ISMRM 24th Annual Meeting & Exhibition • 07-13 May 2016 • Singapore

Scientific Session: Normal Brain Physiology

Tuesday, May 10, 2016
Hall 606
13:30 - 15:30
Moderators: Manus Donahue, Peiying Liu

A differential arterial blood volume response during Lower Body Negative Pressure measured using Pulsed Arterial Spin Labelling with multiple short inversion times
Joseph R Whittaker1, Molly G Bright1,2, Ian D Driver1, Adele Babic1,3, Martin Stuart1, and Kevin Murphy1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom, 2Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom, 3Department of Anesthesia and Intensive Care Medicine, Cardiff University School of Medicine, Cardiff, United Kingdom
A custom made MRI compatible lower body negative pressure (LBNP) chamber induced central hypovolemia in a group of healthy volunteers. Pulsed ASL data with multiple short inversion times was acquired during a baseline period and -40mmHg LBNP in order to estimate arterial cerebral blood volume changes related to cerebral autoregulation. We found a differential response, in which arterial blood volume changes during LBNP were dependent on vessel size. These data provide a useful first step for fully understand the complex vascular changes that occur in the brain to maintain perfusion during systemic physiological perturbations. 

Short-term cerebral blood flow reduction induced “apparent” brain tissue density reduction
Qiu Ge1, Wei Peng1, Yong Zhang2, Yu-Feng Zhang1, Thomas Liu3, Xuchu Weng1, and Ze Wang1
1Hangzhou Normal University, Hangzhou, China, People's Republic of, 2GE Healthcare, MR Research China, Beijing, Shanghai, China, People's Republic of, 3University of California San Diego, San Diego, CA, United States
MRI-identified short-term brain tissue changes have been in debate because of the lack of solid evidence of neurogenesis. Cerebral blood flow (CBF) has been traced as one contributing factor. We used caffeine to modulate CBF and to subsequently examine brain tissue change using MRI. Both CBF reduction and grey matter decrease were observed after caffeine ingestion, which were further related to each other in some brain regions. The data provide direct evidence for the CBF contribution to the short-term apparent tissue changes.

Rethinking macro-vascular artifacts from single post-label delay ASL: can we extract a "free-lunch" arterial transit time metric?
Henk Mutsaerts1, Lena Vaclavu2, Jan-Willem van Dalen2, Andrew Robertson1, Paul Groot2, Mario Masellis1, Edo Richard2, Aart J Nederveen2, and Bradley MacIntosh1
1Sunnybrook Research Institute, Toronto, ON, Canada, 2Academic Medical Center, Amsterdam, Netherlands
In this work, we propose a novel method to infer an ATT estimate from the spatial signal distribution of single-time point ASL CBF maps, using a spatial Coefficient of Variation (CoV). In a large population of elderly with hypertension, we compare crushed (C CBF) and non-crushed CBF maps (NC CBF), from which we derive C CoV and NC CoV, and the FEAST-based ATT estimate. These explorative results show that both ATT and BMI are associated with NC CoV but not with NC CBF, suggesting that ATT ? as estimated by the spatial CoV ? might serve as a global biomarker of cerebrovascular disease.

Traffic and cargo on the venous highway: distribution of venous flow and oxygenation in the human brain.
Jill B. De Vis1, Hanzhang Lu2, Harshan Ravi2, Jeroen Hendrikse1, and Peiying Liu3
1Radiology, University Medical Center Utrecht, Utrecht, Netherlands, 2Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3Radiology, Johns Hopkins University Medical Center, Baltimore, MD, United States
Arterial territory and flow have been well studied, but few studies have been performed to investigate the venous flow distribution. Similarly, little is known about the oxygenation and its heterogeneity among the different venous structures. The purpose of this study was to investigate venous flow distribution and oxygenation. 

Using 3D ASL to assess the change of cerebral blood flow at high altitude: a longitudinal study
Wenjia Liu1, Bing Wu2, Dandan Zheng2, Xin Lou1, Yulin Wang1, Li Zheng3, Jie Liu4, and Lin Ma1
1Department of Radiology, PLA General Hospital, Beijing, China, People's Republic of, 2GE Healthcare, MR Research China, Beijing, Beijing, China, People's Republic of, 3Biomedical Engineering, Peking university, Beijing, China, People's Republic of, 4General Hospital of Tibetan Military Area Command, Lhasa, China, People's Republic of
Although cerebral blood flow(CBF) at high altitude have been researched for years, most previous studies are limited by the use of transcranial Doppler. The conclusion of changes in CBF depend on the assumption that the middle cerebral arterial diameter does not alter in hypoxia, but recent studies suggesting that this is not the case. In our study, CBF was measured by 3D arterial spin labeling (ASL) technique at sea level and high altitude in order to seek the cerebrovascular response to altitude environment.

Imaging Changes in Cross-Sectional Area of the Middle Cerebral Artery through the Cardiac Cycle at 7 Tesla
Esther AH Warnert1, Jasper Verbree2, Richard G Wise1, and Matthias JP van Osch2
1Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, United Kingdom, 2Radiology, Leiden University Medical Center, Leiden, Netherlands
Arterial stiffness is an important marker for cerebrovascular health, as increased stiffness can lead to a range of cerebrovascular pathologies. A non-invasive assessment of cerebral arterial stiffness could therefore be an important imaging marker for cerebrovascular health. Here we show the feasibility of using high field MRI to non-invasively assess cerebral arterial stiffness by measuring the changes in cross-sectional area of the middle cerebral artery throughout the cardiac cycle. 

Impact of calibration method on the reproducibility of CBF mapping using multiple post-labeling-delay PASL - Permission Withheld
Joana Pinto1, Pedro Vilela2, Michael A. Chappell3, and Patrícia Figueiredo1
1ISR-Lisboa/LARSyS and Department of Bioengineering, Instituto Superior Técnico – Universidade de Lisboa, Lisbon, Portugal, 2Imaging Department, Hospital da Luz, Lisbon, Portugal, 3Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
Absolute CBF quantification using ASL requires the normalization of the control-label difference images by the equilibrium magnetization, M0. A voxelwise calibration method is currently recommended for single post-labelling-delay (PLD) PCASL. However, the impact of using an M0t map obtained directly from the ASL data, with no need for an extra scan, by fitting a saturation-recovery curve to the control image time-series in multiple-PLD PASL remains to be investigated. Here, we show that, using this type of acquisition, voxelwise calibration significantly reduced inter- and intra-subject variability in gray matter CBF measurements relative to methods based on a reference tissue.

Regional differences in absolute metabolite level couplings in a longitudinal study of children
Martha J Holmes1, Frances C Robertson1, Francesca Little2, Mark F Cotton3, Els Dobbels3, Andre JW van der Kouwe4,5, Barbara Laughton3, and Ernesta M Meintjes1
1MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Cape Town, South Africa, 2Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa, 3Children’s Infectious Diseases Clinical Research Unit, Department of Paediatrics & Child Health, Tygerberg Children’s Hospital and Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa, 4A.A. Martinos Centre for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 5Department of Radiology, Harvard Medical School, Boston, MA, United States
1H-MRS non-invasively quantifies metabolites that play important roles in neurodevelopment. The physiological functions of these metabolites, however, are still debated. Examining the regional intercorrelations between metabolites such as NAA, creatine, choline and glutamate provides insight about the role of individual and coupled biochemicals in the developing brain. We examined correlations between pairs of metabolites in the midfrontal gray  matter (MFGM), peritrigonal white matter (PWM), basal ganglia (BG) at 5, 7 and 9 years in a cohort of South African children.  We found significant metabolite couplings in both the MFGM and PWM, however no significant couplings were observed in the BG. 

Differential effects of ketamine-propofol vs propofol anaesthesia on cerebral perfusion in children
Ruth L O'Gorman1, Philipp Buehler2, Carola Sabandal2, Ianina Scheer3, Malek Makki1, Markus Weiss2, Christian Kellenberger3, and Achim Schmitz2
1Center for MR Research, University Children's Hospital, Zurich, Switzerland, 2Anaesthesia, University Children's Hospital, Zurich, Switzerland, 3Radiology, University Children's Hospital, Zurich, Switzerland
Anaesthetics such as those used for sedation in pediatric MRI affect cerebral blood flow and hemodynamics to varying degrees. This study examines differences in cerebral perfusion in children undergoing elective MRI under sedation with propofol vs. a combination of propofol and ketamine. Children induced for sedation with ketamine demonstrated on average 14% higher whole brain perfusion values than those induced for sedation with propofol, confirming that ketamine and propofol exert a differential effect on brain activity and hemodynamics.

Evidencing different neurochemical profiles between thalamic nuclei using 2D-semilaser 1H-MRSI at 7T
Maxime Donadieu1,2,3, Yann Le Fur1,2, Sylviane Confort-gouny1,2, Arnaud Le Troter1,2, Maxime Guye1,2, and Jean-Philippe Ranjeva1,2
1CRMBM UMR 7339, Aix Marseille Université CNRS, Marseille, France, Metropolitan, 2CEMEREM Pole d'Imagerie, AP-HM CHU Timone, Marseille, France, Metropolitan, 3Siemens Healthcare, Saint-Denis, France, Metropolitan
Using 2D-semilaser 1H-MRSI sequence centered on thalamus and acquired at 7T in 10 healthy volunteers, we demonstrate that the neurochemical profiles (relative NAA, Cr and Cho levels) are different between pulvinar, ventral-lateral, dorsal-medial and anterior nuclei. Moreover, left/right differences in neurochemical profiles, especially for NAA levels, showed a left NAA lateralization for the ventral-lateral nucleus and the pulvinar and in contrast higher right NAA levels in the anterior nucleus. These results suggest that the various neurochemical profiles of these thalamic nuclei may be related to their functional specificity.

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.