely to vary across cortical locations depending on proximity to vessels. We investigated the temporal evolution and spatial variability of the cortical-depth profiles of the BOLD response within human visual cortex and demonstrated that the response is initially strongest in the mid-cortical depths and in time becomes dominated by the large veins at the pial-surface.

Zhangyan Yang^1,2, Ming Lu³, Gary Drake^2,4, Feng Wang^2,4, Pai-Feng Yang^2,4, Li Min Chen^2,4, John C. Gore^1,2,4,5,6, and Xinqiang Yan^2,4
1Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, ²Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, ³College of Nuclear Equipment and Nuclear Engineering, Yantai University, Shandong, China, ⁴Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, ⁵Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States, ⁶Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States

RF shields are key components of volume coils, but they may cause imaging distortions and the significant heating. The effects of different shielding strategies were evaluated for a birdcage coil used to image animals at 9.4T. Three shields with various thicknesses and two shields with different slot patterns were comparatively investigated ed in terms of performance and temperature rise during fMRI acquisitions.

zhangyan yang^1,2, Pai-Feng Yang^2,3, Huiwen Luo^1,2, Feng Wang^2,3, Jamie L Reed^2,3, William A. Grissom^1,2,3, Li Min Chen^2,3, and John C. Gore^1,2,3,4,5
1Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, ²Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, ³Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, ⁴Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States, ⁵Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States

Optogenetic stimulation combined with MRI detection of blood oxygenation level dependent (BOLD) effects has been developed as a powerful tool to delineate brain circuits. Opsin targeting specific cell types induce neural activity when irradiated with light at a specific wavelength. We detected robust BOLD effects in secondary somatosensory cortex (S2) and downstream interconnected caudate putamen (CPu) of monkey brains from irradiation with low-intensity green light without exogenous green light specific opsin, suggesting hemodynamic changes can be stimulated without any associated neural activity.

Zhengshi Yang^1,2, Xiaowei Zhuang^1,2, Mark Lowe³, and Dietmar Cordes^1,2,4
1Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, United States, ²University of Nevada Las Vegas, Las Vegas, NV, United States, ³Cleveland Clinic, Cleveland, OH, United States, ⁴University of Colorado, Boulder, CO, United States

Accurately localizing brain activation is of great importance for promoting basic science and clinical application of task fMRI data. In this study, we proposed a global and time-efficient way to conduct brain activation analysis, with the property of spatially-adaptive smoothing and determining individual voxel’s activation status with wholebrain fMRI data considered simultaneously. We have demonstrated its advantage over traditional methods in alleviating spatial blurring artifacts.