Karla L Miller¹, Neal K Bangerter², Fidel Alfaro Almagro¹, David L Thomas³, Essa Yacoub⁴, Junqian Xu⁵, Andreas J Bartsch^1,6, Saad Jbabdi¹, Stamatios N Sotiropoulos¹, Mark Jenkinson¹, Jesper Andersson¹, Ludovica Griffanti¹, Peter Weale⁷, Iulius Dragonu⁷, Steve Garratt⁸, Sarah Hudson⁸, Rory Collins^8,9, Paul M Matthews¹⁰, and Stephen M Smith^1
1FMRIB Centre, University of Oxford, Oxford, United Kingdom, ²Electrical and Computer Engineering, Brigham Young University, Provo, UT, United States, ³Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College London, London, United Kingdom, ⁴Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ⁵Icahn School of Medicine at Mount Sinai, New York, NY, United States, ⁶Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany, ⁷Siemens Healthcare (UK), London, United Kingdom, ⁸UK Biobank Ltd, Stockport, United Kingdom, ⁹Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom, ¹⁰Department of Medicine, Imperial College London, London, United Kingdom

UK Biobank is a prospective epidemiological study of 500,000 participants consisting of extensive questionnaires, physical measures and biological samples, linking to long-term health outcomes. The imaging extension for the UK Biobank ultimately aims to image 100,000 subjects from this cohort, including brain, cardiac and body MRI, bone scans and carotid ultrasound. We overview the brain imaging component, which includes structural, functional and diffusion MRI. The value of this open resource arises not only from multi-modal/multi-organ imaging, but also from the depth of other demographic, phenotypic and exposure data, and will increase over time as clinical outcomes are realized in the population.

Yue Zhao¹, Jie Wen², Anne Cross³, and Dmitriy Yablonskiy^2
1Chemistry, Washington University in St. Louis, St. Louis, MO, United States, ²Radiology, Washington University in St. Louis, St. Louis, MO, United States, ³Neurology, Washington University in St. Louis, St. Louis, MO, United States

Establishing baseline MRI biomarkers for normal brain aging is significant and valuable. In this study, we use previously developed approach to measure tissue-specific transverse relaxation rate constant (R2*_t) and BOLD contributions to GRE signal, thus providing information on tissue cellular and hemodynamic properties. The VSF approach is applied for background gradient correction together with navigator echo to minimize artifacts from physiological fluctuations. Our results show age-related R2*_t increases in most cortical regions and age-independent behavior of most hemodynamic parameters. We hypothesize that R2*_t could serve as a biomarker of the cortical “cellular packing density”, which mostly reflects the neuronal density.

Phillip G. D. Ward^1,2, Parnesh Raniga¹, Nicholas J. Ferris^1,3, David G. Barnes^2,4, David L. Dowe², Elsdon Storey⁵, Robyn L. Woods⁶, and Gary F. Egan^1,7
1Monash Biomedical Imaging, Monash University, Clayton, Australia, ²Faculty of Information Technology, Monash University, Clayton, Australia, ³Monash Imaging, Monash Health, Clayton, Australia, ⁴Monash eResearch Centre, Monash University, Clayton, Australia, ⁵Department of Neurology, Monash University, Clayton, Australia, ⁶Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia, ⁷ARC Centre of Excellence for Integrative Brain Function, Melbourne, Australia

In this study we examine venous characteristics of elderly individuals in a large healthy population. Venograms were generated from susceptibility-weighted images and quantitative susceptibility maps using state-of-the-art automated venography. Venous density and oxygen extraction fraction were calculated in different brain regions. The pattern of metabolic demand (oxygen extraction fraction) is found to be consistent with rest and passive observation. Additionally, our results suggest that venous density may be a potential biomarker.

Tanguy Boucneau^1,2, Shuyu Tang^1,3, Misung Han¹, Roland G Henry^1,4, Duan Xu^1,3, and Peder Eric Zufall Larson^1,3
1Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, CA, United States, ²Physics, Ecole Normale Supérieure de Cachan, Cachan, France, ³UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley and University of California, San Francisco, San Francisco, CA, United States, ⁴Neurology, University of California - San Francisco, San Francisco, CA, United States

It has recently been shown that myelin contains ultrashort T2 components with sub-millisecond relaxation times that are not observed with conventional pulse sequences and maybe associated with bound protons in the myelin phospholipid membranes.We performed ultrashort T2* relaxometry in vivo to characterize these components with a 3D ultrashort echo time (UTE) pulse sequence at 7T.We observed an ultrashort T2 component (T2* $$$\approx 100 \mu s$$$) as well as a short T2 component (T2* $$$\approx 1.5 ms$$$) that had a distinct frequency shift corresponding to the methylene proton chemical shift, which to our knowledge has never been observed in vivo.These components were validated in an ex vivo post-mortem brain specimen, and may provide valuable new biomarkers of myelin density, structure, and integrity.

Andre Jan Willem van der Kouwe¹, Fikret Isik Karahanoglu¹, Matthew Dylan Tisdall¹, Paul Wighton¹, Himanshu Bhat², Thomas Benner³, and Jonathan R Polimeni^1
1Athinoula A. Martinos Center, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, ²Siemens Healthcare, Charlestown, MA, United States, ³Siemens Healthcare, Erlangen, Germany

We present an efficient two-sequence protocol for quantifying multiple parameters in a 1 mm isotropic brain morphometry examination. The protocol comprises a multiple gradient echo (TE), multiple inversion (TI) time MPRAGE (MEMPxRAGE) and a two-flip-angle balanced SSFP (TrueFISP) sequence. Proton density and T₁ maps are estimated from the MEMPxRAGE data using the multi-TI data and a Bloch simulation. With the T₁ map and TrueFISP data, the T₂ map is estimated using DESPOT2. Fat, water and B0 maps are obtained from the multi-TE data using the IDEAL algorithm.  The MEMPxRAGE scan includes embedded 3D EPI-based navigators encoding low resolution functional information.

Vasily L. Yarnykh^1,2
1Radiology, University of Washington, Seattle, WA, United States, ²Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation

A new method for fast high-resolution whole-brain three-dimensional (3D) mapping of the macromolecular proton fraction (MPF) based on three source images has been recently proposed. In this study, reproducibility of repeated MPF measurements in white and gray matter with simultaneous estimation of tissue volumes using automated segmentation of 3D MPF maps obtained with isotropic resolution of 1.25 mm was assessed. MPF measurements in brain tissues are highly reproducible with coefficients of variation <1.5%. 3D MPF mapping provides “all-in-one” solution for simultaneous characterization of myelination and volumetric changes in brain tissues.

Aaron Trefler¹, Neda Sadeghi², Adam Thomas¹, Carlo Pierpaoli², Chris Baker¹, and Cibu Thomas^3
1National Institute of Mental Health, Bethesda, MD, United States, ²National Institute of Child Health and Human Development, Bethesda, MD, United States, ³Center for Neuroscience and Regenerative Medicine, Bethesda, MD, United States

Automated measures of brain morphometry derived from T1-weighted (T1W) images are typically used as proxy measures to investigate the relation between brain structure and behavior. However, the computation of T1W morphometric measures can be influenced by subject-related factors such as head motion¹ and level of hydration². Here, we provide a comprehensive assessment of the impact of time-of-day (TOD) on widely used measures of brain morphometry in healthy young adults. Our results show that the apparent volume of all major tissue compartments as well as measures of brain morphometry such as cortical thickness and gray matter density are significantly influenced by TOD. 

Ouri Cohen^1,2, Ville Renvall³, and Jonathan Polimeni^1,2
1Athinoula A. Martinos Center, Charlestown, MA, United States, ²Radiology, Massachusetts General Hospital, Boston, MA, United States, ³Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland

A novel optimized method for high-resolution quantitative EPI measurements of T₁ is introduced and validated on a 3T clinical scanner in a phantom and a healthy volunteer. The method offers a 5-fold acceleration in scan time over previous techniques allowing fully quantitative 1.2 mm³ isotropic T1 maps in less than 30 seconds. 

Dandan Zheng¹, Wenjia Liu², Li Zheng³, and Lin Ma^2
1MR Research China, GE Healthcare, Beijing, China, People's Republic of, ²Radiology Department, Beijing Military General Hospital, Beijing, China, People's Republic of, ³Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China, People's Republic of

Acute mountain sickness is a series of pathologic reactions during rapid exposing to low pressure hypoxic high altitude environment, which is a widespread illness among un-acclimatized individuals in plateau. Human always stay in plain will display some common physiological and pathological changes of brain, such as change of cerebral blood flow, cerebral pressure and brain volume. The aim of the present study was to investigate whether there was different change of gray matter volume in some brain regions related to AMS development before, during and after exposing to the real high altitude environment.

Xiaodong Zhong¹, Zihan Ye², Tucker Lancaster³, Deqiang Qiu³, Brian M. Dale⁴, Amit Saindane³, and John N. Oshinski^2,3
1MR R&D Collaborations, Siemens Healthcare, Atlanta, GA, United States, ²Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States, ³Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States, ⁴MR R&D Collaborations, Siemens Healthcare, Cary, NC, United States

Displacement encoding with stimulated echoes (DENSE) with high motion sensitivity was used to investigate the influence of subject position (prone versus supine) on regional brain motion. Preliminary results in 9 volunteers demonstrated that there is a significant difference in displacement with a change in position. Displacements were significantly increased in the frontal lobe going from the prone to the supine position and significantly increased in the occipital lobe going from the supine to the prone position.