27th ISMRM Annual Meeting • 11-16 May 2019 • Montréal, QC, Canada

Digital Poster Session
Contrast Mechanisms

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Thursday, 16 May 2019
Digital Poster

Imaging Myelin+
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Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

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QSM
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Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

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Pseudo-Continuous & Velocity-Selective ASL
Digital Poster
Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

 Computer # 4944. 51 Cerebral spin compartmentalization based on biexponential modeling of T2-prepared pCASL 3D GRASE data Martin Schidlowski, Markus Boland, Theodor Rüber, Tony Stöcker In this work, a pCASL sequence with T2 preparation module and 3D GRASE readout was developed. We present a novel approach to estimate the spin compartment of labeled protons by a voxel-wise and biexponential fit to whole-brain ASL data. This method allows for the spatial quantification of intra- and extravascular spin fractions of the ASL signal as well as their temporal evolution. 4945. 52 Combined estimation of dispersion and macrovascular signal in multi-PLD pCASL data using a two-component model Merlijn van der Plas, Michael Chappell, Matthias van Osch In pCASL a well-defined, box-shaped bolus is created at the labeling plane and for quantification this shape is assumed to be preserved, however, in reality this shape will be dispersed. With multi-timepoint data, the effects of dispersion can be observed in the macrovascular component, which can be separated from the tissue component using a two-component model. In this study the combined estimation of dispersion and macrovascular signal was investigated. When a gamma distribution dispersion kernel was incorporated into the two-component model, a significant decrease in CBF values was found, while a significant increase in macrovascular signal was observed. 4946. 53 Robust arterial transit time estimation using combined acquisition of Hadamard-encoded pCASL and long-labeled long-delay pCASL: a simulation and in vivo study Shota Ishida, Hirohiko Kimura, Naoyuki Takei, Yasuhiro Fujiwara, Tsuyoshi Matsuda, Masayuki Kanamoto, Nobuyuki Kosaka, R Lebel, Toshiki Adachi A combination scan of 3-delay Hadamard-encoded pseudo-continuous ASL (H-pCASL) and single-delay pCASL with long labeling duration and long post-labeling delay was proposed as the robust arterial transit time (ATT) estimation for prolonged ATTs. Simulation showed that the mean normalized error of the proposed method was small for a wide range of ATTs compared to that of H-pCASL alone. In in vivo experiments, ATTs were not significantly different among the methods. However, 7-delay H-pCASL presented a lower ATT and larger variance. The proposed method improves the robustness of ATT estimation for prolonged ATTs with practical acquisition times in the clinical framework. 4947. 54 Assessment of Hepatic Perfusion Before and After a Meal Challenge Using Pseudo-Continuous Arterial Spin Labeling in MRI: Comparison with Intravoxel Incoherent Motion and Phase Contrast Saori Watanabe, Takashi Hamaguchi, Naoki Ohno, Yudai Shogan, Yu Ueda, Tadanori Takata, Satoshi Kobayashi, Tosiaki Miyati, Toshifumi Gabata To assess hepatic blood flow (HBF) with a noninvasive method, we acquired HBF flow before and after meal ingestion using the pCASL method. In addition, we investigated the relationship of HBF, perfusion-related diffusion coefficient (D*) with intravoxel incoherent motion and portal vein blood flow (PVBF) with phase contrast. For each value of HBF, D*, and PVBF following meal ingestion increased significantly compared with the values prior to ingestion. However, there were no correlations between hepatic blood flow, perfusion-related diffusion coefficient, or portal flow with either pre- or post-ingestion. 4948. 55 Influence of labeling parameters of velocity selective arterial spin labeling for renal perfusion imaging Isabell Bones, Suzanne Franklin, Anita Harteveld, Matthias van Osch, Jeroen Hendrikse, Chrit Moonen, Marijn van Stralen, Clemens Bos Velocity selective arterial spin labeling (VSASL) is a spatially non-selective method that labels spins based on their flow velocity, thereby labeling closer to the target tissue, reducing the influence of arterial transit time (ATT) and requiring no planning. In the abdomen, motion and complex vascular anatomy might, however, require dedicated VS-labeling parameters. We assessed the feasibility of VSASL for renal perfusion measurement by investigating its dependency on essential labeling parameters, and by comparing it with pseudo-continuous ASL (pCASL) as a spatially-selective reference ASL-technique. Our results show, that with carefully chosen sequence parameters, VSASL is feasible for renal perfusion measurement. 4949. 56 Enabling free-breathing renal pCASL with background suppression and motion correction: a comparison with paced-breathing Isabell Bones, Anita Harteveld, Suzanne Franklin, Matthias van Osch, Jeroen Hendrikse, Chrit Moonen, Clemens Bos, Marijn van Stralen Renal perfusion imaging using arterial spin labeling (ASL) is challenged by respiratory motion and physiologic noise, often dealt with by breathing instructions requiring patient cooperation. We investigated if background suppression (BGS) combined with image registration, guided by the ASL-images themselves or additionally acquired fat-images, would enable free-breathing renal ASL. To this end, free-breathing ASL was compared with paced-breathing ASL, both including BGS and image registration. BGS and registration improved the quality of free-breathing renal pCASL, showing increased temporal SNR similar to paced-breathing ASL, without reducing perfusion-weighted signal. In conclusion, free-breathing renal pCASL is possible when employing BGS and image registration. 4950. 57 Quantification of intracranial vascular compliance using multi-PLD pseudo-continuous arterial spin labeling with retrospective cardiac gating Soroush Heidari Pahlavian, Mayank Jog, Samantha Ma, Danny Wang, Lirong Yan Intracranial vascular compliance (IVC) is an important factor in regulating the cerebral perfusion pressure and is believed to be linked to multiple neurological disorders. In this study, a retrospectively-gated multi-PLD pCASL technique was used to estimate arterial cerebral blood volume (aCBV) and compliance. Our results showed that this technique can quantify cardiac-induced variations of aCBV as well as IVC distribution maps. 4951. 58 Exploring dynamic RF shimming for labelling in PCASL at 7T Christopher Mirfin, Paul Glover, Richard Bowtell Despite the intrinsic SNR gains at 7T, pseudo-continuous arterial spin labeling (PCASL) is limited by poor |B+1|$|{B}_{1}^{+}|$ coverage in the labelling plane and the associated high local SAR of the sequence. In this work we perform simulations to consider the usefulness of dynamic RF shimming using a commercially available head-only RF coil equipped with 8-transmit channels, for labelling in PCASL. 4952. 59 Comparison of multi-delay renal PASL-FAIR and pCASL perfusion quantification at 3T Anita Harteveld, Anneloes de Boer, Suzanne Franklin, Tim Leiner, Marijn van Stralen, Clemens Bos ASL has emerged as a non-invasive tool for measuring renal perfusion. Whereas in the brain consensus leans towards pCASL as the preferred labeling strategy, in the kidney PASL-FAIR has been reported on most. A systematic comparison of renal PASL-FAIR and pCASL perfusion measurement was performed at 3T in 16 volunteers, with separate visits to assess repeatability. PASL-FAIR perfusion values were significantly higher than those obtained with pCASL. Moreover, at 3T PASL-FAIR had approximately 2-3 times better repeatability compared to pCASL. 4953. 60 Beyond the consensus: what to include when 5 minutes are available for perfusion imaging by PCASL? Piet Bladt, Matthias van Osch, Eric Achten, Arnold den Dekker, Jan Sijbers While the consensus statement on the recommended implementation of arterial spin labeling (ASL) has advanced ASL to clinical application, variations in labeling efficiency, longitudinal relaxation time of blood and arterial transit times can cause significant quantification errors. With simulation experiments, it is shown that sacrificing ASL scan time for measurements of these parameters improves the estimation reproducibility of the cerebral blood flow on a population level. Furthermore, multi-delay ASL modalities in combination with these extra measurements can compete with or outperform the single-delay consensus implementation in terms of estimation accuracy and precision, depending on the underlying distribution of transit times. 4954. 61 Optimization of Pseudo Continuous Arterial Spin Labeling for renal ASL Rebeca Echeverria-Chasco, Marta Vidorreta, Verónica Aramendía-Vidaurreta, Gorka Bastarrika, María A. Fernández-Seara Arterial Spin Labeling (ASL) is a non-contrast MR perfusion imaging technique. Pseudo continuous ASL (pCASL) is one of its recomended implementations. The efficiency of pCASL has been shown to be dependent on velocity and magnetic field variations. pCASL was assessed through simulations for the measured velocities in the aorta and including off-resonance effects. Five volunteers were imaged with different average gradient to ratio combinations. The results showed that aorta velocities and off-resonance effects shifted the efficiency towards lower ratios and to a constrained smaller range of gradients. A p-value of 0.04 demonstrated that differences in efficiency were significant across Gave values. 4955. 62 Alternative Slice Acquisition Orders for High-Resolution MB-EPI PCASL Imaging with Background Suppression Xiufeng Li, Dingxin Wang, Gregory Metzger, Essa Yacoub, Kamil Ugurbil Relative static tissue signal differences between neighboring slices across slice bands in MB-EPI PCASL imaging with background suppression (BS) are dramatically larger than those in MB-EPI PCASL imaging without BS, and can result in severe subtraction errors/artifacts for imaging data with large subject motion that sometimes cannot be corrected or removed by motion correction. To resolve this issue, alternative slice acquisition orders are proposed and evaluated. Our results suggest that the proposed alternative slice acquisition orders can improve the robustness of MB-EPI PCASL imaging with BS, providing comparable CBF estimates with minimized subtraction errors. 4956. 63 Implementation and validation of ASL perfusion measurements for population-based imaging Esther Warnert, Rebecca Steketee, Meike Vernooij, Mika Vogel, Juan-Antonio Hernandez-Tamames, Gyula Kotek Pseudocontinuous ASL (pCASL) is an ideal tool for non-invasive perfusion measurements in population-based imaging studies, which require longitudinal scanning with an unchanging MRI hardware and software set-up. Herein we present the results of the implementation and validation of a 3D pCASL sequence for use in the Rotterdam Study, running since 2005. 4957. 64 Investigation of the effects of age and gender on normal cerebral blood flow in infants using arterial spin labeling MRI KEKE ZHAO, ZHUANQIN REN, Xiaocheng Wei  This study systematically revealed normal values of cerebral blood flow (CBF) in different age groups of infants using three-dimensional pseudocontinuous arterial spin labeling (3D PCASL) technique. Our results demonstrated a significantly lower CBF value in neonates than in other age groups. We also found a significant positive correlation between age and various regional mean gray matter (GM) and white matter (WM) CBF values in infants. Taken together, our findings demonstrated benefits of the application of the infants perfusion imaging technology to the clinical field by using arterial spin labeling (ASL) to provide information of metabolic status and neurodevelopmental outcomes. 4958. 65 Arterial spin labeling reveals altered cerebral vascular reactivity to carbon dioxide challenge in Q175 mouse model of Huntington's disease Somaie Salajeghe, Johan Van Audekerke, Verdi Vanreusel, Dorian Pustina, Longbin Liu, Mette Skinbjerg, Celia Dominguez, Ignacio Munoz-Sanjuan, Annemie Van der Linden, Marleen Verhoye CVR deficits can cause a negative effect on neurovascular coupling leading to blood delivery impairment in activated brain regions. As such, impaired CVR may lead to neural degeneration over a period of time. We measured CBF and CVR using pCASL in Q175 mouse model of Huntington’s disease (11 transgenic and 10 wild-type at 15 month). In order to measure CVR, we measured changes in CBF during a 10% CO2 vascular challenge. The results indicated an overall decreased CVR in transgenic compared to wild-type mice. 4959. 66 Pseudo-continuous arterial spin labeled renal perfusion imaging at 3T with improved robustness to off-resonance Joshua Greer, Yiming Wang, Ivan Pedrosa, Ananth Madhuranthakam Pseudo-continuous arterial spin labeling (pCASL) has been applied for renal perfusion imaging, where inflowing blood is labeled in the descending aorta, just above the kidneys. However, in some cases when the labeling plane is positioned close to the lungs, significant decreases in SNR have been observed. We hypothesized that this was due to decreased labeling efficiency caused by the off-resonance effects near the lungs. In this study, an unbalanced pCASL gradient scheme that was optimized to be more robust to B0 inhomogeneities was compared with default implementations of pCASL at different labeling locations along the descending aorta. 4960. 67 Convolutional Neural Network based Automatic Planning for Pseudo-Continuous Arterial Spin Labeling Michael Helle, Thomas Lindner, Karsten Sommer Pseudo-continuous arterial spin labeling (pCASL) requires careful planning of the labeling plane to achieve high labeling efficiency, which makes the quality of the imaging results dependent on the experience of the operator. Here we demonstrate the feasibility of using a convolutional neural network to automatically predict an appropriate labeling position based on angiography images, thereby allowing for fully automatic pCASL perfusion scans. 4961. 68 Assessing Morphology of Cerebral Macro- and Microvasculature Using Dynamic Perfusion Tensor Imaging ASL Leonie Petitclerc, Suzanne Franklin, Lydiane Hirschler, Matthias van Osch Time-encoded pseudo-continuous ASL was combined with bipolar crusher gradients to measure a time-resolved perfusion tensor of the brain vasculature. Gradients provided a high degree of attenuation of the intravascular signal which increased with greater gradient strength and decreased (down to 25%) at long post-labeling delays (PLDs). Perfusion tensor images showed correspondence with known structures such as the anterior cerebral artery and the circle of Willis. Fractional anisotropy of perfusion remained elevated and increased with longer PLDs. Adjustments in gradient strength and time-encoding scheme may permit the imaging of microvascular structure. 4962. 69 Compensating T2 blurring in 3D TSE with Cartesian acquisition based arterial spin labeled MRI Yiming Wang, Joshua Greer, Trevor Wigal, Marco Pinho, Joseph Maldjian, Ananth Madhuranthakam 3D fast/turbo spin echo (FSE/TSE) acquisitions are preferred for arterial spin labeled (ASL) MRI due to their higher SNR and compatibility with background suppression. However, 3D TSE suffers from T2 blurring caused by the T2 decay of the ASL signal along the prolonged echo train lengths, which may degrade image quality. This is often more noticeable in 3D TSE with Cartesian acquisitions. In this study, a truncated k-space filter is designed to compensate the T2 blurring of 3D TSE with Cartesian acquisitions and improve sharpness of ASL brain perfusion images. 4963. 70 Robust and SAR-efficient whole-brain pseudo-continuous ASL at 7T Markus Boland, Rüdiger Stirnberg, Eberhard Pracht, Tony Stöcker In this work, a modified pseudo-continuous ASL sequence is presented, which reduces the SAR deposition by ~50% and provides robust labeling efficiency in the presence of off-resonances between -300Hz and 300Hz. The sequence was successfully tested on two coils with different coverage of the neck region at two labeling positions. The method allows PCASL experiments at UHF without a pre-scan in significantly reduced scan time and, therefore, exploits the advantage of UHF for perfusion imaging. 4964. 71 Optimization of Velocity-Selective-Inversion Arterial Spin Labeling (VSI-ASL) with 3D Whole-Brain Coverage Dapeng Liu, Wenbo Li, Doris Lin, Peter Zijl, Qin Qin Velocity-selective arterial spin labeling (VSASL) has the advantage of insensitivity to transit time delay compared to the spatially selective method, thus potentially providing more accurate and robust blood flow measurements in cerebrovascular diseases. Fourier-transform based velocity-selective inversion (FT-VSI) prepared ASL has higher sensitivity to perfusion signal than conventional velocity-selective saturation (VSS) prepared methods. To date, VSASL has largely been implemented with 2D EPI acquisitions. However, a 3D readout is preferred for ASL techniques. This study demonstrated the feasibility of FT-VSI prepared VSASL with 3D whole-brain coverage and compared it with conventional VSS ASL and pseudo-continuous ASL (PCASL) at 3T. 4965. 72 Optimal Strategies for CSF and Tissue Suppression in Velocity-Selective Arterial Spin Labeling Mu-Lan Jen, James Holmes, Kevin Johnson Velocity-selective arterial spin labeling (VS-ASL) inherently suffers from low signal-to-noise ratio (SNR) and contamination from cerebrospinal fluid (CSF) motion. This study aims to develop and evaluate optimal strategies for inversion based background suppression (BGS). Specifically, we investigate the influence of the timing of signal nulling and inflow from outside the region of interest. Our results suggest an optimized BGS which allows VS-ASL based measurement of cerebral blood flow maps with reduced CSF contamination while preserving sufficient perfusion signal. 4966 73 The influence of the cardiac cycle on Velocity Selective and Acceleration Selective Arterial Spin Labeling, using retrospective triggering.Video Permission Withheld Suzanne Franklin, Sophie Schmid, Clemens Bos, Matthias Van Osch In this study, the influence of the cardiac cycle on the amount of label produced by velocity-selective (VSASL) and acceleration-selective arterial spin labeling (AccASL) was investigated. A sequence combining pCASL and VSASL(AccASL) was developed to isolate the arterial blood pool. Results showed significant arterial signal fluctuations in the amount of label produced by VSASL, AccASL and pCASL over the cardiac cycle. Hence, in order to become independent of the cardiac cycle, sufficient averages need to be taken when applying these techniques. Alternatively, these findings could be highly interesting for the purpose of quantifying pulsatility higher up in the vascular tree. 4967. 74 Improved Velocity-Selective Labeling Pulses for Myocardial ASL Vanessa Landes, Terrence Jao, Ahsan Javed, Krishna Nayak Velocity selective ASL is an exciting option for myocardial perfusion imaging as it does not require any contrast agents and is insensitive to coronary arterial transit times.  Feasibility in humans was recently demonstrated with performance primarily limited by 1) spurious labeling of moving myocardium, and 2) low labeling efficiency. We present improvements to the velocity selective labeling pulse that overcome these limitations, leveraging recent developments in velocity-selective MRA.  Specifically, we use Fourier Velocity Encoding to reduce spurious labeling of moving myocardium and use inversion to increase labeling efficiency. 4968. 75 Venous Velocity Selective Inversion for improved selection of the venous blood pool for oxygen extraction fraction determination Sophie Schmid, Suzanne Franklin, Merlijn van der Plas, Matthias van Osch By combining pulsed ASL and Velocity Selective Inversion it is possible to selectively label the venous blood pool. This new method, dubbed venous velocity selective inversion (vVSI) could be used to measure the oxygen extraction fraction in the venous and arterial blood with a single scan.
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Relaxometry
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Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

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Novel Developments in CEST
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Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

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Perfusion & Permeability
Digital Poster
Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

 Computer # 5019. 126 Time-resolved super-selective Arterial Spin Labeling using a ternary matrix based labeling approach Thomas Lindner, Olav Jansen, Michael Helle This study presents a novel approach to simultaneously acquire vessel-selective and time-resolved perfusion images combining a ternary encoding matrix approach with self-controlled super-selective Arterial Spin Labeling. 5020. 127 Investigating Variability Sources in Kidney Perfusion Measurements with Pulsed ASL: A Phantom and In Vivo Pilot Study Jorge Chacon-Caldera, Lisa-Maria Hatz, Anja Kruse, Tanja Uhrig, Fabian Zimmer, Simon Hubertus, Ingo Hermann, Lothar Schad, Frank Zöllner In this work, the variations of a 3D GRASE sequence with a fast pulsed ASL protocol at 3T were tested in isolation using a phantom and in vivo measurements. In vivo, 25 single scans in breath hold with a single volunteer were obtained in one session, thus reducing breathing motion and registration uncertainties as well as shimming, inter-volunteer and hydration stage variabilities. In phantom, we found a perfusion of 94.5 ± 5.4 ml/min/100g and in vivo, we found perfusion values in the expected physiological range with high standard deviation inter-scans but high correlation between kidneys. This suggests physiological instead of signal-to-noise related variations which would yield random inter-kidney variations. 5021. 128 A Split-Label Design for Simultaneous Measurements of Perfusion in Distant Slices by Pulsed Arterial Spin Labeling Celine Baligand, Lydiane Hirschler, Thom Veeger, Suzanne Franklin, Matthias van Osch, Hermien Kan Most Arterial-Spin-Labeling (ASL-)MRI in exercised muscle employ single-slice acquisitions. However, fiber-type and oxidative capacity vary along the length of healthy muscles. Therefore, multi-slice acquisitions are desirable. Multi-slice pulsed ASL coverage is limited because the label is created proximally from the stack of slices. In muscle, this implies long transit times to the most distal slice due to slow flow. We propose a split-label design adaptation of FAIR that allows for sufficient labeling for distant slices. We validated our approach in the brain to take advantage of the high resting-state perfusion, and applied it in the lower leg muscle after exercise. 5022. 129 A Pipeline for ASL Quantification and Analysis using Inter-regional Differences and Machine Learning: Application to Young Onset Alzheimer’s Disease Jack Highton, Enrico De Vita, Jonathan Schott, David Thomas Arterial Spin Labelling (ASL) is an MRI method to measure cerebral blood flow with potential to assist early dementia diagnosis. Here, ASL data acquired from patients with young onset Alzheimer’s disease (AD) was analysed, using both a novel region based statistical approach and voxel based machine learning. This is the first study to analyse ASL data from patients with Posterior Cortical Atrophy using machine learning. Both approaches are shown to identify regions known to be affected by AD. Inter-region analysis suggests the parietal lobe is the most useful benchmark region, to separate region specific hypoperfusion from global perfusion changes. 5023. 130 Quantifying Blood Flow of Rat Spinal Cord Injury Using in vivo Flow-sensitive Alternating Inversion Recovery (FAIR) Seongtaek Lee, Natasha Wilkins, Brian Schmit, Shekar Kurpad, Matthew Budde Perfusion weighted MRI has been widely used as a non-invasive MR biomarker in brain imaging but its application to spinal cord imaging has been limited due to the inherent difficulties. In this study, we evaluated flow-sensitive alternating inversion recovery to quantify spinal cord blood flow (SCBF) in rat spinal cord with varying severities of contusion injury. A trend of decreasing SCBF was observed with greater injury severity, suggesting that arterial spin labeling may be useful as a reliable non-invasive indicator of spinal cord traumatic injury. Furthermore, T1 values demonstrated greater sensitivity to injury severity and functional outcomes. 5024. 131 Quantification of Multiple Boli Arterial Spin Labelling in Mice and Rats Samantha Paterson, Camille Graff, Antoine Vallatos, William Holmes A need for high SNR quantitative ASL has driven the quantification of mbASL, a high SNR ASL sequence that uses adiabatic pulses to label multiple boli of arterial water. The sequence has a hybrid PASL & CASL nature with a modified Buxton kinetic model used to describe this hybrid-like nature. We have shown that experimental results mirror theoretical predictions with signal distribution changing with labelling slice thickness. High SNR mbASL images in mice and rats with significantly higher signal than the standard FAIR sequence have been produced and CBF images and values acquired that agree with the literature. 5025. 132 Imaging Blood Brain Barrier Permeability in a Human African Trypanosomiasis Mouse Model using Diffusion Weighted Multiple Boli Arterial Spin Labelling Samantha Paterson, Antoine Vallatos, Jean Rodgers, William Holmes Human African Trypanosomiasis is a parasitic disease that causes progressive blood brain barrier breakdown. We have developed a non-invasive high SNR ASL technique (mbASL) combined with bipolar diffusion gradients to determine the ratio of intravascular to extravascular signal from the brain. The ratio of this signal will change in a mouse brain infected with HAT due to the barrier breakdown. We have imaged this changing brain along with producing CBF maps, thus using a novel method in imaging a HAT infected mouse. 5026. 133 Optimizing MRF-ASL Scan Design towards Precise Quantification of Hemodynamic Properties in Cerebrovascular Disorders Anish Lahiri, Jeffrey Fessler, Luis Hernandez-Garcia We investigate an optimization method to make fast, precise quantification of hemodynamic and tissue properties from an MRF ASL scan more robust to their respective feasible ranges, particularly when conditions pertaining to cerebrovascular disorders are included in consideration. We further validate our methods on synthetic and healthy human subject data. 5027. 134 Effect of Caffeine on Blood-Brain Barrier Water Permeability Measured with Intrinsic Diffusivity Encoding of Arterial Labeled Spins (IDEALS) Kenneth Wengler, Kwan Chen, Mark Schweitzer, Xiang He Caffeine is a commonly used neurostimulator that also produces cerebral vasoconstriction by antagonizing adenosine receptors. Previous studies demonstrate that acute caffeine intake leads to significant cerebral blood flow (CBF) reduction but have not investigated the effect on blood-brain barrier (BBB) water permeability. Here we provide an initial investigation into the effect of caffeine on BBB water permeability parameters, water extraction fraction (Ew) and permeability surface area product (PSw), using the recently developed Intrinsic Diffusivity Encoding of Arterial Labeled Spins (IDEALS). Significant reductions in CBF, Ew, and PSw were observed after administration of 200 mg caffeine. 5028. 135 In vivo quantification of arterial blood longitudinal relaxation time during graded hyperoxia at 3T using an intermittent cuff occlusion paradigm Erin Englund, Ana Rodriguez-Soto, Felix Wehrli Breathing hyperoxic gas results in dissolved oxygen in blood plasma, shortening T1 of arterial blood (T1a). Quantification of T1a is difficult due to blood flow between the inversion and acquisition. Here, this problem is overcome using an intermittent cuff occlusion protocol to suspend flow in the femoral artery and vein. An inversion recovery-prepared bSSFP sequence was used to measure T1a during normoxia (FiO2=21% O2) and graded hyperoxia (FiO2~33%, 48%, 55%, 100% O2) in ten healthy subjects at 3T. During normoxia, T1a was 1819±142ms, which was shortened to 1522±100ms during maximal hyperoxia, and the relationship between T1a and PETO2 was linear. 5029. 136 Reproducibility of Selective Localised T2-Relaxation-Under-Spin-Tagging (SL-TRUST) for Regional Cerebral Oxygen Extraction Fraction Caitlin O'Brien, Thomas Okell, Peter Jezzard In this study, we offer preliminary results of a reproducibility study on a novel sequence: Selective Localised TRUST (SL-TRUST). SL-TRUST is an MR acquisition method for acquiring spatially specific cerebral tissue oxygen extraction fraction (OEF) values through measurements of venous blood T2 in the superior sagittal sinus. Three subjects underwent four scan sessions over a seven day period and the inter/intra session variability of SL-TRUST was evaluated. The resulting venous blood T2 and tissue OEF values from spatially specific regions (a single hemisphere, and a 70x80x80mm tissue region) are compared to whole brain measures obtained using TRUST. 5030. 137 The spiral trajectory correction effect on arterial spin labeling acquired with high-slew-rate gradient on a compact 3T scanner Daehun Kang, Uten Yarach, Myung-Ho In, Erin Gray, Nolan Meyer, Joshua Trzasko, Yunhong Shu, Matt Bernstein, John Huston Proper design of the arterial spin-labeled (ASL) readout trajectory can minimize signal loss, reduce artifacts, and consequently improve the quality of ASL-derived perfusion maps. High performance gradients can improve MR image quality in spiral acquisition to reduce susceptibility and off-resonance effect. However, the eddy current and the system delay can degrade image quality by causing image rotation and blurring effects. In this work, the image artifact was corrected with a truer trajectory measured by a dynamic field camera.  The effects of the trajectory correction on ASL images are investigated on a low-cryogen, compact 3T MRI system. 5031. 138 An Algorithm for the Automated Quality Assessment and Perfusion Biomarker Determination of Multicentre Dynamic Susceptibility Contrast (DSC-) MRI Stephen Powell, Stephanie Withey, Yu Sun, Lesley Macpherson, Laurence Abernathy, Barry Pizer, Richard Grundy, Simon Bailey, Dipayan Mitra, Dorothee Auer, Shivaram Avula, Theodoros N. Arvanitis, Andrew Peet Dynamic Susceptibility Contrast (DSC-) MRI estimates biomarkers, such as cerebral blood volume (CBV). However, data quality varies between centres and quality control (QC) is carried out by qualitative review, which is time-consuming and subjective. An automated QC pipeline was developed and tested on 34 patient data sets. The pipeline analysed four slices from each patient, producing SNR, RMSE, relative CBV (rCBV), and quality maps for each slice, which were used to quantify QC.  Average values for each parameter were produced for each centre, protocol and field strength, showing variability in data quality and providing a basis for multi-centre protocol optimisation. 5032. 139 Dynamic Perfusion Tensor ImagingPresentation Not Submitted Jing Wang, Yang Fan DCE-MRIprovides a method to continuously measure the spatial and temporal characteristics of local tissue perfusion. This study points out an interesting feature of DCE-MRI: the voxel wised correlation can be encoded in 26 directions, allowing for the measurement of perfusion tensor. We demonstrate this new method, dynamic perfusion tensor imaging (dPTI), facilitates the reconstruction of the local perfusion field, characterized by a perfusion tensor, from which can be derived quantities related to the structure of the local perfusion field, such as the mean perfusion and perfusion anisotropy. 5033. 140 The Effect of the Injection Dose, Rate and Concentration on Carotid Dynamic Contrast-Enhanced MRI: a Simulation Study Yajie Wang, Yishi Wang, Haikun Qi, Xian Liu, Hua Guo, Huijun Chen Dynamic contrast-enhanced MR imaging (DCE-MRI) is an effective tool to quantify inflammation in carotid atherosclerotic plaque, while little is known on the effect of the injection protocol on carotid DCE-MRI. In this study, the effect of the contrast injection protocol, including injection dose and effective injection rate (decided by the injection rate and concentration) on the pharmacokinetic parameters estimation in carotid DCE-MRI were investigated. The results indicated that high injection dose (~0.1mmol/kg) with relative low effective injection rate (~0.5 mmol/s, effective injection rate = rate (ml/s) × concentration (mol/L)) was recommended for the simulated bright-blood DCE protocol. 5034. 141 Repeatability of hepatocellular uptake and efflux in the rat liver: A comparison of Gadoxetate DCE-MRI models Sirisha Tadimalla, Claudia Green, Denise Steinmann, Sascha Koehler, Hans-Paul Juretschke, Iina Laitinen, John Waterton, Paul Hockings, Catherine Hines, Gunnar Schütz, Steven Sourbron A variety of Gadoxetate DCE-MRI models have been proposed to derive hepatocyte uptake and efflux rates in the rat, but it is unclear which provides most reliable measurements. Here, we compare four models in terms of their test-retest repeatability on 9 rats measured in 3 sites. Results indicate that a two-compartment high-flow model, assuming negligible sinusoidal backflux and a fixed population-based extracellular volume fraction, provides most repeatable measures of hepatocellular function in the healthy rat. 5035. 142 Pharmacokinetic Parameter Accuracy Correlates with Image Quality Metrics in Flexible Temporal Resolution DCE-MRI Simulations Allister Mason, Nathan Murtha, James Rioux, Sharon Clarke, Chris Bowen, Steven Beyea The choice of imaging parameters in dynamic contrast enhanced (DCE) MRI, such as temporal resolution, can affect the recovered parameter when using quantitative pharmacokinetic (PK) models, such as Ktrans in the Tofts model. We propose objective image quality metrics (IQMs) as a tool to guide this choice to maximize PK parameter accuracy. DCE MRI simulations were performed on a numerical phantom with user defined PK parameters. IQMs were calculated using the numerical phantom as a reference and references generated from the simulated data. In both cases, a strong correlation between the PK parameter error and IQM score is found. 5036. 143 The role of perivascular spaces in white matter dynamic susceptibility contrast MRI Jonathan Doucette, Enedino Hernández-Torres, Christian Kames, Alexander Rauscher Using vascular parameters obtained from dynamic susceptibility contrast MRI, the gradient echo (GRE) and spin echo (SE) dynamic susceptibility contrast (DSC) induced changes in ΔR(∗)2$\mathrm{\Delta }{R}_{2}^{\left(}$ were simulated at 3T in order to investigate the effects of tissue orientation and perivascular spaces (PVS). We found that the orientation dependence of both ΔR2$\mathrm{\Delta }{R}_{2}$ and ΔR∗2$\mathrm{\Delta }{R}_{2}^{\ast }$ are amplified by PVS, though ΔR2$\mathrm{\Delta }{R}_{2}$ is far more sensitive to PVS. 5037. 144 A 3D-Printed Physiologically-Faithful Perfusion Phantom that Recapitulates Microvasculature Structure for Quantitative Experimental Validation of Fluid Transport John Morgan, Thanh Nguyen, Pascal Spincemaille, Yi Wang Recapitulation of microvascular structure, function and perfusion in vitro can enable studies of vascular biology, provide a model for diseases such as ischemic stroke or tumor angiogenesis and enable quantitative evaluation of physiologic blood or lymph perfusion.  Here we describe the initial design and deployment of a first-generation, self-contained 3D-printed, physiologically-faithful, microfluidic perfusion phantom to form explicit, hierarchically-branching, microvascular structure encapsulated in a type I collagen matrix in vitro, with pump-driven perfusion easily visible via phase-contrast MRI (Fig. 1).  The phantom flexibly supports creation of user-defined vessel network geometries with human vascular cells and allows experimental validation of blood flow, i.e., via constitutive equations for convective and diffusive transport that quantitatively relate the flux of tracers from time-resolved images to transport field quantities.  Thus, the largely qualitative and unmeasurable global arterial input assumption in the traditional Kety’s method can be replaced with measurable and reproducible MRI experimental data, formulated as quantitative transport mapping (QTM). Preliminary data demonstrate that the QTM phantom is promising for characterizing actual blood transport in vitro in healthy and pathological contexts. 5038. 145 A novel trimodality vascular contrast agent for “image-based systems biology” applications Akanksha Bhargava, Priyanka Kushwaha , Ryan Riddle, Manisha Aggarwal, Arvind Pathak Preclinical vascular imaging has been instrumental in advancing our understanding of the role of blood vessels in health and disease. However, currently there are no vascular contrast agents that are simultaneously visible with all three primary imaging modalities, i.e. MRI, CT and optical imaging. Consequently, this poses a hurdle when integrating multiscale, multimodality vascular imaging data for systems biology applications. Therefore, we developed a new vascular contrast agent that delivers trimodal imaging capabilities with MRI, CT and optical imaging for preclinical systems biology investigations. We demonstrate its compatibility with different types of imaging contrasts that allow trimodality, multiscale imaging of healthy (e.g. murine brain, leg, kidney) and pathological microvasculature (e.g. cancer xenografts). 5039. 146 Using D2O As a Diffusible Tracer in Characterizing Tumor Properties on Mice Pei-Lun Yu, Ming Cheng, Xiayu Lyu, Sheng-Min Huang, Kung-Chu Ho, Fu-Nien Wang As a diffusible tracer, D2O was employed as a negative contrast agent in investigating tumor perfusion in this study. Results show that the transfer constant derived from D2O perfusion is able to characterize tumor flow properties. Furthermore, we also demonstrated that the initial area under curve of D2O perfusion has potential in detecting the flow difference between tumor and normal tissue, suggesting the feasibility of semi-quantitative indices for D2O perfusion. 5040. 147 Predicting the rate of stroke evolution in canines using MR-derived time-to-peak perfusion maps Robert King, Matthew Gounis, Mohammed Salman Shazeeb Mechanical thrombectomy for the treatment of ischemic stroke shows high rates of recanalization; however, some patients still have poor clinical outcome. The canine large vessel occlusion model has been developed to better understand new treatments. This model has a drawback of inconsistent rates of stroke growth. Here, MRI perfusion based time-to-peak maps were used to predict the rate of infarct growth as validated by ADC-derived maps. Classification of canines into either fast or slow evolvers was reliably shown with this method of analysis, allowing for a better understanding of new therapeutics and potentially for better patient selection for thrombectomy. 5041. 148 Using multi-bolus injection protocol to improve the robustness of DCE-MRI: application in rabbit liver Sofia Veneti, Daniel BALVAY, Gwennhäel AUTRET, Charles CUENOD Quantitative DCE-MRI suffers from limitations in the liver due to its dual input (hepatic artery, portal vein). Single- and multi-bolus (four) injection protocols were performed in rabbits on a 4.7T small-animal MRI. The Hepatic Perfusion Index (HPI), total hepatic blood flow (F), and distribution volume (Vd) were studied using a computer simulation and evaluated by the Coefficient of Variation (CV) and the 95% Confidence Interval (CI) factors. Statistical tests were performed for 1000 iterations with Mann-Whitney test and p<0.002 statistically significant. Multi-bolus injection protocol strongly improve the DCE precision in the liver particularly for HPI, which is a critical parameter. 5042. 149 Measuring Regional Gas Transport in Injured Rabbit Lungs Using Hyperpolarized Xenon Yi Xin, Kai Ruppert, Maurizio Cereda, Faraz Amzajerdian, Hooman Hamedania, Mehrdad Pourfathi, Sarmad Siddiqui, Ian Duncan, Luis Loza, Tahmina Achekzai, Federico Sertic, Ryan Baron, Harrilla Profka, Stephen Kadlecek, Rahim Rizi Hyperpolarized 129-Xenon MRI measures the regional content of tracer gas in the lungs; it can also differentiate between Xenon contained in the gas phase (GP) and in the dissolved phase (DP), allowing us to characterize regional gas diffusivity and uptake in the pulmonary capillary blood in addition to capturing parameters of alveolar aeration. By measuring absorbed Xenon signal in the left heart and aorta shortly after inhalation, it is theoretically possible to study the next step of gas transfer by measuring the gas that reaches the arterial blood. In this study, we explore the regional gas transport of injured rabbit lungs in two different states of recruitment. 5043 150 Transient respiratory motion artifacts in multiple arterial phases of contrast-enhanced dynamic MR imaging of the abdomen: a comparison using gadoxetate disodium and gadobutrol.Video Permission Withheld Masahiro Tanabe, Mayumi Higashi, Keisuke Miyoshi, Sei Nakao, Etsushi Iida, Matakazu Furukawa, Katsuyoshi Ito  This study compared the occurrence of transient respiratory motion artifacts (TRMA) in multiple arterial phases of contrast-enhanced MR imaging using a rapid acquisition technique with high temporal and spatial resolution between gadoxetate disodium and gadobutrol. This study showed that the frequency of TRMA after third arterial phase was significantly higher in patients using gadoxetate disodium than in patients using gadobutrol. In multiple arterial phase dynamic MR imaging, the frequency of TRMA in gadoxetate disodium increased, compared with gadobutrol, caused by the intolerable respiratory suspension after third arterial phase, possibly due to contrast agent-related effect.
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Electromagnetic Tissue Mapping
Digital Poster
Contrast Mechanisms

Thursday, 16 May 2019
 Exhibition Hall 14:45 - 15:45

 Computer # 5044. 151 Multiple TR Approach for Direct Detection of Fast Oscillating Magnetic Fields Je-Seok Ham, Hyun-Soo Lee, Sung-Hong Park Due to weak amplitude and fast oscillation, it is still controversial whether neuronal activities can be directly detected through MR imaging. In this study, we propose a novel method, multiple-TR approach, which utilized 1) multi-phase acquisition and 2) frequency spectrum multiplication for detecting weak and fast oscillating magnetic fields. We demonstrated with phantom experiments that SNR at the stimulation frequency on the spectrum was remarkably enhanced with the higher number of TRs under almost the same scan time, amplifying oscillation frequency component while suppressing systematic noises. This proposed approach will increase possibility of directly detecting neural oscillations in vivo. 5045. 152 Deep learning brain conductivity mapping using a patch-based 3D U-net Nils Hampe, Ulrich Katscher, Cornelius van den Berg, Khin Tha, Stefano Mandija Conventional Electrical Properties Tomography (EPT) suffers from reconstruction artifacts related to assumptions necessary for solving the equations analytically. To circumvent the necessity for these assumptions, in this study a deep learning approach is utilized to approximate the analytically unsolvable equations. For this purpose, a 3D convolutional neural network was trained on simulations and in-vivo data from healthy volunteers and cancer patients. Results demonstrate the potential of this method, as noise-free conductivity maps were obtained without anatomic apriori information in less than 1:30 min per reconstruction. 5046. 153 Fast MREIT acquisition using Multi-Band and SENSE Techniques Munish Chauhan, Michael Schär, Sulagna Sahu, Thomas Mareci, Rosalind Sadleir Recent studies demonstrated the first current density and conductivity tensor images of human heads during transcranial electrical stimulation (tES), using MREIT techniques. These techniques allowed imaging of three 5-mm slices in a sequence lasting 12 minutes, a typical therapeutic tES administration time. To obtain whole brain coverage, it is important to accelerate existing MREIT sequences. In this study, we combined our existing Gradient-Echo (mFFE) MREIT acquisition methods with parallel imaging. We found the acquisition speed of image data reflecting current distributions in tES was improved 8 times by using Multi-Band (MB) imaging, while maintaining good image quality. 5047. 154 Discrete Laplacian Estimation Using Projection onto ROtating Median Sets (PROMS) for MR Electrical Property Tomography Han-Jae Chung, Jong-Min Kim, You-Jin Jeong, Jae-Won Yoo, Jeong-Hee Kim, Chulhyun Lee, Chang-Hyun Oh The novel contrast mechanism, MREPT, is still difficult to use in the clinical field. This is because the reconstruction of MREPT is performed under many assumptions, which lead to limitations for solving the governing equations, and is highly noise sensitive characteristics to noise in practical use. In this work, we propose a new discrete Laplacian estimation method using Median kernel sets, which has fast and noise-robust features, and show its performance by using in-vivo experiments and EM simulation. For validation of the proposed method, three healthy volunteers were scanned on a clinical MRI system with identical imaging parameters. 5048. 155 Does RF spoiling enhance human in-vivo brain MR Current Density Imaging (MRCDI)? Cihan Göksu, Lars G. Hanson, Hartwig Siebner, Philipp Ehses, Klaus Scheffler, Axel Thielscher MRCDI is an emerging modality for non-invasive measurement of weak currents in the human brain, which is important in several neuroscientific applications. It is based on current-induced field measurements and requires high sensitivity to the extrinsic field changes. Measurement sensitivity can be compromised by irrelevant field changes caused by physiological variation. Here, we compare the performance of the so far most sensitive MRCDI method based on steady-state free precession free induction decay (SSFP-FID) with its RF-spoiled counterpart fast low angle shot (FLASH). No significant sensitivity differences were observed in slices covering the upper part of the brain, but SSFP-FID had ~20% lower noise floors in lower slices. For the relevant acquisition parameters, FLASH exhibits no remarkable image quality enhancements in 2D. 5049 156 Compensation of lead-wire magnetic field contributions in MREIT experiment using image segmentation: a phantom studyVideo Permission Withheld Saurav Zaman Khan Sajib, Munish Chauhan, Guita Banan, Sulagna Sahu, Luning Wang, Thomas Mareci, Rosalind Sadleir For the measurement of current-induced phase using MRI, the effect of stray magnetic fields caused by the current carrying wire on images must be minimized prior to reconstruction of the current density. In this study, we report a method which can effectively remove the effect of lead wire magnetic fields interference during MREIT measurements. Results from phantom experiments and numerical simulations demonstrate the feasibility of the method, which can be used to correct for lead effects when measuring current density in human transcranial direct current stimulation (tDCS) measurements using magnetic resonance electrical impedance tomography (MREIT). 5050. 157 Improving Tissue Electrical Properties Reconstructions by Exploiting the Benefits of Combining Deep Learning-EPT and 3D Contrast Source Inversion-EPT Reijer Leijsen, Cornelis van den Berg, Rob Remis, Andrew Webb, Stefano Mandija We propose a two-step approach to EPT reconstruction where we use the results from a deep-learning approach as the initial estimate for a 3D contrast-source inversion algorithm. The combination of these two methods builds upon the strengths of each. Results using an anatomically accurate head model with and without an artificially inserted tumour show that CSI-EPT improves DL-EPT reconstructions in structures that are not present in the training set, while DL-EPT used as an initial guess for CSI-EPT leads to improved accuracy and convergence. 5051. 158 A dual constraints-based approach to electrical conductivity imaging using MR phase Xiangdong Sun, Lijun Lu, Yingjie Mei, Xiaoyun Liu, Wufan Chen Electrical conductivity imaging of tissue can potentially provide electrical property information of tissues. Here, we proposed a dual constraints based electrical conductivity imaging method to reconstruct the distribution of conductivity. The proposed method transforms the partial differential equation into an optimization problem with total variation and wavelet transform regularization terms. To evaluate the performance of the proposed method numerical simulations and phantom experiments were implemented at 3T. The results showed that the proposed method improves the accuracy of the conductivity estimate and suppress the effect of noise. The proposed method is expected to be applied clinically in the future. 5052. 159 Inverse problem approach to cr-MREPT Yusuf Ider, Celik Boga The convection-reaction partial differential equation (PDE) based algorithm for Magnetic Resonance Electrical Properties Tomograpy, cr-MREPT, does not suffer from internal boundary artifacts but has the Low Convective Field (LCF) artifact. The cr-MREPT PDE is rearranged such that H1+ is the unknown variable and the coefficients depend on the EPs. The EPs are iteratively adjusted to minimize the difference between calculated and measured H1+. The method can be applied to a Region-of-Interest without considering the whole object. Conductivity reconstructions for simulation objects and also for an agar phantom demonstrate that the proposed method does not suffer from boundary and LCF artifacts. 5053. 160 Estimation of transceive phase via LORE-GN algorithm and its use in MREPT Safa Ozdemir, Yusuf Ider Balanced steady state free precession (bSSFP) is a widely used MR sequence since it has high speed, high SNR, motion insensitivity and automatic eddy current compensation. Besides all these advantages, bSSFP sequence is susceptible B0 inhomogeneity and banding artifact occurs in certain off-frequency regions. In this paper, one of the correction methods, LORE-GN, is utilized to obtain transceive phase free from the distortions originating from B0 inhomogeneity. As an application, acquired transceive phase maps are used to obtain conductivity maps. 5054. 161 Limitations of 2-D Field Structure Assumptions in Electrical Properties Tomography and its 3-D CSI-EPT Solution Patrick Fuchs, Reijer Leijsen, Rob Remis CSI-EPT was originally implemented in a two-dimensional formulation and has since been extended to 3-D to allow for volumetric reconstructions without any assumptions on the field structures. Since the 3-D method is computationally much more complex than its 2-D counterpart, here we investigate the 2-D assumption and its requirements. Unfortunately the 2-D assumption breaks down when the object in consideration is not sufficiently longitudinally invariant, even if the fields can still be considered E-polarised. Therefore, to achieve accurate and robust reconstructions of EPs in a practical or clinical setting the 3-D CSI-EPT method is a recommended starting point. 5055. 162 An Explicit EPT Reconstruction Method Based on the Dbar Equation Incorporating Longitudinal Magnetic Field Variations Motofumi Fushimi, Takaaki Nara This paper presents a novel explicit reconstruction method for magnetic resonance-based electrical properties tomography (EPT). We derive the dbar equation for the electric field that incorporates the variation of the magnetic field along the longitudinal axis. This new dbar equation allows an explicit reconstruction of the electrical properties even when the magnetic field varies along that axis. We also propose an iterative reconstruction procedure that solves the dbar equation by the Cauchy–Pompeiu formula and updates EP values in each step. The proposed method correctly reconstructed EPs even in the case that the magnetic field and EPs vary along the longitudinal direction. 5056. 163 Validation of magnetic susceptibility source separation: Monte Carlo simulation and phantom experimentPresentation Not Submitted Jingu Lee, Hyeong-geol Shin, Hyunsung Eun, Dongmyung Shin, Jongho Lee In this study, the recently proposed magnetic susceptibility source separation method, which separates the paramagnetic susceptibility source from the diamagnetic susceptibility source, was validated using Monte-Carlo simulation and phantom experiment. The results demonstrate that the method successfully separates the paramagnetic and diamagnetic susceptibility sources in both simulation and experiment. 5057. 164 Investigating the Relationship Between Conductivity and Bound Sodium Fractions at 21.1 T Ghoncheh Amouzandeh, Nastaren Abad, Jens Rosenberg, Samuel Grant This study investigates the relation between electrical conductivity evaluated using MR Electrical Properties Tomography (EPT), sodium concentrations and their mobility. In particular, the project seeks to determine if conductivity values calculated from EPT differentiate between bound and free sodium measured by triple quantum (TQ) coherence selection. TQ and EPT acquisitions were evaluated over a range of sodium concentration and with different binding conditions to provide insight into the sources of tissue conductivity changes. The correlation between electrical conductivity and ionic content can provide more in depth understanding of how sodium ions are changing in pathological conditions. 5058. 165 Filter design for Breast Conductivity imaging Using phase-based gradient EPT (gEPT) Jun-Hyeong Kim, Jaewook Shin, Soo-Yeon Kim, Dong-Hyun Kim EPT has a potential for immediate clinical use since it does not require additional hardware. However, there are various problems when applying clinical practice. In the case of breast image, to overcome SNR, a reconstruction method called magnitude-weighted polynomial fitting was applied. Recently, a new phase-based technique called ‘gradient-based EPT’ (pgEPT) was proposed. This method removes the boundary artifact by adding a gradient of phase and reduce noise by adding diffusion term. But, it doesn’t work properly for low SNR. In this study, an improved pgEPT for breast conductivity by replacing the Laplacian term with polynomial fitting is proposed. 5059. 166 Optimal temporal resolution for accurate AIF measurement and error-constrained pharmacokinetic modelling of DCE data Silvin Knight, James Meaney, Andrew Fagan A highly-controlled and validated phantom-based method was used to investigate the effects of acquisition temporal resolution (Tres) on the arterial input function (AIF) measurement accuracy and precision for DCE-MRI. The propagation of these AIF measurement errors into errors in pharmacokinetic modelling parameter values could thus also be investigated.  Guideline Tres values which can be used to constrain errors in Ktrans, kep and ve within defined limits (e.g. <5%, <10% etc) are presented. 5060 167 Dynamic susceptibility contrast MRI phantom for validation of clinical perfusion imagingVideo Permission Withheld Slavka Carnicka, Katy Keenan , Stephen Russek, Nikki Rentz, Karl Stupic, Brandon Hancock, John Kirsch, Matthias van Osch , Bradley Erickson, Yunhong Shu, Chad Quarles, Ashley Stokes, Yuxiang Zhou, Edward Jackson, Alex Antolak, Vicky Liao, Alexander Lin , Elizabeth Mirowski, Michael Boss, Nancy Obuchowski, Ona Wu Dynamic susceptibility contrast MR imaging (DSC MRI) is a very promising quantitative imaging technique used increasingly as both a diagnostic and research tool. This technique quantifies susceptibility-induced (R2*) signal loss to assess tissue perfusion (blood supply) and viability. Development of reference phantoms is crucial to determine the in vitro accuracy, test-retest repeatability, and inter-platform reproducibility of ?R2* quantification protocols. Hence, we developed a static DSC phantom suitable for simple and reliable evaluation of acquisition methods to assess susceptibility changes across multiple scanners and time. We also finalized acquisition protocols and developed software to analyze the DSC phantom data. 5061. 168 To evaluate the effect of different initial guess selection approaches on quantitative analysis of DCE-MRI data of brain tumor patients Dinil Sasi, Sameer Manickam, Rakshit Dadarwal, Ayan Debnath, Snekha Thakran, Rakesh K Gupta, Anup Singh Quantitative analysis of dynamic-contrast-enhanced(DCE)-MRI data using various tracer kinetic models is widely used in cancer diagnosis and follow-up. In general, voxelwise model fitting using nonlinear-least-square method requires a long processing time depending upon image-resolution, data noise, choice of initial guess, model type and computer-platform. In this study, we proposed a tissue specific initial guess selection approach, for the voxel wise fitting using nonlinear–least-square method, which substantially reduced computation-time without compromising accuracy of parameters compared to regular global initial guess approach.  It also performed better than recently proposed Image-Downsampling-Expedited-Adaptive-Least-squares fitting approach. Parallel-processing was also implemented to further reduce the time 5062. 169 Susceptibility Contrast at Ultra-low Magnetic field with Superparamagnetic Nanoparticles David Waddington, Thomas Boele, Richard Maschmeyer, Zdenka Kuncic, Matthew Rosen MRI scanners operating at ultra-low fields (ULF) promise to reduce the cost and expand the clinical accessibility of MRI. Here, we use an ULF (6.5 mT) MRI scanner and an efficient balanced steady-state free precession MRI protocol to image superparamagnetic iron oxide nanoparticles (SPIONS) in solution. We observe strong susceptibility effects due to the highly-magnetized state of SPIONs even at ULF. These susceptibility effects enable the most sensitive imaging of a contrast agent at ULF that we are aware of. These results will broaden the clinical applications of ULF MRI, and have implications for drug tracking and delivery in nanotheranostics. 5063. 170 Inversion Recovery Susceptibility Weighted Imaging with Enhanced T2 Weighting (IR-SWIET): Application to Multiple Sclerosis (MS) Lesions Neville Gai, Govind Nair, Erin Beck, Daniel Reich Susceptibility weighted imaging provides important information regarding iron deposition and lesions in multiple sclerosis. However, CSF appears hyperintense on SWI images and can interfere with cortical lesion detection. Cortical lesions are associated with disability and disability progression in MS patients. Here a new 3D sequence (IR-SWIET), which suppresses CSF while maintaining T2 and T2* contrast of SWI is designed and evaluated. IR-SWIET was compared with four other commonly used sequences. CNR analysis in 30 lesions from MS patients showed that the sequence provided superior lesion depiction compared with SWI and compared well with 3D-DIR, MP2RAGE, and FLAIR. 5064. 171 Identification of mutation-dependent heterogeneity in murine models of cerebral small vessel disease using susceptibility weighted imaging at 14.1 Tesla Brice Tiret, Genki Hayashi, Cassandre Labelle-Dumais, Douglas Gould, Myriam Chaumeil Cerebral small vessel diseases (cSVDs) are a poorly understood group of conditions that manifest as intracerebral hemorrhage, microinfarcts, microbleeds and white matter lesions. Here, we used innovative mouse models that recapitulate the clinical spectrum of human cSVDs to investigate whether T2-weighted (T2-w) and Susceptibility Weighted Imaging (SWI) at 14.1Tesla could be used to differentiate between disease subtypes. Our results show that SWI could differentiate between models, with the number of SWI-detected lesions in line with both disease severity and hemosiderin staining. High-field SWI thus demonstrate high potential to non-invasively monitor cSVD evolution and response to therapies in those models. 5065. 172 3D-Printed whole-brain holder for multiple orientation magnetic susceptibility measurements and precise dissection Kwok-Shing Chan, Jeroen Mollink, Renaud Hedouin, Norbert Hermesdorf, Anne-Marie van Cappellen van Walsum, José Marques In this study, we present a whole-brain holder for ex vivo experiments which allows rotating the sample inside a conventional head coil (while ensuring no deformation occurs) and provides guidance for precise correspondence between the MR data and excised tissue. We demonstrate some of these features with two experiments aimed at validating magnetic susceptibility measurements using MRI, where small 5mm cube samples located in different slices through the whole brain can be excised with great precision. 5066. 173 MRI Susceptibility Mapping Suggests Elevated Brain Iron in Sickle Cell Anaemia Russell Murdoch, Jamie Kawadler, Fenella Kirkham, Karin Shmueli Sickle Cell Anaemia (SCA) is a genetic condition characterized by haemolytic anaemia, cerebral vasculopathy and cognitive impairment. The effect of SCA on brain iron concentrations has not been extensively studied. Brain iron is important in cognitive function and iron overload may accelerate neurodegeneration. Here, susceptibility mapping (QSM) was used to compare brain tissue susceptibility values in 86 SCA patients and 25 healthy controls. Elevated susceptibility was found in the red nucleus of the SCA group versus controls, suggesting increased iron accumulation. In SCA subjects there was no significant effect of silent cerebral infarcts or anaemia severity on brain susceptibility values. 5067. 174 B0 Field Map estimation with View Line sequence Shuang Liu, Wenqi Qiu, Gabriel Maggiora, Akihiro Kuwahata, Moriaki Kusakabe, Pablo Irarrazaval, Masaki Sekino In order to visualize the concentration and distribution of magnetic nanoparticles in pre-clinical research of magnetic nanoparticles-based sentinel lymph node biopsy, Quantitative Susceptibility Mapping(QSM) is a promising quantification tool in MRI. However, the strong magnetic field generated by high concentrations of magnetic particles causes the failure of conventional B0 map used in QSM. A novel spin echo-based View Line sequence with radius basic function interpolation-based reconstruction method has been proposed to obtain the B0 map for high concentrations of magnetic nanoparticles. This method has been verified by MRI data and simulation data for a range of iron in Resovist from 41 ug to 654 ug. Comparison of the reconstructed field map and theoretical field map provides normalized root mean square of 0.085±0.054$0.085±0.054$ for the line field map, and 0.065±0.024$0.065±0.024$ for the interpolated field map. 5068. 175 Effect of Intense Utilization of Gradients in Magnetic Resonance Current Density Imaging and its Removal Mehdi Sadighi, Hasan Hüseyin Eroglu, B. Murat Eyüboglu Intense utilization of gradients causes spatial and temporal variations of the main magnetic field which are consistent with resistive heating of the magnet structures. Since MR phase measurements are sensitive to the errors related to the B0B0 inhomogeneities correction strategies are required. Here, it is shown that field variations due to the temperature change of MR equipment in Magnetic Resonance Current Density Imaging (MRCDI) using Induced Current Nonlinear Encoding-Spoiled Multi Gradient Echo (ICNE-SPMGE) pulse sequence introduces a bias to noise distribution of magnetic flux density (BzBz) measurements. Removing this bias reduces the measured noise standard deviation of the BzBz measurements.