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Code: PM	Time Slot/Poster Number: 261	Session: NMR Imaging: Advances, Poster
Cartilage Integrity Probed by Relaxations Along a Fictitious Field (RAFF)
Wen Ling³; Elizabeth Arendt¹; Jennifer Rees³; Timo Liimatainen²; Shalom Michaeli³; Michael Garwood³; Jutta Ellermann³
¹Dept. of Orthopedic Surgery, Univ. of Minnsota, Minneapols, MN; ²Dept. of Biotechnology,Univ. of Kuopio, Kuopio, Finland; ³CMRR, Univ. of Minnesota, Minneapolis, MN
Abstract
A rotating frame contrast relaxations along a fictitious field (RAFF) was evaluated along with T2 and T1rho techniques. our simulation indicates RAFF is selectively targeting slow dynamics ranging 10-3 ~ 10-4 S, coincident with exchange process of cartilage. our experimental results also confirm that RAFF is more sensitive to proteoglycans, which is the main contributor to exchange with different chemical shift. moreover, RAFF produce excellent contrast not shown in both T1rho and T2 contrast.

Code: PM	Time Slot/Poster Number: 262	Session: NMR Imaging: Advances, Poster
A search for a homogeneity phantom filler material for high frequency MRI systems
Raliek Q. Boswell¹; May G. Cheung¹; Brittony C. Lipchick¹; Thomas W. Smith²; Sam Coons³; Phillip E. Steen³; Christina L. Bray¹; Joseph P. Hornak¹
¹RIT Magnetic Resonance Laboratory, Rochester, NY; ²RIT Department of Chemistry, Rochester, NY; ³Invivo Corporation, Gainesville, FL
Abstract
The preferred operating frequency of clinical MRI systems is now 125 MHz (3T) making standing wave artifacts in images of phantoms more of a problem. There is a need for phantom filler materials with a low dielectric constant that load a radio frequency coil similarly to the human body. We have examined several materials for this purpose and focus on two: t-butanol and polyethylene glycol monomethyl ether. Both solutions were doped with Ni(+2) to control T1, and HCl to control the conductivity. They also have a lower dielectric constant than water and load an RF coil similarly to the human body. Properties of the materials and images of phantoms are presented and compared.

Code: PM	Time Slot/Poster Number: 263	Session: NMR Imaging: Advances, Poster
Mapping Isochronous Exchange in the Human Brain by Different Radiofrequency Pulse Preparation Schemes
Silvia Mangia¹; Michael Garwood¹; Timo Liimatainen²; Federico De Martino³; Shalom Michaeli¹
¹CMRR - Univ. of Minnesota, Minneapolis, MN; ²Dept. of Biotech. and Mol. Med., Univ. of Kuopio, Kuopio, Finland; ³Dept. of Cognitive Neurosci., Univ. of Maastricht, Maastricht, The Netherlands
Abstract
In the present work we investigated the sensitivity of several different radiofrequency preparation schemes to probe exchange processes in the human brain using MRI at 4T. Magnetization was prepared prior to the imaging readout either with off-resonance continuous-wave irradiation with incremental pulse time duration, to exploit the magnetization-transfer effect, or with an incremental train of adiabatic pulses with various modulation functions, to exploit adiabatic rotating frame relaxation mechanisms. Results demonstrate that the two approaches are sensitive to different ranges of exchange rate constants and provide different tissue specificity, thus generating complimentary information to characterize the tissue in vivo.

Code: PM	Time Slot/Poster Number: 264	Session: NMR Imaging: Advances, Poster
Specificity- and Sensitivity-Enhanced MR Molecular Imaging and Multicolor MRI by Supramolecular Magnetic Nanoparticles and Active Feedback-Enhanced Imaging
Stephanie Wolahan¹; Kuan-Ju Chen²; Hao Wang ²; Jae-Hyun Lee³; Jinwoo Cheon³; Hsian-Rong Tseng²; Yung-Ya Lin¹
¹Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA; ²Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA; ³Department of Chemistry, Yonsei University, Seoul, Republic of Korea
Abstract
In this work, we present complementary approaches to improve sensitivity and specificity in MR molecular imaging. The first approach is to use nanotechnology to design a MR contrast agent detectable at lower concentrations and with greater specificity than conventional MR contrast agents. The second approach is to engineer the spin dynamics with active feedback-enhanced detection methods to achieve sensitivity enhancements. We will present a sensitivity-enhanced MR molecular imaging probe that relies on a supramolecular nanoparticle (SNP) structure with size-, spacing-, and composition-controllability. The SNP structure enhances r1 by embedding Gd complexes and enhances r2 by embedding superparamagnetic nanoparticles. We will achieve additional contrast enhancement using active feedback-enhanced imaging which is highly sensitive to small variations in magnetic susceptibility.

Code: PM	Time Slot/Poster Number: 265	Session: NMR Imaging: Advances, Poster
Design and Implementation of 2D DESIRE Experiments
Luisa Ciobanu; Nicolas Boulant; Denis Le Bihan
CEA/DSV/I2BM/Neurospin, Paris, France
Abstract
The Diffusion Enhancement of SIgnal and REsolution (DESIRE) method has been proposed as an alternative to the conventional Fourier encoding methods in high resolution magnetic resonance microscopy. Previous studies showed the potential of the technique to increase the sensitivity and contrast and reported 1D DESIRE images. In this paper we propose a strategy for designing and implementing 2D DESIRE experiments and present the first 2D DESIRE image. Our approach allows for the specification of the region to be imaged and corrects for B0 field inhomogeneity.

Code: PM	Time Slot/Poster Number: 266	Session: NMR Imaging: Advances, Poster
In-Vitro Study of Japanese Encephalitis Virus Infection in Porcine Stable Kidney cell (PS) by using 1H NMR spectroscopy
Sarika Tiwari¹; Rishi Kr. Singh¹; Santosh kumar Bharti²; Raja Roy²; Tapan N Dhole¹
¹Sanjay Gandhi Post Graduate Institute of M. S., Lucknow, India; ²Centre of Biomedical Magnetic Resonance, SGPGIMS, Lucknow, UP, India
Abstract
Japanese encephalitis virus (JEV) family Flaviviridae infections were studied on porcine stable kidney cell line. Primary observed by inverted microscopy and then NMR spectroscopy. Both uninfected and infected cells utilize glucose and release lactate, acetate and formate as extracellular metabolites. At the onset of infection, extracellular metabolites lactate was converted to acetate. In the intracellular metabolites of infected cells showed significantly high concentration of valine, leucine, uracil and aspartic acid. Cellular metabolites except lipid components gradually decreased and disappeared during 12–72 hours post infection. The infected cell doesn’t utilize cell lipid as compared to that in uninfected cells. These results show that early detection of JEV infection, and may have implications in virus cell interaction using 1H NMR spectroscopy.

Code: PM	Time Slot/Poster Number: 267	Session: NMR Imaging: Advances, Poster
Amplification of Ionic Currents by Resonance at Rabi Frequency
Winston Yan ; Andrew Kiruluta
Harvard University, Cambridge, MA
Abstract
We present the physical basis and experimental evidence for current detection based on a resonant interaction between the magnetic fields such as those arising from neuron activity, with a spin population that is undergoing Rabi oscillations at a frequency commensurate with the neuron currents. Recognizing that neural activity has an inherent spectral content is the key to the approach proposed and validated here. We demonstrate through the use of an ionic current phantom that B1 excitation at a Rabi frequency commensurate with the frequency of the current flow produces larger changes in the observed NMR signal than those arising solely out simple spin dephasing. These Rabi interactions may form the basis for imaging neural activity directly with MR.

Code: PM	Time Slot/Poster Number: 268	Session: NMR Imaging: Advances, Poster
Application of Diffusion Tensor Imaging to Assess Sarcopenic Effects in Sedentary Rat Muscle
Ihssan S. Masad^{1, 2}; Jacob M. Wilson ¹; Sang-rok Lee ¹; Youngmin Park¹; Paul C. Henning ¹; Bahram H. Arjmandi ¹; Jeong-su Kim ¹; Samuel C. Grant ^{1, 2}
¹The Florida State University, Tallahassee, FL; ²National High Magnetic Field Laboratory, Tallahassee, FL
Abstract
Diffusion tensor imaging (DTI) has shown high sensitivity to study changes in cross-sectional areas (CSA) and myofiber architecture in muscle. However, DTI has not been applied to the study of sarcopenic effects in rodents, which involves muscle wasting. In this work, the effects of age on CSA and anisotropy of water diffusion in skeletal muscle are studied under the influence of advanced aging in rats. Results demonstrate that the soleus CSA and ADC decrease with age until reaching a plateau at advanced time points. FA increases with age until it also plateaus. These findings indicate that DTI is sensitive to sacropenic alterations.

Code: PM	Time Slot/Poster Number: 269	Session: NMR Imaging: Advances, Poster
Simulation tools for T1 measurement optimization applied to standard MRI sequences
Fabien Balezeau^{1, 2}; Yannick Laridon^{1, 4, 5}; Pierre-Antoine Eliat^{1, 2}; Hervé Saint-Jalmes^{1, 3}
¹, Rennes, France; ²LTSI, Univ. Rennes1, Rennes, France; ³CRLCC, Rennes, France; ⁴Univ. Rennes1, Rennes, France; ⁵Univ. rennes1, rennes, France
Abstract
Fast and precise T1 measurement is the key of quantitative dynamic contrast enhanced MRI. MRI sequences used have to be optimized by an accurate choice of the sequence parameters values.The Cramer Rao lowest bound method is an analytical approach that provides the expression of the T1 variability, and enables to determine the set of sequence that minimizes the lowest T1 variability. We used this method to optimize the spin echo and spoiled gradient echo sequences considered as standard T1 measurement sequences.We developped two simulations tools to confirm the theoretical expectations and sutdy other causes of error in T1 measurment. Both provided very coherent results and they constitute a comprehensive and polyvalent tool kit for quantitative MRI optimization.

Code: PM	Time Slot/Poster Number: 270	Session: NMR Imaging: Advances, Poster
Magnetic Resonance Imaging of Oscillating Currents
Nicholas W Halpern-Manners; Vikram Bajaj; Thomas Teisseyre; Alexander Pines
LBNL & UC Berkeley, Berkeley, CA
Abstract
Direct imaging of neuronal activity by MRI would resolve many issues inherent to fMRI, yet common techniques rely on phase measurements which cancel in the presence of oscillatory magnetic fields. We demonstrate methods to perform direct, quantitative, frequency-selective imaging of oscillating currents with no spatial or temporal cancellation. We apply this method in a current loop phantom, mapping its magnetic field and achieving detection sensitivity at the threshold required for detection of neuronal currents. We show how ramped and phase-modulated spin lock radiation can enhance the sensitivity and robustness of the experiment. We further demonstrate the combination of these methods with remote detection, permitting the measurement of currents in small volumes of flowing water with high sensitivity and spatial resolution.

Code: PM	Time Slot/Poster Number: 271	Session: NMR Imaging: Advances, Poster
In vivo SWIFT Imaging of SPIO Labeled Stem Cells Grafted in the Heart
HuaLei Zhang¹; Djaudat Idiyatullin²; Curt Corum²; Jia Zhong¹; Hui Qiao¹; Steen Moeller²; Rong Zhou¹; Michael Garwood²
¹Department of Radiology,University of Pennsylvania, Philadelphia, PA; ²Center for Magnetic Resonance Research, UMN, Minneapolis , MN
Abstract
We demonstrate the first in-vivo cardiac images by ECG-gated SWIFT (SWeep Imaging with Fourier Transformation. Myocardium anatomies are well-visualized on 3D SWIFT magnitude images. The positive contrast on SWIFT imaginary image facilitates the detection of SPIO-containing cells while the magnitude image provides anatomical reference without requirement for additional reference image. The data show that SWIFT offers an alternative to currently available positive contrast methods, with advantages especially for cardiovascular applications.

Code: PM	Time Slot/Poster Number: 273	Session: NMR Imaging: Advances, Poster
Reducing SAR and Enhancing Cerebral SNR with High Permittivity Padding
Qing X Yang
Penn State College of Medicine, Hershey, PA
Abstract
Experimental and computer modeling results of human head imaging at 3T showed that padding around the human head containing appropriate amount of high dielectric material (~ 78) such as water reduced the input RF power for an 180o excitation pulse by 50% while enhancing image SNR by as much as 30 %. Our results demonstrated that placement of high dielectric constant pad enhanced B1 in the head and, thus, offers an effective approach for RF engineering.

Code: PM	Time Slot/Poster Number: 274	Session: NMR Imaging: Advances, Poster
Characterization of new silica based contrast agents by means of the study of their NMRD profiles
Hjordis Skaar²; John Georg Seland²; Gianni Ferrante¹; Salvatore Bubici³; Mike Mallett⁴; Tijs Robinson⁴
¹Stelar s.r.l., Mede (Pv) , Italy; ²Department of Chemistry, University of Bergen, Bergen, Norwey; ³Invento srl, Turin, Italy; ⁴HTS-110, Lower Hutt, New Zeeland
Abstract
Nanosized periodic mesoporous silica (PMS) materials loaded with gadolinium have shown promising properties as potential contrast agents for magnetic resonance imaging (MRI). Objective of present work is to study the complex relaxation behaviour of these types of materials. Knowledge of the field dependence of T1 in a wide range of magnetic field is needed to model the detailed mechanisms of paramagnetic relaxation in these systems. Different samples of PMS have been prepared and relaxation rates have been measured at different temperatures from 0.01 to 80 MHz using a Field Cycling NMR relaxometer and a cryogen free superconductive magnet. The NMRD profiles of all samples, measured at different temperature in the whole range of magnetic field, are presented.

Code: PM	Time Slot/Poster Number: 275	Session: NMR Imaging: Advances, Poster
Inverse Polarization Imaging of the Bis-Allyl and Vinyl Proton Ratio in Fatty Acyl Species Associated with Hepatocarcinogenesis
Jeff Griffitts; Yasvir Tesiram
Oklahoma Medical Research Foundation, Oklahoma City, OK
Abstract
During the hepatocarcinogenesis process, alterations occur in fatty acyl species. NMR is capable of detecting alterations in the fatty acyl species unsaturation by detection of two resonances in the proton spectrum, the vinyl and bis-allyl peaks that arise from unsaturated fatty acids. We have previously shown that a decrease in the ratio measurement of the integral values of these two resonances coincides with the onset of neoplasia in transgenic mice. In the present study, we implemented an inverse polarization method for the visualization of regions where alterations in fatty acid metabolites is occurring. The inverse polarization method eliminates contamination of the proton signal from all other metabolites, enabling the accurate measurement of ratio values arising solely from fatty acyl species.

Code: PM	Time Slot/Poster Number: 276	Session: NMR Imaging: Advances, Poster
Cross-Encoded Magnetic Resonance Imaging in Inhomogeneous Fields
Raphaël Paquin^{1, 2}; Bruno Vitorge¹; Philippe Pelupessy¹; Geoffrey Bodenhausen^{1, 2}
¹Ecole Normale Supérieure, Paris, France; ²Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
Abstract
In magnetic resonance imaging (MRI), the subject should ideally be immersed in a magnetic field that is as homogeneous as possible. However, this stringent requirement is hard to fulfill in many systems, and fast imaging techniques, such as Echo-Planar imaging (EPI) [1], can only compensate for field inhomogeneities with a known profile by pre- or post-acquisition corrections [2]. Our novel cross-encoded MRI schemes [3], which use adiabatic pulses combined with orthogonal gradients during encoding and decoding, can remove undesirable effects of unknown inhomogeneous magnetic fields. The cross-encoded MRI technique enables the acquisition of images in two or three dimensions that are virtually indistinguishable regardless of the inhomogeneity. [1] M. Stehling, R. Turner, P. Mansfield, Science 254 (1991) 43-50. [2] A. Tal, L. Frydman, J. Magn. Reson. 182 (2006) 179-194. [3] R. Paquin, P. Pelupessy, G. Bodenhausen, J. Magn. Reson. 201 (2009) 199-204.