Yuanyuan Jiang¹, David Christopher Hike¹, and Xin Yu^1
1Massachusetts General Hospital, Martinos Center for Biomedical Imaging, Charlestown, MA, United States

This research utilizes a novel high-resolution phase-contrast (PC) MRI method to measure resting-state fluctuation of cerebral blood flow-related velocity (CBFv) from penetrating vessels in the rat parietal cortex. This novel PC-based mapping scheme has identified vessel-specific correlation and anti-correlation patterns between venules and arterioles with the low-frequency oscillatory features less than 0.05Hz in anesthetized rat brains. By combining PC-based CBFv fMRI and single-vessel cerebral blood volume (CBV)-fMRI, we will further study the vasodynamic changes in diseased animal models.

Won Beom Jung¹, Haiyan Jiang^1,2, and Seong-Gi Kim^1,2
1Center for Neuroscience Imaging Research (CNIR), Suwon, Korea, Republic of, ²Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of

Functional connectivity measured by rs-fMRI have generally shown a bilateral organization in homotopic cortices, presumably related to the intrinsic network of spontaneous activity. Alternatively, cortical silencing suppresses spontaneous output activity from the inactivated site and reduces input to downstream areas. Thus, the decrease in fMRI responses due to cortical silencing is related to the strength of resting-state connectivity between the stimulation site and the connected regions. To examine the contribution of spontaneous neuronal communications to bilateral homotopic connectivity of rs-MRI, we compared the somatosensory network by rs-fMRI with cortical silencing fMRI by optogenetic stimulation of interneurons and anatomical tracing data.

Mada Hashem^1,2,3,4, Ying Wu^2,3,4, and Jeff F. Dunn^2,3,4
1Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada, ²Department of Radiology, University of Calgary, Calgary, AB, Canada, ³Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, ⁴Experimental Imaging Centre, University of Calgary, Calgary, AB, Canada

Non-invasive quantitative imaging of cerebral metabolic rate of oxygen (CMRO₂) is essential to understand oxidative metabolism in health and disease. Hypercapnia is often used as a calibration for MRI methods associated with quantifying CMRO₂. Here we show that CMRO­₂ remains constant during hypercapnia. We also provide a novel multimodal NIRS-MRI system that can assess absolute values of multiple metabolic correlates noninvasively in living mouse brain, and with no need for calibration with gas mixtures.  Moreover, this technique is capable to monitor mitochondrial status by measuring the redox state of cytochrome oxidase, the enzyme responsible for oxygen consumption in the cell.

Benjamin C. Tendler¹, Taylor Hanayik¹, Olaf Ansorge², Sarah Bangerter-Christensen², Gregory S. Berns³, Mads F. Bertelsen⁴, Katherine L. Bryant¹, Sean Foxley^1,5, Martijn P. van den Heuvel^6,7, Amy F.D. Howard¹, Istvan N. Huszar¹, Alexandre A. Khrapitchev⁸, Anna Leonte², Paul R. Manger⁹, Ricarda A.L. Menke¹, Jeroen Mollink¹, Duncan Mortimer¹, Menuka Pallebage-Gamarallage², Lea Roumazeilles¹⁰, Jerome Sallet^10,11, Lianne H. Scholtens⁶, Connor Scott², Adele Smart^1,2, Martin R. Turner^1,2, Chaoyue Wang¹, Saad Jbabdi¹, Rogier B. Mars^1,12, and Karla L. Miller^1
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, ²Division of Clinical Neurology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, ³Psychology Department, Emory University, Atlanta, GA, United States, ⁴Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Copenhagen, Denmark, ⁵Department of Radiology, University of Chicago, Chicago, IL, United States, ⁶Department of Complex Trait Genetics, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands, ⁷Department of Child Psychiatry, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands, ⁸Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom, ⁹School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa, ¹⁰Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom, ¹¹Stem Cell and Brain Research Institute, Université Lyon 1, INSERM, Lyon, France, ¹²Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands

We introduce the Digital Brain Bank (open.win.ox.ac.uk/DigitalBrainBank), a digital platform providing open access to curated, multimodal post-mortem neuroimaging datasets. Datasets span three themes; Digital Anatomist: datasets for neuroanatomical investigations; Digital Brain Zoo: datasets for comparative neuroanatomy; Digital Pathologist: datasets for neuropathology investigations. The first release includes 21 distinctive whole-brain diffusion MRI datasets, alongside microscopy and complementary MRI modalities. This includes one of the highest-resolution whole-brain human diffusion MRI datasets ever acquired, whole-brain diffusion MRI in 14 non-human primate species, and one of the largest post-mortem whole-brain cohort imaging studies in neurodegeneration. Our resource facilitates incorporating post-mortem data into neuroimaging studies.

Rakshit Dadarwal^1,2 and Susann Boretius^1,2
1Functional Imaging Laboratory, German Primate Center, Göttingen, Germany, ²Georg-August-University Göttingen, Göttingen, Germany

Cynomolgus and rhesus macaques are widely used in biomedical research due to their physiological proximity to humans, and both are often referred to as macaques. However, the brain morphology of cynomolgus and rhesus macaques differs. Interestingly, as shown here by a Jacobian-determinant-based approach, the smaller cynomolgus brain is not only a scaled-down version of the rhesus macaques. For instance, the gray-to-white matter ratio differs significantly between the two species.

Nathalie Just¹, Martine Batailler², Jean-Philippe Dubois², and Martine Migaud^2
1DRCMR, Copenhagen University Hospital - Amager and Hvidovre, Hvidovre, Denmark, ²INRAE, Nouzilly, France

In-vivo Manganese-Enhanced MRI (MEMRI) studies have shown important potential in rodents for the delineation of cytoarchitectural brain features and of functional details. Ex-vivo MEMRI on the other hand offers the possibility to investigate brain microstructure and function with improved spatial resolution and no motion artefacts. Here, ex-vivo lamb brains were immersed in a highly concentrated MnCl₂ solution for a month and revealed interesting cytoarchitectural features already 24 hours after immersion and up to 3 months after the end of immersion on MPRAGE images at 3T. A novel ex-vivo MEMRI approach is proposed, which could benefit MEMRI translation to human studies.

Mélissa Vincent¹, Xiao Gao^2,3, Myriam Chaumeil^2,3, and Julien Valette^1
1MIRCen / Neurodegenerative Diseases Laboratory, CEA, Fontenay-aux-Roses, France, ²Department of Physical Therapy and Rehabilitation Science, UCSF, San Francisco, CA, United States, ³Department of Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States

Here we propose to use ¹³C diffusion-weighted MRS of hyperpolarized pyruvate and lactate to probe diffusion properties in distinct compartments of the mouse brain, tentatively extracellular (ECS) and intracellular spaces (ICS). Hyperpolarized ¹³C-pyruvate is injected intravenously and taken up by the brain before entering cells, where it is quickly converted to lactate, so that ¹³C-pyruvate concentration in ICS must remain low, while newly produced ¹³C-lactate should remain predominantly intracellular during the relatively short measurement time. We measure faster diffusion for pyruvate even after removing IVIM effect, suggesting faster diffusion in the ECS, and slow release of lactate in the ECS.

Elise Cosenza¹, Laurence Dallet¹, Aurélien Trotier¹, Emeline Ribot¹, Laurent Petit², and Sylvain Miraux^1
1Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Bordeaux, France, ²Groupe dImagerie Neurofonctionnelle, Institut Des Maladies Neurodegeneratives, UMR5293, CNRS, CEA University of Bordeaux, CNRS, Bordeaux, France

A protocol, including Gadolinium-DOTA perfusion or immersion and Diffusion-Weighted multi-shot Spin-Echo EPI was developed to obtain 100μm isotropic resolution tractogram on ex vivo mouse brain. A 3mM Gd-DOTA concentration combined with 16 EPI shots at short TR (400 ms) allows to whole-brain tractograms of excellent quality and reproducible on the 15 mouse brains analyzed.