Nadim Farhat¹, Heching Jin², Tales Santini¹, Tiago Martins², Jacob Berardinelli¹, Noah Schweitzer¹, Salem AlKhateeb ¹, Milos Ikonomovic¹, Julia Ann Kofler³, Joseph Mettenburg³, Howard J. Aizenstein¹, and Tamer S. Ibrahim^1
1University of Pittsburgh, pittsburgh, PA, United States, ²Bioengineering, University of Pittsburgh, pittsburgh, PA, United States, ³UPMC Presbyterian Hospital, Pittsburgh, PA, United States

We present a comprehensive ex-vivo brain ultra-high field ex-vivo brain MRI workflow that addresses transmit magnetic field in-homogeneities without the need to build a dedicated ex-vivo coil. Additionally, we show that 7T T1w ex-vivo with high quality grey to white matter contrast is feasible with MP2RAGE .

Afis Ajala¹, Seung-Kyun Lee¹, Daehun Kang², Luca Marinelli¹, Desmond Teck Beng Yeo¹, and Thomas Foo^1
1Magnetic Resonance Imaging, GE Global Research, Niskayuna, NY, United States, ²Mayo Clinic, Rochester, MN, United States

The maximum gradient amplitude (G_max) and slew rate (SR_max) determine the minimum number of interleaves (and total scan time) in a 3D pseudo-continuous arterial spin-labeling (3DpCASL) acquisition with a stack-of-spirals readout module for a given spatial resolution. The higher G_max and SR_max of a recently developed head-only gradient system (MAGNUS) was utilized to reduce the total scan time of a clinical 3DpCASL acquisition by a factor of 2 compared to a similar acquisition carried out at a lower G_max and SR_max of a conventional whole-body system (CWBS) while maintaining comparable image quality.

Qandeel Shafqat¹, Ying Wu¹, A. Max Hamilton¹, Mada Hashem¹, and Jeff F Dunn^1
1Department of Radiology, University of Calgary, Calgary, AB, Canada

Systemic inflammation is linked to a range of neurological diseases. Reductions in cerebral blood flow (CBF) and the presence of brain hypoxia have been detected in animal models of inflammation and in multiple sclerosis, a disease with significant inflammation. Reduced CBF combined with hypoxia could exacerbate damage in neuroinflammatory conditions. To study this link, we used in-vivo 9.4T MRI to quantify CBF and R₂^*, a marker of deoxyhemoglobin, following systemic inflammation induced by bacterial lipopolysaccharide. We found reduced CBF and increased R₂^* in 4 regions, including the cortex and hippocampus—indicating that inflammation is accompanied by hypoxia and reduced CBF.

Yuka Sugamura¹, Arati Sridharan¹, Umu Jalloh¹, Babak Moghadas¹, Livia De Mesquita Teixeira¹, Jitendran Muthuswamy¹, and Vikram Kodibagkar^1
1Arizona State University, Tempe, AZ, United States

Chronic implantation of neural interfaces often experiences decrease in signal reliability over time. Tissue response, including the alteration of the oxygen kinetics, is thought to be a major cause. Here, we report the spatial mapping of brain oxygenation around chronically implanted electrodes using a previously developed quantitative MRI-based oxygen sensing technique, PISTOL. Seven 200 um diameter electrodes implanted in four mice allowed quantitative pO2 mapping throughout the 7-week study. No changes were observed in the baseline brain tissue oxygenation as well as the response to respiratory challenge. Future studies will combine this approach with electrophysiology, and ultimately perform simultaneous assessment.

Larry Allen Kramer¹, Khader H. Hasan¹, Xu Zhang², Brandon R. Macias³, Karina Marshall-Goebel⁴, Steven S. Laurie⁴, and Eric M. Bershad^5
1Diagnostic Imaging, UTSHC-Houston, Houston, TX, United States, ²UTSHC-Houston, Houston, TX, United States, ³NASA, Houston, TX, United States, ⁴KBR, Houston, TX, United States, ⁵BCM, Houston, TX, United States

Headward fluid shift is a natural consequence of working in microgravity. It is theorized to be the cause of changes in brain morphology and the development of optic nerve pathology in astronauts.  This study looked at the application of artificial gravity in the form of short-arm centrifugation at 0.3g as a potential countermeasure in 24 healthy volunteers over a 60 day period.  Headward fluid shift was simulated using a head down tilt bed rest model.  Both continuous and intermittent artificial gravity for 30 minutes per day failed to show any benefit on intracranial changes associated with chronic headward fluid shift.

Sudipto Dolui¹, Ariana M. Chao¹, Noel N. Williams¹, Thomas A. Wadden¹, and John A. Detre^1
1Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States

Obesity is a significant risk factor for cerebrovascular disease including dementia. Cerebral blood flow (CBF) provides a biomarker of cerebrovascular health and can be measured non-invasively using arterial spin labeled (ASL) perfusion MRI. Here we examined longitudinal ASL data from adult women with obesity who underwent bariatric surgery. We demonstrated that weight loss was associated with significant increases in CBF from baseline to 6 and 18 months after surgery. Change in glucose and insulin level did not mediate the relationship, suggesting a more direct association between obesity and CBF.

Qandeel Shafqat¹, Rehman Tariq¹, Rania Muhammed¹, Ying Wu¹, and Jeff F. Dunn^1
1Department of Radiology, University of Calgary, Calgary, AB, Canada

With the reduction in use of gadolinium enhanced MRI for assessment of neuroinflammation, it is important to identify new non-invasive biomarkers of brain inflammation, as well as to understand the link between inflammation induced pathology and MRI. We used quantitative T₂, behaviour and histology to study gray matter in an LPS mouse model of inflammation. There was a significant reduction in T₂, along with behaviour and histological markers indicating inflammation. Although T₂ appears useful as biomarker for inflammation, it may be that the precision needed will make it difficult to implement in patients.

Petrice M Cogswell¹, Matthew C Murphy¹, Muhammad T Bhatti², Jeremy K Cutsforth-Gregory³, John Huston III¹, and John J Chen^2
1Radiology, Mayo Clinic, Rochester, MN, United States, ²Opthalmology, Mayo Clinic, Rochester, MN, United States, ³Neurology, Mayo Clinic, Rochester, MN, United States

Morphological changes in the pituitary gland and brain stiffness in idiopathic intracranial hypertension (IIH) are not well understood. We evaluated the difference in pituitary height and regional brain stiffness between IIH patients and controls and how these metrics change following acute and chronic treatment. The pituitary gland is smaller in IIH patients than controls and increases in size after chronic, but not acute, treatment of raised intracranial pressure. IIH patients have a different pattern of brain stiffness than controls, including stiffer occipital lobes. Following chronic treatment, the stiffness pattern becomes more like controls, though occipital stiffness does not significantly change.

Mohammad Rakeen Niaz¹, Abdur Raquib Ridwan¹, Yingjuan Wu¹, Shengwei Zhang², David A. Bennett², and Konstantinos Arfanakis^1,2
1Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, United States, ²Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, United States

The Multichannel Illinois Institute of Technology & Rush university Aging (MIITRA) atlas constructed using high quality MRI data on a large (N=400), diverse, community cohort of non-demented older adults, contains high resolution (0.5mm isotropic) structural and diffusion tensor imaging templates. The purpose of this work was to build and evaluate a comprehensive array of gyral-based, cytoarchitecture-based, and functional connectivity-based gray matter labels in MIITRA space in order to enhance the functionality of the MIITRA atlas and its interoperability with complementary atlases.

Sichen Ludwig Zhao¹, William S Tackett², Banafsheh Shakibajahromi², Sudipto Dolui³, Ilya M Nasrallah³, David A Wolk², Corey T McMillan², Farshid Sepehrband⁴, and John A Detre^2
1Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States, ²Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, ³Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, ⁴Laboratory of Neuroimaging, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States

Perivascular spaces (PVS) are a component of the glymphatic system, the brain-wide waste drainage pathway, but the pathophysiological significance of enlarged perivascular space volume is incompletely characterized. We obtained PVS segmentations from 167 cognitively intact or mildly symptomatic older subjects from high-resolution T1-weighted MRI using an automated approach and correlated PVS volume with both amyloid status, as determined by amyloid PET, and cortical thickness changes from normative values. Automated PVS segmentations required additional masking of CSF spaces and manual exclusion of some lacunar infarcts. PVS volume was correlated with brain atrophy and not amyloid status.

Thanh D Nguyen¹, Liangdong Zhou¹, Elizabeth M Sweeney¹, Melanie Marcille¹, Susan A Gauthier¹, Yi Wang¹, and Yi Li^1
1Weill Cornell Medicine, New York, NY, United States

We applied FAST-T2 multi-component T2 relaxometry to 145 MS patients and found that the mean hippocampal CSF fraction, a measure of glymphatic clearance dysfunction in the hippocampus, was negatively associated with verbal learning and memory performance measured by the California Verbal Learning Test after adjusting for age, sex, MS phenotype, disease duration, and log total lesion volume.

Yanning Liu¹, Henk M De Feyter², Robert K Fulbright², Scott McIntyre², Terence W Nixon², and Robin A de Graaf^1,2
1Department of Biomedical Engneering, Yale University, New Haven, CT, United States, ²Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States

Deuterium Metabolic Imaging (DMI) is an emerging method to spatially map metabolism in vivo. To enhance the time efficiency of a combined MRI-DMI protocol, interleaved MRI-DMI acquisitions were developed for multiple clinical MRI sequences. The protocol includes four MRIs that are commonly used in neurological MRI exams, namely FLAIR, T₂W, SWI and T₁W MP-RAGE, with DMI acquisition in parallel, acquired in 28 minutes. We demonstrate the performance of the interleaved MRI-DMI protocol on healthy human brain and discuss the guiding principles as well as limitations of extending other MRI sequences with DMI using the presented interleaving strategy. 

Hong Hsi Lee¹, Berkin Bilgic¹, and Susie Y Huang^1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States

Correcting image distortions in echo-planar-imaging (EPI) due to B0 field inhomogeneity usually requires additional acquisitions, such as a B0 field map or blip-up-blip-down image pair. Interestingly, susceptibility distortions in EPI with parallel imaging can be corrected by leveraging the mismatch in phase-encoding polarity and/or effective echo-spacing between the auto-calibration-signal and under-sampled data, obviating the need for additional image acquisitions. Here we demonstrate the proposed pipeline of susceptibility distortion correction in in vivo diffusion MRI data of a healthy subject, and the results and estimated field values are comparable with the conventional method.