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Elles P. Elschot^1,2, Marieke van den Kerkhof^1,2, Robert J. van Oostenbrugge^2,3,4, Abraham A. Kroon^4,5, Walter H. Backes^1,2,4, and Jacobus F. A. Jansen^1,2,6
1Radiology & Nuclear Medicine, Maastricht University Medical Center +, Maastricht, Netherlands, ²School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands, ³Neurology, Maastricht University Medical Center +, Maastricht, Netherlands, ⁴School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands, ⁵Internal Medicine, Maastricht University Medical Center +, Maastricht, Netherlands, ⁶Electrical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands

Keywords: Contrast Mechanisms, Perfusion

Ultra-high-field exploits the possibilities of MRI techniques, which are less sensitive at lower field strength, such as spin-echo (SE) perfusion MRI. We assessed the feasibility of SE dynamic susceptibility contrast MRI at 7T and investigated the ability to measure variations in perfusion in an elderly, partially hypertensive, population (n=36). Microvascular cerebral blood flow (CBF) was higher in grey matter compared to white matter, corresponding with biological expectations, serving as a first validation step. Furthermore, CBF significantly decreased with age.

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Thomas Lindner¹, Monika Huhndorf², Christine Eimer³, Tobias Becher³, Hajrullah Ahmeti⁴, Olav Jansen², Michael Synowtiz⁴, Michael Helle⁵, and Stephan Ulmer^2,6
1UKE Hamburg, Hamburg, Germany, ²Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Kiel, Germany, ³Department of Anesthesia, University Hospital Schleswig-Holstein, Kiel, Germany, ⁴Department of Neurosurgery, University Hospital Schleswig-Holstein, Kiel, Germany, ⁵Philips Gmbh Innovative Technologies, Hamburg, Germany, ⁶neurorad.ch, Zurich, Switzerland

Keywords: Arterial spin labelling, Brain, Anesthesia

In this study, we non-invasively evaluated the change in cerebral blood flow (CBF) and correlation with mean arterial pressure (MAP) before and during anesthesia using Arterial Spin Labeling. It could be shown that both CBF and MAP are reduced comparing the awake and anesthesia-induced state in patients.

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Xingfeng Shao¹, Qinyang Shou¹, Kimberly Felix², Brandon Ojogho¹, Xuejuan Jiang^2,3, Brian T. Gold⁴, Megan M. Herting², and Danny JJ Wang^1
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, ²Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ³Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ⁴Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, KY, United States

Keywords: Arterial spin labelling, Permeability, BBB water exchange, permeability, ageing

We studied age-related BBB water exchange rate (kw) changes in a wide range of age groups with 115 subjects using diffusion prepared pseudo-continuous arterial spin labeling (DP-pCASL). We observed a significant trend of decreasing kw with age (slow when ≤50 years old and fast when >50 years old) and large spread of kw values in subjects >50 years, which may indicate compromised BBB function in some ageing populations. The inverted U-shaped correlations between kw versus age suggest a more complex age dependent changes in hippocampus and PHG regions.

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Moss Y Zhao¹, Audrey P Fan², Mohammad Mehdi Khalighi¹, Dawn Holley¹, Kim Halbert¹, Maria Jovin¹, Bin Shen¹, Guido A Davidzon¹, Elizabeth Tong¹, Michael Moseley¹, and Greg Zaharchuk^1
1Department of Radiology, Stanford University, Stanford, CA, United States, ²Department of Biomedical Engineering, University of California Davis, Davis, CA, United States

Keywords: Arterial spin labelling, Perfusion

Cerebrovascular reserve (CVR) is an important biomarker to assess vascular hemodynamics and link to the risk for acute strokes. Whilst several imaging modalities have been applied to measure CVR, their reproducibility remains to be elucidated. Here we compare the reproducibility of CVR measurements in 22 normal subjects between single and multi-delay ASL using 15O-water PET as the reference. Results implied that multi-delay ASL achieved a higher reproducibility and should be the preferred non-invasive modality for clinical applications.

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Amnah Mahroo¹ and Matthias Günther^1,2,3
1Imaging Physics, Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany, ²MR-Imaging and Spectroscopy, University of Bremen, Bremen, Germany, ³mediri GmbH, Heidelberg, Germany

Keywords: Arterial spin labelling, Brain, Blood-brain barrier Permeability, Aging, Multi-TE ASL

With age the integrity of blood-brain barrier (BBB) slowly deteriorates. Multi-TE ASL, being a water-based MRI method, offers detection of subtle changes in the BBB by probing T2 relaxation. In this study, we evaluated the sensitivity of multi-TE ASL method in detecting changes in the BBB occurring due to age using two models; a physiologically informed biophysical (PIB) model by estimating exchange time and a simpler tri-exponential decay (TD) model by determining the rate of change of tissue fraction. We found that both models were able to detect age-based changes in BBB. Moreover, PIB model showed higher robustness.

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Verónica Aramendia-Vidaurreta^1,2, Sergio M. Solís-Barquero^1,2, Ana Ezponda^1,2, Marta Vidorreta³, Rebeca Echeverria-Chasco^1,2, Marina Pascual⁴, Gorka Bastarrika^1,2, and María A. Fernández-Seara^1,2
1Radiology, Clínica Universidad de Navarra, Pamplona, Spain, ²IdiSNA, Instituto de Investigación Sanitaria de Navarra, Pamplona, Spain, ³Siemens Healthineers, Madrid, Spain, ⁴Cardiology, Clínica Universidad de Navarra, Pamplona, Spain

Keywords: Arterial spin labelling, Perfusion

Splenic switch-off, defined as the stress to rest splenic blood flow (SBF) attenuation in response to adenosine, is an indicator of stress adequacy. This study aims to explore the ability of pseudo-continuous arterial spin labeling (PCASL) to identify splenic switch-off in patients with suspected CAD. In healthy subjects, multi-delay PCASL data were acquired to quantify SBF and determine the adequate postlabeling delay. In patients, single-delay PCASL and first-pass perfusion images were acquired under rest and adenosine conditions. This study could demonstrate the feasibility of PCASL to identify splenic switch-off during adenosine perfusion MRI.

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Emiel C.A. Roefs¹, Lydiane Hirschler¹, Natalia Petridou², and Matthias J.P. van Osch^1
1Radiology, C.J. Gorter MRI Center, Leiden Univeristy Medical Center, Leiden, Netherlands, ²Radiology, Center for Image Sciences, Univeristy Medical Center Utrecht, Utrecht, Netherlands

Keywords: Arterial spin labelling, High-Field MRI

White matter (WM) perfusion measurements are challenging because of the generally lower perfusion in combination with a longer bolus arrival time (BAT). We investigated the use of long-PLD perfusion measurements at high-field (7T) to compensate for longer BAT in WM.  We showed that 3D background suppressed FAIR at 7T with a PLD of 2300ms provides robust perfusion measurement in almost 80% of deep WM within 4min of scan time.

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Nikou Louise Damestani^1,2, John Jacoby¹, Barnaly Rashid^1,3, Allison E Lovely¹, Shrikanth M Yadav¹, Aurea Michael¹, Marziye Eshghi⁴, Melissa Terpstra⁵, Carlos Cruchaga^6,7,8, David H Salat^1,2,9, and Meher R Juttukonda^1,2
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Department of Neurology, Harvard Medical School, Boston, MA, United States, ⁴MGH Institute of Health Professions, Boston, MA, United States, ⁵MU School of Medicine, University of Missouri, Columbia, MO, United States, ⁶Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, United States, ⁷NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, MO, United States, ⁸Hope Center for Neurologic Diseases, Washington University, St. Louis, MO, United States, ⁹Neuroimaging Research for Veterans Center, VA Boston Healthcare System, Boston, MA, United States

Keywords: Arterial spin labelling, Aging

Identifying biomarkers that could characterize typical from atypical aging is crucial for understanding the aging process. One of the most significant genetic risk factors for Alzheimer’s Disease, an age-related neurodegenerative disorder, is the presence of an apolipoprotein-E (APOE) ε4 allele. Here, we investigate the impact of APOE genotype on cortical hemodynamics in a large cohort of participants across the lifespan, accounting for interacting effects of age, sex, and cardiovascular risk. We found unique spatial patterns of cerebral blood flow and arterial transit time between males and females within distinct APOE genotypes, potentially indicating the presence of a complex interaction.  

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Channelle Tham¹, Ahmed Abdalle², Joseph G Woods³, Maria-Eleni Dounavi⁴, Andre Pascoal⁵, and Udunna Anazodo^6
1Department of Cognitive Neuroscience, Radboud University, Nijmegen, Netherlands, ²Schulich School of Medicine and Dentistry, Western University, London, ON, Canada, ³Wellcome Centre for Integrated Neuroimaging, FMRIB, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, ⁴Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom, ⁵Instituto de Radiologia e Departamento de Radiologia e Oncologia, University of Sao Paulo, Sao Paulo, Brazil, ⁶Montreal Neurological Institute, McGill University, Montreal, QC, Canada

Keywords: Arterial spin labelling, Challenges, Reproducibility

While the recommendation for ASL acquisition is widely adopted to standardize quantification of cerebral blood flow (CBF), ASL analysis still produces wide variability in CBF estimates. The recent OSIPI-ISMRM ASL MRI Challenge highlighted how differences in image processing contribute to CBF variability. Here, we explored the replicability of ASL image processing approaches when used as documented to quantify CBF. The results of 5 of the 8 ASL Challenge teams were replicated and compared to their submitted results. The overall errors in global mean CBF were 0.03-5 times larger in the replicated results, demonstrating the need for ASL analysis standards. 

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Yiran Li¹, Xiufeng Li², John A Detre³, and Ze Wang^1
1University of Maryland School of Medicine, Baltimore, MD, United States, ²University of Minnesota, Minneapolis, MN, United States, ³University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States

Keywords: Arterial spin labelling, Arterial spin labelling

Cerebral blood flow (CBF) and arterial transit time (ATT) can be quantified through fitting the arterial spin labeling (ASL) perfusion MRI signal acquired at different post-labeling delays (PLDs) into a kinetic model. Acquiring multiple-PLD ASL MRI needs exponentially prolonged total scan time compared to the single-PLD acquisition, making it highly sensitive to motions and impractical for clinical use. We proposed a deep neural network that can reliably estimate ATT and CBF maps from significantly fewer PLD ASL MRI acquisitions without image quality loss.

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Limin Zhou¹, Yiming Wang², Marco C. Pinho^1,3, Durga Udayakumar^1,3, Michael Youssef^4,5, Joseph A. Maldjian^1,3, and Ananth J. Madhuranthakam^1,3
1Department of Radiology, University of Texas Southwestern Medical Center, DALLAS, TX, United States, ²Philips Healthcare, Shanghai, China, ³Advanced Imaging Research Center, University of Texas Southwestern Medical Center, DALLAS, TX, United States, ⁴Department of Neurology, University of Texas Southwestern Medical Center, DALLAS, TX, United States, ⁵Department of Hematology and Oncology, University of Texas Southwestern Medical Center, DALLAS, TX, United States

Keywords: Arterial spin labelling, Perfusion, Dynamic susceptibility contrast (DSC), Brain, Cancer, Glioblastoma (GBM)

We evaluated whether arterial spin labeled (ASL) MRI is competitive or complementary to dynamic susceptibility contrast (DSC) MRI measured perfusion in 20 glioblastoma (GBM) patients among 78 imaging sessions. In over 90% of scans, ASL was competitive to DSC. Among these competitive cases, ASL was either equivalent or superior to DSC, making ASL a very attractive alternative to DSC. In some cases (less than 10%), however, ASL and DSC were complementary to each other and combining their strength could provide a more comprehensive information of the whole tumor. 

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Lena Vaclavu¹ and Matthias JP van Osch^1
1C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands

Keywords: Arterial spin labelling, Perfusion, super-selective, time-encoded, borderzones

The borders between cerebral perfusion territories are regions of the brain that are susceptible to infarction. In this study, time-encoded super-selective pCASL was implemented to study the hemodynamic properties of the border zones between the left internal carotid artery and basilar artery perfusion territories. Perfusion territories were well-defined with little-to-no detectable overlap. The longest arrival times were found at the border zones, compared to 'inland' of the perfusion region. Combining time-encoded with super-selective pCASL enables the simultaneous investigation of border zones and their arrival times. 

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Nikou Louise Damestani^1,2, John Jacoby¹, Qiyuan Tian^1,2, Allison E Lovely¹, Shrikanth M Yadav¹, David H Salat^1,2,3, and Meher R Juttukonda^1,2
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Neuroimaging Research for Veterans Center, VA Boston Healthcare System, Boston, MA, United States

Keywords: Arterial spin labelling, Aging

White matter perfusion has been difficult to measure with arterial spin labeling (ASL) MRI due to the elongated arterial transit times of white matter. Here, we identified changes in white matter cortical hemodynamics associated with age and between sex for the first time using multi-delay pseudo-continuous ASL with tract-based analyses in a large typically aging cohort. We found reductions in white matter CBF and increases in white matter ATT with advancing age, as well as widespread sex differences across tracts. This work serves as the first step towards understanding the relationship between white matter physiology and age-related structural decline.

Logan X. Zhang^1,2 and Michael Chappell^1,3
1Sir Peter Mansfield Imaging Centre and Mental Health & Clinical Neurosciences, School of Medicine, University of Nottingham, Nottingham, United Kingdom, ²Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom, ³Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

Keywords: Arterial spin labelling, Arterial spin labelling

The blood-brain barrier integrity can be reflected by the pre-exchange lifetime of water molecules, Tex, which can be measured using multi-TE multi-delay ASL. Nevertheless, the low SNR of ASL limits the detectability of subtle Tex changes within a feasible scan time for clinical applications. In this study, optimised protocols were evaluated for the theoretical detectability of 10% changes in haemodynamic parameters. Simulation shows that while changes in CBF and arterial transit time (ATT) could be detected on individual level in a five-minute scan, the same detectability of Tex would require a minimum of 6 subjects within ten minutes of scanning. 

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Amnah Mahroo¹, Simon Konstandin^1,2, Daniel Christopher Hoinkiss¹, Jochen Hirsch¹, and Matthias Günther^1,2,3
1Imaging Physics, Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany, ²mediri GmbH, Heidelberg, Germany, ³MR-Imaging and Spectroscopy, University of Bremen, Bremen, Germany

Keywords: Arterial spin labelling, Brain, Blood-brain Barrier (BBB) Permeability, caffeine, multi-TE ASL

Caffeine is a commonly used stimulant drug and is known to change brain physiology by constricting vessels leading to decreased perfusion. We tested the impact of caffeine ingestion on blood-brain barrier (BBB) permeability by measuring exchange time using multi-TE ASL technique. Six healthy volunteers were examined for five pre-caffeine sets and six post-caffeine sets. The multi-TE two-compartment model was used to estimate exchange time (Tex) along with perfusion and ATT. We found that perfusion and Tex decreased over time while ATT increased. Decreased Tex indicates that the labelled water transferred at a faster rate reflecting increased BBB permeability.

Bin Jiang¹, Yangyang Tian², Ximing Wang¹, Peng Wu³, Jiayi Wan¹, Mengjiao Yin¹, Ning Wang¹, Rui Xu¹, Linkun Hu², and Mo Zhu^1
1Department of Radiology, The First Affiliated Hospital of Soochow University, Suzhou, China, ²Department of Urology, The First Affiliated Hospital of Soochow University, Suzhou, China, ³Philips Healthcare, Shanghai, China

Keywords: Arterial spin labelling, Kidney

Allograft injury continues to be a major problem in renal allograft recipients, which leads to eventual graft loss. Non-invasive and reliable detection of impaired renal allograft function is crucial to preventing irreversible nephron loss and graft failure. This study aims to investigate the value of ASL combined with DTI for the detection of impaired renal allograft function. Results showed that a higher diagnostic efficacy could be achieved through the combined use of ASL and DTI.

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Dan Zhu^1,2, Feng Xu^1,2, Dapeng Liu^1,2, Doris Lin², Peter van Zijl^1,2, and Qin Qin^1,2
1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, ²The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, MD, United States

Keywords: Arterial spin labelling, Arterial spin labelling

The most-used 3D acquisition for ASL at 3T is GRASE or stack-of-spiral (SOS) based FSE, which requires multiple shots to cover the full k-space. Alternatively, turbo FLASH (TFL) acquisition allows longer echo trains with slower T₁ (than T₂) relaxation, and 3D SOS-TFL has the potential to reduce the number of shots to even single-shot, thus improving the temporal resolution for ASL. Here we demonstrated comparable performance of 3D SOS-TFL with 3D GRASE on PCASL- and VSASL-derived CBF mapping and VSASL-derived CBV mapping at 3T on 12 healthy subjects, and the utility of 3D SOS-TFL on a stroke patient. 

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Limin Zhou¹, Yiming Wang², Marco C. Pinho^1,3, Durga Udayakumar^1,3, Michael Youssef^4,5, Joseph A. Maldjian^1,3, and Ananth J. Madhuranthakam^1,3
1Department of Radiology, University of Texas Southwestern Medical Center, DALLAS, TX, United States, ²Philips Healthcare, Shanghai, China, ³Advanced Imaging Research Center, University of Texas Southwestern Medical Center, DALLAS, TX, United States, ⁴Department of Neurology, University of Texas Southwestern Medical Center, DALLAS, TX, United States, ⁵Department of Hematology and Oncology, University of Texas Southwestern Medical Center, DALLAS, TX, United States

Keywords: Arterial spin labelling, Precision & Accuracy, Reproducibility, Precision Accuracy, Perfusion, Cancer, Glioblastoma (GBM), Translational studies

We evaluated the intra-session repeatability and inter-session reproducibility of brain and tumor perfusion measured using 3D pseudo-continuous Arterial spin labeled (PCASL) MRI with TSE based Cartesian acquisition with spiral profile reordering (CASPR) in comparison to 3D pCASL with GRASE in healthy volunteers and glioblastoma (GBM) patients at 3T. 3D pCASL with TSE-CASPR or GRASE provided high intra-session repeatability and 3 weeks inter-session reproducibility in both volunteers and GBM patients.  While both readouts generated robust images, TSE-CASPR provided images with reduced distortion particularly in GBM patients and could be a better readout for pCASL measured perfusion in GBM patients.

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Ryan A. Barnes^1,2, Conan Chen^1,2,3, Eric C. Wong^1,3,4, Thomas T. Liu^1,3,4,5, and Divya S. Bolar^1,3
1Center for fMRI, University of California San Diego, La Jolla, CA, United States, ²Department of Electrical and Computer Engineering, UC San Diego, La Jolla, CA, United States, ³Department of Radiology, UC San Diego, La Jolla, CA, United States, ⁴Department of Psychiatry, UC San Diego, La Jolla, CA, United States, ⁵Department of Bioengineering, UC San Diego, La Jolla, CA, United States

Keywords: Arterial spin labelling, Arterial spin labelling, Velocity-selective ASL, CBF

Velocity-selective ASL labels arterial blood spins close to the microvasculature if a sufficiently low velocity cutoff (V_cut) is used. Lowering V_cut, however, introduces diffusion and eddy current effects that confound the CBF measurement. A V_cut of 2 cm/s is typical to minimize these effects, but labels blood slightly upstream from the microvasculature; in this scenario, a non-zero post-labeling delay (PLD) allows time for additional microvascular delivery. We evaluate microvascular specificity (using the spatial coefficient of variation of CBF) as a function of PLD. We find that macrovascular specificity increases with PLD up to around 500ms for a typical ASL resolution.

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Alexander D. Cohen¹ and Yang Wang^1
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States

Keywords: Arterial spin labelling, Data Analysis, Coupling, Simultaneous BOLD/ASL

Impaired neurovascular coupling (NVC) plays a critical role in many neurovascular pathological processes. Several resting state fMRI methods have been used to estimate NVC including BOLD/CBF coupling and, to a lesser extent, ALFF and fALFF. In this study, resting state BOLD/CBF coupling was evaluated using advanced multiband multi-echo BOLD/ASL sequence and correlated with ALFF and fALFF in healthy volunteers. Significant correlation between BOLD/CBF coupling and ALFF and fALFF was seen in major brain network hubs. These results indicate MBME BOLD/ASL may provide similar, but complimentary measures of NVC compared to traditional RS metrics.