Joseph R Whittaker¹, Molly G Bright^1,2, Ian D Driver¹, Adele Babic^1,3, Martin Stuart¹, and Kevin Murphy^1
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. 

Qiu Ge¹, Wei Peng¹, Yong Zhang², Yu-Feng Zhang¹, Thomas Liu³, Xuchu Weng¹, and Ze Wang^1
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.

Henk Mutsaerts¹, Lena Vaclavu², Jan-Willem van Dalen², Andrew Robertson¹, Paul Groot², Mario Masellis¹, Edo Richard², Aart J Nederveen², and Bradley MacIntosh^1
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.

Jill B. De Vis¹, Hanzhang Lu², Harshan Ravi², Jeroen Hendrikse¹, and Peiying Liu^3
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. 

Wenjia Liu¹, Bing Wu², Dandan Zheng², Xin Lou¹, Yulin Wang¹, Li Zheng³, Jie Liu⁴, and Lin Ma^1
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.

Esther AH Warnert¹, Jasper Verbree², Richard G Wise¹, and Matthias JP van Osch^2
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. 

Joana Pinto¹, Pedro Vilela², Michael A. Chappell³, and Patrícia Figueiredo^1
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 M_0t 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.

Martha J Holmes¹, Frances C Robertson¹, Francesca Little², Mark F Cotton³, Els Dobbels³, Andre JW van der Kouwe^4,5, Barbara Laughton³, and Ernesta M Meintjes^1
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. 

Ruth L O'Gorman¹, Philipp Buehler², Carola Sabandal², Ianina Scheer³, Malek Makki¹, Markus Weiss², Christian Kellenberger³, and Achim Schmitz^2
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.

Maxime Donadieu^1,2,3, Yann Le Fur^1,2, Sylviane Confort-gouny^1,2, Arnaud Le Troter^1,2, Maxime Guye^1,2, and Jean-Philippe Ranjeva^1,2
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.