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fMRI Acquisition Hall B Monday 14:00-16:00 1077. Separating FID and Echo Contribution in Pass-Band BSSFP FMRI with Multiple-Phase Angle Cycling Sung-Hong Park1,2, Tae Kim1, Ping Wang1, Timothy Q. Duong2, Seong-Gi Kim1 1Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 2Research Imaging Institute, Ophthalmology/Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States We acquired high resolution multiple phase-cycled bSSFP fMRI datasets in rat brains at 9.4T and separated FID and main echo components based on Fourier analysis. The FID component showed stronger fMRI signals than the main echo component, but it showed stronger correlation with both intracortical veins and cortical surface veins. The fMRI signal from the main echo component could contribute up to half of that from the FID component, implying that the main echo component should not be neglected in interpreting pass-band bSSFP fMRI signals. 1078. A Novel Multi-Echo FMRI Weighting Strategy Using Principal Component Analysis for BOLD Contrast Sensitivity Enhancement Mark Chiew1,2, Simon James Graham1,2 1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; 2Rotman Research Institute, Toronto, Ontario, Canada The use of multi-echo imaging techniques for contrast enhancement in BOLD fMRI is gaining momentum, particularly in real-time fMRI applications. A novel method is presented for combining multi-echo signals in weighted summation using principal component analysis (PCA) derived weights. The method is evaluated on human volunteers performing a simple motor task at 1.5 T, and is compared to other reported weighting schemes. The data driven PCA weighting method is demonstrated to produce time-series that achieve high relative contrast-to-noise ratio gain, without requiring additional data collection. 1079. Variable Density Spiral FMRI Catie Chang1, Gary Harold Glover1 1Electrical Engineering & Radiology, Stanford University, Stanford, CA, United States We propose a novel variable-density (VD) spiral k-space trajectory for brain fMRI. The trajectory consists of an Archimedean spiral from the origin out to an arbitrary radius k1, extending beyond k1 with a spiral in which the sampling density decreases as the k-space radius increases. Thus, it allows for a reduction in readout time at the expense of undersampling only high spatial frequencies. We implemented the VD spiral in a single-shot 2D spiral-in/out sequence for high (128x128) resolution, and demonstrate improved activation in a sensory-motor task compared to conventional (fully Archimedean) single-shot and interleaved sequences. 1080. High Resolution BOLD FMRI Using MHASTE Yongquan Ye1, Yan Zhuo1, Xiaohong Joe Zhou2 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics,CAS, Beijing, China; 2University of Illinois Medical Center, Chicago, IL, United States High resolution BOLD fMRI data on visual cortex were acquired using mHASTE, a novel GRAPPA accelerated single shot TSE technique, and the results were compared with those of GE- and SE-EPI. Higher SNR was obtained with mHASTE than both EPIs, and increased functional activation was detected by mHASTE but not by EPI when going from low resolution to high resolution. mHASTE was also found to have greater activation than both EPI in some cases,especially at high resolution, suggesting a more robust BOLD contrast mechanism for mHASTE in high resolution fMRI. 1081. Functional Magnetic Resonance Imaging Using PROPELLER EPI Martin Krämer1, Thies Halvor Jochimsen1, Marc Roth1, Jürgen Rainer Reichenbach1 1Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany A method to improve spatial and temporal resolutions in fMRI using PROPELLER-EPI. First results are shown which demonstrate that a sliding window reconstruction of high resolution long-axis propeller (LAP) data is suitable for simple fMRI experiments. Additionally the results achieved by the LAP measurements are compared to the standard 64x64 EPI sequence which is usually used in fMRI. From there it is shown that the activation maps created from the LAP scans are better localized along the cortex. 1082. Passband BSSFP: Functional Contrast Compared to GRE-EPI and SE-EPI at 3T. Pål Erik Goa1, Anders Kristoffersen1, Michael H. Chappell2, Rob H. Tijssen3, Asta K. Håberg4, Karla L. Miller3 1Dept. of Medical Imaging, St. Olavs University Hospital, Trondheim, Norway; 2Dept. of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; 3FMRIB Centre, Oxford University, Oxford, Oxon, United Kingdom; 4Dept. of Neuromedicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway The functional contrast in passband balanced steady-state free precession (pbSSFP) with 3D segmented EPI readout is compared to that of GRE-EPI and SE-EPI at 3T. For pbSSFP, TR is varied from 6.5 ms to 45 ms. Standard flickering checkerboard paradigm is used. We find that the best functional contrast is obtained at TR = 33 ms with corresponding EPI-factor of 40. At this TR, the functional contrast in pbSSFP is approximately half that of GRE-EPI and twice that of SE-EPI with otherwise comparable scan parameters. False detections due to banding artefacts are present in pbSSFP. 1083. Isotropic Sub-Millimeter FMRI in Humans at 7T Robin Martin Heidemann1, Dimo Ivanov1, Robert Trampel1, Joeran Lepsien1, Fabrizio Fasano2, Josef Pfeuffer3, Robert Turner1 1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Fondazione Santa Lucia, Rome, Italy; 3Siemens Healthcare Sector, Erlangen, Germany For isotropic high resolution fMRI at ultra-high field strength, susceptibility effects and T2* decay must be properly addressed. A combination of reduced FOV imaging (zoomed imaging) and parallel imaging is optimized here, achieving acceleration factors of up to 5.5. The high acceleration reduces distortions and image blurring, while incurring no other image artifacts. With this approach, high quality single-shot EPI acquisitions can be obtained with an isotropic resolution of 0.65 mm and sufficient coverage for e.g. fMRI in the visual cortex of the human brain. 1084. Automatic Functional and Anatomical Registration for FMRI Using Optimized 3D Flyback Echo Planar Imaging Thomas Sushil John1, Michael Lustig2,3, John Mark Pauly2 1Electrical Engineering , Stanford University, Stanford, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States; 3Electrical Engineering and Computer Science, UC Berkeley, Berkeley, CA, United States Echo planar imaging (EPI) is the most widely used method for functional MRI. However, functional images are often distorted because EPI is highly sensitive to field inhomogeneities, eddy currents, and gradient delays. Functional and neuro-anatomical registration is complicated by these distortions and by the fact that functional and anatomical images are usually obtained with different imaging sequences. This work investigates the use of an optimized 3D flyback EPI trajectory with echo time shifting to obtain functional and anatomical images that have minimal distortions and are inherently co-registered. 1085. Recovery of Signal Using Spiral-In K-Space Trajectories: Phase Coherence or Intensity Displacement? Kimberly Brewer1,2, James Rioux1,2, Martyn Klassen3, Chris Bowen1,4, Steven Beyea1,4 1Institute for Biodiagnostics (Atlantic), National Research Council of Canada, Halifax, Nova Scotia, Canada; 2Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada; 3Robarts Research Institute, University of Western Ontario, London, Ontario, Canada; 4Physics and Atmospheric Science, Radiology and Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada Spiral pulse sequences are commonly used in fMRI, and spiral-in is known to be considerably better than spiral-out at signal recovery in regions with strong susceptibility field gradients. Previously proposed theories in the literature do not address the probability of signal displacement or fully explain all of the differences in signal recovery between spiral-out and spiral-in. In the current work we demonstrate that the difference in image intensity is not due to differences in signal displacement between spiral-in and spiral-out, but rather the increased phase coherence of the displaced pixels when using spiral-in. 1086. Mitigating the Effects of Motion in EPI Time Series John M. Ollinger1, Andrew L. Alexander1 1Waisman Laboratory for Brain Imaging, University of Wisconsin, Madison, WI, United States A model for image variance due to motion is developed and validated. It can be used minimize motion effects by optimizing EPI sequence parameters. In general, variance is minimized by minimizing the partial derivative of the steady-state magnetization along the slice axis. In particular, sidelobes contribute much of the noise at high flip angles; an optimum flip angle exists for a specified degree of motion and can be computed; and inter-slice gaps increase variance due to motion rather than decrease it. 1087. Quantitative Evaluation of FMRI Acquisition Strategies at 7T Using NPAIRS Robert L. Barry1,2, J Christopher Gatenby1,2, Allen T. Newton1,2, Stephen C. Strother3,4, John C. Gore1,2 1Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 2Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 3Rotman Research Institute of Baycrest, Toronto, ON, Canada; 4Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada Although 2D single-shot EPI is common in BOLD fMRI, recent studies have suggested that 3D multi-shot sequences such as PRESTO-SENSE may offer superior BOLD CNR through improved temporal efficiency. A four-way comparison was performed between 2D and 3D acquisition sequences at two voxel resolutions (1.19x1.19x2 mm3 and 2.19x2.19x2 mm3) at 7T. The quality of fMRI data was evaluated via independent and unbiased metrics of prediction and reproducibility using NPAIRS. Results suggest that EPI provides higher prediction and reproducibility for this study. Future work will investigate within-subject optimization, and further compare EPI with PRESTO-SENSE for an fMRI study requiring whole-brain coverage. 1088. The Effect of Parallel Imaging on the Sensitivity of BOLD Signal to Physiological Noise Tomas Jonsson1, Tie-Qiang Li1 1Department of Medical Physics, Karolinska University Hospital, S-141 86, Stockholm, Sweden The sensitivity to physiological noises of the reconstructed BOLD MR images is altered by the employed parallel imaging strategies. In this study, we mapped and compared the physiological noise sensitivity of BOLD fMRI data acquired with and without employing parallel imaging at two different spatial resolutions. Using higher spatial resolution reduces the signal strength and the relative sensitivity to physiological noise. This can be of SNR advantage particularly for time series fMRI data acquired at higher magnetic field. 1089. Multi-Slice Two- And Four-Fold Acceleration with Single- And Eight-Channel Coils, Respectively Andrzej Jesmanowicz1, Shi-Jiang Li1, James S. Hyde1 1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States Complex-valued tailored pulses have been used in an EPI sequence to excite two or more slices in human brain using a whole-brain transmit coil. One or more members of a receive-coil array have been used to acquire multi-channel image data. Complex-valued coil profiles have been used to recover slices, and parallel image formation has been demonstrated. Acceleration by a factor of 4 has been achieved with an eight-channel head coil. 1090. Detecting Single Cortical Column Activation Under Super High Spatial Resolution at 9.4 T Using Single-Shot Half K-Space GR-EPI Rupeng Li1, Patrick Hettinger2, Younghoon Cho1, Christopher P. Pawela1, Ji-Geng Yan2, Andrzej Jesmanowicz1, Anthony Hudetz3, Hani Matloub2, James Hyde1 1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, United States; 3Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States Single-shot half k-space GR-EPI sequence was used to push the BOLD imaging resolution to 300 micron cubic voxel and unique single column cortical activation in the sensory cortex was detected when stimulating the middle phalange of all 8 digits of rat. 1091. Development and Evaluation of Alternative Imaging Methods for FMRI at 7 Tesla John Sexton1,2, Jascha Swisher3, Frank Tong3, Baxter Rogers1,2, J Christopher Gatenby1,4, John C. Gore1,4 1Vanderbilt University Institute of Imaging Science, Nashville, TN, United States; 2Biomedical Engineering, Vanderbilt University, Nashville, TN, United States; 3Psychology, Vanderbilt University, Nashville, TN, United States; 4Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States We compare single-shot gradient-echo 2D-EPI, multi-shot gradient-echo 3D-FFE and multi-shot gradient-echo 3D-PRESTO in a polar angle retinotopic mapping experiment at four isotropic resolutions (1.12mm3, 1.67mm3, 2mm3, and 3mm3) at 7 Tesla. Retinotopic maps in agreement with literature were obtained at all resolutions. The 3D sequences provided similar BOLD sensitivity and significantly less distortion compared to 2D-EPI. In addition, 3D-PRESTO provided much higher temporal resolution than 2D-EPI. Our findings suggest rich potential for high-resolution 3D imaging sequences in retinotopic mapping and other functional MRI experiments at high field. 1092. What Is the Optimum FMRI Procedure with Auditory Stimulation? Karsten Mueller1, Toralf Mildner1, Tom Fritz1, Joeran Lepsien1, Christian Schwarzbauer2, Harald E. Möller1 1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Aberdeen Biomedical Imaging Centre, University of Aberdeen, United Kingdom To present auditory stimuli in the absence of scanner noise, the sparse temporal sampling (STS) approach was introduced. The interleaved-silent steady-state (ISSS) technique is combining the idea of splitting image acquisition and stimulus presentation with a better sampling of the fMRI signal. We performed an auditory experiment with pleasant and unpleasant stimuli using four fMRI sessions: STS, ISSS, and simultaneous stimulus presentation and image acquisition with axial and sagittal scanning. The total acquisition time was the same in all four sessions. The best sensitivity for detecting activations of sub-cortical regions (such as the amygdala) was found for ISSS. 1093. Feasibility of BOLD Magnetic Resonance Imaging of Lung Tumors at 3T Qing Yuan1, Yao Ding1, Rami R. Hallac1, Paul T. Weatherall1, Robert Doug Sims1, Thomas Boike2, Robert Timmerman2, Ralph P. Mason1 1Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States; 2Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States It is expected that BOLD MRI should be sensitive to tumor vascular oxygenation. In lung tumors BOLD MRI is challenging due to potential image artifacts from motion, blood flow, and susceptibility. The goal of this preliminary study was to optimize the BOLD imaging technique at 3T in patients with untreated lung cancer. A respiratory-gated multi-echo gradient-echo technique is demonstrated as a feasible method to quantify T2* values of lung tumors. The response of tumor T2* measurements to an oxygen-breathing challenge should be sensitive to tumor hypoxia and could therefore serve as a prognostic indicator before therapy. 1094. Interleaved T1- And T2*-Weighted Imaging Can Evaluate Dynamic Oxygen Challenge: A Feasibility Study Yao Ding1, Ralph P. Mason1, Qing Yuan1, Rami R. Hallac1, Roderick W. McColl1, Robert D. Sims1, Paul T. Weatherall1 1Radiology, UT southwestern medical center at Dallas, Dallas, TX, United States The present 2D respiratory-triggered interleaved T1- and T2*-weighted sequence provides a promising means to study TOLD and BOLD response simultaneously without the need for registration and with good temporal resolution (less than 30 seconds). 1095. Does the BOLD Response to EPI-Related Acoustic Noise Change Over an FMRI Experiment? Oliver Hinds1, Aaron Hess2, M. Dylan Tisdall3, Todd Thompson1, Hans Breiter3, André van der Kouwe3 1A. A. Martinos Imaging Center at the McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA, United States; 2Human Biology, University of Cape Town, Cape Town, South Africa; 3A. A. Martinos Center for Biomedical Imaging, Department of Radiology, MGH, Harvard Medical School, Charlestown, MA, United States If the BOLD response to EPI acoustic noise changes over the time course of a standard fMRI experiment, both Type I and Type II errors can be made in fMRI group analysis. We used a pulse sequence based on single-voxel functional spectroscopy to silently measure the BOLD response induced by EPI-like scanner noise over about 40 minutes. No significant habituation or facilitation with respect to the scanner noise was found over that time. This result eliminates a possible confound for auditory and speech neuroimaging studies, especially those involving learning. 1096. Reproducibility of FMRI Localisation Within the Human Somatosensory System. Rishma Vidyasagar1, Laura M. Parkes2,3 1MARIARC, University of Liverpool , Liverpool, Merseyside, United Kingdom; 2School of Cancer and Imaging Sciences, University of Manchester; 3Biomedical Imaging Institute, University of Manchester, Manchester, United Kingdom fMRI data can often be affected by issues such as registration and scanner system errors. These issues affect interpretation of data and is especially relevant in longitudinal studies depending on accurate reproducibility of data. This study compared different analysis techniques of fMRI data to establish the most accurate means of overcoming these issues by focusing on fMRI data from the somatosensory system in the human brain. 1097. Real Time FMRI – Avoiding Drift Using Answer Blocks Thomas WJ Ash1, T Adrian Carpenter1, Guy B. Williams1 1Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom Where real time fMRI needs solely a digital (e.g., task vs rest or task 1 vs task 2) output, answer blocks can provide a means of circumventing the drift that is known to affect results. Using answer blocks, we improve performance compared to averaging over a block using classifiers from 53% to 84%, and using ROI techniques from 53% to 64%. This also gives a means for presenting probabilistic outputs to class membership, which are vital when dealing with impaired patients, for whom this kind of technique may be their only communication channel. 1098. Simultaneous Optical Tomography (OT) and FMRI with and Without Task Activation Jan Mehnert1,2, Christoph Schmitz2,3, Harald E. Möller1, Hellmuth Obrig1,2, Karsten Müller1 1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Berlin Neuroimaging Center, Charité University Hospital Berlin, Berlin, Germany; 3NIRx Medizintechnik GmbH, Berlin, Germany Correlation analysis of low-frequency fluctuations in blood-oxygen level dependent (BOLD) fMRI data is known to yield functional connectivity maps. The procedure, also referred to as ‘resting-state connectivity’, has previously been applied to optical tomography (OT) data using dense probe arrays. Here, we assess whether a sparser topographical sampling still yields results that are comparable to the ‘gold standard’ of resting-state network assessment, i.e. fMRI. In a first step, we used a subset of optical fibers (2-3cm inter-optode distance) covering both motor cortices and combined OT with concurrent fMRI measurements to cross-validate our resting-state data analysis. 1099. High Resolution Functional MR Venography with 7T MRI Seo-Hyun Lee1, Chang-Ki Kang1, Chan-A Park1, Young-Bo Kim1, Zang-Hee Cho1,2 1Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea, Republic of; 2Department of Radiological Sciences, University of California, Irvine, Irvine, CA, United States MR venography using susceptibility weighted imaging (SWI) has been utilized for the study of venous morphology and the venous vasculature in disease states. However, SWI has poor intrinsic temporal resolution, thus it is not able to provide information on high temporal dynamic changes within a few seconds that occur during neural stimulation. In this paper, we proposed a technique, which we labeled functional MR venography (fMRV), to investigate the venous dynamic response to external stimulation using 7T MRI. The presented result suggests that this technique may provide important, more precise information regarding the venous response and its role in the overall hemodynamic response to neural activity with high spatial (0.5 isotropic) and temporal (3 seconds) resolution. 1100. The Orbitofrontal FMRI Experiment with Correction of the Susceptibility Artifact Sung Suk Oh1, SungDae Yun1, Bumseok Jeong2, HyunWook Park1 1Department of Electrical Engineering, KAIST, Daejeon, Korea, Republic of; 2Department of Psychiatry, Eulji University Hospital, Daejeon, Korea, Republic of The signal loss by the susceptibility artifact makes it difficult analyze the fMRI data of the orbitofrontal region of the brain. In addition, an EPI sequence, which is used in many fMRI experiments, has the geometric distortion and Nyqust ghosts. For the fMRI experiment with correction of these artifact and distortion, we used a flat RF pulse which provides nearly constant signal intensity against the magnetic susceptibility and a gradient echo sequence. In the result, it is shown that the signal loss in the orbitofrontal region of the brain is recovered without geometric distortion and Nyqust ghosts and the activation in that region was analyzed successfully. 1101. Concurrent Transcranial Direct Current Stimulation (TDCS) and Functional MRI Reveals Modulatory Effects on Brain Activation During a Simple Motor Task Peter Dechent1, Rafael Polania2, Carsten Schmidt-Samoa1, Walter Paulus2, Andrea Antal2 1MR-Research in Neurology and Psychiatry, University Göttingen, Göttingen, Germany; 2Department of Clinical Neurophysiology, University Göttingen, Göttingen, Germany Anodal/cathodal tDCS have facilitatory/inhibitory effects, respectively, on the stimulated cortical networks. Here we used concurrent tDCS-fMRI to test whether anodal/cathodal tDCS result in BOLD-fMRI signal changes during a resting condition. Furthermore, we examined tDCS-effects on brain activation during voluntary finger tapping. Anodal/cathodal tDCS over left M1 induced no detectable BOLD signal change. However, anodal/cathodal tDCS combined with finger tapping resulted in a decreased BOLD response in SMA, but not M1, in comparison to voluntary finger tapping without stimulation. This suggests that in contrast to the rest condition the combination of neuronal polarization and motor activation induces inhibition in remote brain areas. 1102. High-Resolution Fingersomatotopy at 7T Using HGS-Parallel Technique SungDae Yun1, Jun-Young Chung2, Hyo Woon Yoon3, Zang-Hee Cho3, HyunWook Park1 1Department of Electrical Engineering, KAIST, Daejeon, Korea, Republic of; 2Neuroscience Research Institute, Gachon University of Medicine and Science , Incheon, Korea, Republic of; 3Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea, Republic of In a high field MRI, improvements in SNR and image quality are very noticeable, even though there are some drawbacks such as increased field inhomogeneity and relatively short T2*. For EPI-based methods, these drawbacks are major challenges in performing fMRI. To reduce such problems, we employed the HGS-Parallel technique as an fMRI imaging method which used the conventional gradient echo. This sequence is relatively robust to field inhomogeneity and the T2* decay than the EPI. With the HGS-Parallel technique, we performed an fMRI experiment at a 7T for mapping the finger somatosensory area in a high quality and resolution form. 1103. Effectiveness of Mental Imagery Strategy in Controlling an Activation of the Left Middle Frontal Gyrus: Biofeedback Study Based on the Real-Time FMRI Mikhail Zvyagintsev1,2, Yury Koush3, Miriam Dyck3, Klaus Mathiak3 1IZKF, RWTH Aachen University, Aachen, NRW, Germany; 2Psychiatry, RWTH Aachen University, Aachen, NRW, Germany; 3Psychiatry, RWTH Aachen University, Germany Biofeedback based on a real-time fMRI is a promising tool especially in clinical research. In this study we show feasibility of controlling the left middle frontal gyrus by using mental imagery strategy. 1104. Sensitivity and Spatial Specificity of Multiple Phase-Cycled Pass-Band BSSFP FMRI at 9.4T Sung-Hong Park1,2, Tae Kim1, Ping Wang1, Timothy Q. Duong2, Seong-Gi Kim1 1Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 2Research Imaging Institute, Ophthalmology/Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States We performed high-resolution pass-band bSSFP fMRI at multiple phase cycling angles on rat brain at 9.4T. Activation foci in fMRI maps shifted as a function of phase cycling angle and the location of the foci was correlated with hyperintense regions in corresponding baseline transition-band bSSFP, some of which were also correlated with cortical surface veins or intracortical veins. The results indicated that there is spatial heterogeneity in signal sources (T2 or T2*) of pass band bSSFP fMRI. Baseline transition band bSSFP could be used to predict outcomes of corresponding pass-band bSSFP fMRI maps. 1105. Interleaved TMS/CASL: State Dependence of Repetitive TMS Effects on the Dorsal Premotor Cortex Marius Moisa1, Rolf Pohmann1, Hartwig Roman Siebner2, Axel Thielscher1 1Max Planck Institute for Biological Cybernetics, Tübingen, BW, Germany; 2Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, Copenhagen, Denmark We have recently demonstrated the technical feasibility and the potential advantages of combining transcranial magnetic stimulation (TMS) with continuous arterial spin labeling (CASL) imaging. Here, we use this novel approach to assess the effects of repetitive TMS applied to the left dorsal premotor cortex (PMd) on rCBF (regional cerebral blood flow) during different motor states. The state-dependent effects of left PMd rTMS on rCBF, is in concordance with previous results using BOLD imaging and a different task. As a next step, we will analyze the time dependence of the observed TMS effects across the different experimental blocks of one run. 1106. Development of Simulator Training to Reduce Head Motion Artifact in FMRI Shawn Ranieri1,2, Shaun Boe3, Fred Tam1, Lauren Gordon4, Tara Dawson1, Jon Ween5, William McIlroy6, Simon J. Graham1,7 1Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, ON, Canada; 2Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada; 3Toronto Rehabilitation Institute, Toronto, ON, Canada; 4Faculty of Health Sciences, Queen's University, Kingston, ON, Canada; 5Kunin-Lunenfeld Applied Research Unit , Brain Health Complex, Toronto, ON, Canada; 6Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada; 7Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada There has been a longstanding need to develop techniques that improve data quality in fMRI by suppressing motion artifact. Head motion exceeding a few millimetres remains problematic and high interest participants including motor stroke patients often exceed this threshold. Here, a new technique is described that attempts to reduce participant head motion through visual feedback training in an fMRI simulator. Results from three stroke patients show that simulator training had a significant effect in suppressing head motion: (1) 11.25 mm before, 0.83 mm after; (2) 1.63 mm before, 0.67 mm after; (3) 4.47 mm before, 0.51 mm after. 1107. Scan Time Reduction in FMRI Using a 32 Channel Phased Array Receive Coil Christina Triantafyllou1,2, Sheeba Arnold1, Steven Shannon1, John Gabrieli3, Susan Whitfield-Gabrieli3 1A.A. Martinos Imaging Center, McGovern Institute for Brain Research, MIT, Cambridge, MA, United States; 2A.A. Martinos Center for Biomedical Imaging, Department of Radiology, MGH, Charlestown, MA, United States; 3Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, United States Long durations in fMRI are typical, but that is unfeasible for specific populations. Scan-time reduction is possible if one could capitalize on the increased sensitivity afforded by high field strength or multiple channel phased arrays in the high-resolution regime. We evaluated this using a 32-channel coil at 3T with the n-back task on 18 subjects. Compared to 12-channel coil, working memory activation was significantly more (paired t-test) with two-thirds of the 32-channel data. Combination of 32-channel coil and high-resolution could imply lesser sample size, prevent additional data collection and enable studies that would otherwise be impossible due to time restrictions. 1108. Multi-Sequence Comparison of Temporal Lobe FMRI Activation at 4.0 T Lindsay Cherpak1,2, Kimberly Brewer1,2, Jodie Gawryluk1,3, Nicole Pelot1,2, Chris Bowen1,4, Ryan D'Arcy1,3, Steven Beyea1,4 1Institute for Biodiagnostics (Atlantic), National Research Council of Canada, Halifax, Nova Scotia, Canada; 2Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada; 3Psychology, Dalhousie University, Halifax, Nova Scotia, Canada; 4Physics and Atmospheric Science, Radiology and Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada This study involved a comprehensive evaluation of commonly-used techniques like EPI and spiral-out, as well as techniques designed to recover signal in SFG regions using BOLD methods (spiral-in, spiral-in/out, spiral-in/in and ASE spiral) and non-BOLD methods (FAIR and spin-echo spiral-in/out) at 4.0 T. A cognitive task used to evaluate temporal lobe epilepsy patients was presented to elicit activation in the inferior temporal lobe (as well as other brain regions). Notably, this work allowed us to examine the differing effects that the contrast and signal recovery mechanisms have on fMRI activation in both SFG and non-SFG regions. 1109. Time Resolved FMRI: 100 Ms Resolution in Time for Extended Network Analysis of the Human Brain Julia Reinhardt1,2, Ernst Nennig3, Stephan Walther4, Sabine Heiland2, Christoph Stippich1,2 1Department of Neuroradiology, University of Basel Hospital, Basel, Switzerland; 2Division of Neuroradiology, Department of Neurology, University of Heidelberg, Medical Center, Heidelberg, Germany; 3OptiMed Medizinische Instrumente GmbH, Ettlingen, Germany; 4Center for Psychosocial Medicine, General Psychiatry, University of Heidelberg, Medical Center, Heidelberg, Germany Until now the temporal resolution in fMRI was mostly restricted by the used TR. Employing a new method to enhance the time resolution in fMRI below 100 ms we are able to trace neuronal network pathways with extremely short reaction times. The temporal dynamics of somatosensory processing could be measured and correspond with the known values from electrophysiological measures. With this new approach BOLD-fMRI enables to study the temporal dynamics of cortical processing with a temporal resolution of 10 ms. 1110. Evaluating Feraheme as a Potential Contrast Agent for Clinical IRON FMRI Joseph B. Mandeville1, Krishna Srihasam2, Wim Vanduffel1, Margaret S. Livingstone2 1Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States; 2Department of Neurobiology, Harvard Medical School, Boston, MA, United States Feraheme is a newly FDA-approved drug for treating chronic iron anemia in clinical populations. The approved iron dose of 510 mg falls within a weight-normalized range of 5-10 mg/kg for human subjects within the range 50-100 kg. To evaluate this drug as a potential contrast-enhancing agent for human clinical fMRI, we performed experiments in awake non-human primates at 3 Tesla to validate theoretical calculations. Results suggest that this agent could enhance the CNR ratio of clinical fMRI by factors of 5 and 2.5 and 1.5 at 3 Tesla, respectively. 1111. Reproducibility of T1 and Tissue Fractional Volume Mapping Using FRASIER: An Application to FMRI Settings Wanyong Shin1, Hong Gu1, Yihong Yang1 1Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, United States Recently, FRActional Signal mapping from InvErsion Recovery (FRASIER) was proposed to map T1 and tissue fractional volume in the brain. In this study we incorporated FRASIER into an fMRI protocol and assessed the reproducibility of the technique. Using FRASIER, 15 slice T1 and fractional volume maps were acquired in every 10 seconds with 64¡¿64 matirx size. Standard deviations of the T1 and fractional volume maps was within 37ms and 3.5% in this study, demonstrating feasibility of FRASIER in fMRI settings. 1112. Functional MRI on an Open 1.0 T MRI Scanner: A Comparison with a State-Of-The-Art 3.0 T MRI Scanner Elsmarieke van de Giessen1, Paul F.C. Groot2, Jan Booij1, Wim van den Brink3, Dick J. Veltman3, Aart J. Nederveen2 1Nuclear Medicine, Academic Medical Center, Amsterdam, Netherlands; 2Radiology, Academic Medical Center, Amsterdam, Netherlands; 3Amsterdam Institute for Addiction Research, Academic Medical Center, Amsterdam, Netherlands This study is the first, to our knowledge, that tests the feasibility of fMRI on an open MRI system, with a magnetic field strength of 1.0 T, and compares the results with fMRI on a state-of-the-art 3.0 T MRI scanner. The optimal echo time for fMRI on an open 1.0 T MRI system was found to be around 70 ms. Results show that fMRI on an open 1.0 T MRI scanner is feasible for studies that are designed to analyze data at a group level, though not optimal for studies on single subjects. Yüklə 4,25 Mb. Dostları ilə paylaş:
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