ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Scientific Session • Brain Oxygenation, Perfusion & Metabolic Rate

Thursday 4 June 2015

Constitution Hall 107

13:30 - 15:30


Richard B. Buxton, Ph.D. & Jeff F. Dunn, Ph.D.

13:30 0892.   
Imaging oxygen extraction fraction in the visual cortex during functional activation using turbo QUIXOTIC
Jeffrey N Stout1, Elfar Adalsteinsson1,2, Bruce R Rosen3, and Divya S Bolar3,4
1Harvard-MIT Health Sciences and Technology, Institute of Medical Engineering and Science, Cambridge, Massachusetts, United States, 2Department of Electrical Engineering and Computer Science, MIT, MA, United States, 3Martinos Center for Biomedical Imaging, MGH/Harvard Medical School, MA, United States, 4Department of Radiology, Massachusetts General Hospital, Boston, MA, United States

Using a turbo spin echo version of QUIXOTIC we measure changes in oxygen extraction fraction (OEF) in the visual cortex at baseline and during visual stimulation in a fraction of the time required by the original QUIXOTIC technique. The measured baseline and relative change in oxygen extraction fraction (OEF) compares favorably to literature values and suggests that with further validation tQUIXOTIC MRI may be useful to monitor regional OEF in the clinic.

13:42 0893.   Exploring human brain oxidative metabolism and neurotransmitter cycling via coupled 13C MRS at 7T
Vikram Jakkamsetti1, Levi Good1, Dorothy Kelly1, Sergey Cheshkov2, Karthik Rajasekaran1, Dean Sherry2, Juan Pascual1, Craig Malloy2, and Ivan Dimitrov2,3
1Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, United States, 2Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, 3Philips Medical Systems, Cleveland, Ohio, United States

13C NMR spectra measure the rate of energy production in vivo for human brains, but require prolonged 90–120 min infusions in the magnet which is difficult for patients with brain disorders. We infused 13C-enriched glucose to steady-state outside the magnet followed by an hour of 13C NMR spectroscopy at 7T without 1H decoupling. We report stable (for at least 60 min) and distinctly identified signals for spin-coupled doublet D45 and natural abundance singlet in glutamate C5, a prominent 13C- bicarbonate signal and essentially undetectable alanine and lactate.

13:54 0894.   Optimization of Oxygen Extraction Fraction Mapping using Joint Parametric Estimation
Youngkyoo Jung1,2, Naeim Bahrami2, and Megan E Johnston2
1Radiology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States, 2Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States

Oxygen extraction fraction (OEF) is an important indicator of the oxygen metabolism in the brain. Currently there are two approaches to measure or map OEF in the brain using MRI; one approach uses the T2 of venous blood, while the other uses the magnetic susceptibility difference between tissue and blood. We introduce a novel OEF estimation method using the joint information of T2 and the magnetic susceptibility difference of blood signal, and present voxel-wise CMRO2 mapping in conjunction with CBF measured with an arterial spin labeling method. A breath-hold paradigm was performed to test the feasibility of the algorithm.

14:06 0895.   Quantitative and Simultaneous Imaging of CMRO2, CBF and OEF in Resting Human Brain
Xiao-Hong Zhu1, Hannes M Wiesner1, Byeong-Yeul Lee1, Ming Lu1, Kamil Ugurbil1, and Wei Chen1
1CMRR, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, United States

The ability to noninvasively imaging the cerebral metabolic rate of oxygen (CMRO2) is essential for studying oxygen metabolism and its roles in human brain function and dysfunction. We have recently established an in vivo 17O-MR based approach incorporated with a simple breathing test and a sophisticated quantification model capable of quantitative and simultaneous imaging of three important physiology parameters of CMRO2, cerebral blood flow (CBF) and oxygen extraction factor (OEF) in the human brain via a brief 17O-labeled oxygen gas inhalation. In the present study, we apply this approach to study these parameters and their correlations in the resting brains of healthy human volunteers and the inter- and/or intra-subject variations at 7 Tesla. We found that the resting state CMRO2, CBF and OEF values were in good agreement with the literature; they also varied in different subjects, brain tissues and regions. A strong dependence of CMRO2 on gray matter fraction, a positive correlation between CMRO2 and CBF, and a negative correlation between CBF and OEF were consistently observed in all subjects studied. The overall findings indicate that the 17O-MR based approach provides a robust and quantitative neuroimaging tool for noninvasive assessment of CMRO2, CBF and OEF in healthy and diseased human brains.

14:18 0896.   
Neurochemical and BOLD Responses in Activated Blob and Interblob Neuronal Populations Measured in the Human Visual Cortex at 7T
Petr Bednarik1,2, Ivan Tkac1, Federico Giove3,4, Dinesh Deelchand1, Lynn Eberly1, Felipe Barreto1,5, and Silvia Mangia1
1University of Minnesota, Minneapolis, MN, United States, 2Central European Institute of Technology, Masaryk University, Brno, Czech Republic,3MARBILab c/o Fondazione Santa Lucia, "Enrico Fermi" Centre, Rome, Italy, 4", Department of Physics - G1 Group, University of Rome "La Sapienza", Rome, Italy, 5Physics Department, University of Sao Paulo, Sao Paulo, Brazil

Different functional metabolisms might be expected in selectively activated blob and interblob neuronal populations due to different cytochrome-oxidase contents. Here we acquired fMRI and fMRS data during chromatic and achromatic visual stimuli, which selectively activate blob and interblob neurons, respectively. Neurochemical and fMRI-BOLD responses were measured from 12 subjects, each scanned twice. We observed robust BOLD-fMRI signals as well as functional changes in concentration of Glu, Lac, Asp and Glc for both stimuli. No significant differences in neurochemical and BOLD responses between chromatic and achromatic stimuli were found, consistent with equal aerobic responses in blob and interblob neuronal populations.

14:30 0897.   
Slower DMN, faster reaction: coupling of resting-state CBF and BOLD oscillations in specific frequency bands predicts vigilance task performance
Xiaopeng Song1, Shaowen Qian2, Kai Liu2, Zhenyu Zhou3, Gang Sun2, and Yijun Liu1
1Department of Biomedical Engineering, Peking University, Beijing, Beijing, China, 2Department of Medical Imaging, Jinan Military General Hospital, Shandong, China, 3GE Health Care, Beijing, China

We found that subject with slower resting-state BOLD oscillation frequency in DMN reacted faster in psychomotor vigilance test under both normothermic and hyperthermic conditions. CBF mainly contributes to BOLD oscillations of 0.01-0.04Hz under both conditions. The coupling of CBF and BOLD oscillations in 0-0.01Hz and 0.04-0.1Hz were significantly decreased with hyperthermia. Our study linked resting-state brain rhythms to task performance, and for the first time revealed the frequency-specific coupling between blood supply and BOLD oscillation topology during rest and its modulation in response to hyperthermia, which may shed light on the physiological basis of resting-state BOLD activities.

14:42 0898.   
Three-dimensional acquisition of cerebral blood volume, blood flow and blood oxygenation-weighted responses during functional stimulation in a single scan
Ying Cheng1,2, Qin Qin1,3, Peter C. M. van Zijl1,3, James J. Pekar1,3, and Jun Hua1,3
1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States, 2Dept. of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States, 3Neurosection, Div. of MRI Research, Dept. of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland, United States

Quantitative approaches have been developed to estimate CMRO2 dynamics from BOLD, CBF, and CBV responses. The ability to measure BOLD, CBF, and CBV signals in one single scan would be useful to improve acquisition efficiency and reduce temporal variations. We extended the recently proposed 3D “VASO-FAIR” approach, which combines the VASO and FAIR-ASL techniques to simultaneously detect CBV and CBF responses, with a T2-preparation module to induce T2-weighted BOLD contrast, allowing concurrent measurement of BOLD, CBV, and CBF responses. For visual stimulation, the proposed method could achieve similar activation patterns, image quality, tSNR, and CNR as the separate individual scans.

14:54 0899.   Blood oxygenation, CBF, OEF, and CMRO2 changes during hypercapnia and hyperoxia using pCASL and TRUST MRI
Jeroen C.W. Siero1, Carlos C. Faraco2, Alex Bhogal1, Megan K. Strother2, Peiying Liu3, Hanzhang Lu3, Jeroen Hendrikse1, and Manus J. Donahue2
1Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2Radiology and Radiological Sciences, Nashville, Vanderbilt University School of Medicine, Tennessee, United States, 3Radiology Advanced Imaging Research Center, UTSouthwestern Medical Center, Texas, United States

Here we evaluate the assumption that two common hypercapnic stimuli (5%CO2; and carbogen) are iso-metabolic using MRI-based measures of changes in venous blood oxygenation. Wholebrain CBF (pCASL), and Yv (TRUST-MRI) changes were measured for hypercapnic-normoxia, normocapnia-hyperoxia, and hypercapnic-hyperoxia stimuli allowing calculation of OEF and CMRO2. After correcting for the plasma-dissolved arterial and venous O2, no significant differences in OEF were found between 5%CO2 and carbogen. Significant CMRO2 decreases from room air were observed only for the hypercapnic-normoxic condition. We believe these findings will be of importance for interpreting calibrated fMRI and BOLD CVR measurements using hypercapnic or carbogen stimuli.

15:06 0900.   
Temporal and spatial changes of BOLD signal, CBF and CBV in the activated human visual cortex during mild hypoxia
Felipe Rodrigues Barreto1, Silvia Mangia2, and Carlos Ernesto Garrido Salmon3
1Department of Physics, University of Sao Paulo, RIbeirao Preto, SP, Brazil, 2Department of Radiology, CMRR, University of Minnesota, MN, United States,3Department of Physics, University of Sao Paulo, Ribeirao Preto, SP, Brazil

In the present study we used multimodal fMRI to quantify in the human visual cortex the effects of mild hypoxic hypoxia on stimulus induced variations of cerebral blood flow (CBF), cerebral blood volume (CBV), BOLD signal, as well as oxygen consumption (CMRO2) and oxygen extraction fraction (OEF) during visual stimulation. Hypoxia produced substantial reductions in the active volumes detected in BOLD, CBF and CBV images, which might indicate smaller cortex recruitment. The brain regions commonly activated during hypoxia and normoxia had reduced BOLD amplitudes and smaller OEF reductions, but no changes in the amplitude of vascular and CMRO2 responses.

15:18 0901.   Cerebral blood flow is mediated by brain cells expressing glucose transporter 2
Hongxia Lei1,2, Frederic Preitner3, Bernard Thorens3, and Rolf Gruetter4,5
1AIT, Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland, 2University of Geneva, Geneva, Geneva, Switzerland, 3Center for Integrative Genomics (CIG), University of Lausanne, Lausanne, Vaud, Switzerland, 4Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland, 5Department of Radiology, University of Lausanne, Lausanne, Vaud, Switzerland

Glucose transporter isoform 2 (glut2) has been shown to not only meditating glucose sensing mechanism in pancreatic tissue but also preferentially being highly located in brain regions and nuclei which regulate the neuroendocrine and autonomic nervous system. we hypothesized that glut2 positive brain cells might be involved in glucose sensing mechanism in brain and thus deleting glut2 would affect brain metabolism under euglycemia and mediate vascular responses upon hypoglycemia. This study applied a non-invasive perfusion MRI technique, continuous arterial spin labeling (CASL), to measure cerebral blood flow (CBF) under euglycemia and upon hypoglycemia in glut2 positive brain cells nulled mice compared to their countertypes. Unlike the elevated CBF increases in the wild type mice, the dimished repsponses were observed. We conclude that brain cells expressing glut2 are implicated in regulating the CBF response to hypoglycemia.