MRS of the CNS 1

Monday 12 May 2014

Anant Bahadur Patel¹, Pandichelvam Veeraiah¹, Mohammad Shamim¹, and M Jerald Mahesh Kumar^1
1NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Hyderabad, Andhra Pradesh, India

Despite key role of neurotransmitters in brain function, brain energy metabolism has not been explored during healthy aging. In this study, we have investigated neuronal and astroglial metabolism in the cerebral cortex, hippocampus and striatum of adult and aged C57BL6 mice by using ¹H-[¹³C]-NMR spectroscopy together with infusion of ¹³C labeled substrates. The ¹³C turnover of amino acids was analyzed using a three compartment metabolic model to derive the metabolic rates. Aging is associated with an increased in astroglial flux and decrease in glutamatergic and GABAergic rates across different brain regions.

Ruoyun Ma^1,2, Ann-Kathrin Stock³, S.Elizabeth Zauber⁴, James B. Murdoch⁵, Shalmali Dharmadhikari^1,2, Zaiyang Long^1,2, Christian Beste³, and Ulrike Dydak^1,2
1School of Health Sciences, Purdue University, West Lafayette, IN, United States, ²Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, United States, ³Cognitive Neurophysiology Department of Child and Adolescent Psychiatry, Technical University Dresden, Dresden, Germany, ⁴Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, United States, ⁵Toshiba Medical Research Institute USA, Mayfield Village, OH, United States

Chronic occupational exposure to Manganese (Mn) has been associated with cognitive and motor disorders similar to Parkinson disease. Based on a previous observation of elevated GABA levels in Mn-exposed workers, this study investigates the connection between thalamic GABA levels measured by MRS, motor function, and behavior measures of action control and inhibition in typical US welders. The significant correlations between these measures indicate that GABA may serve as biomarker for early diagnosis of Mn-induced neurotoxicity.

Dinesh K Deelchand¹, Uzay E Emir^1,2, Diane Hutter¹, Christopher M Gomez³, Lynn E Eberly⁴, Khalaf O Bushara⁵, and Gulin Oz^1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ²FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, ³Department of Neurology, University of Chicago, Chicago, IL, United States, ⁴Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, United States, ⁵Department of Neurology, Medical School, University of Minnesota, Minneapolis, MN, United States

In this study, MR spectroscopy was used to monitor disease progression in SCA1 patients. Subjects were scanned at baseline and after an ~18 month follow-up on 3 T. We found that in pons, [tNAA]/[Ins] was significantly reduced in SCA1 at visit #2 vs. visit #1 while no difference was detected in controls. The change in ataxia rating scale between the two visits did not reach significance suggesting that MRS is more sensitive to detect a small change due to disease progression than clinical assessment.

Ai-Ling Lin¹, Daniel Coman², Lihong Jiang², Douglas L Rothman², and Fahmeed Hyder^2
1Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, ²Magnetic Resonance Research Center, Yale University, New Haven, CT, United States

While caloric restriction extends mammalian lifespan, its effect on neuronal function and energy demand – especially in healthy aging – remains largely unknown. Using ¹H[¹³C] MRS techniques, we show that healthy aging rats had significantly lower rates of neuronal energy production and neurotransmission relative to their younger counterparts; however, caloric restriction mitigated the age-related deceleration of brain physiology. These results provide a rationale for caloric restriction-induced sustenance of brain health with extended lifespan.

Niklaus Zoelch¹, Andreas Hock^1,2, and Anke Henning^1,3
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ²Department of Psychiatry, Psychotherapy and Psychosomatics, University of Zurich, Zurich, Switzerland, ³Max Planck Institute for Biological Cybernetics, Tuebingen, Germany

The goal of this work was to enable absolute quantification of brain metabolites in small voxels, which is desirable in the clinical routine, especially to improve the diagnosis of brain lesion. For this purpose, non-water suppressed MRS via the metabolite cycling technique was combined with the calibration method ERETIC. The combination of these two techniques was tested invivo in 6 healthy volunteers. The concentrations obtained with MC and ERETIC are in good agreement with concentrations determined from water suppressed spectra by using the internal water as reference.

Ryan J. Larsen¹, Michael Newman^1,2, Chao Ma^3,4, and Bradley Sutton^1,5
1Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ²Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ³Beckman Institute, Urbana, IL, United States, ⁴Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁵Department of Biomedical Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States

Much work has been performed to use structural MRI scans as prior knowledge to construct anatomically-constrained metabolites maps from multi-voxel Magnetic Resonance Spectroscopy Imaging scans. In many implementations, the anatomical reconstruction is performed on the signal from the metabolite, without quantitation. We demonstrate a post-processing pipeline that combines both quantitation and anatomical reconstruction based on prior knowledge. Our technique employs water-scaling to quantify the distribution of metabolites. We then apply a Projection on a Convex Set (POCS) algorithm that revises the metabolite distribution by using prior knowledge from the MRI scan. The final result is average metabolite concentration values within anatomically distinct regions of the brain.

Vincent O. Boer¹, Tessa N. van de Lindt¹, Peter R. Luijten¹, and Dennis W.J. Klomp^1
1radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands

Lipid suppression in MRI and MRSI is generally associated with delays in the sequence and increased TR’s. In this work we apply a crusher coil for lipid suppression where a switchable local distortion of the magnetic field in the skull is induced instead of RF excitation or inversion. With the crusher coil lipid suppression is possible without increases in SAR, or lengthening of the sequences. For MSRI this allows a shortening of the TR of an order of magnitude, leading to the possibility to acquire very high resolution MRSI of the human brain.

Robin A. de Graaf¹ and Kevin L. Behar^1
1Yale University, New Haven, CT, United States

Nicotinamide adenine dinucleotide (NAD+) has a central role in cellular metabolism and energy production and is related to gene expression, calcium mobilization, aging, cell death and timing of metabolism via the circadian rhythm. The in vivo detection of NAD+ has been limited and has only recently become feasible with high-field 31P NMR spectroscopy. Here 1H NMR spectroscopy is presented as a simple, but robust alternative for the in vivo detection of NAD+. Special attention is given to the interaction between NAD+ and water magnetization. Perturbation of the water protons should be minimized to ensure full NAD+ signal detection efficiency.

Alfredo Liubomir Lopez Kolkovsky¹, Boucif Djemai¹, and Fawzi Boumezbeur^1
1CEA/Saclay/Neurospin, Commissariat a l'Energie Atomique, Gif-sur-yvette, Essonne, France

At ultra-high magnetic fields such as 17.2 T, it is crucial to establish T₁ and T₂ relaxation times in order to optimize MRS acquisition parameters and to achieve proper quantification. In this study we present measurements of T₁ relaxation times of 20 metabolites and macromolecules in the rat brain in vivo at 17.2T. Results show a convergence of T₁ relaxation times to 1690 ms, with the exception of Taurine (2212 ± 99 ms) and Cr-CH2 (1152 ± 32 ms). T₁ values were slight longer than those measured at lower magnetic fields, which is consistent with the Bloembergen-Purcell-Pound theory of dipolar relaxation.

Alfredo Liubomir Lopez Kolkovsky¹, Boucif Djemai¹, and Fawzi Boumezbeur^1
1CEA/Saclay/Neurospin, Commissariat a l'Energie Atomique, Gif-sur-yvette, Essonne, France

Normal brain aging is usually associated with a decline in brain function. Yet, the neural basis of age-related cognitive dysfunction in normal brain aging remains to be entirely elucidated. In this study, we sought to explore further these metabolic alterations in the brain of healthy rats with in vivo short echo time ¹H MRS at 17.2 T. Comparing metabolic profiles from young and elderly rats (1 and 16 months old respectively), it was found a decrease in neurotransmitters (Gln+Glu, GABA) and increase in Ins and tCho consistent with decline of neural function and chronic low-level glial activation consistent with previous observations in humans.