Multimodal fMRI

Tuesday 13 May 2014

Christin Y. Sander^1,2, Jacob M. Hooker¹, Ciprian Catana¹, Bruce R. Rosen^1,3, and Joseph B. Mandeville^1
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, ²Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, ³Health Sciences and Technology, Harvard-MIT, Cambridge, MA, United States

Receptor internalization is an adaptation mechanism shown to occur in response to large agonist doses. To date, there has not been a method for detecting internalization in vivo, although it may affect functional imaging signals. In this study, we use simultaneous PET/fMR imaging and graded doses of a D2 agonist in order to investigate D2 receptor internalization. We propose a model that combines fMRI timecourses with dynamic receptor occupancies measured by PET to derive an in vivo index of dopamine receptor internalization non-invasively.

Marjorie Villien¹, Joseph B. Mandeville¹, Hsiao-Ying Wey¹, Ciprian Catana¹, Jonathan R. Polimeni¹, Christin Y. Sander², Nicole R. Zürcher¹, Daniel B. Chonde¹, Joanna S. Fowler³, Bruce R. Rosen¹, and Jacob M. Hooker^1
1Martinos Center for Biomedical Imaging, MGH/Harvard Medical School, Boston, MA, United States, ²2Department of Electrical Engineering and Computer Science, MIT, Boston, MA, United States, ³Biosciences Department, Brookhaven National Laboratory, Upton, NY, United States

Brain mapping of task-associated changes in metabolism with PET has been accomplished in the past by subtracting scans acquired during two distinct static states. Here we show that PET can provide truly dynamic information on cerebral metabolism using concepts common to fMRI. Using 2-[18F]-fluoro-deoxyglucose (FDG), we show that quantitative glucose utilization changes during multiple visual stimuli can be determined using FDG constant infusion in a single-imaging experiment. This functional PET (fPET-FDG) method can be accomplished simultaneously with fMRI (BOLD and ASL) and thus enables the first direct comparisons in time, space and magnitude of glucose utilization, hemodynamics and oxygen consumption.

Hans F Wehrl¹, Mosaddek Hossain¹, Michael Walker¹, Gerald Reischl¹, Petros Martirosian², Fritz Schick², and Bernd J Pichler^1
1Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of Tuebingen, Tuebingen, Germany, ²Section on Experimental Radiology of Dept. of Diagnostic and Interventional Radiology, University of Tuebingen, Tuebingen, Germany

Brain connectivity is mainly derived from fMRI data. Here we present an approach to visualize functional and metabolic networks in the rat brain using combined PET and MR imaging. Three different PET tracers, mapping glucose, perfusion and serotonin transporter contributions to functional connectivity are compared with fMRI. Our results reveal that fundamental information about functional and metabolic brain networks is encoded in dynamic and static PET data. This opens the arena for quantitative PET based functional connectivity methods that can be complemented with fMRI.

Yu-Shin Ding^1,2, Adriana Di Martino³, Bangbin Chen⁴, Krishna Somandepalli³, Christopher Glielmi⁵, Kritika Nayar³, and Francisco X Castellanos^3,6
1Radiology, New York University School of Medicine, New York, NY, United States, ²Psychiatry, New York University School of Medicine, New York, NY, United States, ³Child and Adolescent Psychiatry, New York University School of Medicine, NY, United States, ⁴National Taiwan University Hospital, Taiwan, ⁵Siemens Healthcare, NY, United States, ⁶Neuroscience and Physiology, New York University School of Medicine, NY, United States

Our results demonstrated the feasibility of correlating FDG metabolism and resting-state fMRI data acquired simultaneously via a combined PET/MR on healthy participants. We showed that PCC-based intrinsic functional connectivity with the anterior node of the default network is positively related to glucose consumption, which in turn is related to fluctuations in the BOLD signal specific to gray matter regions. The fMRI signals are indirect measures of neuronal activity; thus, the ability to simultaneously interrogate metabolism and fMRI indices of brain function in the same temporal and spatial frames of reference provides greater insights into whole brain network organization.

Xiao Liu¹, Toru Yanagawa², David A. Leopold³, Naotaka Fujii², and Jeff H. Duyn^1
1NINDS, National Institutes of Health, Bethesda, MD, United States, ²RIKEN Brain Science Institute, Saitama, Japan, ³NIMH, National Institutes of Health, MD, United States

To investigate the neural correlate of fMRI resting-state networks (RSNs), we recorded and analyzed large-scale ECoG data from macaques during eyes-closed wakefulness, sleep, and two anesthetic regimes. A data-driven analysis on co-variations of spontaneous power fluctuations revealed 8 spatial patterns that corresponded closely to previously reported RSNs. These patterns were similar across spectral frequency bands and behavioral conditions. We conclude that fMRI RSNs reflect the spatial organization of spontaneous broadband neural activity, which appears to be a core aspect of the brain’s physiology that is preserved across various states of consciousness.

Han Yuan¹, Lei Ding^1,2, Min Zhu², and Jerzy Bodurka^1,3
1Laureate Institute for Brain Research, Tulsa, OK, United States, ²School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, United States, ³College of Engineering, University of Oklahoma, Norman, OK, United States

We developed a method to reconstruct the resting state networks (RSNs) from high-resolution EEG data. We combined electrophysiological source imaging and independent component analysis to obtain cortical distributions of eight RSNs from temporal independent EEG microstates. We further compared both spatial and temporal similarities of EEG-derived RSNs and BOLD-fMRI-derived RSNs from simultaneously acquired data. We found a high spatial similarity and temporal correlations among all eight RSNs independently identified from multimodal data. Results demonstrate the intrinsic connection between fast neuronal activity and slow hemodynamics fluctuation, and also show the utility of EEG in studying resting brain networks.

Wen-Ju Pan¹, Garth Thompson¹, Jacob Billings¹, Josh Grooms¹, Sadia Shakil^1,2, and Shella Keilholz^1
1Biomedical Engineering, Emory University/ Georgia Institute of Technology, Atlanta, GA, United States, ²Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States

Cerebral slow vasomotion, termed 0.1-Hz oscillation, might confound neurovascular coupling in resting-state fMRI BOLD signal. To explore neural contribution to the 0.1-Hz oscillation, simultaneous fMRI and full-band LFP recording in rat cortex were performed. Coherence analyses on the concurrent BOLD, infraslow LFPs and high-frequency LFPs revealed close relationship between each others at ~0.1 Hz during spontaneous oscillation.

Hsiao-Ying Wey¹, Jacob M Hooker¹, Bruce R Rosen¹, and Joseph B Mandeville^1
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States

Simultaneous PET/fMRI offers the unique opportunity to relate neurochemical events to the functional changes underlying neural activity. In this study, we present simultaneous PET/fMRI study with pharmacological challenges given to nonhuman primates to determine the relationship between opioid receptor occupancy, dopamine release, and changes in CBV. CBV-fMRI shows dose-response to opioid agonist challenges. PET and fMRI demonstrated concurrent signal changes overlapping in the basal forebrain, such as the caudate, putamen, and nucleus accumbens (NAc). In addition, the temporal response of dopamine release matches a fast CBV decrease in the NAc, while other brain regions show a slow CBV increase comparable to the temporal dynamic of opioid receptor binding.

Manus Donahue¹, Swati Rane¹, Erin Hussey¹, Emily Mason¹, Subechhya Pradhan¹, Kevin Waddell¹, and Brandon Ally^1
1Vanderbilt University, Nashville, TN, United States

MRS measurements of the primary inhibitory neurotransmitter, GABA, and MRI measurements of CBF, fractional gray matter volume, and arterial arrival time (AAT) are recorded in human visual cortex from adult male volunteers. The primary finding is that occipital GABA derived from J-edited MEGA-PRESS inversely correlates with CBF in the same region. This finding provides some physiological basis for the reported inverse relationships between BOLD responses and GABA. A secondary finding is that AAT does not correlate strongly with GABA, but failure to account for AAT in ASL measurements can reduce or eliminate the detectability of CBF-GABA relationships.

HSIN-YI LAI^1,2, PO-CHUN CHU³, HSIANG-WEI HU⁴, YOU-YIN CHEN⁵, YEN-YU IAN SHIH⁶, and YU-CHENG PEI^1,2
1School of Medicine, Chang Gung University, Taoyuan, Taiwan, ²Department of Physical Medicine and Rehabilitation, Chang-Gung Memorial Hospital, Taoyuan, Taiwan, ³Electrical Engineering, Chang Gung University, Taoyuan, Taiwan, ⁴Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan, ⁵National Yang-Ming University, Taipei, Taiwan, ⁶Department of Neurology, Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NORTH CAROLINA, United States

This study demonstrates focused ultrasound co-administrated with microbubbles can modulate local brain activities. Focused ultrasound with acoustic pressures of 0.3 MPa produced reliable and reversible brain modulation. This present study proposed a novel non-invasive, reversible and localized brain modulated method which is suitable for a variety of neurophysiological experiments and clinical applications.