Mario G. Báez-Yáñez¹, Jeroen Siero^1,2, and Natalia Petridou^1
1Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands, ²Spinoza Centre for Neuroimaging Amsterdam, Royal Netherlands Academy of Arts and Sciences, Amsterdam, Netherlands

We present a statistical 3D computational model that mimics the human cortical vascular network. This approach allows to study the hemodynamic changes and to simulate biophysical effects across the vascular network, as well as to investigate the dynamic BOLD fMRI signal formation. In order to extract quantitative parameters of the BOLD fMRI signal in humans, it is necessary to adopt a computational model that resembles the human cortical vasculature and mimics realistic hemodynamic fluctuations triggered by neurovascular coupling. Simulating the biophysical effects of tissue related to hemodynamic changes will provide accurate information on the origins of the BOLD signal time-course.

Wouter Schellekens¹, Alex Bhogal¹, Jeroen Siero¹, and Natalia Petridou^1
1Radiology, UMC Utrecht, Utrecht, Netherlands

In the current study, we investigate the contribution of non-neuronal and neuronal-related hemodynamic changes to the BOLD signal for micro- and macro-vascular compartments. Vascular reactivity was assessed using CO2 and O2 gas administration, as well as brief visual stimuli, while we used gradient-echo and spin-echo across different cortical depths to specifically target different vascular compartments. We found that gradient-echo responded clearly to the gas challenges, also affecting the neurovascular hemodynamic response function. These effects were not seen for spin-echo, suggesting that the spatiotemporal characteristics of micro-vessels may not solely be affected by vascular properties.

Hui-Chieh Yang¹, Tsai-Ying Liao², Guan-Jie Wang³, Chun-Ming Chen⁴, and Shin-Lei Peng^3
1Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, ²School of Medicine, China Medical University, Taichung, Taiwan, ³Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan, ⁴Department of Radiology, China Medical University Hospital, Taichung, Taiwan

Previous studies have demonstrated that cerebrovascular reactivity (CVR) depends on the baseline vascular dilation status between groups. Within the brain, there also exist spatial variations in resting cerebral blood flow (CBF) and CVR across different cerebral regions; however, the relationship between regional CBF and CVR remains unclear. We found the frontal lobe had the maximal resting CBF but the minimal vascular response to hypercapnia, whereas the occipital lobe had the lowest rest CBF but the maximal reactivity to hypercapnia, suggesting that there is a small and a large autoregulatory efficiency at high and low resting CBF in the brain, respectively.

Yu-Lun Su¹, Hong-Yi Wu², Po-Yi Chen², Chi-Yun Liu¹, Ai-Ling Hsu³, Yi-Ping Chao⁴, and Changwei Wesley Wu^5
1Taipei Medical University, Taipei, Taiwan, ²National Taiwan University, Taipei, Taiwan, ³Quanta Computer Inc., Taoyuan, Taiwan, ⁴Chang Gung University, Taoyuan, Taiwan, ⁵Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, Taipei, Taiwan

To estimate the reliability of task-fMRI, we conducted a repeated measure fMRI study of psychomotor vigilance task once per day and 30 days in total. Salivary cortisol and sleep duration were taken into consideration based on previous study. However, we found dramatic within-subject variability in the brain activity of dACC and primary motor cortex. The cortisol showed insignificant association with brain activity, but sleep duration affected the motor and temporal cortices. Such finding suggests that the PVT-based fMRI showed large variability across different days, which might be associated with the deviations of sleep duration.  

Guan-Jie Wang¹, Chun-Ming Chen², and Shin-Lei Peng^1
1Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan, ²Department of Radiology, China Medical University Hospital, Taichung, Taiwan

Obesity is accompanied with damage to several organs including the brain. Although an extensive body of neuroimaging literature indicates that brain structure deteriorates with obesity, little information related to the relationship between CBF and obesity is available. In this study, we investigated the potential influence of body mass index (BMI) on brain abnormalities in young adults by combining functional and structural MRI studies. Results show CBF measured with the noninvasive MRI technique decreased as the BMI increased, as manifested by altered CBF in thalamus and visual-associated areas, including Brodmann areas (BA)7, BA18, and BA19

Janne Kananen¹, Timo Tuovinen², Vesa Korhonen², Niko Huotari², Hanna Ansakorpi³, Pierre LeVan⁴, and Vesa Kiviniemi^2
1Medicine, Radiology, OFNI, University of Oulu, Oulu, Finland, ²University of Oulu, Oulu, Finland, ³Oulu University Hospital, Oulu, Finland, ⁴University of Freiburg, Freiburg, Germany

Fast-fMRI has become a potent tool in researching brain physiology more accurately than before and it can detect changes in the blood oxygen level‐dependent signal, even if there is no epileptiform activity present. These detectable changes suggest that in epilepsy there are alterations in the brain physiology. With utilization of coefficient of variation (CV) method for patients with epilepsy (PWE), we detected a robust increase of CV in patients with in white matter, brainstem and temporal lobes in PWE at group level. Importantly, individual mapping of possible epileptic abnormality is also possible. 

Rebecca J Williams¹, Jacinta L Specht¹, Wen-Ming Luh², Erin L Mazerolle¹, and G. Bruce Pike^1
1University of Calgary, Calgary, AB, Canada, ²National Institute on Aging, National Institutes of Health, Baltimore, MD, United States

Estimating M value using a gas challenge is an essential component of calibrated fMRI. M is the maximal possible BOLD response and reflects baseline physiology such as CBF, CBV and CMRO₂. Despite its common use, it is unknown how caffeine ingestion affects M. Here it is demonstrated that caffeine increases M regionally, with frontal brain regions including the paracingulate and anterior cingulate gyrus particularly affected. M increases were found in the context of decreased baseline CBF. These results indicate that caffeine may be implicated in regional uncoupling between CBF and CMRO₂ which causes an increase in M.

Maria Concetta Morrone¹, Alessandro Benedetto¹, Mauro Costagli², Michela Tosetti², and Paola Binda^1
1Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy, ²IRCCS Stella Maris, Calambrone, Pisa, Italy

Behavioral visual sensitivity modulates rhythmically in synchrony with the onset of a voluntary action. Using 7T fMRI, we demonstrate similar oscillations of primary visual cortex (V1) BOLD responses to brief visual stimuli presented at different delays from the onset of an action. The oscillations are limited to the stimulated V1 region and not to peripheral V1 (which responds to the motor action). The peak responses of V1 BOLD activity are functionally connected to primary motor cortex, suggesting that motor cortex drives the rhythmic oscillation of V1. These results support the suggestion of a possible role of oscillations for visuo-motor coordination.

JiaYing Gong^1,2, Guanmao Chen¹, Yanbin Jia³, Long Qian⁴, Li Huang¹, and Ying Wang^1
1Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China, ²Department of Radiology, Six Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, ³Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China, ⁴MR Research, GE Healthcare, Beijing, China

The alterations of brain dynamics in bipolar disorder (BD) with suicidality are still unknown. Dynamic amplitude of low-frequency fluctuations (dALFF) was evaluated using sliding window analysis, and the severity of suicidality was predicted using a multivariate regression model between 106 BD II participants. Our findings suggest that alterations of temporal variability in the precuneus/ posterior cingulate cortex (PCC) is a common feature of BD participants, the right temporal lobe involved in impulsivity, social and emotional processing are associated with suicidality in BD II depression  

Bo Liu¹, Xiaochun Wang^1,2, Le Wang², Qiaojun Qu¹, Xiang Feng³, Wei Zhang¹, Bin Wang⁴, and Hui Zhang^1,2
1College of Medical Imaging, Shanxi Medical University, Taiyuan 030001, Shanxi Province, China, ²Department of Radiology, First Clinical Medical College, Shanxi Medical University, Taiyuan 030001, Shanxi Province, China, ³MR Scientific Marketing, Diagnosis Imaging, Siemens Healthcare Ltd, Beijing 100102, China, ⁴College of Information and Computer, Taiyuan University of Technology, Taiyuan 030001, Shanxi Province, China

The effect of attention field (AF) is not only constrained to spatial positions of attention but also to size. However, the direct link of AF size to receptive field (RF) has not been well established. In our study, we demonstrated remarkable modulation of AF in the early visual cortex, with regard to size and location of population receptive field (pRF), emphatically. Specially, the differences in pRF size between focused and distributed attention conditions increase with eccentricity, especially in the V3 area. Considering pRF location, eccentricity is larger under distributed attention conditions than under focused attention conditions at the perifovea in the V3 area.

Claire V Burley^1,2, Susan T Francis³, Samuel JE Lucas¹, and Karen Mullinger^4
1Centre for Human Brain Health, University of Birmingham, Birmingham, United Kingdom, ²3Dementia Centre for Research Collaboration, University of New South Wales, Sydney, Australia, ³Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom, ⁴School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom

Resting cerebral blood flow (CBF) and cerebrovasculature responsiveness (CVR) are becoming key measures of brain health. However, traditionally accepted CBF/CVR changes with age/fitness have been recently questioned using a variety of imaging modalities. Here we investigate the source of these discrepancies, performing Doppler and MRI measures on the same groups. We find similar changes in CBF but opposing changes in CVR measures between groups. There was no significant correlation of CBF MRI and Doppler measures across the cohort. Our work shows the necessity to further understand driving factors of CBF/CVR across modalities before use as a clinical research tool.

Zixuan Lin¹, Dengrong Jiang¹, Zachary Baker¹, Dapeng Liu¹, Yang Li¹, Xirui Hou¹, Jay J. Pillai¹, Qin Qin¹, Yulin Ge², and Hanzhang Lu^1
1Department of Radiology, Johns Hopkins University, Baltimore, MD, United States, ²Department of Radiology, New York University Langone Medical Center, New York, NY, United States

Water-extraction-with-phase-contrast-arterial-spin-tagging (WEPCAST) MRI was proposed recently as a non-invasive technique to assess blood-brain barrier (BBB) permeability to water. However, the reproducibility of this technique and cross-vendor reliability has not been reported. In this study, we harmonized WEPCAST technique across two major MRI vendors, Philips and Siemens and examined the test-retest reproducibility of the technique. The results showed that WEPCAST MRI can give a reliable assessment of BBB permeability with an excellent reproducibility.

Ícaro A F de Oliveira^1,2, Wietske van der Zwaag¹, Luisa Raimondo¹, Serge O Dumoulin^1,2,3, and Jeroen CW Siero^1,4
1Spinoza Centre for Neuroimaging, Amsterdam, Netherlands, ²Experimental and Applied Psychology, VU University, Amsterdam, Netherlands, ³Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, Netherlands, ⁴Radiology, University Medical Centre Utrecht, Utrecht, Netherlands

We used 3D-EPI VASO to simultaneously measure CBV and BOLD signal changes in the primary motor cortex. We aimed to investigate differences in neurovascular coupling as measured by BOLD and CBV signal changes during a hand movement task with increasing movement rates. In agreement with previous findings, the BOLD response was found to behave nonlinearly with respect to the movement rate. Remarkably, the CBV response amplitude also shows a similar and strong nonlinear behavior where the amplitude saturates at fast movement rates (≥ 1 Hz).

Rosemary Nicholas¹, Paul Greenhaff¹, Jordan McGing¹, Ayushman Gupta¹, and Susan Francis^1
1University of Nottingham, Nottingham, United Kingdom

To investigate the integrated impact of exercise on cardiac (CI) and cerebral (CBF) blood flow and oxygenation (OEF), measures were made concurrently in older active males at rest, during steady-state exercise and recovery. There was high association between aortic and biplane CI measures, and CBF increases with CI.  Exercise induced increases in CI, CBF and the cerebral metabolic rate of oxygen (CMRO₂), which were not seen on recovery. OEF was inversely associated with  CI at rest, and increased on recovery. Exercise and recovery changes support the need for and highlight the utility of in-scanner exercise studies to investigate cardiovascular regulation. 

Javier Gonzalez-Castillo¹, Daniel A Handwerker¹, and Peter A Bandettini^1,2
1Section on Functional Imaging Methods, NIMH, Bethesda, MD, United States, ²FMRI Facility, NIH, Bethesda, MD, United States

Wakefulness fluctuations during rest are a key confound for dynamic functional connectivity. Yet, tracking such fluctuations is not trivial when lacking concurrent EEG and/or eye-tracking. Recent work suggests that ultra-slow CSF fluctuations accompany descent into sleep. Here we evaluate how such fluctuations help track wakefulness in rest scans acquired on non sleep-deprived subjects using sequences not optimized for detecting such inflow-related fluctuations. We conclude that those fluctuations can be easily detected in other samples, and that they may provide valuable time-resolved information about fluctuations in wakefulness, as well as a means to segregate subjects according to their overall wakefulness levels.

Hyun-Ji Shim^1,2 and Seong-Gi Kim^1,2,3
1Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon-si, Korea, Republic of, ²Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University (SKKU), Seoul, Korea, Republic of, ³Department of Biomedical Engineering, Sungkyunkwan University (SKKU), Suwon-si, Korea, Republic of

Evoked fMRI findings of anesthetized mice are inconsistent possibly due to uncontrolled vascular physiology. In our studies under ketamine and xylazine anesthesia, localized BOLD response was observed in the spontaneously breathing condition, which is known to cause hypercapnia. Here we performed blood gas analysis and functional studies of spontaneously breathing vs. mechanical ventilating mice. The mechanical ventilation maintained mice at normal physiology and induced larger hemodynamic and BOLD responses to forepaw stimulation. Spontaneous breathing induced severe hypercapnia and acidosis, but surprisingly showed significant evoked functional responses. These results suggest that both methods can be used for functional experiments.

Nikos Priovoulos¹, Dimo Ivanov¹, Benedikt Poser¹, Linda Pagen¹, Vitaly Napadow^2,3, Roberta Sclocco², Frans Verhey¹, and Heidi Jacobs^1,2
1Maastricht University, Maastricht, Netherlands, ²Harvard Medical School, Boston, MA, United States, ³Logan University, Chesterfield, MT, United States

Vagus nerve stimulation has been suggested to cause wide-spread changes in the hemodynamic response function in rats. Here, we demonstrate in humans that a non-invasive variant of vagus nerve stimulation is linked with neurovascular and global blood flow changes, and associated with increased salivary alpha-amylase, suggesting potential noradrenaline release. Our results provide support for the role of noradrenaline in modulating BOLD fMRI contrast via blood flow.

Francisco Moreira Azevedo¹, João Jorge^2,3, Wietske van der Zwaag⁴, and Patrícia Figueiredo^1
1ISR-Lisboa/LARSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal, Lisbon, Portugal, ²Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, Lausanne, Switzerland, ³Systems Division, Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland, Lausanne, Switzerland, ⁴Spinoza Centre for Neuroimaging, Amsterdam, Netherlands, Amsterdam, Netherlands

The haemodynamic response to neuronal activity measured by BOLD-fMRI exhibits substantial trial-by-trial variability, but the underlying sources remain largely unknown. Here, we investigated whether single-trial BOLD responses were modulated by cardiac and respiratory cycles, by recording the BOLD responses to single trials of brief visual stimulation using an ultrafast acquisition (TR=0.4s) at ultrahighfield (7T). We found that, when binning trials according to the respiratory phase, the BOLD responses were more similar to each other when occurring up to 1sec following expiration. Our results suggest that trial-by-trial variability of BOLD responses may partly be explained by the respiratory cycle.

Xiaoqing Alice Zhou¹, Zengmin Li², Hsu-Lei Lee³, Elizabeth Coulson⁴, and Kai-Hsiang Chuang^3
1QBI/SBMS, The University of Queensland, Brisbane, Australia, ²QBI, The University of Queensland, Brisbane, Australia, ³QBI/CAI, The University of Queensland, Brisbane, Australia, ⁴SBMS/QBI, The University of Queensland, Brisbane, Australia

1. BOLD activation by 1.5s short event can be reliably measured with ultrafast multiband EPI.
2. HRF in different brain regions of the visual pathway can be derived. 
3. The HRF timing discrepancy may suggest timing difference in neural activity.

 

Shichun Chen¹, Wenna Duan¹, Li Zhao², David C. Alsop², Wenming Luh³, and Weiying Dai^1
1Computer Science, State University of New York at Binghamton, Binghamton, NY, United States, ²Radiology, Beth Israel Deaconess Medical Center & Harvard Medical School, Boston, MA, United States, ³National Institute on Aging, National Institite of Health, Baltimore, MD, United States

Global fluctuations of arterial spin labeling (ASL) signals may emerge from global synchronization of resting-state brain networks. We aimed to investigate the synchrony of ASL global signal with brain neural activity using simultaneously recorded ASL perfusion images and EEG. The correlation between the EEG frequency power time series and ASL global time courses was evaluated. The shape for time course of the correlation is very similar to hemodynamic response functional curve. The peak correlation time indicates that the global ASL signals follow the neural activity and the function of human brain is organized by the presence of global functional synchronization.

Won Beom Jung^1,2, Hyun-Ji Beom Shim^1,3, and Seong-Gi Kim^1,2
1Cener for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon-si, Gyeonggi-do, Korea, Republic of, ²Department of Biomedical Engineering, Sungkyunkwan University, Suwon-si, Gyeonggi-do, Korea, Republic of, ³Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Suwon-si, Gyeonggi-do, Korea, Republic of

The wide-spread and/or bilateral activity patterns in cortical and thalamic areas were common observation in response to innocuous and noxious electrical stimulation in mouse BOLD fMRI studies. Those findings may be related to the global BOLD effect confounded by stimulus-induced changes in cardiac functions such as heart rate and blood pressure, rather than originated from underlying neural activity. Under the ketamine-xylazine anesthesia, sympathetic activity is known to be suppressed. Here, we measured the response specificity of the BOLD signal responding from innocuous to putative noxious stimuli in mice under ketamine-xylazine anesthesia.

Zhenliang Xiong¹, Chong Tian¹, Jie Huang², Xianchun Zeng¹, Dongxue Li¹, Lisha Nie³, Pu-Yeh Wu³, and Rongpin Wang^1
1Department of Radiology, Guizhou Provincial People's Hospital, Guiyang, China, ²Department of Radiology, Michigan State University, East Lansing, MI, United States, ³GE Healthcare, Beijing, China

The current study investigated the relationship of the sensorimotor and visual cortical functional connectivity (FC) networks between the resting and task states. Our study demonstrated a general relationship of the task-evoked FC network with its corresponding intrinsic FC network, regardless of the tasks.

Frederico Severo¹, Alfonso Renart¹, and Noam Shemesh^1
1Champalimaud Research, Champalimaud Centre for the Unknown, Lisboa, Portugal

Auditory offset responses due to cessation of auditory stimuli have been previously described, suggesting the existence of a dedicated auditory offset pathway. These responses are of major importance in auditory perception, as temporal cues like sound duration can be crucial for sound identification and interpretation. Still, studies on the subject are scarce compared to classic auditory onset responses. Here, we investigate the BOLD dynamics upon the cessation of sound using BOLD fMRI in the rat. We find differences between Onset and Offset paradigms suggesting negative BOLD responses observed in the latter are likely due to an active process.

Yayan Yin¹, Lang Qin², and Jie Lu^1
1Radiology, Capital Medical University, Beijing, China, ²Linguistics, the University of Hong Kong, Beijing, China

The oxygen extraction fraction (OEF) is a key physiological marker of cerebral oxygen metabolism. While the availability of oxygen plays a crucial role in oxygen metabolism, the effect of mild hypoxia on OEF during brain activity remains largely unclear. In this study, a novel OEF dynamic measurement technique, multiecho asymmetric spin echo pulse sequence, was used to investigate the OEF response during motor task in both normoxia and mild hypoxia. Results demonstrated that the motor-induced OEF response change was larger in mild hypoxia (-23% ± 6%) than that in normoxia (-12% ± 4%) and was positively correlated with oxygen saturation. 

Nicholas J. Luciw^1,2, Benjamin I. Goldstein^2,3, and Bradley J. MacIntosh^1,2
1Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ²Sunnybrook Research Institute, Toronto, ON, Canada, ³Departments of Psychiatry and Pharmacology, University of Toronto, Toronto, ON, Canada

Functional brain networks reflect inherent inter-regional relationships that subserve behaviour and information processing. There is evidence that the correlations of regional brain function across individuals partly reflect functional connectivity. The current study focuses on region-to-region covariation of cerebral blood flow (CBF) across participants using arterial spin-labelled MRI. To investigate the stability of this CBF covariance mapping, we compare maps acquired within the same day but before and after a single exercise session. To refine our CBF covariance mapping methodology, we consider whether choice of anatomical atlas and use of partial volume correction impact the results of our between-session comparison.

Stefano Moia¹, Rachael C. Stickland², Maite Termenon¹, Eneko Uruñuela-Tremiño¹, César Caballero-Gaudes¹, and Molly G. Bright^2,3
1Basque Center on Cognition Brain and Language, San Sebastián, Spain, ²Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States, ³Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States

Cerebrovascular reactivity (CVR) is an important measure of vascular function, but true variability in CVR can be masked by numerous confounds. We explore the variability of CVR maps, extracted using breath-holding and resting state data, over 9 weekly scanning sessions. Our results show that CVR demonstrates robust spatial patterns that vary across known neural networks. 

Henning Matthias Reimann¹, Jurjen Heij¹, Joao Periquito¹, Antje Els¹, Haopeng Han¹, and Thoralf Niendorf^1,2
1Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany, ²Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany

In recent years, the identification of pain-specific biomarkers has become the holy grail of pain research in the fMRI community. Painful stimuli, salient (attention capturing) non-painful stimuli, and nociceptive stimuli in analgesic subjects (who cannot feel pain) elicit similar BOLD patterns that cannot be resolved at 3T. Recognizing this shortcoming we present preliminary fMRI data at 7T (double spatial resolution), comparing painful stimuli with isosalient non-painful stimuli in healthy volunteers and an analgesic subject who is insensitive to pain. The overall goal of this study is to detail the evoked neurosignatures for pain-specificity and identify diagnostic biomarkers of pain experience.

Suk-tak Chan¹, Karleyton C Evans², Tian-yue Song¹, Juliette Selb¹, Andre van Kouwe¹, Bruce R Rosen¹, Yong-ping Zheng³, Andrew C Ahn¹, and Kenneth K Kwong^1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Biogen Inc., Cambridge, MA, United States, ³Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong

We showed that the oscillations of breath-by-breath O₂-CO₂ exchange ratio (bER) were superior to those of end-tidal CO₂ in correlating with the low frequencies (0.008-0.03Hz) of resting state cerebral hemodynamic fluctuations (CHF). Brain regions showing significant association of ΔBOLD with bER overlapped with many regions of default mode network. Transcranial Doppler sonography and fMRI were used to measure CHF and time series of partial pressure of O₂ and CO₂ were collected. bER-CHF coupling is a novel metric to measure brain-body interaction that may provide some answers to the physiological contributions to low frequencies of CHF.

Suk-tak Chan¹, Karleyton C Evans², Tian-yue Song¹, Juliette Selb¹, Andre van Kouwe¹, Bruce R Rosen¹, Yong-ping Zheng³, Andrew C Ahn¹, and Kenneth K Kwong^1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Biogen Inc., Cambridge, MA, United States, ³Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong

Here we tested the hypothesis that the cerebrovascular responses to brief breath hold epochs were coupled not only with increased partial pressure of carbon dioxide (PCO₂), but also with decreased partial pressure of oxygen (PO₂). fMRI map of cerebrovascular reactivity (CVR) to breath-by-breath O₂-CO₂ exchange ratio covers similar regions as map of CVR to exogenous CO₂ challenge. Substantially fewer regions in fMRI map of CVR to endogenous end-tidal CO₂ satisfied statistical significance. Our results support the hypothesis that hypoxia and hypercapnia work synergistically to enhance cerebrovascular responses to breath hold.

Yaoyu Zhang¹, Wenying Du², Ying Han^2,3,4, and Jia-Hong Gao^1
1Center for MRI Research, Peking University, Beijing, China, ²Department of Neurology, XuanWu Hospital of Capital Medical University, Beijing, China, ³Center of Alzheimer’s Disease, Beijing Institute for Brain Disorders, Beijing, China, ⁴National Clinical Research Center for Geriatric Disorders, Beijing, China

Subjective cognitive decline (SCD) is a high risk for Alzheimer’s disease. Most of the existing studies made their observations during the resting state of the brain. This study compared the responses of SCD and normal controls (NC) evoked by loaded N-back tasks. A load-dependent effect is clearly seen in both groups. CBF, as compared to other parameters, shows higher sensitivity in detecting the difference between SCD and NC subjects. Our results may help understand the physiological mechanisms and develop early diagnostic strategies of SCD.

Fatemehsadat Arzanforoosh¹, Marion Smits¹, and Esther AH Warnert ^1
1Radiology and Nuclear medicine, Erasmus MC, Rotterdam, Netherlands

Cerebral hypoxia occurs in a plethora of brain diseases, including stroke and brain tumor. This work provides a step towards a rapid, non-invasive imaging protocol for clinically feasible cerebral oxygenation mapping. In this study we use an asymmetric spin echo (ASE)-based streamlined-qBOLD (sq-BOLD) technique to non-invasively monitor hemodynamic properties of the brain in two states (baseline and activation). Our results show that, despite the low signal-to-noise ratios likely due to macroscopic magnetic field gradients (MFGs), sq-BOLD has the potential to measure changes in oxygen extraction fraction in the activated area. 

Luo bing Wu¹, Ying Wei¹, Cai hong Wang¹, Kai yu Wang¹, and Jing liang Cheng^1
1GE Healthcare, MR Research China, Beijing, Zheng Zhou, China

The resting state functional images of 53 patients with chronic pontine infarction and 35 healthy controls were collected, and A and B were used to evaluate the difference and sensitivity of functional information integration between single brain regions and hemispheres.It was associated with clinically relevant cognitive function scores.Finally, the contribution of the left and right sides to the difference was evaluated.The results showed that the difference and contribution of the right infarction group were significantly higher than that of the left infarction group.In the future, functional integration between the two hemispheres will be further studied.