Traditional Posters: Miscellaneous

Elena Vescovo¹, Federico Di Cesare², Dan Stefan², Danielle Graveron-Demilly², Steve Williams<sup>3

1</sup>Image Science and Biomedical Engineering,, The University of Manchester, Manchester, Greater Manchester, United Kingdom; ²Laboratoire CREATIS-LRMN, CNRS UMR 5220, Universite' Claude Bernard Lyon 1, Lyon, France; ³Image Science and Biomedical Engineering, The University of Manchester, Manchester, Greater Manchester, United Kingdom

Magnetic resonance spectroscopy can provide a non-invasive approach to measure the internal temperature of the brain; it relies on the linear relationship between the 1H MR resonance frequency of water in the tissue and the tissue’s temperature. The absolute temperature is obtained by measuring the chemical shift of water relative to a reference compound such as N-Acetylaspartate (NAA). To convert the frequency difference between these two signals into temperature, it is necessary to apply a calibration curve. All these procedures could be performed using a plugin of jMRUI, a Java-based Graphical User Interface that allows time-domains analysis of MRS, MRSI and HRMS-NMR signals. In this work we used jMRUI v4.x, a new version of the software that enabled the user to add their own plugin.

952. Efficient Generation of a Magnetic Field-Free Line

Tobias Knopp¹, Marlitt Erbe¹, Timo F. Sattel¹, Sven Biederer¹, Thorsten M. Buzug<sup>1

1</sup>Institute of Medical Engineering, University of Lübeck, Lübeck, Germany

Spatial encoding in magnetic particle imaging (MPI) is achieved by moving a field-free point (FFP) through the imaging volume. Recently, it was shown that the sensitivity of MPI can be increased by taking advantage of a field-free line (FFL) for spatial encoding. However, until today the power loss of an FFL scanner was thousand times higher than the power loss of an FFP scanner. In this work, the first feasible coil setup is presented, which has a power loss of the same order as an FFP scanner.

953. Relaxation Enhancement by Longitudinal Multispin Orders

Loyola D'Silva¹, S. Sendhil Velan<sup>1

1</sup>Laboratory for Molecular Imaging, Singapore Bioimaging Consortium, Singapore, Singapore

There is a great interest in increasing the longitudinal relaxation of nuclear spins for hyperpolarized imaging experiments. Longitudinal multispin orders (LOMO) correspond to the non-equilibrium population distribution and can be created in spin systems that exhibit J couplings, dipolar couplings or quadrupolar couplings. It can also be created via cross-correlated relaxation between different relaxation pathways present for the given spin system. A two fold increase in longitudinal magnetization is achieved using the frequency cycling approach.

954. Improved Estimation of the Magnetic Nanoparticle Diameter with a Magnetic Particle Spectrometer and Combined Fields

Sven Biederer¹, Tobias Knopp¹, Timo Frederik Sattel¹, Marlitt Erbe¹, Thorsten M. Buzug<sup>1

1</sup>Institute of Medical Engineering, University of Luebeck, Luebeck, Germany

In Magnetic Particle Imaging the iron-core size distribution is a very important criterion for the imaging quality as well as for a model based reconstruction. An estimation of such a distribution is possible by using magnetization spectra of a Magnetic Particle Spectrometer. In this contribution a method is presented to improve the condition of the minimization problem. For this purpose offset fields are added to the sinusoidal excitation of the Magnetic Particle Spectrometer. This leads to a more stable and robust estimation of the iron-core size distribution.

955. Assignment of the NMR ²H Double Quantum Filtered Signals in Nerves and Spinal Cords to Their Anatomical Compartments

Hadassah Shinar¹, Tal Ben -David¹, Uzi Eliav¹, Gil Navon<sup>1

1</sup>School of Chemistry, Tel Aviv University, Tel Aviv, Israel

²H double quantum filtered (DQF) NMR of nerves and spinal cords enabled the assignment of the different signals to their anatomical compartments. In nerves the signals with the quadrupolar splittings of approximately 1500, 500, and 200 Hz were assigned to the water in the epineurium, myelin sheaths and endoneurium respectively. A narrow signal was also observed and assigned to intraaxonal water. In spinal cords only the 500 Hz satellites and the narrow signal were detected. The assignment was based on a series of experiments including the effects of collagenase, stretching, Wallerian degeneration, diffusion and was corroborated by histology. <

956. In Vivo Proton MR Spectroscopic (¹H-MRS) Investigations of Metabolic Changes in Human Brain Associated with Unspecific Low Back Pain

Alexander Gussew¹, Reinhard Rzanny¹, Hans Christoph Scholle², Juergen R. Reichenbach<sup>1

1</sup>Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany; ²Division Motor Research, Pathophysiology and Biomechanics, Department of Trauma, Hand and Reconstruc, Jena University Hospital, Jena, Germany

In vivo ¹H-MRS detection of metabolic changes associated with chronic pain may provide deeper understanding of biochemical neuronal dysfunctions caused by chronification and may potentially help to specify therapeutic approaches. In this study absolute concentrations of metabolites N-acetyl aspartate, creatine, total choline, myo-Inositol and glutamate were measured by single voxel ¹H-MRS at 3 T in anterior insular, anterior cingulate cortex and thalamus of six patients with chronic low back pain and corresponding healthy controls. In all investigated brain regions, concentration decrease of all metabolites up to 36% was observed in patients.