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Cerebral Metabolites (cerebral + metabolite)
Selected AbstractsRelative increase in choline in the occipital cortex in chronic fatigue syndromeACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2002B. K. Puri Puri BK, Counsell SJ, Zaman R, Main J, Collins AG, Hajnal JV, Davey NJ. Relative increase in choline in the occipital cortex in chronic fatigue syndrome. Acta Psychiatr Scand 2002: 106: 224,226. © Blackwell Munksgaard 2002. Objective:,To test the hypothesis that chronic fatigue syndrome (CFS) is associated with altered cerebral metabolites in the frontal and occipital cortices. Method:,Cerebral proton magnetic resonance spectroscopy (1H MRS) was carried out in eight CFS patients and eight age- and sex-matched healthy control subjects. Spectra were obtained from 20 × 20 × 20 mm3 voxels in the dominant motor and occipital cortices using a point-resolved spectroscopy pulse sequence. Results:,The mean ratio of choline (Cho) to creatine (Cr) in the occipital cortex in CFS (0.97) was significantly higher than in the controls (0.76; P=0.008). No other metabolite ratios were significantly different between the two groups in either the frontal or occipital cortex. In addition, there was a loss of the normal spatial variation of Cho in CFS. Conclusion:,Our results suggest that there may be an abnormality of phospholipid metabolism in the brain in CFS. [source] Adding another spectral dimension to 1H magnetic resonance spectroscopy of hepatic encephalopathy,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2005Nader Binesh PhD Abstract Purpose To evaluate a localized two-dimensional correlated magnetic resonance spectroscopic (L-COSY) technique in patients with hepatic encephalopathy (HE) and healthy subjects, and to correlate the cerebral metabolite changes with neuropsychological (NP) test scores. Materials and Methods Eighteen minimal hepatic encephalopathy (MHE) patients and 21 healthy controls have been investigated. A GE 1.5-T magnetic resonance (MR) scanner was used in combination with a body MR coil for transmission and a 3-inch surface coil for reception. A 27-mL voxel was localized by three slice-selective radio frequency (RF) pulses (90°-180°-90°) in the anterior cingulate region. The total duration of each two-dimensional L-COSY spectrum was approximately 25 minutes. The NP battery included a total of 15 tests, which were grouped into six domains. Results MR spectroscopic results showed a statistically significant decrease in myo-inositol (mI) and choline (Ch) and an increase in glutamate/glutamine (Glx) in patients when compared to healthy controls. There was also an increase in taurine (Tau) in patients. The NP results indicated a significant correlation between motor function assessed by NP tests and mI ratios recorded using two-dimensional L-COSY. Conclusion The study demonstrated the feasibility of evaluating the two-dimensional L-COSY sequence in a clinical environment. The results showed additional cerebral metabolites that can be measured with the technique in comparison to one-dimensional study. J. Magn. Reson. Imaging 2005;21:398,405. © 2005 Wiley-Liss, Inc. [source] Correlation of the apparent diffusion coefficient and the creatine level in early ischemic stroke: A comparison of different patterns by magnetic resonanceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2001Helmut Rumpel PhD Abstract It has been reported that reduction of the apparent diffusion coefficient (ADC) after stroke can persist for several days, after which the ADC increases gradually to an abnormally high level. We evaluated ADC values of stroke lesions and compared the results to the cellular density of the lesion by means of the creatine (Cre) level. This two-parameter estimation is of particular relevance in ascertaining the underlying cellular status. Lesion-to-contralateral ADC ratios (ADCn) were obtained based on diffusion-weighted echo-planar and fast spin-echo imaging. Single-voxel localized spectroscopy was used for quantification of cerebral metabolites in infarcted regions. Their levels were also compared to that in homotopic contralateral regions. Fifteen patients with ischemic stroke were examined at times ranging from 18,88 hours following the onset of symptoms. In the stroke lesion, there was a significant correlation between the ADC and the Cre level showing that the higher the cell density the lower the ADC value. For ADCn vs. the lesion Cre concentration and the lesion-to-contralateral Cre ratio (Cren), the strengths of relationship were R2 = 0.70 and 0.58, respectively. It is concluded that ADC is a good reflection of cell density. Greatly lowered ADC values occur within the context of a stable cellularity. ADC and the Cre level have complementary roles in the characterization of stroke lesion with regard to the sequential stage. J. Magn. Reson. Imaging 2001;13:335,343. © 2001 Wiley-Liss, Inc. [source] Brain metabolism of exogenous pyruvateJOURNAL OF NEUROCHEMISTRY, Issue 1 2005Susana Villa Gonzalez Abstract Pyruvate given in large doses may be neuroprotective in stroke, but it is not known to what degree the brain metabolizes pyruvate. Intravenous injection of [3- 13C]pyruvate led to dose-dependent labelling of cerebral metabolites so that at 5 min after injection of 18 mmoles [3- 13C]pyruvate/kg (2 g sodium pyruvate/kg), approximately 20% of brain glutamate and GABA were labelled, as could be detected by 13C nuclear magnetic resonance spectrometry ex vivo. Pyruvate, 9 mmoles/kg, was equivalent to glucose, 9 mmoles/kg, as a substrate for cerebral tricarboxylic acid (TCA) cycle activity. Inhibition of the glial TCA cycle with fluoroacetate did not affect formation of [4- 13C]glutamate or [2- 13C]GABA from [3- 13C]pyruvate, but reduced formation of [4- 13C]glutamine by 50%, indicating predominantly neuronal metabolism of exogenous pyruvate. Extensive formation of [3- 13C]lactate from [2- 13C]pyruvate demonstrated reversible carboxylation of pyruvate to malate and equilibration with fumarate, presumably in neurones, but anaplerotic formation of TCA cycle intermediates from exogenous pyruvate could not be detected. Too rapid injection of large amounts of pyruvate led to seizure activity, respiratory arrest and death. We conclude that exogenous pyruvate is an excellent energy substrate for neurones in vivo, but that care must be taken to avoid the seizure-inducing effect of pyruvate given in large doses. [source] Quantitative t1, NMR spectroscopy of rat cerebral metabolites in vivo: Effects of global ischemiaMAGNETIC RESONANCE IN MEDICINE, Issue 5 2004Mikko I. Kettunen Abstract The NMR relaxation times (T1,, T2, and T1) of water, N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), and lactate (Lac) were quantified in rat brain at 4.7 T. In control animals, the cerebral T1, figures, as determined with a spin-lock field of 1.0 G, were 575 ± 30 ms, 380 ± 19 ms, 705 ± 53 ms, and 90 ± 1 ms for NAA, Cr, Cho, and water, respectively. The T1, figures were 62,103% longer than their respective T2 values determined by a multiecho method. In global (ischemic) ischemia, T1, of NAA declined by 34%, that of Cr and Cho did not change, and that of water increased by 10%. The T1, of lactate in ischemic brain was 367 ± 44 ms. Similar patterns of changes were observed in the multiecho T2 of these cerebral metabolites. The T1 of water and NAA changed in a fashion similar to that of T1, and T2. These results show differential responses in metabolite and water T1, relaxation times following ischemia, and indicate that metabolite T1, and T2 relaxation times behave similarly in the ischemic brain. The contributions of dipolar and nondipolar effects on T1, relaxation in vivo are discussed in this work. Magn Reson Med 51:875,880, 2004. © 2004 Wiley-Liss, Inc. [source] Proton T2 relaxation of cerebral metabolites of normal human brain over large TE rangeNMR IN BIOMEDICINE, Issue 1 2005E. E. Brief Abstract T2 of NAA, creatine and choline-containing compounds were measured in posterior frontal white matter and occipital grey matter in 10 healthy human volunteers. Decay curves comprised signals from eight TE times ranging from 30 to 800,ms with TR 2000,ms acquired with a PRESS sequence on a 1.5,T clinical scanner. Simulations were conducted to assess the precision of T2 estimates from decay curves comprising varying numbers and ranges of TE points. Mean and standard errors for T2s of NAA, creatine and choline-containing compounds were 300(8), 169(3) and 239(4) ms in posterior frontal white matter and 256(6), 159(8) and 249(8) ms in occipital grey matter. In vivoT2s found for choline and NAA were shorter than the T2s in the literature. The elevation of literature T2s is accounted for by the simulation results, which demonstrated that there is a bias towards lengthened T2s when T2 is measured with a maximum TE , T2. Concentration estimates are at risk of being underestimated if previously reported T2 corrections are used. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||