Xingfeng Shao¹, Fanhua Guo², Qinyang Shou¹, Kai Wang¹, Lirong Yan^1,3, Kay Jann^1,3, Peng Zhang², and Danny JJ Wang^1,3
1Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ²State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, ³Department of Neurology, University of Southern California, Los Angeles, CA, United States

High-resolution (iso-1mm) 7T ASL scans were performed on the primary motor cortex (M1) to characterize layer-dependent resting CBF, and perfusion activity to sensory input/motor output. Finger tapping (FT)-induced CBF increase shows a clear ‘double-peak’ pattern, consistent with the hypothesis that FT engaged neural activity of somatosensory input in the superficial layers and motor output in the deep layers. Finger brushing (FB)-induced CBF increase was overall smaller, and mainly peaked in superficial layers (somatosensory input and minimal motor output). These results demonstrate the high spatial specificity of 7T ASL, capable of resolving layer-dependent input and output activity in human M1.

Jörn Huber¹, Daniel Hoinkiss¹, and Matthias Günther^1,2
1Fraunhofer MEVIS, Bremen, Germany, ²University of Bremen, Bremen, Germany

Assessement of CBF using Arterial Spin Labeling (ASL) can yield valuable functional information regarding different neuropathological diseases like tumors and stroke without exogenous contrast agents. However, being a subtractive technique, ASL shows high sensitivity to motion artifacts. ASL in combination with a 3D GRASE PROPELLER (3DGP) readout allows self-navigated retrospective motion correction but motion estimates using the standard reconstruction are inaccurate due to geometric distortion. In this work, a novel 3DGP reconstruction algorithm is therefore demonstrated which jointly estimates the distortion field as well as motion parameters without the need for additional reference scans.

Lincoln Craven-Brightman¹, Yulin Chang², Thomas Witzel³, Nicolas S. Arango⁴, Meher R. Juttukonda^1,5, Luis Hernandez-Garcia⁶, Marta Vidorreta⁷, John A. Detre^8,9, Lawrence L. Wald^5,10, and Jason Stockmann^5,10
1Massachusetts General Hospital, Charlestown, MA, United States, ²Siemens Medical Solutions USA, Inc., Malvern, PA, United States, ³Qbio Inc, San Carlos, CA, United States, ⁴Dept. of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, ⁵Harvard Medical School, Boston, MA, United States, ⁶Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States, ⁷Siemens, S.A., Madrid, Spain, ⁸Neurology, University of Pennsylvania, Philadelphia, PA, United States, ⁹Radiology, University of Pennsylvania, Philadelphia, PA, United States, ¹⁰A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States

We apply dynamic local B0 field control with a multi-coil (MC) shim array to improve ASL labeling. Labeling efficiency can be regulated by dynamically shimming the labeling plane during a pCASL tagging pulse train. We demonstrate this capability through territory mapping with an unspecialized MC head shim array – Through shimming, we shift target arteries relative to the labeling pulse bandwidth. Implementation takes less than 10 minutes during a scan, without previous subject information. We also simulate the improvement possible with a specialized MC neck shim array, which enables regulation in more inferior labeling planes and higher field control efficiency.

Hyun-Seo Ahn¹, Jaeseok Park², Chul Ho Sohn³, and Sung-Hong Park^1
1Department of Bio and Brain Engineering, Korea Advnaced Institute of Science and Technology, Daejeon, Korea, Republic of, ²Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ³Department of Radiology, Seoul National University Hospital, Seoul, Korea, Republic of

Measurement of changes in blood-brain barrier permeability is important for early diagnosis of brain diseases. In this study, we propose multi-slice multi-delay diffusion-weighted arterial spin labeling for simultaneous acquisition of various quantitative perfusion estimates including the water exchange rate and the permeability surface area product, which are known to be closely related to BBB permeability, and blood perfusion and arterial blood volume. The water exchange rate in 4 Alzheimer patients were smaller than that in 6 normal subjects, opposed to common knowledges on BBB permeability. The proposed approach may work as a new biomarker for early diagnosis of Alzheimer disease.

Charith Perera¹, Jack Wells¹, Ian Harrison¹, David Thomas^2,3,4, and Mark Lythgoe^1
1Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom, ²Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, ³Leonard Wolfson Experimental Neurology Centre, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, ⁴Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom

We employed an interleaved short/long echo-time ASL sequence to better understand the differential response of vessels associated with the blood brain barrier (BBB), and the relatively understudied blood-cerebrospinal fluid barrier (BCSFB) to pharmacological perturbation in the healthy and aged brain. We measured changes in both cortical perfusion and the BCSFB-ASL signal in response CO_­2, caffeine, and vasopressin. Additionally, we demonstrated a marked decrease in BCSFB reactivity towards vasopressin in the aged vs adult brain. Together, these novel data highlight the value of this translational approach to capture simultaneous and differential pharmacological modulation of vessel tone at the BBB and BCSFB.

Wenbo Li^1,2, Peter van Zijl^1,2, and Qin Qin^1,2
1Radiology Department, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ²Kirby Image Center, Kennedy Krieger Institute, Baltimore, MD, United States

A T₂-oximetry method is proposed to map the venous oxygenation by using Fourier-transform based velocity-selective inversion plus non-selective inversion to null the arterial blood signal while using Fourier-transform based velocity-selective saturation to suppress the tissue signal. Compared to previous schemes, the proposed method has the benefit of high SNR and insensitivity to arterial transit delays. Using this method, the venous oxygenation values obtained from two volunteers at 3T are similar between gray matter and white matter and comparable to the values measured globally.  

Joseph G Woods¹, Eric C Wong¹, Emma Boyd², and Divya S Bolar^1
1Radiology, UCSD, La Jolla, CA, United States, ²Neurosciences, UCSD, La Jolla, CA, United States

Velocity-selective ASL (VSASL) accurately depicts cerebral perfusion, even in regions of severely prolonged arterial transit time (ATT). In contrast, spatially-selective ASL, such as pulsed or pseudo-continuous ASL (PCASL), preserves macrovascular signal of blood flowing to these regions. Recent work highlights the importance of using both methods in a complementary way to more completely assess cerebrovascular pathology. In this study, we describe a novel ASL pulse sequence, dubbed VESPA ASL, in which VSASL and PCASL data are simultaneously acquired within a single scan. We further describe a signal model to quantify cerebral blood flow and ATT from these two data sets.

Minhui Ouyang¹, John Detre², Chenying Zhao^1,3, Samantha Lam¹, J. Christopher Edgar^1,2, and Hao Huang^1,2
1Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, PA, United States, ²Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, ³Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States

During early infancy, rapid increases of regional cerebral blood flow (rCBF) supports the metabolic needs for the dramatic maturation of infant brains. In this study, we delineated the developmental pattern of infant’s rCBF from 0-18months, with an optimized 3D multi-shot, stack-of-spirals pCASL sequence for high-resolution rCBF at isotropic 2.5mm. Significant age-related rCBF increases were found during this period. The rCBF growth rates were inhomogeneous across the cortex, with faster maturation rates in the heteromodal association cortex and slower in unimodal sensorimotor cortices. Cortical regions with more rapid rCBF growth were associated with faster microstructural maturation of adjacent white matter. 

Hualu Han^1,2, Zixuan Lin^2,3, Melissa Rundle⁴, Anja Soldan⁵, Corinne Pettigrew⁵, Joshua F. Betz⁶, Kumiko Oishi⁷, Yang Li², Binu P. Thomas⁸, Peiying Liu², Marilyn Albert⁵, Denise Park⁴, and Hanzhang Lu^2,3,9
1Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, ²The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ³Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁴Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, TX, United States, ⁵Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁶Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States, ⁷Center for Imaging Science, Johns Hopkins University, Whiting School of Engineering, Baltimore, MD, United States, ⁸Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁹F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States

Characterization of age-related changes in blood supply is important in understanding brain aging. The present work reports longitudinal studies of age-related changes in cerebral blood flow (CBF) in two separate cognitively-healthy cohorts using complementary MRI techniques. We found that CBF decreased with age and the longitudinal rate of decline was faster than that from the cross-sectional data. The rate of CBF reduction was faster in younger than in older individuals, in contrast to the temporal pattern of brain volume atrophy. There were also significant spatial differences and hemispheric asymmetry in CBF decline rates.

Joshua S Greer^1,2,3, Mubeena Abdulkarim¹, Gerald F Greil^1,3, Ayesha Zia¹, Ananth J Madhuranthakam^2,3, and Tarique Hussain^1,2
1Pediatrics, UT Southwestern Medical Center, Dallas, TX, United States, ²Radiology, UT Southwestern Medical Center, Dallas, TX, United States, ³Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States

In this study, pulmonary perfusion imaging using arterial spin labeling (ASL) was demonstrated in pediatric patients with pulmonary embolism. A method to quantify pulmonary vascular obstruction was proposed using ASL to estimate improvements in pulmonary perfusion following treatment, which moderately agreed with obstruction measured by CTA. Perfusion defects were successfully detected in all patients. A follow-up ASL scan also showed significantly improved perfusion in a patient following treatment, and a few patients had residual perfusion defects in ASL images that were not seen by CTA, suggesting that perfusion to the microvasculature was not immediately restored following resolution of the emboli.