ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Traditional Poster Session • Magnetic Susceptibility Contrast & Mapping
1698 -1739 Quantitative Susceptibility Mapping (QSM)

Tuesday 2 June 2015
Exhibition Hall 13:30 - 15:30

1698.   What is the Lorentz sphere correction for the MRI measured field generated by tissue magnetic susceptibility: the spatial exclusivity of source and observer and the Cauchy principal value
Yi Wang1, Dong Zhou1, and Pascal Spincemaille1
1Cornell University, New York, New York, United States

The imaginary Lorentz sphere is used to calculate the tissue susceptibility induced field observed by water protons in MRI, which has led to unsettling discussions. Using spatial smoothing of microscopic quantities to derive macroscopic quantities, tissue is modeled as a continuous medium with steady electronic susceptibility sources and steady proton observers. The magnetic field is described as distribution. The electronic sources and proton observers have to be spatially separated to preserve the definition of susceptibility. This leads to the Cauchy principal value integration of the dipole kernel over tissue magnetization for calculating the susceptibility field, without referring the observer geometry.

1699.   Oligodendrocytes and the role of iron in magnetic susceptibility driven frequency shifts in white matter
Tianyou Xu1, Sean Foxley1, and Karla Miller1
1Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, University of Oxford, Oxford, Oxfordshire, United Kingdom

Previous works aimed at describing the relation between susceptibility-driven properties of white matter and the resultant MR signal have relied on models consisting of only hollow cylinders, which simulate axons and their myelin sheaths. While these models benefit from simplicity, they do not capture the full diversity of microstructures present in white matter. Other neuroglia, with their distinct magnetic susceptibilities and volumes, may also have significant influence modulating the MR signal. We demonstrate that the incorporation of iron-rich oligodendrocytes has a significant impact on the underlying frequency distribution and MR signal by virtue of their nontrivial volume fractions and magnetic susceptibility.

1700.   Lorentz cavity field in media with magnetic structure
Alexander Ruh1 and Valerij G. Kiselev1
1Dept. of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany

The notion of the Lorentz cavity is fundamental for NMR. It has been recently revised to include effects of fine magnetic structure carried by the cellular architecture in biological tissues such as brain white matter. We point out that the inclusion of cells in the Larmor cavity crucially depends on the relation of their size to the diffusion length during the acquisition of the free induction decay (FID). We demonstrate using numerical simulations how the cavity field interpolates between the classical value for small cells and the generalized one for large cells.

1701.   Correlation between paramagnetic ions and quantitative susceptibility values of postmortem brain study
Jeam Haroldo Oliveira Barbosa1,2, Rafael Emídio3, Ana Tereza Di Lorenzo Alho3, Camila Fernandes Nascimento3, André Henrique Fais Silva1, Alexandre Valotta Silva3, Maria Conception Garcia Otaduy3, Maria da Graça Martin3, Edson Amaro Junior3, Oswaldo Baffa1, and Carlos Ernesto Garrido Salmon1,4
1Department of Physics - FFCLRP, University of Sao Paulo, Ribeirao Preto, Select, Brazil, 2CNRS, ICube, FMTS, Université de Strasbourg, Strasbourg, Bas-Rhin, France,3Department of Radiology - FM, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil, 4University of Nottingham, Sir Peter Mansfield Magnetic Resonance Center, Nottingham, Bas-Rhin, United Kingdom

Correlation between paramagnetic ions and quantitative susceptibility values of postmortem brain study: QSM showed sensitive and specific only for the paramagnetic ion Fe+3 present in no-haem proteins as transferrin and ferritin.

1702.   Detection and Quantification of Microbleeds on Fixed Brain Specimens
Shunshan Li1, Mark J Fisher2, Ronald C Kim3, David Cribbs4, Mark J Hamamura1, Vitaly Vasilevko4, Annlia P Hill2, and Min-Ying Su1
1Tu&Yuen Center for Functional Onco-Imaging, University of California, Irvine, CA, United States, 2Department of Neurology, University of California, Irvine, CA, United States,3Department of Pathology, University of California, Irvine, CA, United States, 4Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, United States

It is difficult to confirm microbleeds found in in-vivo MRI with pathological examination. Specimen imaging may be used to verify the detected microbleeds and further to correlate with disease progression of patients before death. In this study 27 brains were imaged. A special vacuum chamber with ultrasound probe was built to remove bubbles on the surface of the specimen. Microbleeds were found in 16/27=59% cases. Of 16 cases with confirmed pathology, microbleeds were found in 3/9=33% normal aging subjects, and in 3/5=60% Alzheimer’s disease patients. An analysis software is being developed to improve the detection sensitivity and size quantification.

1703.   Estimation of Blood Oxygenation using Quantitative Susceptibility Mapping
Alexey Dimov1,2, Thanh Nguyen2, Zhe Liu1,2, Kofi Deh2, Jingwei Zhang1,2, Martin Prince2, and Yi Wang1,2
1Biomedical Engineering, Cornell University, Ithaca, NY, United States, 2Radiology, Weill Cornell Medical College, New York, NY, United States

Oxygen level is a quantity of interest for studying ischemia, arteriovenous shunts, and the assessment of muscle metabolic properties. In this study, we present in vivo results of estimating venous blood oxygenation using quantitative susceptibility mapping. Comparison with blood oximetry showed high degree of correlation.

1704.   Susceptibility and cross-sectional area quantifications of small veins in human brain
Ching-Yi Hsieh1, Yu-Chung Norman Cheng1, Jaladhar Neelavalli1, and E. Mark Haacke1
1Wayne State University, Detroit, MI, United States

We showed the alternative approach to quantifying magnetic moment, susceptibility and cross-sectional area of veins in human without any a priori information. By summing up MR signals surrounding the object, the magnetic moment, susceptibility and the cross-sectional area of the object can be solved. Here, we tackled three practical issues-low signal to noise ratio inside the object, local background field and the cylindrical object at the low orientation to the main field. The results of the susceptibility in veins agree with the recent published papers.

1705.   MRI susceptometry measurements of murine brown and white adipose tissue
Henry H. Ong1, Robert A. Horch1,2, John C. Gore1, and E. Brian Welch1
1Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, 2Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

Characterization of the magnetic susceptibility (lower case Greek chi) of biological tissues may provide insight into their composition and microarchitecture. Despite their biological significance for energy storage and metabolic regulation, there have been few reports of the magnetic properties of white adipose tissue (WAT) and, to the best of our knowledge, none on brown adipose tissue (BAT). For the first time, we report ex vivo MRI susceptometry measurements of murine BAT and WAT. WAT lower case Greek chi agreed with previous reported values, while BAT lower case Greek chiwas measured to be even more diamagnetic than water. Further study is needed to elucidate the basis of this difference.

1706.   MR-based R2* and quantitative susceptibility mapping (QSM) of liver iron overload: comparison with SQUID-based biomagnetic liver susceptometry
Samir D. Sharma1, Bjoern P. Schoennagel2, Jin Yamamura2, Peter Nielsen2, Regine Grosse2, Hendrik Kooijman3, Roland Fischer2,4, Diego Hernando1, Gerhard Adam2, Peter Bannas1, and Scott R. Reeder1,5
1Radiology, University of Wisconsin, Madison, WI, United States, 2University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 3Philips Healthcare, Hamburg, Germany,4UCSF Benioff Children's Hospital Oakland, Oakland, CA, United States, 5Medical Physics, University of Wisconsin, Madison, WI, United States

Assessment of iron burden is essential for the longitudinal monitoring and treatment of patients with liver iron overload. The purpose of this work was to investigate the relationship between MR-based R2* and quantitative susceptibility mapping (QSM) with SQUID-based biomagnetic liver susceptometry in patients with suspected liver iron overload. Eleven patients were recruited for this study from a population undergoing cardiac MRI and liver susceptometry as part of their regular iron monitoring. The correlation between R2* and SQUID was found as R2 = 0.88. Linear regression analysis between QSM and SQUID yielded: slope = 0.63±0.09, y-intercept = -0.38±0.23, R2 = 0.87. 

1707.   Measurement of Brain Iron and Calcium using MR QSM and CT: validation using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
Jingwei Zhang1,2, Cynthia Wisnieff1,2, Becky Schur3, Lu Zhengrong3, David Pitt4, and Yi Wang1,2
1Biomedical Engineering, Cornell University, New York, New York, United States, 2Radiology, Weill Cornell Medical College, New York, New York, United States, 3Biomolecular Engineering, Case Western Reserve University, Ohio, United States, 4Neurology, Yale School of Medicine, CT, United States

This study aims at demonstrating the feasibility of correcting calcium susceptibility for more accurate [Fe] maps utilizing both QSM and CT images in brain specimens. The results are compared with ICP-OES results served as the golden standard.

2D-segmented, multi-TE 3D-EPI for high-resolution R2* and quantitative susceptibility mapping at 7 Tesla
Rüdiger Stirnberg1, Julio Acosta-Cabronero2, Benedikt A. Poser3, and Tony Stöcker1,4
1German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 2German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany, 3Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, 4Department of Physics and Astronomy, University of Bonn, Bonn, Germany

Recently, the feasibility of quantitative susceptibility mapping (QSM) at 3 Tesla using segmented 3D-EPI requiring only a fraction of conventional gradient echo (GRE) acquisition times, has been demonstrated. Moving to higher field strengths usually involves higher spatial resolutions and shorter echo times. The use of additional in-plane segmentation in 3D-EPI is proposed here to meet both requirements at 7 Tesla. Multiple R2* weightings further increase the sequence flexibility. QSM results at 0.8mm in-plane resolution show that more than one EPI average is hardly needed when compared to GRE. More advanced applications, such as susceptibility tensor imaging, thus become feasible.

Wave-CAIPI and TGV for fast sub-millimeter QSM at 7 Tesla
Christian Langkammer1, Berkin Bilgic1, Celine Louapre1, Costanza Gianni1, Sindhuja T Govindarajan1, Kawin Setsompop1, and Caterina Mainero1
1MGH/HST Martinos Center for Biomedical Imaging, Harvard Medical School, Boston, MA, United States

In this work we combined a novel efficient acquisition approach based on 3D gradient recalled echo with wave-CAIPI acceleration for its usefulness in quantitative susceptibility mapping at higher spatial resolution. The proposed setup allows QSM of the entire brain with 0.5 mm isotropic resolution in 4 minutes.

1710.   Rapid phase imaging with 3D echo-planar imaging (EPI) for quantitative MRI – A simulation study on image artifacts
Paul Polak1, Robert Zivadinov1,2, and Ferdinand Schweser1,2
1Department of Neurology, Buffalo Neuroimaging Analysis Center, State University of New York at Buffalo, Buffalo, NY, United States, 2Molecular and Translational Imaging Center, MRI Center, Clincal and Translational Research Center, Buffalo, NY, United States

Gradient echo (GRE) imaging has received increased attention because of the GRE signal's effectiveness in elucidating information about magnetic tissue properties and microscopic tissue architecture. However, multi-echo GRE sequences are hindered by their lengthy acquisition times. Multi-shot GRE 3D echo-planar imaging (EPI) attempts to circumvent this problem by acquiring multiple k-space lines per shot – but what effect these acquisition strategies have on the underlying magnitude and phase components is not clear. In this work we systematically investigate the effect of magnitude signal decay and phase evolution during the readout on the accuracy of complex-valued GRE signals measured with simulated segmented 3D EPI sequences.

1711.   Improving Quantitative Susceptibility and R2* Mapping by Applying Retrospective Motion Correction
Xiang Feng1, Alexander Loktyushin2, Andreas Deistung1, and Juergen R. Reichenbach1
1Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany, 2Empirical Inference, Max Planck Institute for Intelligent Systems, Tübingen, Germany

Subject motion during MR scans can cause motion artifacts in magnitude and phase images, and impair subsequent quantitative susceptibility mapping and R2* analysis. We propose using an autofocusing-based fully data-driven retrospective rigid motion correction approach (GradMC) to suppress the motion artifacts in both magnitude and phase images prior to computing QSM and R2*. Our experiments demonstrate the improved accuracy of QSM and R2* techniques in the presence of subject motion, and open promising directions for the future research.

1712.   Image quality improvement using short range finite difference in QSM reconstruction
Maximilian Maerz1, Dong Zhou2, Yan Zhang2,3, Pascal Spincemaille2, Lars Ruthotto1, and Yi Wang2
1Department of Mathematics and Computer Science, Emory University, Atlanta, GA, United States, 2Weill Cornell Medical College, New York, NY, United States, 3Department of Radiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei, United States

Gradient is an essential operation in the reconstruction of quantitative susceptibility mapping (QSM). There are central difference and short difference implementation for gradient. We found that different finite difference methods strongly affect image quality in data sets acquired with low resolution (greater than 1mm). Checker board pattern artifacts appeared in the central difference implementation and were effectively suppressed with the short difference implementation.

1713.   Optimizing the data acquisition strategy for quantitative susceptibility mapping in the liver
Samir D. Sharma1, Diego Hernando1, Debra E. Horng1,2, and Scott B. Reeder1,2
1Radiology, University of Wisconsin, Madison, WI, United States, 2Medical Physics, University of Wisconsin, Madison, WI, United States

Quantitative susceptibility mapping (QSM) in the liver has focused on the reconstruction of the susceptibility map from the B0 field, whereas little consideration has been given to the data acquisition. The purpose of this work was to optimize the data acquisition parameters for QSM in the liver. We calculated the Cramér-Rao Bound (CRB) on the B0 field and performed Monte-Carlo simulations to optimize the data acquisition. CRB analysis and Monte-Carlo simulations revealed that generally a shorter first echo time, short echo spacing (~0.5ms), and larger number of echoes result in lower variance of the B0 field and susceptibility map estimates.

1714.   Interleaved 3D multi-slab echo shift sequence for fast T2* weighted imaging
Yajun Ma1, Wentao Liu1, Weinan Tang1, and Jia-Hong Gao1
1Center for MRI, Peking University, Beijing, Beijing, China

We propose a novel echo shift method, which can simultaneously reduce the scanning time and maintain the high image SNR for T2* weighted imaging.

1715.   Limitations of Accelerated QSM by FOV Restriction to Deep Gray Matter
Ahmed M. Elkady1, Hongfu Sun1, and Alan H. Wilman1
1Dept. of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada

Field of View (FOV) restriction to deep Gray Matter (GM) only would significantly accelerate Quantitative Susceptibility Mapping (QSM) acquisitions, facilitating its clinical use in diseases such as Multiple Sclerosis. However, nonlocal effects of dipole fields require careful examination of accelerated QSM through FOV restriction, which were studied through simulations and in vivo MRI acquisitions in each direction (x,y,z). FOV restriction parallel to the main field (z-axis) was found to significantly reduce QSM accuracy. Optimally, coronal FOV restriction (y-axis) should be used for accelerated QSM, requiring a FOV of 133mm or more to obtain accurate QSM results of deep GM.

1716.   Ferumoxytol-enhanced Plural Contrast Imaging of the Human Brain
Samantha J Holdsworth1, Thomas Christen1, Kristen Yeom1, Jae Mo Park1, Greg Zaharchuk1, and Michael E Moseley1
1Department of Radiology, Stanford University, Stanford, CA, United States

In the present study, we generate multiple contrast mechanisms following the injection of Ferumoxytol (an FDA-approved ultra-small paramagnetic iron oxide [USPIO] compound) in the pediatric brain. The high magnetic susceptibility of ferumoxytol and its long half–life allows the acquisition of high quality/high spatial resolution 3D ME-GRE images in only 5:44-minutes and subsequent generation of R2* maps, field maps, Susceptibility-Weighted Imaging (SWI), Time-of-Flight (TOF), and Quantitative Susceptibility Maps (QSM).

1717.   Inference at the cluster level from the relationship between QSM and age
Julio Acosta-Cabronero1, Arturo Cardenas-Blanco1, and Peter J Nestor1
1German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Saxony-Anhalt, Germany

This study explores, with relatively unbiased methods, the relationship between increased paramagnetism in brain parenchyma and age. Brain magnetostatics was probed with quantitative susceptibility mapping (QSM) revealing strong striatal effects as a function of age. In addition, QSM clusters in the diencephalon, mesencephalon—and in a more patchy distribution—, across the cerebral cortex and posterior white matter—also emerged as age-related effects.

1718.   QSM standardisation routine for unbiased whole-brain analysis
Julio Acosta-Cabronero1, Matthew TJ Betts1, Arturo Cardenas-Blanco1, Shan Yang2, Oliver Speck2, and Peter J Nestor1
1German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Saxony-Anhalt, Germany, 2Biomedical Magnetic Resonance (BMMR), Otto-von-Guericke University, Magdeburg, Saxony-Anhalt, Germany

This abstract presents a processing pipeline for whole-brain analysis of quantitative susceptibility MRI data. The routine detailed in the abstract consists of an optimised series of QSM and co-registration methods, which yielded highly spatially concordant maps using multi-echo GRE data at 7 Tesla. The present demonstration suggests QSM is ready for large-scale clinical studies.

1719.   Automated segmentation of midbrain structures using quantitative susceptibility mapping images
Benjamín Garzón1, Grégoria Kalpouzos1, and Rouslan Sitnikov2
1Aging Research Center, Karolinska Institute and Stockholm University, Stockholm, Sweden, 2MRI Research Centre, Karolinska University Hospital, Stockholm, Sweden

We present a fully automated algorithm for segmentation of the red nucleus, substantia nigra and subthalamic nucleus from a pair of T1w and quantitative susceptibility (QSM) images, aimed at providing accurate, objective and reproducible segmentations. The algorithm produces spatial probabilistic maps via a multi-atlas label fusion scheme by combining global (T1w) and local (QSM) non-linear registrations. These probabilistic maps are employed as priors in a model representing QSM intensities as a Gaussian mixture. Manual segmentations were obtained for 16 subjects and used to train and validate the model. Cross-validated Dice scores ranged between 0.66 (subthalamic nucleus) and 0.85 (red nucleus).

1720.   Reproducibility of Quantitative Susceptibility Mapping (QSM) and R2* in the Human Brain
Joon Yul Choi1, Yoonho Nam1, Jingu Lee1, and Jongho Lee1
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Seoul, Korea

In this works, we explored the intra-scan reproducibility of QSM and R2* of the human brain in detail.

1721.   Anatomically dependent variations in magnetic susceptibility produces spectral asymmetries in high spectral and spatial resolution MRI of post-mortem mouse brain
Sean Foxley1, Miriam Domowicz2, Nancy Schwartz2, and Gregory S Karczmar3
1FMRIB Centre, University of Oxford, Oxford, OXON, United Kingdom, 2Department of Pediatrics, University of Chicago, Illinois, United States, 3Department of Radiology, University of Chicago, Illinois, United States

Post-mortem mouse brain was imaged using high spectral and spatial resolution MRI. This differs from more conventional susceptibility weighted imaging approached because a water spectrum is produced for each image voxel. Specifically, the FID was sampled in 50x50x70 micron resolution voxels and Fourier transformed to produce water spectra with 3.5 Hz spectral resolution. Waterline asymmetries specific to deep white matter tracts as well as between differing layers of the cerebellum were observed. This indicates that differing microstructurally driven susceptibilities are producing varying resonances in a single voxel, which are detectable using this approach.

1722.   Quantification of Labeled Cell Clusters in a Rat Brain In Vivo Using MRI
Paul Kokeny1, Xie He2, Saifeng Liu3, Ching-Yi Hsieh4, Quan Jiang5,6, Yu-Chung Norman Cheng1, and E. Mark Haacke1,4
1School of Biomedical Engineering, Wayne State University, Detroit, MI, United States, 2School of Physics, Wayne State University, Detroit, MI, United States, 3School of Biomedical Engineering, McMaster Univeristy, Hamilton, Ontario, Canada, 4Department of Radiology, Wayne State University, Detroit, MI, United States, 5Department of Neurology, Henry Ford Health System, Detroit, MI, United States, 6Department of Radiology, Henry Ford Health System, Detroit, MI, United States

Currently, the tracking of nanoparticle labeled cells via MRI is a qualitative process. However, given the magnetic moment of a labeled cell cluster along with the mass magnetization of the labeling agent and the average cellular iron uptake, it is possible to estimate the number of cells present in a cluster in vivo. In this work, the magnetic moments of six labeled cell clusters are quantified using a complex summation method that is accurate for small objects. The effect of high-pass filtering is analyzed through simulations. From these results, the number of cells present in each cluster is estimated.

1723.   A Dixon Method for Positive Contrast Imaging of Very Small Superparamagnetic Iron Oxide Nanoparticles in MRI
Dirk Krüger1, Silvia Lorrio González1, and René M. Botnar1
1Division of Imaging Sciences & Biomedical Engineering, King's College London, London, United Kingdom

The aim of this project is to develop and validate a Dixon MR imaging technique to achieve positive contrast of very small superparamagnetic iron oxide nanoparticles (VSOPs). We assessed the proposed method in a phantom study and compared the results with three established positive contrast imaging techniques. The reference techniques were GRadient-echo Acquisition for Superparamagnetic particles (GRASP), Inversion Recovery with ON-resonant water suppression (IRON), and Susceptibility Gradient Mapping (SGM). The Dixon method demonstrated superior sensitivity, relative ease of implementation and reliability.

1724.   Susceptibility quantification for ferritin and Fe3O4 nanoparticles: Observation of hyperfine shift in phase images and comparison between phase measurement and CISSCO
He Xie1, Yu-Chung Norman Cheng2, Ching-Yi Hsieh2, Paul Kokeny3, and E.Mark Haacke2
1Physics and Astronomy, Wayne State University, Detroit, Michigan, United States, 2Radiology, Wayne State University, Detroit, Michigan, United States, 3Biomedical Engineering, Wayne State University, Detroit, Michigan, United States

This study focused on phase measurement in susceptibility quantification. Phase shift due to hyperfine structure was observed in ferritin and iron oxide nanoparticles. Susceptibility quantification results from phase measurement were compared with results from our CISSCO method. The results indicates that a more careful work might be needed before QSM methods can be applied to the phase images. This study also suggests that CISSCO is a reliable quantification method for magnetic susceptibility.

1725.   Ultrashort Echo Time Quantitative Susceptibility Mapping (UTE-QSM) of Cortical Bone
Qun He1, Zhe Liu2, Tian Liu2, Yi Wang2, and Jiang Du1
1Radiology, UC, San Diego, San Diego, CA, United States, 2Biomedical Engineering, Cornell University, Ithaca, New York, United States

A combination of 3D UTE and QSM (UTE-QSM) approach was used to access the susceptibility map using of a cortical bone sample using a clinical 3T scanner.

1726.   A Fully Flow Compensated Dual Echo Sequence:The Role of Acceleration and Background Gradient Effects on Flow Compensation
Dongmei Wu1, Sagar Buch2, Saifeng Liu2, and E. Mark Haacke1,3
1Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China, 2School for Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada, 3Department of Radiology, Wayne State University School of Medicine, Detroit, MI, United States

In this abstract, we present a fully flow compensated double echo sequence with alternating readout gradients for the reconstruction of both MR angiography and MR venography simultaneously. We then use the phase from both the positive and negative polarities to extract the non-compensated flow phase arising from background field inhomogeneities and acceleration effects. This phase is then removed from the original phase to provide a more pristine phase image from which we can create better SWI and QSM images. This new approach makes it possible to do SWI and QSM in practical clinical settings.

1727.   SWI of the Cervical-Spinal Cord with Respiration Noise correction using Navigator Echo
Hongpyo Lee1, Yoonho Nam2, Dongyeob Han1, Sung-Min Gho1, and Dong-Hyun Kim1
1Electrical & Electronic Engineering, Yonsei University, Seodaemun-gu, Soeul, Korea, 2Electrical & Computer Engineering, Soeul National University, Gwanak-gu, Soeul, Korea

Susceptibility Imaging can be useful for assessing structural integrity in the spinal cord, which plays an important role in many neurological disorders.1 However, physiological noise from respiration causes artifacts in in-vivo images. This phenomenon is particularly evident in the Cervical-spinal (C-spine) cord because the distance between the C-spine and the lungs is closer than other regions 2. In order to characterize and correct these respiration-induced artifacts of images, navigator echo approaches have been widely used in functional MRI, Diffusion Imaging etc 3 In this study, B0 shift due to respiration is analyzed and this effect is compensated using navigator echoes. Susceptibility weighted image (SWI) of the C-spine is obtained using the correction scheme.

1728.   Optimization of Inter-Echo Variance Channel Combination Technique for Susceptibility Weighted Imaging at 3T and 7T
Zahra Hosseini1, Junmin Liu2, and Maria Drangova2,3
1Biomedical Engineering Graduate Program, Western University, London, Ontario, Canada, 2Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada,3Medical Biophysics, Western University, London, Ontario, Canada

Susceptibility weighted imaging (SWI) allows for visualization of veins using intrinsic tissue properties. This technique has gained popularity in the clinic in the past decade. SWI requires accurate phase images in order to generate a reliable mask and ultimately good contrast between veins and adjacent structures. Multi-channel acquisition therefore requires a channel combination technique that preserves the quality of the phase image. We present the application of the inter-echo variance channel combination technique for SW imaging and demonstrate single-slice SWI for the first time.

1729.   Dipole filtering, decomposition and quantification with 3D radial acquisition
Curtis A. Corum1, Lauri J. Lehto2, Djaudat S. Idiyatullin1, Olli Gröhn2, and Michael Garwood1
1Center for Magnetic Resonance Research, Radiology, University of Minnesota, Minneapolis, Minnesota, United States, 2Department of Neurobiology, Biomedical Imaging Unit, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Northern Savonia, Finland

Susceptibility weighted imaging and quantitative susceptibility mapping are sensitive to magnetic field changes due to tissues and exogenous agents. For many tissues, pathologies, and contrast agents of interest (such as magnetic nanoparticles), quantification is desirable and full mapping of the susceptibility or other electrical properties is not yet practical. An intermediate approach may be useful. We combine a dipole matched filter to count dipole sources in the field of view with model based dipole source decomposition of the phase offsets in 3D radial sampled data.

1730.   Improved contrast in multi-echo susceptibility-weighted imaging by using a non-linear echo combination
Zhaolin Chen1, Guillaume Gilbert2, and Miha Fuderer1
1Clinical Excellence and Research, R&D, Philips Healthcare, Best, Noord-Brabant, Netherlands, 2MR Clinical Science, Philips Healthcare, Montreal, Canada

In this work, a non-linear echo combination approach is introduced to optimize susceptibility contrast in multi-echo SWI. A voxel-wise non-linear combination of magnitude images is introduced prior to calculating SW images. The analytical SNR and CNR of the proposed echo-combination approach are derived and are used to compare the proposed multi-echo approach with the existing single-echo and multi-echo approaches. As shown both experimentally and analytically, the proposed approach provides enhanced susceptibility contrast compared with previous single-echo and multi-echo approaches.

1731.   Artefact removal in high phase gradient regions in susceptibility weighted images.
Amanda Ching Lih Ng1, Shawna Farquharson2, Sonal Josan3, and Roger J Ordidge1
1Dept of Anatomy and Neuroscience, The University of Melbourne, The University of Melbourne, VIC, Australia, 2Imaging, The Florey Institute of Neuroscience and Mental Health, Melbourne, VIC, Australia, 3Siemens Healthcare, Melbourne, VIC, Australia

SWI processing traditionally involves homodyne filtering of the raw complex image data to simultaneously unwrap and high pass filter the phase. In regions where there are high phase gradients, homodyne filtering may inadequately unwrap and filter the phase, resulting in substantial artefacts that appear hypo-intense on the SWI image. Such artefacts can lead to problems in the assessment of important vascular structures located in or near these regions of high phase gradients, e.g. in brain regions surrounding the sinuses. Here we demonstrate that combining a post-processing technique that reduces the high phase gradient artefacts present in SWI images.

1732.   Magnetic Susceptibility (QSM) of Thalamic Sub-Nuclear Groups in Multiple Sclerosis
Ferdinand Schweser1,2, Devika Rattan1, Jesper Hagemeier1, Paul Polak1, Michael G Dwyer1, Christopher R Magnano1, and Robert Zivadinov1,2
1Buffalo Neuroimaging Analysis Center, Dept. of Neurology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, United States, 2MRI Molecular and Translational Imaging Center, Buffalo CTRC, State University of New York at Buffalo, Buffalo, NY, United States

In this work we investigate for the first time magnetic susceptibility of the thalamic nuclear groups in patients with multiple sclerosis (MS). Visibility of thalamic nuclei on susceptibility maps considerably varied between subjects, with highest visibility in CIS and lowest visibility in SP-MS patients. These results challenge current analysis strategies, which consider basal ganglia nuclei as homogeneous structures. Careful analysis of susceptibility in sub-nuclear groups promises to provide more specific information on pathology-related tissue changes.

Magnetic susceptibility in gray matter is associated with age-related neuropathology: An ex-vivo QSM study in a community cohort
Arnold Moya Evia Jr.1, David A Bennett2,3, Julie A Schneider2,3, Aikaterini Kotrotsou4, Robert J Dawe2, and Konstantinos Arfanakis1,2
1Illinois Institute of Technology, Chicago, Illinois, United States, 2Rush Alzheimer's Disease Center, Illinois, United States, 3Rush University Medical Center, Illinois, United States,4MD Anderson Cancer Center, Texas, United States

The relationship between magnetic susceptibility and age-related neuropathology, specifically TDP43, hippocampal sclerosis, and Alzheimer's Disease was explored. Associations with neuropathologic correlates and magnetic susceptibility were found.

1734.   Susceptibility Mapping in Parkinson’s Disease Patients at 3T
Johannes Lindemeyer1, Ana-Maria Oros-Peusquens1, Kathrin Reetz1,2, and N. Jon Shah1,2
1Institute of Neuroscience and Medicine 4, INM-4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, Jülich, Germany, 2Faculty of Medicine, Department of Neurology, RWTH Aachen University, JARA, Aachen, Germany

This abstract describes a study investigating and quantifying the effect of Parkinson’s disease on the magnetic susceptibility observed in regions of the central brain, measured with a clinical protocol at 3T. The analysis workflow includes customized field map estimation, background field correction and susceptibility reconstruction.

1735.   Quantitative Susceptibility Mapping of the Squirrel Monkey at 3T and 11.7T: Application to a Model of Parkinson’s Disease
Mathieu David Santin1,2, Alexandra Petiet1,2, Elodie Laffrat1,2, Stéphane Lehéricy1,2, Chantal François2, and Stéphane Hunot2
1Centre de NeuroImagerie de Recherche (CENIR), Paris, France, 2Institut du Cerveau et de la Moelle épinière, Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Paris, France

Brain QSM at ultra high field in a primate model of Parkinson's disease

1736.   Quantitative susceptibility mapping (QSM) indicates possible iron deficiency in the thalamus and dentate nucleus in restless legs syndrome (RLS)
Xu Li1,2, Hongjun Liu1,2, Richard P. Allen3, Christopher J. Earley3, Richard A.E. Edden1,2, Peter B. Barker1,2, Tiana E. Cruz3, and Peter C.M. van Zijl1,2
1F.M. Kirby Research Center, Kennedy Krieger Institute, Baltimore, MD, United States, 2Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States,3Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Quantitative susceptibility mapping (QSM) at 7T was utilized to assess brain iron levels in restless legs syndrome (RLS) (aka Willis Ekbom disease), using the measured tissue magnetic susceptibility as an iron index. Data collected on 30 RLS patients and 26 age-matched normal controls showed significantly decreased magnetic susceptibility in RLS patients as compared to controls in dentate nucleus and thalamus. Similar findings were confirmed by a voxel-based analysis, which suggests that substructures such as the sub-thalamic nuclei may also be affected by iron deficiency in RLS.

1737.   Measuring Venous Blood Oxygenation using Quantitative Susceptibility Mapping: A Study using Acetazolamide Challenge in Patients with Chronic Stenosis of Major Arteries
Deqiang Qiu1, Fadi Nahab2, and Seena Dehkharghani1
1Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States, 2Neurology, Emory University, GA, United States

In this paper, we studied the venous blood oxygenation using quantitative susceptibility mapping in a group of patients with chronic stenosis in the internal carotid and/or the middle cerebral arteries. We evaluated the baseline venous oxygenation level as well as after acetazolamide (Diamox) challenge.

1738.   Quantifying Peripheral Vascular Calcifications with Quantitative Susceptibility Mapping
Huan Tan1, Tian Liu2, Yi Wang3, and Robert R. Edelman4,5
1Surgery, University of Chicago, Chicago, IL, United States, 2MedImageMetric LLC, New York, NY, United States, 3Radiology, Weill Cornell Medical College, New York, NY, United States, 4Radiology, NorthShore University HealthSystem, Evanston, IL, United States, 5Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States

In this study we tested the feasibility of applying quantitative susceptibility mapping (QSM) to quantify vascular calcification in patients with peripheral vascular diseases. The preliminary result has demonstrated the capability of using QSM for in-vivo measurements of the diamagnetic susceptibility associated with vascular calcifications.

1739.   Can Susceptibility weighted with quantitative phase MR imaging be diagnostic in differentiation of Haemorrhagic from calcified female pelvic lesion? - A preliminary study
sakshi khurana1, Rakesh Kumar Gupta1, Mukta Kapila2, Swati Mittal2, Manavita Mahajan2, Ritu Tyagi1, and kirti verma1
1Radiology, fortis memorial research institute, Gurgaon, Haryana, India, 2gynaecology, fortis memorial research institute, Gurgaon, Haryana, India

Susceptibility weighted with phase imaging is a useful technique in definitive characterization of various stages of blood as well as in calcification in brain; however it has never been used in the evaluation of female pelvis. We studied various pelvic lesions on 3 Tesla MRI scanner and quantified the phase value. Due to the differential para- and di-magnetic nature of calcification and various stages of hemorrhage significant quantitative difference in phase values was seen. With no additional scan time, valuable information obtained from phase MR imaging can give a definitive answer for characterization of various pelvic pathologies in females.