MRS of the CNS 2

Wednesday 14 May 2014

Jasmien Orije¹, Firat Kara¹, Caroline Guglielmetti¹, Jelle Praet¹, Marleen Verhoye¹, Peter Ponsaerts², and Annemie Van der Linden^1
1Bio-Imaging Lab, University of Antwerp, Wilrijk, Antwerp, Belgium, ²Laboratory of Experimental Hematology, University of Antwerp, Wilrijk, Antwerp, Belgium

In this study, we employed quantitative in vivo 1H MRS to longitudinally monitor metabolic changes in the corpus callosum of C57BL/6 mice receiving a 0.2% cuprizone supplemented diet. Significant alterations in N-acetylaspartate, glycerophosphorylcholine, taurine and macromolecules and lipids were observed in the early demyelination phase (week 4 and 6) in the cuprizone fed mice compared to control mice, fed with standard rodent chow. Six week after the cuprizone withdrawal, these metabolic changes were no longer present suggesting that metabolic changes observed with ¹H MRS reflect key pathological features, such as demyelination, inflammation and axonal injury, caused by the cuprizone treatment.

Petr Bednarik^1,2, Ivan Tkac¹, Federico Giove^3,4, Dinesh K Deelchand¹, and Silvia Mangia^1
1CMRR - Dept. of Radiology, University of Minnesota, Minneapolis, MN, United States, ²CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic, ³Magnetic Resonance for Brain Investigation Lab, Enrico Fermi Center, Roma, Italy, ⁴Dipartimento di Fisica, Sapienza Università di Roma, Roma, Italy

Functional magnetic resonance spectroscopy (fMRS) is able to measure very small changes of metabolite concentrations during visual stimulation. These changes are ascribed to increased energetic neuronal oxidative metabolism. The aim of the current study was to correlate the neurochemical responses measured by fMRS with the metabolic/hemodynamic responses measured by the BOLD effect. Significant correlation between BOLD-fMRI signals and glutamate concentration changes during visual stimulation was found. Additionally, higher baseline GABA concentration measured at baseline predicted lower BOLD responses.

Jannie P Wijnen^1,2, Itamar Ronen², Anaree Techawiboonwong³, Andrew Webb², Dennis WJ Klomp¹, Hilleke E Hulshoff Pol⁴, Rene S Kahn⁴, and Rene CW Mandl^4
1Radiology, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands, ²Radiology, Leiden University Medical Centre, Leiden, Netherlands,³Electrical Engineering, Mahidol University, Salaya, Nakhon Pathom, Thailand, ⁴Psychiatry, Brain Center Rudolf Magnus, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands

This study shows the feasibility of 1D Diffusion Weighted Spectroscopy in an array along a specific fiber tract that was visualized on the fly using Diffusion Tensor Imaging with fiber tracking. This approach could be used to measure difference between parallel and perpendicular diffusion of various metabolites in specific fiber tracts.

Ece Ercan¹, Emily T. Wood^2,3, Mark van Buchem⁴, Andrew G. Webb¹, and Itamar Ronen^1
1C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, ²NINDS, National Institutes of Health, Bethesda, Maryland, United States, ³Dept of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States,⁴Department of Radiology, Leiden University Medical Center, Leiden, Netherlands

Conventional MRI from SLE patients with neurological and psychiatric symptoms (SLEwNP) frequently appear normal and fail to explain the clinical symptoms, making the diagnostic procedure rather difficult and restricted to per exclusionem. Here we utilize DWS of brain metabolites in normal appearing white matter in the CC to investigate the tissue microstructural correlate of SLEwNP for the first time. The results suggest a disruption of astrocytic structure or physiology, which is in line with the inflammatory nature of the disease and show that ADC(tCho) may potentially become a biomarker for SLEwNP.

Alec Landow¹, Elena Ackley², Stephen R. Dager³, Dennis Shaw^3,4, Mindy Dixon⁴, and Stefan Posse^1,2
1Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, United States, ²Department of Neurology, University of New Mexico, Albuquerque, NM, United States, ³Department of Radiology, University of Washington, Seattle, WA, United States, ⁴Seattle Children's Hospital, Seattle, WA, United States

Diffusion tensor spectroscopic imaging (DTSI) in human brain provides intracellular markers for studying axonal development. DTSI was implemented at 3 Tesla using cardiac gated proton-echo-planar-spectroscopic-imaging (PEPSI). Movement-related phase and amplitude errors were corrected using spatially localized navigators. Data were acquired in 6 healthy volunteers (age range: 3 months – 58 years) using 1-4.5 cc voxel size, bmax = 1734 s/mm2, and 6 gradient directions. The apparent diffusion coefficients of Cho, Cr and NAA in a 3-month old subject were significantly higher and the fractional anisotropy values were lower than those in the adults, consistent with studies of water diffusion.

Malgorzata Marjanska¹ and Melissa Terpstra^1
1Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, United States

Oxidative stress occurs at an early stage of age related cognitive decline. Ascorbate (Asc, vitamin C) and glutathione (GSH) are key contributors to the antioxidant network. Although lower ¹H MRS GSH signal has been measured in the occipital cortex (OCC) of an elder cohort, that finding could have been confounded by differing transverse relaxation (T₂). The purpose of this work was to utilize short echo time ¹H MRS to overcome confounding by age associated difference in T₂ to quantify GSH concentration in the aging brain in OCC and posterior cingulate cortex (PCC, pertinent to the pathology of Alzheimer’s disease).

Francesca Branzoli¹, Ece Ercan², Emily T. Wood³, Mathijs Buijs², Andrew Webb², and Itamar Ronen^2
1Centre de Neuro-imagerie de Recherche de l’Institut du Cerveau et de la Moelle Epiniere, Paris, France, ²C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, ³Neuroimmunology Branch (NINDS), National Institutes of Health, Bethesda, MD, United States

In this study we compare the diffusion properties of water and the neuronal metabolite N-acetylaspartate (NAA) in the corpus callosum of elderly and young subjects, measured at 7T by combining diffusion tensor imaging and diffusion-weighted spectroscopy. Thanks to the specificity of NAA as a probe of intra-axonal space, the method employed here allows to distinguish axonopathy from other processes such as demyelination, which has been previously associated to the observed increase in water mean diffusivity and decrease in water fractional anisotropy in aging. The decrease in NAA axial diffusivity observed in aging for the first time in this study is likely to be related to the presence of structural disruptions associated with axonal degeneration in WM of elderly subjects.

In-Young Choi^1,2, Phil Lee^1,3, Eric D Vidoni⁴, William M Brooks^1,2, and Jeffrey M Burns^2
1Hoglund Brain Imaging Center, University of Kansas Medical Center, Kansas City, KS, United States, ²Neurology, University of Kansas Medical Center, Kansas City, KS, United States, ³Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, United States, ⁴Alzheimer's Disease Center, University of Kansas Medical Center, Kansas City, KS, United States

GSH is a key cerebral antioxidant that protects cells from oxidative stress, a central process contributing to aging and neurodegeneration, and a reduction in GSH is noted in brain tissue undergoing oxidative stress. Physical exercise has been suggested as a neuroprotective strategy against loss of antioxidants. In this study, we measured the influence of aerobic exercise on cerebral GSH levels in older adults using doubly-selective multiple quantum GSH CSI at 3T. The GSH levels were significantly increased after exercise intervention, providing insights into the effect of exercise on the cerebral antioxidant system to promote brain health of the aging population.

Meng Gu¹, Adam B. Kerr², Ralf E. Hurd³, and Daniel M. Spielman^1
1Radiology, Stanford University, Stanford, California, United States, ²Electrical Engineering, Stanford University, Stanford, California, United States, ³GE Healthcare, Menlo Park, California, United States

MEGA PRESS has been used to edit the GABA resonance at 3ppm. Due to the wide transition bandwidth of the editing pulse, macromolecule resonances are coedited. To suppress macromolecule signals, a symmetric suppression method has been proposed resulting in reduced GABA signal. We present a new editing method by incorporating spatial and spectral selectivity into the PRESS refocusing RF pulses to achieve both GABA editing and macromolecule suppression. Phantom studies showed higher edited GABA signal compared with MEGA PRESS and 90% macromolecule suppression. In-vivo studies demonstrated significantly higher edited GABA signal compared with MEGA PRESS.

Assaf Tal¹ and Oded Gonen^2
1NYU Langone School of Medicine, New York, NY, United States, ²Radiology, NYU Langone School of Medicine, New York, NY, United States

Localization is an essential requirement for almost all proton magnetic resonance spectroscopy (MRS) acquisitions. Localization modules either acquire the spin echo (e.g., PRESS, LASER, semi-LASER, etc) or the stimulated echo (STEAM). We propose a localization module which acquires both coherence pathways. Compared to PRESS, this substantially reduces chemical shift displacements, specific absorption rates, minimum TE and increases B1+ immunity, much like STEAM, but at only a modest reduction in signal to noise (i.e. without the 50% signal loss associated with STEAM).