Proton MR spectroscopy of cerebellitis

Single voxel proton MR spectroscopy ((1)H-MRS) of the vermis was obtained in two patients with cerebellitis. In the acute phase (1)H-MRS revealed low N-acetyl-aspartate (NAA)/creatine (Cr) and NAA/choline (Cho) and normal Cho/Cr ratios. Decrease of the concentration of NAA was confirmed by quantitative analysis in one patient. The NAA/Cr and NAA/Cho ratios and NAA concentration were increased in (1)H-MRS examinations obtained 10 and 24 months after the acute episode. (1)H-MRS demonstrates reversible metabolite changes in cerebellitis.     

Experimental hypoxic–ischemic encephalopathy: comparison of apparent diffusion coefficients and proton magnetic resonance spectroscopy

This study aims to compare the apparent diffusion coefficients (ADCs) and proton magnetic resonance spectroscopy (¹H-MRS) in the first 24 h of acute hypoxic-ischemic brain damage (HIBD) in piglets. Twenty-five 7-day-old piglets were subjected to transient bilateral common carotid artery occlusion followed by ventilation with 4% oxygen for 1 h. Diffusion-weighted imaging (DWI) and ¹H-MRS were performed on cessation of the insult or at 3, 6, 12 or 24 h after resuscitation (all n=5). ADCs, N-acetylaspartate/choline (NAA/Cho), NAA/creatine (NAA/Cr), lactate/NAA (Lac/NAA), Lac/Cho and Lac/Cr were calculated. Cerebral injury was evaluated by pathological study and Hsp70 immunohistochemical analysis. On cessation of the insult, ADCs, NAA/Cho and NAA/Cr reduced, Lac/NAA, Lac/Cho and Lac/Cr increased. From 3 to 12 h after resuscitation, ADCs, Lac/NAA, Lac/Cho and Lac/Cr recovered, NAA/Cho and NAA/Cr reduced. Twenty-four hours after resuscitation, ADCs reduced once more, Lac/NAA, Lac/Cho and Lac/Cr increased again, whereas NAA/Cho and NAA/Cr decreased continuously. Pathological study revealed mild cerebral edema on cessation of the insult and more and more severe cerebral injury after resuscitation. No Hsp70-positive cells were detected on cessation of the insult. From 3 to 12 hours after resuscitation, Hsp70-positive cells gradually increased. Twenty-four hours after resuscitation, Hsp70-positive cells decreased. Throughout the experiment, changes in NAA/Cho and pathology had the best correlation (R=–0.729). In conclusion, NAA/Cho is the most precise ratio to reflect the pathological changes of early HIBD. Transient ADCs and Lac ratios recovery do not predict the reversal of histological damage of early HIBD. Reducing astrocytic swelling is of great clinical significance.     

Proton MR spectroscopy features of normal appearing white matter in neurofibromatosis type 1

To determine whether differences exist between neurofibromatosis type 1 (NF1) patients with or without focal lesions and healthy normal volunteers in the metabolite ratios of normal appearing white matter, 27 patients with NF1 (with parenchymal lesion, MR positive, n: 17; without parenchymal lesions, MR negative, n: 10) and 20 healthy volunteers underwent MRI and short TE (31 ms) proton MR spectroscopy (MRS). In 17 patients with parenchymal lesions, 61 focal lesions were detected by MRI. MRS was performed from normal appearing frontal and posterior parietal white matter (FWM and PWM) in NF1 and from control groups. NAA/Cr, Cho/Cr and MI/Cr ratios were calculated. Significant increase in Cho/Cr and MI/Cr ratios were found in FWM and PWM in MR negative and positive groups when compared to control group. NAA/Cr ratio in MR positive group was significantly decreased in FWM compared to control group. There were no significant differences between FWM and PWM in all metabolite ratios of MR negative group. MI/Cr ratio in MR positive group was significantly elevated in PWM compared to FWM. Metabolite changes detected by MRS could indicate demyelination and gliosis in normal appearing white matter in all NF1 patients, and additionally neuroaxonal damage in the FWM of NF1 patients with focal lesions. For that reason, in the clinical evaluation and follow-up of these patients MRS features of normal appearing white matter should be considered in addition to focal lesions.     

Magnetic resonance spectroscopy of the brain in neurologically asymptomatic HIV-infected patients

The CNS involvement is frequently found in human immunodeficiency virus (HIV) infection. The purpose of our study was to determine whether proton magnetic resonance spectroscopy (MRS) could detect early brain involvement in neurologically asymptomatic HIV-infected patients with normal MR imagings and to find the correlation between MRS and the immune status. We performed MRS in 30 HIV seropositive neurologically asymptomatic patients with normal MRI and compared the MRS findings with 13 controls. A statistically significant reduction in N-acetylaspartate (NAA)/creatine (Cr) and N-acetylaspartate (NAA)/choline (Cho) in both centrum semiovale (p < 0.005) and thalamic areas (p < 0.05) was found. There is no statistically significant difference as to choline (Cho)/creatine (Cr) and myoinositol (mI)/creatine (Cr) ratios in both regions. The difference of NAA/Cr was more pronounced in the white matter than in the gray matter. As for the immune status, there was a trend towards correlation between CD4 counts and NAA/Cr but devoid of statistical significance. Our results suggest that MRS is more sensitive than conventional MR imaging in detecting CNS involvement in neurologically asymptomatic HIV patients and may, therefore, be used for early detection of brain damage induced by HIV.     

Noninvasive evaluation of cerebral glioma grade by using multivoxel 3D proton MR spectroscopy

Objective

To determine whether metabolite ratios in multivoxel 3D proton MR spectroscopy (¹H MRS) is different between low-grade and high-grade gliomas and may be useful for glioma grading.

Materials and Methods

Thirty-nine patients (23 male and 16 female; 22-75 years old; mean age, 44.92±12.65 years) suspected of having gliomas underwent 3D ¹H MRS examinations. Metabolite ratios [choline (Cho)/creatine (Cr), N-acetylaspartate (NAA)/Cr and Cho/NAA] were measured. Tumor grade was determined by using the histopathologic grading. Receiver operating characteristic analysis of metabolite ratios was performed, and optimum thresholds for tumor grading were determined. The resulting sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for identifying high-grade gliomas were calculated.

Results

Diagnostic-quality 3D ¹H MRS with readily quantifiable Cho, Cr and NAA peaks was obtained in 94.87% of the cases. The Cho/Cr and Cho/NAA ratios were significantly higher in high-grade than in low-grade glioma (P<.001), whereas the NAA/Cr ratios were significantly lower in high-grade than in low-grade glioma (P<.001). Receiver operating characteristic analysis demonstrated a threshold value of 2.04 for Cho/Cr ratio to provide sensitivity, specificity, PPV and NPV of 84.00%, 83.33%, 91.30% and 71.43%, respectively. Threshold value of 2.20 for Cho/NAA ratio resulted in sensitivity, specificity, PPV and NPV of 88.00%, 66.67%, 84.62% and 72.73%, respectively. Overall diagnostic accuracy was not statistically significantly different between Cho/Cr and Cho/NAA ratios (χ²=0.093, P=.76).

Conclusion

Metabolite ratios of low-grade gliomas were significantly different from high-grade gliomas. Cho/Cr and Cho/NAA ratios could have the superior diagnostic performance in predicting the glioma grade.     

颐脑解郁方对抑郁大鼠脑1H波谱的干预作用

该文主要研究抑郁大鼠脑的¹H MRS变化及颐脑解郁方的干预作用. 将雄性Wistar大鼠随机分为正常组、模型组、西药组和中药组,每组5只. 正常组常规饲养,模型组、中药组和西药组给予21 d的慢性不可预知的温和应激. 应激结束中药组予颐脑解郁方、西药组予盐酸氟西汀进行干预. 干预结束后,通过检测左侧海马及前额叶皮质N-乙酰天门冬氨酸（NAA）、胆碱（Cho）、肌酸（Cr）等代谢物水平,分别计算NAA、Cho与Cr的比值,进而对脑组织代谢进行定性及定量分析. 得到：1. 海马区域：与正常组相比,模型组、西药组大鼠海马NAA/Cr降低（P<0.01）,中药组大鼠NAA/Cr与模型组相比升高（P<0.05）;与正常组相比,模型组Cho/Cr升高（P<0.05）,中药组Cho/Cr比模型组显著低（P<0.01）. 2. 前皮质区域：与正常组相比,模型组、西药组大鼠前皮质NAA/Cr降低（P<0.01）,中药组大鼠NAA/Cr较模型组显著升高（P<0.01）;模型组、西药组Cho/Cr与正常组相比显著升高（P<0.01）;与模型组相比,中药组、西药组Cho/Cr降低（P<0.01,P<0.05）. 这些结果说明颐脑解郁方可改善大鼠海马和前皮质的物质代谢,推测其抗抑郁作用主要与调节脑组织异常代谢有关.     

Spectroscopic imaging of radiation-induced effects in the white matter of glioma patients

External radiation therapy of brain tumors may cause adverse effects on normal brain tissue, resulting in severe neuropsychological and cognitive impairment. We investigated the late delayed radiation effects in the white matter (WM) using (1)H magnetic resonance spectroscopic imaging ((1)HMRSI). Nine glioma patients with local radiation-induced signal abnormalities in the T(2)-weighted MR images were studied with nine age- and sex-matched controls. The metabolite ratios in the radiation-induced hyper intensity area (RIHA) and in the normal appearing white matter (NAWM) of the patients were compared with respective WM areas of the controls. In RIHA, choline/creatine (Cho/Cr) was 17% decreased (1.22 +/- 0.13 vs 1.47 +/- 0.16, p = 0.0027, significant (s), unpaired Student's t test with Bonferroni correction) in the patients compared to the controls, while there was no difference in N-acetyl aspartate/Cr (NAA/Cr) (2.49 +/- 0.57 vs 2.98 +/- 0.32, p = 0.039) or NAA/Cho (2. 03 +/- 0.40 vs 2.04 +/- 0.17, p = 0.95). In NAWM, Cho/Cr was 24% decreased (1.21 +/- 0.15 vs 1.59 +/- 0.13, p < 0.0001, s) and NAA/Cho was 20% increased (2.49 +/- 0.49 vs 1.98 +/- 0.15, p = 0. 0082, s) in the patients compared to the controls, while there was no difference in NAA/Cr (2.99 +/- 0.46 vs 3.16 +/- 0.32, p = 0.38). NAA(RIHA)/NAA(NAWM) was 25% decreased (0.75 +/- 0.20 vs 1.00 +/- 0. 12, p = 0.0043, s) and Cr(RIHA)/Cr(NAWM) was 16% decreased (0.89 +/- 0.15 vs 1.06 +/- 0.10, p = 0.013, s) in the patients compared to the controls, while there was no difference in Cho(RIHA)/Cho(NAWM) (0.92 +/- 0.23 vs 0.98 +/- 0.10, p = 0.47). (1)HMRSI reveals widespread chemical changes in the WM after radiation therapy. In RIHA, there is loss of NAA, Cho, and Cr implying axonal and membrane damage and in NAWM, there is loss of Cho, reflecting membrane damage.     

In vivo proton magnetic resonance spectroscopy studies of human brain

In vivo localized proton magnetic resonance spectroscopy (MRS) studies of brain were performed on eighteen normal subjects using the stimulated echo (STE) sequence. The absolute concentrations and proton relaxation times of N-acetyl aspartate (NAA), total creatine (Cr) and choline (Cho) were estimated. The MRS data was quantitatively analyzed for repeatability and intersubject variability. Quantitative analysis indicates excellent spectral repeatability. Significant intersubject variations in [NAA] and [Cr] have been observed while the intersubject variability in [Cho] has been found to be fairly small. Significant intensity distortions have been observed for mixing times longer than 50 msec.     

Serial Precision of Metabolite Peak Area Ratios and Water Referenced Metabolite Peak Areas in Proton MR Spectroscopy of the Human Brain

The precision of cerebral proton magnetic resonance spectroscopy (MRS) measurements is critical both in the clinical setting and for research purposes. Marshall et al. have recently concluded that “disappointing in vivo repeatability…is likely to limit” the ability of MRS to detect modest changes. We present here a comprehensive study of the precision of short- and long-term metabolite peak area ratios and water referenced metabolite peak areas for long echo time point resolved spectroscopy (PRESS) spectra (repetition time (TR) = 2000 ms, echo time (TE) = 136 ms) acquired from the occipital lobes of normal volunteers and a phantom using a conventional whole body 1.5 T MR system and conventional acquisition and analysis protocols. Short-term in vitro precision determined by five repeat scans on five occasions was excellent as measured by a mean coefficient of variation (NAA/Cho = 1.3%, NAA/Cr + PCr = 1.0%, Cho/Cr + PCr = 1.6%, NAA/H₂O = 0.5%, Cho/H₂O = 1.2%, Cr + PCr/H₂O = 0.8%). Long term in vitro precision using 100 spectra acquired over 2 years was also very good (NAA/Cho = 2.7%, NAA/Cr + PCr = 1.4%, Cho/Cr + PCr = 2.2%, NAA/H₂O = 1.5%, Cho/H₂O = 2.4%, Cr + PCr/H₂O = 1.5%). Short-term in vivo precision determined by five repeat scans in a single scanning session on eight subjects was also excellent (NAA/Cho = 5.2%, NAA/Cr + PCr = 3.0%, Cho/Cr + PCr = 6.6%, NAA/H₂O = 1.4%, Cho/H₂O = 4.9%, Cr + PCr/H₂O = 2.7%) and only worsened slightly for long-term in vivo precision determined by five repeat scans on eight subjects over 3 months (NAA/Cho = 5.2%, NAA/Cr + PCr = 4.8%, Cho/Cr + PCr = 7.7%, NAA/H₂O = 2.5%, Cho/H₂O = 6.4%, Cr + PCr/H₂O = 3.8%). We attribute the excellent precision reported here to the use of highly automated techniques for voxel shimming, water suppression and peak area measurements. These results allow us to repudiate Marshall’s assertion regarding disappointing repeatability of in vivo MRS.     

Magnetic resonance spectroscopy study of proton metabolite level changes in sensorimotor cortex after upper limb replantation-revascularization

We aimed to investigate the changes in proton metabolite levels at the motor and somatosensory cortex by magnetic resonance spectroscopy (MRS) after upper extremity replantation or revascularization. Nine patients who referred to our clinic suffering from major total (two) and subtotal (seven) amputation of the upper extremity were enrolled in this study. Mean time value between the injury and operation was 5.1 h. Mean follow-up period or mean time between the injury and MRS analysis was 26.2 months (ranging from 7 to 41 months). Voxels (TR: 2000; TE: 136 ms) were placed onto locations in the bilateral precentral and postcentral cortex area of the cerebral hemispheres that represent the upper extremity. Contralateral sides of the brain hemisphere that represent the injured extremity were accounted as control groups. Metabolite ratios [NAA (N-acetyl aspartate)/Cr (creatine) and Cho (choline)/Cr] of the motor and somatosensory cortex were calculated. The NAA/Cr and Cho/Cr metabolite ratios between the two groups were found to be insignificant, and these results may indicate that there is no remarkable somatosensorial cortex disruption or demyelination in these patients. Fifty-six percent of patients were found as functional according to Chen's scale.     

Feasibility of proton chemical shift imaging with a stereotactic headframe

To prove feasibility of proton chemical shift imaging ((1)H CSI) during stereotactic procedure, authors performed (1)H CSI in combination with a stereotactic headframe and selected targets according to local metabolic information, evaluated the pathologic results. The (1)H CSI directed stereotactic biopsy was performed in four patients. (1)H CSI and conventional Gd-enhancement stereotactic MRI were performed simultaneously after the fitting of a stereotactic headframe. Focal areas of increased phosphocholine(Cho)/phosphocreatine(Cr) and Lactate/Cr ratios were selected as target sites in the stereotactic MR images. (1)H CSI is possible with the stereotactic headframe in place. Pathologic samples taken from areas of increased Cho/Cr ratios and decreased NAA/Cr ratios provided information upon increased cellularity, mitoses and cellular atypism, and facilitated diagnosis. Pathologic samples taken from areas of increased Lac/Cr ratio showed predominant feature of necrosis. (1)H CSI was feasible with the stereotactic headframe in place. The final pathologic results obtained were concordant with the local metabolic information from (1)H CSI. We believe that (1)H CSI-directed stereotactic biopsy has the potential to significantly improve the accuracy of stereotactic biopsy targeting.     

Quantification of cerebral metabolites in glioma patients with proton MR spectroscopy using T2 relaxation time correction

This study was aimed to investigate the significance of absolute concentration of metabolites in glioma patients using proton MR spectroscopy (MRS) with T2 relaxation time correction using three different echo times. The absolute concentrations of metabolites in 7 normal subjects and in 23 gliomas (10 low-grade, 13 high-grade) were obtained by proton MRS using a tissue water signal as an internal standard. The signal intensities of metabolites and tissue water were corrected by T2 relaxation time. In low-grade glioma, the T2 relaxation time of NAA was shorter, and T2 relaxation time of water was prolonged as compared to normal subjects (p < 0.001). In high-grade glioma, the T2 relaxation time of NAA (p < 0.001) and T2 relaxation time of Cr (p < 0.01) were shorter, and T2 relaxation time of water (p < 0.001) was prolonged as compared to normal subjects. Moreover, high-grade gliomas revealed a shorter T2 relaxation time of Cr than low-grade gliomas (p < 0.05). In glioma, NAA and Cr concentration were decreased, and Cho were increased as compared to normal subjects. Moreover, high-grade glioma revealed a significant lower Cr (p < 0.001) and Cho (p < 0.01) concentration compared to low-grade gliomas. Low Cr concentration is the most reliable indicator of malignancy in glioma. Cho concentration did not correlate with malignancy in gliomas.     

Occupational prolonged organic solvent exposure in shoemakers: brain MR spectroscopy findings

Our purpose was to investigate, by magnetic resonance (MR) spectroscopy, the metabolite changes in the brains of subjects in the shoemaking industry who had been chronically exposed to organic solvents. A total of 49 male subjects and 30 age-matched healthy volunteers underwent detailed neurological and psychiatric examinations. All subjects had long-echo [repetition time (TR) 2000 ms, echo time (TE) 136 ms] single-voxel MR spectroscopy. Voxels (15 x 15 x 15 mm(3)) were placed in the parietal white matter, thalamus, and basal ganglia. N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were calculated. There was no significant difference between the study subjects and the control group in NAA/Cr ratios obtained from thalamus, basal ganglia, and parietal white matter. Cho/Cr ratios in thalamus, basal ganglia, and parietal white matter were found to be significantly increased compared to controls. There was a positive correlation between basal ganglia Cho/Cr ratio and duration of exposure (r = 0.63). MR spectroscopy should be performed to reveal metabolite changes and determine the degree of brain involvement in solvent-related industry workers.     

High-field localized 1H NMR spectroscopy in the anesthetized and in the awake monkey

Localized cerebral in vivo ¹H NMR spectroscopy (MRS) was performed in the anesthetized as well as the awake monkey using a novel vertical 7 T/60 cm MR system. The increased sensitivity and spectral dispersion gained at high field enabled the quantification of up to 16 metabolites in 0.1- to 1-ml volumes. Quantification was accomplished by using simulations of 18 metabolite spectra and a macromolecule (MM) background spectrum consisting of 12 components. Major cerebral metabolites (concentrations >3 mM) such as glutamate (Glu), N-acetylaspartate (NAA), creatine (Cr)/phosphocreatine (PCr) and myo-inositol (Ins) were identified with an error below 3%; most other metabolites were quantified with errors in the order of 10%. Metabolite ratios were 1.39:1 for total NAA, 1.38:1 for glutamate (Glu)/glutamine (Gln) and 0.09:1 for cholines (Cho) relative to total Cr. Taurine (Tau) was detectable at concentrations lower than 1 mM, while lactate (Lac) remained below the detection limit. The spectral dispersion was sufficient to separate metabolites of similar spectral patterns, such as Gln and Glu, N-acetylaspartylglutamate (NAAG) and NAA, and PCr–Cr. MRS in the awake monkey required the development and refinement of acquisition and correction strategies to minimize magnetic susceptibility artifacts induced by respiration and movement of the mouth or body. Periods with major motion artifacts were rejected, while a frequency/phase correction was performed on the remaining single spectra before averaging. In resting periods, both spectral amplitude and line width, that is, the voxel shim, were unaffected permitting reliable measurements. The corrected spectra obtained from the awake monkey afforded the reliable detection of 6–10 cerebral metabolites of 1-ml volumes.     

Development of the time course for processing conflict: an event-related potentials study with 4 year olds and adults

Background

The neurological complications of HIV infection remain poorly understood. Clinically, in vivo ¹H magnetic resonance spectroscopy (MRS) demonstrates brain injury caused by HIV infection even when the MRI is normal. Our goal was to undertsand the dynamics of cerebral injury by performing a longitudinal in vivo ¹H MRS study of the SIV/macaque model of neuroAIDS.

Results

Eight rhesus macaques were infected with SIVmac251 and serially imaged with MRI and ¹H MRS to terminal AIDS or the endpoint of 2 years. During acute infection, there were stereotypical brain MRS changes, dominated by a significant elevation of the Cho/Cr ratio in the frontal cortex. Subsequently, brain metabolic patterns diverged between animals. There was an elevation of basal ganglia Cho/Cr four weeks post-inoculation in 2 animals that developed SIV encephalitis (p = 0.022). Metabolite ratios averaged across all 8 animals were not significantly different from baseline at any time point after 2 weeks post inoculation. However, linear regression analysis on all 8 animals revealed a positive correlation between a change in frontal lobe Cho/Cr and plasma viral load (P < 0.001, R = 0.80), and a negative correlation between NAA/Cr in the basal ganglia and the plasma viral load (P < 0.02, R = -0.73). No MRI abnormalities were detected at any time.

Conclusions

After infection with SIV, macaque brain metabolism changes in a complex manner that is dependent on brain region, host factors and viral load. An elevation of basal ganglia Cho/Cr 4 weeks after SIV infection may be marker of a propensity to develop SIV encephalitis. Elevations of Cho/Cr, often observed in CNS inflammation, were associated with increased plasma viral load during acute and chronic infection. Evidence of neuronal injury in the basal ganglia was associated with increased plasma viral load in the chronic stage of infection. These observations support the use of drugs capable of controlling the viral replication and trafficking of virus into the CNS, and may help explain the reduction in incidence of HIV-associated dementia in the era of HAART despite the inability of most of those drugs to effectively enter the CNS.     

Single-voxel proton MR spectroscopy in toluene abuse

Inhalation of toluene, which is an organic solvent, causes toxic encephalopathy characterized by cognitive impairment, cerebellar and extra-pyramidal symptoms. We studied cranial MR images and single-voxel MR spectroscopy of 22 toluene abusers and age-matched control subjects. The mean age of the abusers and mean duration of abuse were 18,1 years and 47 months, respectively. We got three MR spectra from the centrum semiovale, cerebellum and thalamus by using STEAM sequence with a TE value of 30 ms. N-acetyl aspartate (NAA)/Creatine (Cr), Choline (Cho)/Cr, myo-inositol (mI)/Cr peak integral ratios were calculated. NAA/Cr in the cerebellum and centrum semiovale of the abusers were significantly lower than those of the control subjects. mI/Cr in centrum semiovale and cerebellum were higher in toluene abusers. No significant difference was found in the metabolite ratios of the thalami. The association of NAA/Cr and mI/Cr ratios in cerebellum and centrum semiovale with the duration of abuse was significant. Normal level of NAA in thalamus, which was a neuron rich gray matter structure, might imply that toluene inhalation did not cause direct neuronal injury. Selective reduction of NAA and increased level of mI in white matter supported the theory of that axonopathy and gliosis were the main mechanisms of pathophysiology in chronic toluene encepholopathy. Insignificance of elevation of Cho/Cr ratios demonstrated that toluene inhalation did not cause active demyelination.     

Assessment of the metabolic profile in Type 2 diabetes mellitus and hypothyroidism through proton MR spectroscopy

The metabolic changes in the brain of patients affected with Type 2 diabetes mellitus (DM) alone, both Type 2 DM and hypothyroidism and hypothyroidism only were investigated using proton magnetic resonance spectroscopy ((1)H MRS). Single-voxel spectroscopy was carried out in right and left frontal lobe white matter, left parietal white matter and left occipital gray matter. Choline (Cho)/creatine (Cr) value was found to be increased in the left occipital gray matter of the subjects affected with Type 2 DM and both Type 2 DM and hypothyroidism as compared to controls. No significant change in the Cho/Cr value in the occipital gray matter was observed in hypothyroid subjects as compared to controls. However, they showed an increased level of Cho/Cr in the frontal white matter. High Cho is associated with altered membrane phospholipid metabolism. The high Cho in frontal white matter in hypothyroids and occipital gray matter in diabetic patients suggests that, though both the diseases are endocrine disorders, they differ from each other in terms of regional brain metabolite changes.     

MRS study of the effects of minocycline on markers of neuronal and microglial integrity in ALS

Objective

Magnetic resonance spectroscopy (MRS) allows to monitor brain metabolites noninvasively in amyotrophic lateral sclerosis (ALS). The objective of this study was to use MRS to monitor the effect of minocycline treatment (200 mg/day) over a short period (6 weeks) on the brain metabolites in the precentral gyrus and brainstem in newly diagnosed ALS patients.

Methods

Ten ALS patients (not on riluzole treatment) were recruited and submitted to single-voxel proton MRS longitudinal examinations (1) before minocycline treatment, (2) 3 weeks and (3) 6 weeks after initiation of treatment.

Results

Results did not show the expected decrease of N-acetylaspartate/creatine (NAA/Cr) in the precentral gyrus, and an increased NAA/Cr ratio in the brainstem suggested neuronal recovery. The myo-inositol (mI)/Cr ratio was unchanged in the precentral gyrus, but increased in the brainstem, indicating a glial reaction.

Conclusions

MRS results suggest that minocycline treatment could be beneficial in the early stages of ALS.     

A (1)H magnetic resonance spectroscopy study of aging in parietal white matter: implications for trials in multiple sclerosis

1H magnetic resonance spectroscopy (MRS) provides a unique tool to detect and quantify brain metabolites. In multiple sclerosis it can be used to investigate axonal loss or dysfunction through measurement of N-acetyl aspartate (NAA), a neuronal marker. Previous studies in adults have reported variable effects of aging on metabolite concentrations but have predominantly focused on changes in the elderly. This study has examined a younger adult age group to provide a reference database more applicable to the multiple sclerosis population. Single voxel (1)H MRS was carried out in 44 subjects between 22 and 62 years of age. Sixteen subjects underwent repeat examination after one year. Absolute concentrations of NA (the sum of NAA and N-acetyl aspartate glutamate), NAA, creatine/phosphocreatine (Cr), choline containing compounds (Cho) and myo-inositol (mI) were measured. NA, NAA and mI concentrations did not correlate with age but there were significant correlations between age and Cr (r = 0.43, p = 0.004) and Cho (r = 0.38, p = 0. 011) concentrations. No significant differences in metabolite concentrations were seen over one year. This study provides evidence that age-related changes of metabolite concentrations occur even in a young to middle aged adult population. This emphasizes the need to perform absolute quantification of metabolite concentrations rather than ratios and the importance of age-matching in (1)H MRS studies of multiple sclerosis.