Brain Changes in Long-Term Zen Meditators Using Proton Magnetic Resonance Spectroscopy and Diffusion Tensor Imaging: A Controlled Study

Introduction

This work aimed to determine whether ¹H magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls.

Materials and Methods

Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. ¹H-MRS (1.5 T) of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL) and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC) and fractional anisotropy (FA) by MR-DTI.

Results

Myo-inositol (mI) was increased in the posterior cingulate gyrus and Glutamate (Glu), N-acetyl-aspartate (NAA) and N-acetyl-aspartate/Creatine (NAA/Cr) was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r = 0.518; p = .019). We also found significant negative correlations between Glu (r = −0.452; p = .045), NAA (r = −0.617; p = .003) and NAA/Cr (r = −0.448; P = .047) in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC) in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r = −0.4850, p = .0066).

Conclusions

The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators.     

P-31 Nuclear Magnetic Resonance Analysis of Brain: The Perchloric Acid Extract Spectrum

Abstract: Perchloric acid (PCA) extracts were prepared from liquid-N₂-frozen guinea pig brains and their organophosphate profiles examined by P-31 nuclear magnetic resonance (NMR) spectroscopy. Thirty-two phosphorus-containing brain metabolites were characterized and quantitated. A distinctive feature of brain tissue metabolism relative to that of other tissues probed by P-31 NMR is its pronounced ribose 5-phosphate content. Comparison of brain metabolite levels following control or sublethal cyanide treatment (4 mg/kg) revealed specific cyanide-induced changes in brain metabolism. Brains from cyanidetreated animals were characterized by a reduced phosphocreatine content and elevated α-glycerolphosphate and inorganic orthophosphate contents relative to control. P-31 NMR spectra of brain PCA extracts at pH 7.2 were also obtained under conditions that approximate those used for in vivo and intact tissue in vitro P-31 spectroscopic analyses. The spectra reveal nine separate resonance bands corresponding to: sugar phosphates, principally ribose 5-phosphate (3.7δ); inorganic orthophosphate (2.2δ); glycerol 3-phosphorylethanolamine (0.3δ); glycerol 3-phosphorylcholine (−0.1δ); phosphocreatine (−3.2δ); adenosine tri-(β-ATP) and di-(β-ADP) phosphate ionized end-groups (−6.2δ); α-ATP, α-ADP, and nicotinamide adenine dinucleotides esterified end-groups (−11.1δ); uridine diphosphohexose, hexose esterified end-groups (−13.0δ); and β-ATP ionized middle group (−21.6δ). Knowledge of the phosphatic molecules that contribute resonances to the brain P-31 NMR spectrum as well as understanding their magnetic resonance properties is essential for the interpretation of in vivo brain spectroscopic data as well as brain extract data, since these same compounds contribute to the intact brain P-31 spectrum.     

Metabolic Changes in the Visual Cortex of Binocular Blindness Macaque Monkeys: A Proton Magnetic Resonance Spectroscopy Study

Purpose

To evaluate proton magnetic resonance spectroscopy (¹H-MRS) in a study of cross-modal plasticity in the visual cortex of binocular blindness macaque monkeys.

Materials and Methods

Four healthy neonatal macaque monkeys were randomly divided into 2 groups, with 2 in each group. Optic nerve transection was performed in both monkeys in the experimental group (group B) to obtain binocular blindness. Two healthy macaque monkeys served as a control group (group A). After sixteen months post-procedure, ¹H-MRS was performed in the visual cortex of all monkeys. We compared the peak areas of NAA, Cr, Cho, Glx and Ins and the ratios of NAA/Cr, Cho/Cr, Glx/Cr and Ins/Cr of each monkey in group B with group A.

Results

The peak area of NAA and the NAA/Cr ratio in the visual cortex of monkey 4 in group B were found to be dramatically decreased, the peak area of NAA slightly decreased and the NAA/Cr ratio clearly decreased in visual cortex of monkey 3 in group B than those in group A. The peak area of Ins and the Ins/Cr ratio in the visual cortex of monkey 4 in group B slightly increased. The peak area of Cho and the Cho/Cr ratio in the visual cortex of all monkeys in group B dramatically increased compared with group A. The peak area of Glx in the visual cortex of all monkeys in group B slightly increased compared with group A.

Conclusions

¹H-MRS could detect biochemical and metabolic changes in the visual cortex and therefore this technique can be used to provide valuable information for investigating the mechanisms of cross-modal plasticity of binocular blindness in a macaque monkey model.     

Vitamin D and Caudal Primary Motor Cortex: A Magnetic Resonance Spectroscopy Study

Background

Vitamin D is involved in brain physiology and lower-extremity function. We investigated spectroscopy in a cohort of older adults to explore the hypothesis that lower vitamin D status was associated with impaired neuronal function in caudal primary motor cortex (cPMC) measured by proton magnetic resonance spectroscopic imaging.

Methods

Twenty Caucasian community-dwellers (mean±standard deviation, 74.6±6.2 years; 35.0% female) from the ‘Gait and Brain Study’ were included in this analysis. Ratio of N-acetyl-aspartate to creatine (NAA/Cr), a marker of neuronal function, was calculated in cPMC. Participants were categorized according to mean NAA/Cr. Lower vitamin D status was defined as serum 25-hydroxyvitamin D (25OHD) concentration <75 nmol/L. Age, gender, number of comorbidities, vascular risk, cognition, gait performance, vitamin D supplements, undernourishment, cPMC thickness, white matter hyperintensities grade, serum parathyroid hormone concentration, and season of evaluation were used as potential confounders.

Results

Compared to participants with high NAA/Cr (n = 11), those with low NAA/Cr (i.e., reduced neuronal function) had lower serum 25OHD concentration (P = 0.044) and more frequently lower vitamin D status (P = 0.038). Lower vitamin D status was cross-sectionally associated with a decrease in NAA/Cr after adjustment for clinical characteristics (β = −0.41, P = 0.047), neuroimaging measures (β = −0.47, P = 0.032) and serum measures (β = −0.45, P = 0.046).

Conclusions

Lower vitamin D status was associated with reduced neuronal function in cPMC. These novel findings need to be replicated in larger and preferably longitudinal cohorts. They contribute to explain the pathophysiology of gait disorders in older adults with lower vitamin D status, and provide a scientific base for vitamin D replacement trials.     

P-31 Nuclear Magnetic Resonance Analysis of Brain: II. Effects of Oxygen Deprivation on Isolated Perfused and Nonperfused Rat Brain

Phosphatic metabolite (perchloric acid extractable) concentrations of cerebral tissues were analyzed by phosphorus-31 nuclear magnetic resonance (P-31 NMR) spectroscopy following external perfusion of the isolated rat brain (30 min or 60 min) under the following conditions: (a) constant perfusion pressure with either fluorocarbon- or erythrocyte-based medium, and (b) constant perfusate flow rate (3 ml/min) with the erythrocyte-based medium. Metabolite concentrations of control perfused brains were compared with those in nonperfused controls to provide a basis for detecting any qualitative or quantitative changes in cerebral metabolite composition. Metabolic responses of perfused brains to ischemia (incomplete ischemia, 83% reduction in flow for 10 min; transient complete ischemia for 1.5 or 2 min) were evaluated immediately after the ischemic episode and at selected time points during reperfusion (3 and 15 min). Alterations in cerebral metabolite levels induced by hypoxia were analyzed using a nonperfused rat brain model. Irrespective of the perfusion method employed, the phosphatic metabolites of control perfused rat brains were identical quantitatively to those of the nonperfused controls. Cerebral ischemia resulted in significantly increased levels of ADP, AMP + IMP, Pi, fructose 1,6-diphosphate, and glycerol 3-phosphate (global ischemia only), whereas ATP and phosphocreatine (PCr) levels declined significantly. The magnitude of these changes varied with the severity of the ischemia; however, following 15 min of control reperfusion metabolite levels had reverted to preischemic values. Significant perturbations in tissue phosphoethanolamine (3.84 delta resonance) content were evident at various time points during ischemia and postischemic recovery, which varied according to the perfusion conditions. In contrast to the changes observed in response to ischemia, hypoxia affected only cerebral high-energy phosphate levels. ATP and PCr levels were reduced, while a concomitant, essentially equimolar, increase in Pi and ADP was observed. The present studies indicate that in terms of phosphatic metabolites, the control equilibrated isolated perfused rat brain is quantitatively and qualitatively indistinguishable from the nonperfused rat brain in vivo regardless of the perfusion conditions (constant flow versus constant pressure). The metabolic responses to ischemia and hypoxia, as measured by P-31 NMR, were consistent with the pattern of changes reported elsewhere. Overall, P-31 NMR spectroscopic evaluation of the intact rat brain provides a potential experimental context for dynamic measures of cerebral metabolism under exogenously controlled conditions. Th     

BMI and Neuronal Integrity in Healthy,Cognitively Normal Elderly: A Proton Magnetic Resonance Spectroscopy Study

Recent studies associated excess body weight with brain structural alterations, poorer cognitive function, and lower prefrontal glucose metabolism. We found that higher BMI was related to lower concentrations of N‐acetyl‐aspartate (NAA, a marker of neuronal integrity) in a healthy middle‐aged cohort, especially in frontal lobe. Here, we evaluated whether NAA was also associated with BMI in a healthy elderly cohort. We used 4 Tesla proton magnetic resonance spectroscopy (¹H MRS) data from 23 healthy, cognitively normal elderly participants (69.4 ± 6.9 years; 12 females) and measured concentrations of NAA, glutamate (Glu, involved in cellular metabolism), choline‐containing compounds (Cho, involved in membrane metabolism), and creatine (Cr, involved in high‐energy metabolism) in anterior (ACC) and posterior cingulate cortices (PCC). After adjustment for age, greater BMI was related to lower NAA/Cr and NAA/Cho ratios (β < ?0.56, P < 0.008) and lower Glu/Cr and Glu/Cho ratios (β < ?0.46, P < 0.02) in ACC. These associations were not significant in PCC (β > ?0.36, P > 0.09). The existence of an association between NAA and BMI in ACC but not in PCC is consistent with our previous study in healthy middle‐aged individuals and with reports of lower frontal glucose metabolism in young healthy individuals with elevated BMI. Taken together, these results provide evidence that elevated BMI is associated with neuronal abnormalities mostly in frontal brain regions that subserve higher cognitive functions and impulse control. Future studies need to evaluate whether these metabolite abnormalities are involved in the development and maintenance of weight problems.     

Anterior Insula GABA Levels Correlate with Emotional Aspects of Empathy: A Proton Magnetic Resonance Spectroscopy Study

Background:

Empathy is a multidimensional construct referring to the capacity to understand and share the emotional and affective states of another person. Cerebral γ-aminobutyric acid (GABA)-ergic levels are associated with a variety of neurological and psychiatric disorders. However, the role of the GABA system in different dimensions of empathy has not been investigated.

Materials and Methods:

Thirty-two right-handed healthy volunteers took part in this study. We used proton magnetic resonance spectroscopy to determine GABA concentrations in the anterior insula (AI) and the anterior cingulate cortex (ACC) and to examine the relationship between the GABA concentrations and the subcomponents of empathy evaluated by the Interpersonal Reactivity Index (IRI).

Result:

Pearson correlation analyses (two-tailed) showed that AI GABA was significantly associated with the empathy concern score (r = 0.584, p<0.05) and the personal distress score (r = 0.538, p<0.05) but not significantly associated with other empathy subscales. No significant correlation was found between ACC GABA and empathy subscores.

Conclusion:

Left AI GABA was positively correlated with the emotional aspects of empathy. These preliminary findings call into question whether AI GABA alterations might predict empathy dysfunction in major psychiatric disorders such as autism and schizophrenia, which have been described as deficits in emotional empathic abilities.     

Neuroprotective Effects of Ethyl Pyruvate on Brain Energy Metabolism after Ischemia-Reperfusion Injury: A 31P-Nuclear Magnetic Resonance Study

The neuroprotective effects of ethyl pyruvate (EP), a stable derivative of pyruvate, on energy metabolism of rat brain exposed to ischemia-reperfusion stress were investigated by ³¹P-nuclear magnetic resonance (³¹P-NMR) spectroscopy. Recovery level of phosphocreatine after ischemia was significantly greater when superfused with artificial cerebrospinal fluid (ACSF) with 2 mM EP than when superfused with ACSF without EP. EP was neuroprotective against ischemia only when administered before the ischemic exposure. Intracellular pH during ischemia was less acidic when superfused ahead of time with EP. EP did not show neuroprotective effects in neuron-rich slices pretreated with 100 μM fluorocitrate, a selective glial poison. It was suggested that both the administration of EP before ischemic exposure and the presence of astrocytes are required for EP to exert neuroprotective effects. We suggest the potential involvement of multiple mechanisms of action, such as less acidic intracellular pH, glial production of lactate, and radical scavenging ability. Special issue article in honor of Dr. Akitane Mori.     

Maternal Smoking during Pregnancy and Fetal Organ Growth: A Magnetic Resonance Imaging Study

Objective

To study whether maternal cigarette smoking during pregnancy is associated with alterations in the growth of fetal lungs, kidneys, liver, brain, and placenta.

Design

A case-control study, with operators performing the image analysis blinded.

Setting

Study performed on a research-dedicated magnetic resonance imaging (MRI) scanner (1.5 T) with participants recruited from a large teaching hospital in the United Kingdom.

Participants

A total of 26 pregnant women (13 current smokers, 13 non smokers) were recruited; 18 women (10 current smokers, 8 nonsmokers) returned for the second scan later in their pregnancy.

Methods

Each fetus was scanned with MRI at 22–27 weeks and 33–38 weeks gestational age (GA).

Main outcome measures

Images obtained with MRI were used to measure volumes of the fetal brain, kidneys, lungs, liver and overall fetal size, as well as placental volumes.

Results

Exposed fetuses showed lower brain volumes, kidney volumes, and total fetal volumes, with this effect being greater at visit 2 than at visit 1 for brain and kidney volumes, and greater at visit 1 than at visit 2 for total fetal volume. Exposed fetuses also demonstrated lower lung volume and placental volume, and this effect was similar at both visits. No difference was found between the exposed and nonexposed fetuses with regards to liver volume.

Conclusion

Magnetic resonance imaging has been used to show that maternal smoking is associated with reduced growth of fetal brain, lung and kidney; this effect persists even when the volumes are corrected for maternal education, gestational age, and fetal sex. As expected, the fetuses exposed to maternal smoking are smaller in size. Similarly, placental volumes are smaller in smoking versus nonsmoking pregnant women.     

Diet-Quality Scores and Prevalence of Nonalcoholic Fatty Liver Disease: A Population Study Using Proton-Magnetic Resonance Spectroscopy

Dietary pattern analysis is an alternative approach to examine the association between diet and nonalcoholic fatty liver disease (NAFLD). This study examined the association of two diet-quality scores, namely Diet Quality Index-International (DQI-I) and Mediterranean Diet Score (MDS) with NAFLD prevalence. Apparently healthy Chinese adults (332 male, 465 female) aged 18 years or above were recruited through a population screening between 2008 and 2010 in a cross-sectional population-based study in Hong Kong. DQI-I and MDS, as well as major food group and nutrient intakes were calculated based on dietary data from a food frequency questionnaire. NAFLD was defined as intrahepatic triglyceride content at ≥5% by proton-magnetic resonance spectroscopy. Multivariate logistic regression models were used to examine the association between each diet-quality score or dietary component and prevalent NAFLD with adjustment for potential lifestyle, metabolic and genetic factors. A total of 220 subjects (27.6%) were diagnosed with NAFLD. DQI-I but not MDS was associated with the prevalence of NAFLD. A 10-unit decrease in DQI-I was associated with 24% increase in the likelihood of having NAFLD in the age and sex adjusted model (95% CI: 1.06–1.45, p = 0.009), and the association remained significant when the model was further adjusted for other lifestyle factors, metabolic and genetic factors [OR: 1.26 (95% CI: 1.03–1.54), p = 0.027]. Multivariate regression analyses showed an inverse association of the intake of vegetables and legumes, fruits and dried fruits, as well as vitamin C with the NAFLD prevalence (p<0.05). In conclusion, a better diet quality as characterized by a higher DQI-I and a higher consumption of vegetables, legumes and fruits was associated with a reduced likelihood of having NAFLD in Hong Kong Chinese.     

Effect of Long-Term Feeding with Acetyl-L-Carnitine on the Age-Related Changes in Rat Brain Lipid Composition: A Study by 31P NMR Spectroscopy

Changes in brain lipid composition have been determined in 24 months-old Fischer rats with respect to 6 months-old ones. The cerebral levels of sphingomyelin and cholesterol were found to be significantly increased in aged rats, whereas the amount of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and phosphatidic acid appear to be unaffected by aging. Long-term feeding with acetyl-L-carnitine was able to reduce the age-dependent increase of both sphingomyelin and cholesterol cerebral levels with no effect on the other measured phospholipids. These findings shown that changes in membrane lipid metabolism and/or composition represent one of the alterations occurring in rat brain with aging, and that long-term feeding with acetyl-L-carnitine can be useful in normalizing these age-dependent disturbances.     

Early Detection of Ventilation-Induced Brain Injury Using Magnetic Resonance Spectroscopy and Diffusion Tensor Imaging: An In Vivo Study in Preterm Lambs

Background and Aim

High tidal volume (V_T) ventilation during resuscitation of preterm lambs results in brain injury evident histologically within hours after birth. We aimed to investigate whether magnetic resonance spectroscopy (MRS) and/or diffusion tensor imaging (DTI) can be used for early in vivo detection of ventilation-induced brain injury in preterm lambs.

Methods

Newborn lambs (0.85 gestation) were stabilized with a “protective ventilation” strategy (PROT, n = 7: prophylactic Curosurf, sustained inflation, V_T 7 mL/kg, positive end expiratory pressure (PEEP) 5 cmH₂O) or an initial 15 minutes of “injurious ventilation” (INJ, n = 10: V_T 12 mL/kg, no PEEP, late Curosurf) followed by PROT ventilation for the remainder of the experiment. At 1 hour, lambs underwent structural magnetic resonance imaging (Siemens, 3 Tesla). For measures of mean/axial/radial diffusivity (MD, AD, RD) and fractional anisotropy (FA), 30 direction DTI was performed. Regions of interests encompassed the thalamus, internal capsule, periventricular white matter and the cerebellar vermis. MRS was performed using a localized single-voxel (15×15×20 mm³, echo time 270 ms) encompassing suptratentorial deep nuclear grey matter and central white matter. Peak-area ratios for lactate (Lac) relative to N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) were calculated. Groups were compared using 2-way RM-ANOVA, Mann-Whitney U-test and Spearman''s correlations.

Results

No cerebral injury was seen on structural MR images. Lambs in the INJ group had higher mean FA and lower mean RD in the thalamus compared to PROT lambs, but not in the other regions of interest. Peak-area lactate ratios >1.0 was only seen in INJ lambs. A trend of higher mean peak-area ratios for Lac/Cr and Lac/Cho was seen, which correlated with lower pH in both groups.

Conclusion

Acute changes in brain diffusion measures and metabolite peak-area ratios were observed after injurious ventilation. Early MRS/DTI is able to detect the initiation of ventilation-induced brain injury.     

Effect of External pH on the Cytoplasmic and Vacuolar pHs in Mung Bean Root-Tip Cells: A 31P Nuclear Magnetic Resonance Study

The effect of the external pH on the intracellular pH in mungbean (Vigna mungo (L.) Hepper) root-tip cells was investigatedwith the ³¹P nuclear magnetic resonance (NMR) method. The ³¹PNMR spectra showed three peaks caused by cytoplasmic G-6-P,cytoplasmic P_i and vacuolar P_i. The cytoplasmic and vacuolarpHs could be determined by comparing the P_i chemical shiftswith the titration curve. When the external pH was changed overa range from pH 3 to 10, the cytoplasmic pH showed smaller changesthan the vacuolar pH, suggesting that the former is regulatedmore strictly than the latter. The H⁺-ATPase inhibitor, DCCD,caused the breakdown of the mechanism that regulates the intracellularpH. H⁺-ATPase appears to have an important part in the regulationof the intracellular pH. (Received January 4, 1984; Accepted August 27, 1984)     

31P Nuclear Magnetic Resonance In Vivo Spectroscopy of the Metabolic Changes Induced in the Awake Rat Brain During KCN Intoxication and Its Reversal by Hydroxocobalamine

Radiofrequency surface coils were chronically implanted in rats, which were subsequently subjected to 31P nuclear magnetic resonance (NMR) investigations at 4.7 T. The implanted coil allowed study of the animals without need for anesthesia, which is a prerequisite for studies of normal brain metabolism. The animals may be kept in the NMR probe for several hours. During subsequent experiments, they may be placed in the same position, therefore allowing follow-up studies for periods as long as 2 months. This method has been used in the study of sublethal KCN intoxication. KCN, a cytochrome c oxidase inhibitor, induces a blockade of cell respiratory processes, which is reflected, in a dose-dependent manner, by a decrease in phosphocreatine content and pH and an increase in inorganic phosphate content, whereas ATP levels remain constant until high doses of KCN (6 mg/kg i.p.) are reached. 31P NMR allows the time course of these metabolic changes to be followed. For high KCN doses, a new peak, termed X, is observed, which is interpreted as being due to a pool of inorganic phosphate at very low pH (5.65), corresponding to a subset of cells that did not survive KCN injury. Hydroxocobalamine, a specific antidote of KCN, suppresses the metabolic changes due to 6 mg/kg of KCN.     

A Nuclear Magnetic Resonance Study of Hydrated Systems Using the Frequency Dependence of the Relaxation Processes

A practical method is described for determining some characteristics of the spectrum of proton mobilities in a hydrated system from the frequency dependence of the nuclear magnetic resonance (NMR) relaxation processes. The technique is applied to water in association with agarose and gelatin. The results for agarose are consistent with the hypothesis that a fraction of the protons is distributed over states of reduced mobility and exchanges rapidly with the remaining fraction which is attributed to water in the normal state. No variation in the characteristics of the modified fraction could be detected for water concentrations in the range 1.2-50 g H₂O/g agarose. Within the modified fraction, higher mobilities are more common than low mobilities; at 1.2 g H₂O/g agarose, not more than 10% of the proton population has mobilities more than 100 times smaller than normal. The modified proton fraction is tentatively identified with agarose hydroxyl protons and possibly water molecules bound to the polymer. Proton states with mobilities intermediate between water and ice have also been detected in hydrated gelatin. As in agarose, higher mobilities are the most common. In contrast to agarose, the characteristics of the modified proton states are markedly dependent on water concentration. They are tentatively attributed to gelatin protons coupled for spinlattice relaxation with those of the bulk phase by exchange and spin diffusion.     

Evaluation of the Diagnostic Performance of Magnetic Resonance Spectroscopy in Brain Tumors: A Systematic Review and Meta-Analysis

Object

The aim of this study was to determine the suitability of magnetic resonance spectroscopy (MRS) for screening brain tumors, based on a systematic review and meta-analysis of published data on the diagnostic performance of MRS.

Methods

The PubMed and PHMC databases were systematically searched for relevant studies up to December 2013. The sensitivities and specificities of MRS in individual studies were calculated and the pooled diagnostic accuracies, with 95% confidence intervals (CI), were assessed under a fixed-effects model.

Results

Twenty-four studies were included, comprising a total of 1013 participants. Overall, no heterogeneity of diagnostic effects was observed between studies. The pooled sensitivity and specificity of MRS were 80.05% (95% CI = 75.97%–83.59%) and 78.46% (95% CI: 73.40%–82.78%), respectively. The area under the summary receiver operating characteristic curve was 0.78. Stratified meta analysis showed higher sensitivity and specificity in child than adult. CSI had higher sensitivity and SV had higher specificity. Higher sensitivity and specificity were obtained in short TE value.

Conclusion

Although the qualities of the studies included in the meta-analysis were moderate, current evidence suggests that MRS may be a valuable adjunct to magnetic resonance imaging for diagnosing brain tumors, but requires selection of suitable technique and TE value.     

Proteomics,and Metabolomics: Magnetic Resonance Spectroscopy for the Presurgical Screening of Thyroid Nodules

We review the progress and state-of-the-art applications of studies in Magnetic Resonance Spectroscopy (MRS) and Imaging as an aid for diagnosis of thyroid lesions of different nature, especially focusing our attention to those lesions that are cytologically undetermined. It appears that the high-resolution of High-Resolution Magic-Angle-Spinning (HRMAS) MRS improves the overall accuracy of the analysis of thyroid lesions to a point that a significant improvement in the diagnosis of cytologically undetermined lesions can be expected. This analysis, in the meantime, allows a more precise comprehension of the alterations in the metabolic pathways induced by the development of the different tumors. Although these results are promising, at the moment, a clinical application of the method to the common workup of thyroid nodules cannot be used, due to both the limitation in the availability of this technology and the wide range of techniques, that are not uniformly used. The coming future will certainly see a wider application of these methods to the clinical practice in patients affected with thyroid nodules and various other neoplastic diseases.     

Age-Related Differences in the Effect of Dichloroacetate on Postischemic Lactate and Acid Clearance Measured In Vivo Using Magnetic Resonance Spectroscopy and Microdialysis

Abstract: Numerous studies using adult animal models suggest that dichloroacetate (DCA) may have neuroprotective properties by virtue of its ability to increase rates of metabolism and, therefore, clearance of brain lactic acidosis, which may accumulate during cerebral ischemia. We tested the hypothesis that postischemic DCA administration affects lactate and acid clearance to different extents in immature versus mature brain. ³¹P and ¹H magnetic resonance spectroscopy were used to measure intracellular acid and lactate clearance rates in vivo in newborn and 1-month-old swine after a 14-min episode of transient near-complete global ischemia. Simultaneous monitoring of extracellular lactate efflux and clearance was measured in the same animals by in vivo microdialysis. Plasma glucose concentrations were elevated in order to study animals with severe cerebral lactic acidosis. Maximal levels of brain lactosis (16–20 µmol/g) and acidosis (pH_{intracellular} 5.8–6.0) were reached during the first 10 min of recovery and were the same in age groups and in subgroups either acting as controls or treated with DCA (200 mg/kg) given from the last minute of ischemia to 5–7 min after ischemia. For newborns, DCA administration improved the postischemic clearance rate of cerebral acidosis and cerebral phosphocreatine, with similar trends for the clearance of lactosis and increased rates of recovery of nucleotide triphosphates, compared with controls. In contrast, DCA administration in 1-month-olds resulted in a modest trend for improvement of cerebral lactate clearance, but did not affect acid clearance or the recovery rate of phosphocreatine or nucleotide triphosphates. Extracellular brain lactate concentrations had similar relative increases and rates of decline for subgroups of either age treated with DCA versus controls. The results of this study indicate that postischemic DCA administration helps to resolve cerebral acidosis to a greater degree in immature than more mature brain, suggesting that DCA may have cerebroprotective properties for neonatal hypoxic-ischemic encephalopathy.