Session PC. There are 36 abstracts in this session.

Session: IMAGING (MRI / MRS), poster number: 179

Predictive Value of Myoinositol Measured by Magnetic Resonance Spectroscopic Imaging during Anti-angiogenic Treatment in Recurrent Glioblastoma

Michael Wenke1; Jorg Dietrich3; Elizabeth Gerstner2; Mark Vangel2; Otto Rapalino1; Julian He1; Daniel Kim1; Melanie Fu1; Wesley Shin2; Isabel Arrillaga4; Deborah Forst3; Yi-fen Yen2; Ovidiu Andronesi2; Jayashree Kalpathy-Cramer2; Bruce Rosen2; Tracy Batchelor3; R. Gilberto Gonzalez1; Eva-Maria Ratai1
1Department of Radiology, Neuroradiology, MGH, Boston, MA; 2AA Martinos Center for Biomedical Imaging, Charlestown, MA; 3Harvard Medical School, Boston, MA; 4Massachusetts General Hospital Cancer Center, Boston, MA

Patients with recurrent glioblastoma (rGBM) are treated with anti-angiogenic agents such as bevacizumab (BEV), but not all benefit from this therapy. We examined whether MR spectroscopic imaging (MRSI) of myoinositol (MI) could distinguish responders from non-responders. We scanned twenty-two rGBM patients with MRSI at baseline (BL) prior to BEV-based therapy, as well as 1-3 days and 4 weeks afterwards. MI normalized by creatine in the tumor was significantly higher in patients who survived 9 months than those who did not, and lower MI levels up through the 4-week scan were associated with better prognostic outcomes. Among other metabolic indicators such as N-acetylaspartate and choline, MI could be a useful marker for early tumor cell invasion.

Session: IMAGING (MRI / MRS), poster number: 180

Simultaneous Detection of ZQ→DQ and DQ→ZQ Pathways in Phase-Incrementing SSel-MQC (pi-SSelMQC) with Application to Recover Lost Tumor Marker Signals

Qiuhong He; Hong Yuan; Yen-Yu Ian Shih
University of North Carolina, Chapel Hill, North Carolina

A novel phase-incrementing Soft Selective Multiple Quantum Coherence Transfer (pi-SSelMQC) method was developed to detect full Sel-MQC spectroscopic imaging signals of biomarkers with excellent water and lipid suppression.  For demonstration, the pi-SSelMQC experiments were carried out to map lactate spatial distributions in a yogurt phantom and in vivo in murine 344SQ lung tumors grown subcutaneously on the right thigh of syngeneic 129X1/SvJ male mice.  Both ZQ→DQ and DQ→ZQ coherence transfer pathways were detected by synchronizing the phase-encoding gradient steps and RF phase increments of the selective MQ-excitation pulse.  The lactate images from the two different MQ-coherence pathways were detected with opposite imaging offsets away from spurious residual signals of unwanted biochemicals, recovering the 50% lost signal in the original SSel-MQC method.

Session: IMAGING (MRI / MRS), poster number: 181

Semi-LASER based Accelerated Correlated Spectroscopic Imaging

Manoj Sarma; M. Albert Thomas
UCLA Geffen School of Medicine, Los Angeles, CA

Echo-planar correlated spectroscopic imaging (EP-COSI) which combines L-COSY with an echo-planar (EPI) readout for the detection of better-resolved 2D spectra from multiple spatial regions, suffers from large chemical shift displacement error (CSDE), non-uniform refocusing, and spatially dependent magnetization transfer due to limited RF bandwidth. The above issues can be mitigated using adiabatic slice selective refocusing pulses. Here, for the first time, we implemented a novel semi-LASER based EP-COSI using two pairs of slice selective adiabatic full passage (AFP) RF pulses. Further, it was combined with an acceleration technique to extend it to 5D EP-COSI. Semi-LASER EP-COSI enabled a homogeneous spatial profile with high SNR spectra throughout the VOI localization representing sharper excitation.

Session: IMAGING (MRI / MRS), poster number: 182

Neurite Density and Myelination Differences During Normal Aging Assessed Using Multicomponent Diffusion and Relaxometry Imaging

Wenshu Qian; Nikkita Khattar; Abinand C. Rejimon; Richard G. Spencer; Mustapha Bouhrara
National Institute on Aging, Baltimore, MD

While sensitive to microstructural changes, conventional quantitative MR techniques, such as diffusion tensor imaging, are not specific to underlying physiological mechanisms. Advanced multi-shell diffusion and multicomponent relaxometry analyses have been shown to provide more specific insights regarding microstructural differences with age and disease. In this study, we combined our multicomponent relaxometry method for myelin mapping and the neurite orientation dispersion and density imaging (NODDI) method to investigate neurite myelination and density in a cohort of cognitively unimpaired participants. Quadratic relationships were observed between neurite density and myelination, and age, in critical brain regions.

Session: IMAGING (MRI / MRS), poster number: 183

Optimizing Diffusion MRI to Improve Microstructural Modelling

Thomas H. Mareci
University of Florida, Gainesville, FL

Diffusion weighted imaging has become a powerful tool for the analysis of brain structure. Diffusion MRI data acquisition can require a long time, but improvements in image acceleration provide the opportunity for more robust diffusion acquisitions allowing fine structure determination. An optimal diffusion acquisition scheme must compromise between the total scan time and the robustness of the acquisition. This study focuses on optimizing the number of gradient strengths and directions while staying within a feasible total scan time for human measurements. To optimize the acquisition, a diffusion acquisition with 30 b-values with 20 directions per shell was collected and an optimal set of 9 b-values was determined.

Session: IMAGING (MRI / MRS), poster number: 184

MRS in Neurosciences – In-vivo spectroscopy methods and applications at the Stanford Center for Cognitive and Neurobiological Imaging (CNI)

Laima Baltusis
Stanford University, Stanford, CA

Interest of measuring metabolic changes via MRS techniques and combining that information with functional MRI measurements continues to grow. CNI continues to support the research of its user community by providing state-of-the-art data acquisition and state-of-the-art data management and analysis capabilities for in-vivo spectroscopy.

We will show examples of studies at CNI using spectroscopic techniques to characterize biomarkers following transcranial magnetic stimulation, and in conditions such as substance addiction, pain, depression, and various forms of dementia.

We will present results from the CNI development program of new advanced data acquisition sequences and accompanying visualization and analysis pipelines.

These studies will illustrate integrated tools accessible to the user community which simplify the use and sharing of spectroscopy results in neuroimaging applications.

Session: IMAGING (MRI / MRS), poster number: 185

Magnetic resonance measurements of cellular and sub-cellular membrane structures in live and fixed neural tissue

Nathan Williamson1, 2; Rea Ravin1; Dan Benjamini2; Hellmut Merkle3; melanie falgairolle3; Michael O'Donovan3; Dvir Blivis3; Dave Ide3; Teddy Cai2; nima ghorashi4; ruiliang bai2; Peter Basser2
1NIGMS, NIH, Bethesda, MD; 2NICHD, NIH, Bethesda, MD; 3NINDS, NIH, Bethesda, MD; 4NHLBI, NIH, Bethesda, MD

We develop magnetic resonance (MR) methods for measuring real-time changes of tissue microstructure and membrane permeability of live and fixed neural tissue. Diffusion and exchange MR measurements are performed using the large static gradient produced by a single-sided permanent magnet. Using tissue delipidation methods, we show that water diffusion is restricted solely by lipid membranes.  Most of the diffusion signal can be assigned to water in tissue which is far from membranes. The remaining 25% can be assigned to water restricted within membrane structures in the range of 200--1400 nm at the cellular, organelle, and vesicle levels. Diffusion exchange spectroscopy measures water exchanging between membrane structures and free environments at 100 s-1.

Session: IMAGING (MRI / MRS), poster number: 186

Optimizing Radial-Keyhole-Based Hyperpolarized Magnetization Decay Correction via Uncertainty Propagation

Mariah Costa1, 2; Peter Niedbalski1; Zackary Cleveland1
1Cincinnati Children's Hospital, Cincinnati, OH; 2University of Cincinnati, Cincinnati, OH

Advances in hyperpolarization (HP) have established NMR and MRI with HP media as indispensable tools in basic and applied research. To mitigate intrinsic HP decay, we introduced a method to map magnetization dynamics by combining Bloch-equation-based modeling and keyhole reconstruction. Here extend the approach to include rigorous uncertainty estimation to enable a prior improvements. With this analytical approach we compared linear keyhole with an interleaved approach (keys of odd/even numbered projections) to extract HP decay. Both strategies were tested in digital phantoms and human ventilation imaging with HP 129Xe. The linear approach yielded uniform decay values, while interleaved keyhole generated physically improbable distributions, demonstrating uncertainty propagation can optimize experimental design without lengthy or expensive preliminary experiments.

Session: IMAGING (MRI / MRS), poster number: 187

Chirped RARE with a single sided MRI

Nu Le; Muller Gomes; Alek Nacev
Promaxo Inc, Oakland,

We report a RARE (Rapid Acquisition and Relaxation Enhancement) pulse sequence designed to be used with a single sided MRI scanner. RARE is a fast imaging sequence that employs an RF excitation pulse followed by a train of refocusing pulses to produce multiple echoes from a single excitation, with each echo sampling a line in k space, speeding up image acquisition. To use it with Promaxo MRI scanner, RARE was modified to have as short an echo time as possible while also being used with broadband chirped pulses. Unlike RARE used with cenventional MRI scanner, RARE used with Promaxo MRI scanner is implemented to move forward in k space between the acquisitions from the refocusing pulses in the echo train, allowing for shorter times between acquisitions.

Session: IMAGING (MRI / MRS), poster number: 188

In vivo Phase-Incrementing MRSI (pi-MRSI) for Multi-Biomarker Imaging with Applications to Human MDA-MB-231 Breast Cancer Xenograft Mouse Model

Qiuhong He; Yuan Hong; Yen-Yu Ian Shih
University of North Carolina, Chapel Hill, NC

Phase-incrementing Magnetic Resonance Spectroscopic Imaging (pi-MRSI) method has resolved overlapping biomarker images in the presence of read-gradient.  On a Bruker 9.4T MRI spectrometer, the pi-SEE-HSelMQC sequence was implemented.  The choline-selective and lactate CH-selective RF pulses were phase incremented by 10° in opposite signs, synchronized with the phase-encoding steps.  The lactate and choline images from the Yogurt phantom displayed opposite image offsets without image overlapping.  In vivo one-dimensional pi-SEE-HSelMQC CSI images of lactate and choline, acquired from the MDA-MB-231 human breast cancer xenograft in a nude mouse, also had opposite image offsets, shifted away from the spurious residual water signals in the image center.   The pi-SEE-HSelMQC method completely suppresses lipid and water with potential clinical applications in disease diagnosis and therapeutic interventions.

Session: IMAGING (MRI / MRS), poster number: 189

SNR Improvement with ultral-High Dielectric Constant (uHDC) materials for 7T 2D MRS imaging

Mohan Jayatilake1; Navid P. Gandji1; Christopher Sica1; Zhu Xiao-Hong2; Wei Chen2; Maryam Sarkarat3; Michael Lanagan3
1Penn State Health Milton S. Hershey Medical Center, Hummelstown, PA; 2CMRR, Department of Radiology, University of Minn, Minnesota, MN; 3Department of Engineering Science and Mechanics,, University Park, PA

We investigated the effects of uHDC materials on SNR enhancement at 45.75 MHz for deuterium (2H) imaging (MRS) at 7.0 T. Simulations, in MATLAB and CST software, and in-vivo imaging was done for a setup that included a copper coil (14 mm diameter), a uHDC cylindrical disk (permittivity/thickness/ diameter/ = 3000/4.0 mm/12 mm), and a 2H phantom (relative permittivity/conductivity/diameter= 60/0.05 S/m/20 mm) placed on top of the disk. The point resolved spectroscopy (PRESS) sequence was used to obtain the 2H spectra (at multiple locations) with and without the disk (TE/TR = 5.25/1095 ms, voxel size=3×3×3 mm3). The disk enhanced SNR from 715 to 2332. HDC material seems to decrease the noise level enhancing the feasibility of 2H imaging.

Session: IMAGING (MRI / MRS), poster number: 190

Z encoded Phase Yields Refocused Slices (ZEPHYRS) Imaging with a Single Sided MRI

Muller Gomes
Promaxo, Oakland, CA

We report a new imaging pulse sequence that allows for one to maintain a consistent field of view when using a surface MRI. Surface gradient coils tend to produce gradients that decrease in strength as one moves away from the coil, resulting in an inconsistent field of view as one scans at different distances from the gradient coils. This can be corrected with a ZEPHYRS sequence, where a gradient is applied during a chirped pulse, resulting in some locations away from the coil receiving more phase than others, compensating for the existing variation. 

Session: IMAGING (MRI / MRS), poster number: 191

In Vivo Magnetic Resonance Spectroscopy and Imaging Studies in the Brains of Old Female Wistar Rats 

Belen Ramírez-Cordero1; Roberto Santín-Márquez1; Juan Ortíz-Retana2; Martín García-Servín3; Sarael Alcauter-Solórzano2; Luis Concha-Loyola2; Mina Konigsberg-Fainstein1
1UAM-Iztapalapa, Mexico, Mexico; 2LANIREM, Neurobiology Institute, UNAM, Juriquilla, Mexico; 3Bioterium, Neurobiology Institute, UNAM, Juriquilla, Mexico

In this work we used MRS and MRI to non-invasively study the aging brain of Wistar female rats. Using diffusion-weighted images, Fractional Anisotropy (FA), Apparent Diffusion Coefficient (ADC), Axial Diffusivity (AD) and Radial Diffusivity (RD) were measured in several regions of young and old animals. Our data showed significative AD and RD reduction in corpus callosum of old rats (24 months) vs. young rats (4 months). MRS of cortex and hippocampus showed general metabolites concentration reduction between 7 and 21 months compared to young rats. Old rat hippocampus showed a significative NAA reduction and myo-Inositol increased levels, which have been related with impaired neuronal function and neuroinflammation respectively. Additionally, we find lower correlation between metabolites levels in oldest animals.

Session: IMAGING (MRI / MRS), poster number: 192

Pilot Investigation of Effects of Nicotinamide Riboside Supplementation on Nicotinamide Adenine Dinucleotide Concentration in Human Skeletal Muscle Using 31P MR Spectroscopy

Howard Smithline1, 2; Miles Bartlett3; Jane Kent3; Nagendra Yadava2, 4; Rajakumar Nagarajan5
1Dept. Emergency Medicine, Baystate Medical Center, Springfield, MA; 2University of Massachusetts Med School - Baystate, Springfield, MA; 3Dept. of Kinesiology, University of Massachusetts, Amherst, MA; 4Dept. of Biology, University of Massachusetts, Amherst, MA; 5Human Magnetic Resonance Center, IALS, UMass, Amherst, MA

Decreased intracellular nicotinamide adenine dinucleotide (NAD), oxidative phosphorylation, and skeletal muscle function have been implicated in several diseases including normal aging process. Nicotinamide riboside, a NAD precursor and nutritional supplement, has been shown to improve intracellular NAD concentration and skeletal muscle function in animal models. Understanding the pharmacodynamics of nicotinamide riboside in humans is essential for determining the appropriate dosing regimen for clinical trials. This pilot study supports that nicotinamide riboside increases skeletal muscle NAD and that 31P MRS can be used to study its pharmacodynamics in humans. 

Session: IMAGING (MRI / MRS), poster number: 193

A High Throughput Volume Receive Array for Multiple-Mouse Imaging with SENSE

Ananda Kumar1; Lilia Ileva2; Joseph D. Kalen2
1Lambda Z Technologies, Inc., Baltimore, MD; 2Small Animal Imaging Program, Frederick Nat'l Lab, Frederick, MD

A scalable four-channel volume receiver array coil for high throughput whole body multiple-mouse imaging was developed for preclinical cancer research. The coil elements were designed with optimized saddle coil geometry for homogeneity which produced superior SNR and low coil coupling compared to those of unshielded linear high-pass birdcage resonators. Full-wave simulations, bench measurements, and phantom experiments were performed in the design and development of this volume array coil. Turbo-spin echo images of in-vitro mice with SENSE acceleration of 4 times and without acceleration were performed and they were found to be of similar image quality.

Session: IMAGING (MRI / MRS), poster number: 194

Elimination of Motion-Induced Signal Losses in Diffusion Weighted Imaging using Intra-Sequence Motion Updates

Artan Kaso; Thomas Ernst
U Maryland Medical School, Baltimore, MD

Diffusion weighted imaging (DWI) employs strong gradients to sensitize scans to microscopic molecular motion. However, this inevitably makes DWI sensitive to head movements, which may lead to partial or complete signal loss due to incomplete re-phasing. Prospective motion correction using fast optical tracking can attenuate motion effects in MR imaging and spectroscopy. In prior studiers, movement-induced signal losses in DWI were attenuated by quasi-continuous updates of gradients and RF-pulses during diffusion-encoding, or by applying a single dynamic update to restore the gradient balance. Here, we propose a simplified correction scheme for the monopolar DWI sequence that requires only 1 intra-scan motion update. This approach dramatically reduces the motion-sensitivity of DWI and can eliminate signal dropouts almost entirely.

Session: IMAGING (MRI / MRS), poster number: 195

Investigation of metabolomic association with androgen sensitivity in murine prostate cancer model using dynamic metabolic imaging of hyperpolarized [1-13C]pyruvate

Aditya Jhajharia; Dexue Fu; Maninder Singh; Shu Wang; Ian Qian; Aidan Kennedy; Mohummad M. Siddiqui; Dirk Mayer
University of Maryland School of Medicine, Baltimore, Maryland, USA

This study investigates different metabolic signatures of androgen-dependent (LNCaP) and androgen-independent (CSS90) murine model prostate tumors by utilizing hyperpolarized 13C pyruvate imaging. Higher pyruvate-to-lactate conversion in CSS90 compared to LNCaP tumors were confirmed by higher glycolysis in CSS90 by measuring extracellular acidification rate (ECAR) of the tumor slices. After treatment with MDV3100, a second-generation AR antagonist, a reduced pyruvate-to-lactate conversion in LNCaP tumors was a positive response to targeted therapy and was also supported by higher oxidative phosphorylation by oxygen consumption rate measurements. These initial findings demonstrated that hyperpolarized pyruvate metabolism is a useful biomarker to characterize the tumor type-specific differences and can potentially access the responses to therapies.

Session: IMAGING (MRI / MRS), poster number: 196

Characterizing brain tumor microstructure and heterogeneity with non-parametric diffusion tensor distributions

Joao Pedro De Almeida Martins1; Samo Lasic2; Yuan Zheng3; Qing Wei3; Sirui Li4; Wenbo Sun4; Haibo Xu4; Karin Bryske2; Daniel Topgaard1
1Division of Physical Chemistry, Lund University, Lund, Sweden; 2Random Walk Imaging AB, Lund, Sweden; 3United Imaging Healthcare, Shanghai, China; 4Zhongnan Hospital of Wuhan University, Wuhan, China
While useful to probe micro-structural tissue changes within a clinical setting, conventional diffusion MRI metrics are too ambiguous for straightforward interpretation. When approaching this problem, we have translated solid-state NMR techniques for correlating isotropic and anisotropic molecular sites into the field of diffusion MRI, and devised a family of protocols that quantify microscopic heterogeneity with diffusion tensor distributions (DTDs). Here, we present a clinically-feasible implementation of our DTD approach. Voxel-wise DTDs were retrieved using a non-parametric Monte Carlo algorithm and converted to parameter maps that characterise and quantify the diffusion properties of the various sub-voxel tissue environments within brain tumours. The DTD-derived maps were observed to provide structural insight not attainable with conventional methods.

Session: IMAGING (MRI / MRS), poster number: 197

Proton magnetic resonance spectroscopic imaging study of frontal white matter metabolic alterations in patients with Parkinson’s disease

Senthil Kumaran; Shefali Chaudhary; Vinay Goyal; Gauri Shanker Kaloiya; M Kalaivani
AIIMS, Ansari Nagar, India

In vivo magnetic Resonance Spectroscopy (MRS) was carried out in the frontal white matter of patients with Parkinson’s disease, which revealed alterations of NAA (and NAA/Cho ratio) in patients in comparison with healthy controls, suggesting neuronal loss, injury or altered membrane metabolism.

Session: IMAGING (MRI / MRS), poster number: 198

T Echo Planar Spectroscopic Imaging: A Pilot Study

Manoj Sarma1; Samantha Joseph1; Andres Saucedo1; Silvia Mangia2; Shalom Michaeli2; M. Albert Thomas1
1Radiological Sciences, UCLA School of Medicine, Los Angeles, CA; 2Radiology, University of Minnesota, Minneapolis, MN

The rotating frame transverse relaxation time constant Tis a function of multiple relaxation processes in tissue including dipolar interactions, and isochronous and anisochronous exchange. It is inherently sensitive to slow molecular motions. Although multiple versions of the T techniques have been applied in MRI, there have been only two spectroscopic implementations. Here, we evaluated the feasibility of T MRSI using hyperbolic-secant AFP pulses to estimate metabolites T relaxation times from multiple voxels at 3T. We calculated the T values for several metabolites including Glx, tNAA, total choline in a brain phantom. Further implementation and evaluation of the technique in-vivo is currently in progress. Physico-chemical models of metabolite T may provide insight into progression and diagnostic assessment of clinical disorders.  

Session: IMAGING (MRI / MRS), poster number: 199

Quantitative Heterogeneity MRS (qhMRS):   A New Paradigm for Line Shape Evaluation of NMR Resonances Sensitive to Physicochemical Parameters

Norbert Lutz; Monique Bernard
Aix-Marseille University, Marseille, France

It is well known that the chemical shifts of particular NMR resonances depend on physicochemical parameters such as temperature, pH, or certain ion concentrations. While this phenomenon has been exploited to measure those parameter values by MRS, the line shapes in question may appear broadened and "deformed" for samples that are heterogeneous with respect to the associated parameters. Here, we present a method that is able to extract multifaceted quantitative information on sample heterogeneity from such a line shape. As an example, water 1H MRS/I resonances are converted to temperature profiles yielding statistical descriptors characterizing temperature distributions within volumes/voxels of samples with temperature gradients. We then generalize our paradigm to include further physicochemical parameters relevant to materials and tissue analysis.

Session: IMAGING (MRI / MRS), poster number: 200

Mapping Dissolved 129Xe T2* in Mouse Lungs using 3D Radial MRI

Brice Albert1; Peter Niedbalski1; Zackary Cleveland1, 2
1Cincinnati Children's Hospital, Cincinnati, OH; 2University of Cincinnati, Cincinnati, OH

Hyperpolarized (HP) 129Xe MRI allows regional lung function to be assessed across a range of pathologies. Specifically, lung disease alters gas exchange in a spatially dependent manner, but routine clinical metrics provide only global information about lung dysfunction. Quantifying regional HP 129Xe uptake by gas exchange tissues thus offers promising biomarkers of disease severity. While more refined in human research, gas-exchange MRI for basic, preclinical research remains poorly developed – particularly in mouse models. Notably, the T2* of 129Xe dissolved in the mouse lung has yet to be reported. Using 3D radial MRI at 7 T, the dissolved 129Xe T2* is measured to be ~0.8 ms in the lungs of control mice and of a mouse model of lung fibrosis.

Session: IMAGING (MRI / MRS), poster number: 201

Detection of Residual Dipolar Coupling in Vastus Lateralis by Two-dimensional Localized Correlated Spectroscopy

Rajakumar Nagarajan1; Andres Saucedo2; Manoj Sarma2; Payton Andrews1; Jane A Kent3; M. Albert Thomas2
1Human Magnetic Resonance Center, IALS, UMass, Amherst, MA; 2Radiological Sciences, UCLA School of Medicine, Los Angeles, CA; 3Kinesiology, UMass, Amherst, MA

Magnetic resonance spectroscopy (MRS) is a non-invasive technology for distinguishing IMCL from EMCL in the skeletal muscle.  Foot angle variations influence the MR spectrum by changing the pennation angles of the muscle fibers. Due to the small chemical shift separation ( 0.2ppm)  between IMCL and EMCL as well as overlapping of saturated and unsaturated lipids, it is very difficult to quantify those chemicals by one dimensional (1D) MRS techniques using short TE. A two-dimensional (2D) localized correlated spectroscopy (L-COSY) technique is able to distinguish IMCL and EMCL peaks, and also detect creatine/ phosphocreatine cross peaks due to residual dipolar coupling in the vastus lateralis.  

Session: IMAGING (MRI / MRS), poster number: 202

Inside-out imaging of alternating currents in commercial rechargeable batteries

Stefan Benders; Mona Mohammadi; Alexej Jerschow
New York University, New York, NY

Rechargeable batteries form a key technology in many fields, yet the internal processes of commercial batteries are often not accessible for investigation. An obstacle for NMR techniques is the inability for radio-frequency to penetrate through the metal casing of these cells, which was overcome with the introduction of the inside-out approach (ioMRI).

In this work, we present an MR technique to map fields generated by alternating current (AC) in an inside-out fashion. While the analysis of impedance changes in electrochemical systems with AC frequency using electrical impedance spectroscopy (EIS) is an important technique in this field, these measurements only provide a global assessment. With the ioMRI approach presented here, we envision characterizing AC distributions across the whole cell.

Session: IMAGING (MRI / MRS), poster number: 203

Evidence for Diffusive Diffraction Behavior in Bottlebrush Polymer Melt

Velencia J Witherspoon; Michal E. Komlosh; Dan Benjamini; Peter J. Basser
National Institutes of Health, Bethesda, MD

We present experimental evidence for long-range correlated motion in a neutral bottle-brush polymer melt via nuclear magnetic resonance diffusion correlation spectroscopy. We investigate the time and length scale associated we correlated center of mass motion and determine correlation time to persist on the order of 101  ms with periodically correlated clusters sizing on the order of 101 µm. Our result suggests that density fluctuations in bottlebrush polymer melt systems lead to anomalous Brownian motion and cause correlated motion similar to that found in polyelectrolyte colloid systems.

Session: IMAGING (MRI / MRS), poster number: 204

Comparison of Eddy Current Artifacts on Different Coils and Nuclei

Mary Mclean1; Scott Hinks2; Joshua Kaggie1; Ramona Woitek1; Frank Riemer1; Martin Graves1; Dominick McIntyre1; Ferdia Gallagher1; Rolf Schulte3
1University of Cambridge, Cambridge, United Kingdom; 2GE Healthcare, Milwaukee, WI; 3GE Healthcare, Munich, Germany

Using pulse-acquire spectroscopy, the magnitude of eddy current induced frequency shifts was investigated for three nuclei and two coils using the same spherical phantom on a clinical MRI scanner. In the absence of standard frequency pre-emphasis, the amplitude of these shifts scaled with the gyromagnetic ratio, although their time constants were similar. A correction to eddy current compensation is proposed to account for the X-nucleus gyromagnetic ratio, which was shown to dramatically reduce spectral distortions.  

Session: IMAGING (MRI / MRS), poster number: 205

Denoising effect of ultra high dielectric constant (HDC) materials

Navid Pourramzangandji1; Mohan Jayatilake1; Christopher Sica1; Hannes Wiesner2; Xiao-Hong Zhu2; Maryam Sarkarat1; Michael Lanagan1; Wei Chen2; Qing Yang1
1PennState University, CNMRR, Hershey, PA; 2University of Minnesota, CMRR, Minneapolis, MN

In this work we investigated the effect of the ultra high dielectric constant (HDC) materials on reducing the noise level and enhancing the B1+ efficiency for low-γ nuclear spectroscopy application at 78 MHz (23Na at 7 Tesla scanner). By using HDC material, the conservative electric (E) field within the sample under test will be reduced, therefore the non-conservative E-field which becomes dominant and the transmit efficiency as well as the receive sensitivity enhances. We calculated normalized noise level and the B1 efficiency map and experimentally demonstrated that the noise level is reduced in the presence of HDC material.

Session: IMAGING (MRI / MRS), poster number: 206

A Novel Field-Frequency Lock for Fast Field Cycling NMR: Experimental Proof Of Concept And Extension to FFC-MRI

Giacomo Galuppini1; Yong Xia2; Lalo Magni1; Gianni Ferrante2
1University of Pavia, Pavia, Italy; 2Stelar s.r.l., Mede (Pv), Italy
Fast Field Cycling MRI and NMR experiments require the magnetic field to reach different values in few milliseconds and field oscillations to stay within a few ppms during signal acquisition. Such specifications call for the introduction of a novel Field-Frequency Lock (FFL) system. In fact, control schemes based only on current feedback may not guarantee field stability.
The aim of this work is the design of a novel field-frequency control system and its experimental validation. The design of ad-hoc hardware and firmware solutions allowed improvement of the performance and ensured its functionality when applied to a FFC MRI scanner, with very little interference with the main system. Experimental results are presented.

Session: IMAGING (MRI / MRS), poster number: 207

Low temperature, DNP-enhanced magnetic resonance microimaging


Hsueh-Ying Chen
LCP/NIDDK/NIH, Bethesda,

Magnetic resonance imaging (MRI) has been used to image various objects ranging from a human brain to animal/plant cells by adding field gradients to nuclear magnetic resonance (NMR) measurement. The limitation of the spatial resolution in MRI is the signal-to-noise (SNR) of NMR signals available from a single image element. We demonstrated an image of isotropic 2.8-microns from a sample at ~30 K. We are combining dynamic nuclear polarization (DNP) to further increase the 1H polarization. With substantial signals from DNP, the total experiment time is limited to k-space sampling instead of signal averaging. We developed a slice selection sequence for solid samples to reduce the required field of views and obtained a preliminary 3D image with 1.5-µm isotropic resolution.

Session: IMAGING (MRI / MRS), poster number: 208

Rheo-NMR for the investigation of protein aggregation and polymer dynamics

Benjamin Kohn1; Roland Vogel1; Vincent Körber1; Enno Stündel1; Erik Walinda2; Kenji Sugase3; Daichi Morimoto3; Petrik Galvosas4; Ulrich Scheler1
1Leibniz Institut für Polymerforschung Dresden e.V., Dresden, Germany; 2Department of Molecular and Cellular Physiology, Kyoto, Japan; 3Department of Molecular Engineering,, Kyoto, Japan; 4Chemical and Physical Sciences, Victoria Universit, Wellington, New Zealand

Rheological NMR is applied to investigate the molecular response to of shear in a double cylinder geometry. Flow pattern measured under oscillatory shear reveal considerable counterflow at the flow reversal for low-viscosity fluids. Thus results in flow gradients and thus shear rates more than three times higher than those found at the maximum velocity.

Insight on the molecular dynamics is obtained from T2 relaxation measurements. Contrary to the expectations the mobility of polymer chains increases under shear, which must be due to changes of entanglements. Novel measurements under oscillatory shear reveal the onset of the faster polymer mobility at strains in excess of 100. In proteins where significantly less internal motion is observed shear induced aggregation is observed.

Session: IMAGING (MRI / MRS), poster number: 209

An open field cycling magnetic resonance system

Baosong Wu; Charles Rogers III; Gigi Galiana; R. TODD Constable
Yale University, New Haven, CT

Point-of-care diagnostics has attracted interest in low-field MRI devices recently. Our group is developing an approach that combines a rampable and nonuniform electromagnet for polarization and slice selection. Additionally, RF encoding utilizing the Bloch-Siegert shift replaces conventional gradients for in-plane encoding.  Since the natural gradient of the electromagnet provides slice selection, the scanning system is silent. In this work we present results on the field cycling, parameter optimization and preliminary data. Our future work will demonstrate the feasibility of inhomogeneous field imaging.

Session: IMAGING (MRI / MRS), poster number: 210

Electron Paramagnetic Resonance Based on Z-axis Detection of Fictitious Field Modulation

Xueyan Tang; Michael Garwood; Steven Suddarth
CMRR/Dept of Radiology, University of Minnesota, Minneapolis, MN

Whitfield and Redfield found that an xy-plane radiofrequency (RF) field alone could polarize spins along the z-axis. By turning on and off the RF field, they acquired z-magnetization signal for 2,2-diphenyl-1-picrylhydrazyl (DPPH). This phenomenon could be well explained by fictitious field in the rotating frame. Herein, we repeated their experiment and extended it to iron-oxide nanoparticles (IONP).  Based on this z-axis detection approach, we built a one-dimensional (1D) imaging system that can do simultaneous transmit and receive with minimum leakage signal. Multi-dimensional imaging systems are currently under development in our lab.

Session: IMAGING (MRI / MRS), poster number: 211

Orientation free tracking of MR-Catheters during interventional MRI, wirelessly through induction coupling

Omar Nassar; Dario Mager; Jan Korvink
Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany

The geometrical tracking of a catheter's tip within an MR environment is a topic has caused repeated interest during the past decade, as a prerequisite for the further development of minimally invasive medical interventions. By placing a microresonator on the tip of the catheter, and tracking the resulting bright spot in the MR image, it allows surgeons to locate the tip's orientation with respect to the patient's body. The resonator can be tracked wirelessly via inductive coupling, to prevent the heating hazards from using the conductive cable. Here we propose a microresonator design based on a double saddle coil, which maintains constant coupling between the microresonator on the catheter and the external coil through the different axial orientations.

Session: IMAGING (MRI / MRS), poster number: 212

Using deep learning to predict T2 Maps from MR Images

Bragi Sveinsson1; Akshay Chaudhari2; Bo Zhu1; Neha Koonjoo1; Matthew Rosen1
1MGH - Martinos Center, Charlestown, MA; 2Stanford University, Stanford, CA

MRI scan protocols sometimes omit valuable scanning methods due to time constraints. For example, the osteoarthritis initiative (OAI) performed several morphological MRI scans on the both knees of a large patient cohort, but only acquired T2 maps in the right knee of most patients. Using deep learning, we train a conditional GAN to use the morphological scans acquired in both knees to predict the T2 map, using the acquired T2 map in the right knee as a training target. Post-training, we apply the network to predict T2 values in the left knee, without an acquired T2 map.

Session: IMAGING (MRI / MRS), poster number: 213

Zero- to Ultralow-Field Nuclear Magnetic Resonance Imaging

Nataniel Figueroa1; John Blanchard1; James Eills1; Silvia Lopez2; Román Picazo1; Teng Wu1; Dmitry Budker1, 3
1Helmholtz-Institut Mainz, Mainz, Germany; 2Universidad de Cantabria, Santander, Spain; 3University of California, Berkeley, CA

Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) is an emerging technique in which samples are studied in the absence of the large magnetic field typically used in NMR experiments. We report a method for acquiring spatially resolved ZULF NMR spectra. The technique employs phase-encoded Fourier imaging, and is somewhat reminiscent of B1 imaging. The acquired spectra retain the full chemical resolution characteristic of ZULF NMR and can then be used for mapping spatial distributions of different molecules, or changes in pH or solvent dielectric constant. We are exploring ways to extend this technique to allow for 2D and 3D imaging, providing a new tool for spatially resolved spectroscopy with high chemical specificity, even in heterogeneous or conductive samples.

Session: IMAGING (MRI / MRS), poster number: 214

Towards Magnetic Resonance Imaging in a 36-T Powered Magnet

Xinxing Meng1; Samuel Holder3; Nastaren Abad3; Jeffrey L. Schiano1; Samuel C. Grant2, 3
1The Pennsylvania State University, University Park, PA; 2National High Magnetic Field Laboratory, Tallahassee, FL; 3Florida State University, Tallahassee, FL

While low temperature superconductors (LTS) operating in the self-persistent mode provide the spatial homogeneity and temporal stability required for MRI, their physical properties limit the maximum field strength. Higher fields will increase spatial resolution and enable studies using low-gamma nuclei.  In this study we describe our efforts to generate an MR image using a 36-T Series-Connected Hybrid magnet. Strategies for acquiring an image in the presence of temporal fluctuations caused by power supply ripple and variations in the cooling system are presented. These include the utilization of a flux regulation system to decrease field fluctuations, and the selection of an imaging sequence that alleviates the effect of temporal field fluctuations on image fidelity.