(1)H magnetic resonance spectroscopy of autosomal ataxias

Multiple forms of autosomal ataxia exist which can be identified by genetic testing. Due to their wide variety, the identification of the appropriate genetic test is difficult but could be aided by magnetic resonance data. In this study, magnetic resonance spectroscopy (MRS) and imaging (MRI) data were recorded for 20 ataxia patients of six different types and compared to 20 normal subjects. Spectra were acquired in the pons, left frontal lobe, left basal ganglia, left cerebellar hemisphere and vermis. Both metabolite spectra and absolute metabolite concentrations were determined. Differences in metabolite levels were observed between ataxia patients and control subjects and between ataxia patients of different types. A number of correlations were found between metabolite ratios, atrophy levels, number of repeats on the small and large allele, age at examination, symptoms duration and age at symptoms onset for ataxia patients. These MR characteristics are expected to be useful for the identification of the ataxia type.     

Cognitive impairment: assessment with brain magnetic resonance imaging and proton magnetic resonance spectroscopy

BACKGROUND: In vivo proton magnetic resonance spectroscopy is a safe and noninvasive tool that can be used to study aspects of brain chemistry and metabolism. This study was designed to evaluate its role in routine application to reveal the diagnostic reasons for cognitive impairment. METHOD: 37 Alzheimer's disease patients (NINCDS-ADRDA criteria), 31 patients with subcortical ischemic vascular dementia (Chui et al. criteria), and 13 subjects with subjective cognitive impairment (DSM-IV criteria) were included in this retrospective study. Magnetic resonance images were used for atrophy rating; additionally, proton magnetic resonance spectroscopy was performed. RESULTS: Significantly reduced N-acetylaspartate levels (p <.05) were found in both patients with Alzheimer's disease and patients with subcortical ischemic vascular dementia compared to the group with subjective memory complaints. The ratios of N-acetylaspartate/creatine and N-acetylaspartate/myo-inositol were significantly lower in Alzheimer's disease patients compared to patients with vascular dementia (p =.012) or patients with subjective memory impairment (p =.002). N-acetylaspartate/creatine and N-acetylaspartate/myo-inositol ratios were positively correlated to the degree of cerebral atrophy. Disoriented patients displayed a low N-acetylaspartate/creatine ratio. In contrast, we were not able to relate concurrent psychotic or behavioral symptoms to any spectroscopic parameter. CONCLUSION: This study indicates that proton magnetic resonance spectroscopy parameters could provide additional information in differentiating between Alzheimer's disease, subcortical ischemic vascular dementia, and subjective cognitive impairment. Therefore, this method can contribute to the routine diagnosis of dementia. Psychiatric and behavioral symptoms associated with dementia or due to a major psychiatric disorder cannot be related to changes in the measured proton magnetic resonance spectroscopy parameters.     

Magnetic resonance imaging and magnetic resonance spectroscopy in dementias

This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in dementia, including Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, idiopathic Parkinson's disease, Huntington's disease, and vascular dementia. Magnetic resonance imaging and magnetic resonance spectroscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential diagnosis and early detection of affected individuals, monitoring disease progression, and evaluation of therapeutic effect.     

Combined magnetic resonance imaging and proton magnetic resonance spectroscopy of patients with acute stroke.

BACKGROUND AND PURPOSE: The prospect for a therapeutic window for treatment of ischemic stroke encourages the noninvasive investigation of metabolic changes in acute ischemia. Recently, localized proton spectroscopy became available at 1.5-T magnetic resonance systems. In this study we evaluated the usefulness of combined magnetic resonance imaging and spectroscopy on the diagnosis of acute and chronic infarctions. METHODS: Combined magnetic resonance imaging and spectroscopy investigations were carried out with a 1.5-T system in 16 volunteers, eight patients with chronic infarction (greater than 8 months), and 10 patients with acute ischemic stroke (less than 8 hours). We used a stimulated echo sequence to acquire localized spectra from image-guided volumes of interest (16-27 ml). RESULTS: There were no significant interindividual differences of choline, creatine, phosphocreatine, and N-acetyl aspartate resonances in the spectra from volunteers. In chronic infarctions, N-acetyl aspartate was decreased in relation to choline. Acute ischemic infarctions were characterized by decreased N-acetyl aspartate resonances and elevation of lactate. CONCLUSIONS: The study demonstrates the feasibility of proton spectroscopy in stroke patients. Metabolic alterations in ischemic tissue can be monitored and can distinguish acute from chronic lesions.     

Magnetic resonance imaging in spinocerebellar ataxias

Magnetic resonance (MR) imaging is widely used to visualize atrophic processes that occur during the pathogenesis of spinocerebellar ataxias (SCAs). T1-weighted images are utilized to rate the atrophy of cerebellar vermis, cerebellar hemispheres, pons and midbrain. Signal changes in the basal ganglia and ponto-cerebellar fibers are evaluated by T2-weighted and proton density-weighted images. However, two-dimensional (2D) images do not allow a reliable quantification of the degree of atrophy. The latter is now possible through the application of three-dimensional (3D) true volumetric methods, which should be used for research purposes. Ideally, these methods should allow automated segmentation of contrast-defined boundaries by using region growing algorithms, which can be applied successfully in structures of the posterior fossa and basal ganglia. Thin slice thickness helps to minimize partial volume effects. Whereas volumetric approaches rely on predetermined anatomical boundaries, voxel-based morphometry has been developed to determine group differences between different types of SCA (cross-sectional studies) or within one SCA entity (longitudinal studies). We will review recent results and how these methods are currently used to (i) separate sporadic and dominantly inherited forms of cerebellar ataxias; (ii) identify specific SCA genotypes; (iii) correlate patho-anatomical changes with SCA disease symptoms or severity; and (iv) visualize and estimate the rate of progression in SCA.     

Neuro-cysticercosis with Japanese encephalitis: magnetic resonance imaging with diffusion and spectroscopy

Neuro-cysticercosis (NCC) and Japanese encephalitis (JE) are common in tropical countries. Two cases of NCC with coexistent JE are presented, which share same socio-demographic and ecologic factors and have the same intermediate host (pig). Patients were on treatment for NCC and presented in comatose state. Sudden clinical deterioration of a patient with NCC should warrant a search for coexistent JE. We report findings of magnetic resonance spectroscopy and diffusion-weighted imaging of the JE.     

Magnetic resonance spectroscopy and magnetic resonance imaging findings in Krabbe's disease.

Two twins with late infantile globoid cell leukodystrophy of Krabbe's disease were studied with conventional magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy. Brain MRI demonstrated brain atrophy with extensive bilateral symmetric abnormal T2 signal in the posterior periventricular white matter, parietal lobes, corona radiata, centrum semiovale, and splenium of the corpus callosum. Magnetic resonance imaging-guided proton magnetic resonance spectroscopy revealed prominent peaks from choline-containing compounds, total creatine, and inositols. The N-acetylaspartate peak was markedly reduced, and the choline-to-N-acetylaspartate ratio was abnormally high; in one of the twins, lactic acid was also detected. The constellation of magnetic resonance spectroscopy findings is indicative of extensive demyelination, gliosis, and loss of axons in the involved white matter; the latter two events occur in the later stages of globoid cell leukodystrophy. In conjunction with brain MRI, these magnetic resonance spectroscopy findings may alert clinicians to the possibility of leukodystrophy in children with progressive encephalopathy.     

Magnetic resonance imaging and magnetic resonance spectroscopy in isolated sulfite oxidase deficiency

Isolated sulfite oxidase deficiency is a rare genetic neurometabolic disease. The first symptoms of this disorder (similar to symptoms of ischemic events) may lead to misdiagnosis and to subsequent birth of affected children in these families. This study characterizes the magnetic resonance (MR) imaging and (for the first time, to our knowledge) the MR spectroscopy features of isolated sulfite oxidase deficiency to provide a means for early and correct diagnosis. Three patients with isolated sulfite oxidase deficiency are studied who manifested intractable seizures and severe hypotonia in the immediate postnatal period with an unknown diagnosis, despite extensive workup. MR imaging and proton MR spectroscopy examinations were performed early in the neonatal period in 2 infants and after 5 months in the third infant. The prominent MR features were early cystic white matter damage, accompanied by profound cerebral atrophy in the third infant. Compared with hypoxic-ischemic disorder, MR findings in isolated sulfite oxidase deficiency demonstrate a more severe condition, without subsequent recovery. The MR spectroscopy studies indicate early onset of energetic and metabolic imbalance. Urine stick findings demonstrated high sulfite levels in 2 patients, and the final diagnosis was subsequently made based on molecular, biochemical, and genetic findings. Magnetic resonance imaging and MR spectroscopy measurements may help differentiate isolated sulfite oxidase deficiency from hypoxic-ischemic condition in patients in whom this diagnosis is not clinically suspected and may lead to further genetic antenatal inquiry that might prevent the birth of other infants affected with this severe and incurable congenital disease.     

Magnetic resonance imaging and magnetic resonance spectroscopy for detection of early Alzheimer's disease

Alzheimer's disease is the most common form of neurodegenerative disorder and early detection is of great importance if new therapies are to be effectively administered. We have investigated whether the discrimination between early Alzheimer's disease (AD) and elderly healthy control subjects can be improved by adding magnetic resonance spectroscopy (MRS) measures to magnetic resonance imaging (MRI) measures. In this study 30 AD patients and 36 control subjects were included. High resolution T1-weighted axial magnetic resonance images were obtained from each subject. Automated regional volume segmentation and cortical thickness measures were determined for the images. 1H MRS was acquired from the hippocampus and LCModel was used for metabolic quantification. Altogether, this yielded 58 different volumetric, cortical thickness and metabolite ratio variables which were used for multivariate analysis to distinguish between subjects with AD and Healthy controls. Combining MRI and MRS measures resulted in a sensitivity of 97% and a specificity of 94% compared to using MRI or MRS measures alone (sensitivity: 87%, 76%, specificity: 86%, 83% respectively). Adding the MRS measures to the MRI measures more than doubled the positive likelihood ratio from 6 to 17. Adding MRS measures to a multivariate analysis of MRI measures resulted in significantly better classification than using MRI measures alone. The method shows strong potential for discriminating between Alzheimer's disease and controls.     

Review of magnetic resonance imaging and spectroscopy studies in children with bipolar disorder

Pediatric bipolar disorder is a serious condition that affects a child's ability to function normally during important developmental stages. Pediatric bipolar disorder often presents with a different symptom complex than adult-onset bipolar disorder, including higher rates of irritability and rapid cycling. Due to these differences, it is important to understand the neural substrates of the disease as it presents in children, especially when compared with adults. Understanding the brain abnormalities associated with pediatric bipolar disorder may provide much needed markers useful in diagnosing childhood-onset bipolar disorder, give insight into the neurobiological etiology of the disorder and lead to more effective treatments. Currently, there has been little neuroimaging research into pediatric bipolar disorder, specifically with regards to brain function. This review summarizes the neurobiological research that has been conducted on childhood- and adolescent-onset bipolar disorder using magnetic resonance technology. Future directions of research needed in this area also are discussed in the context of the existing literature.     

Sepsis-associated encephalopathy: a magnetic resonance imaging and spectroscopy study

Brain dysfunction is frequently observed in sepsis as a consequence of changes in cerebral structure and metabolism, resulting in worse outcome and reduced life-quality of surviving patients. However, the mechanisms of sepsis-associated encephalopathy development and a better characterization of this syndrome in vivo are lacking. Here, we used magnetic resonance imaging (MRI) techniques to assess brain morphology and metabolism in a murine sepsis model (cecal ligation and puncture, CLP). Sham-operated and CLP mice were subjected to a complete MRI session at baseline, 6 and 24 h after surgery. Accumulation of vasogenic edematic fluid at the base of the brain was observed in T₂-weighted image at 6 and 24 h after CLP. Also, the water apparent diffusion coefficients in both hippocampus and cortex were decreased, suggesting a cytotoxic edema in brains of nonsurvival septic animals. Moreover, the N-acetylaspartate/choline ratio was reduced in brains of septic mice, indicating neuronal damage. In conclusion, noninvasive assessment by MRI allowed the identification of new aspects of brain damage in sepsis, including cytotoxic and vasogenic edema as well as neuronal damage. These findings highlight the potential applications of MRI techniques for the diagnostic and therapeutic studies in sepsis.     

Diagnosis and prognosis evaluation of 1,2-dichloroethane encephalopathy--magnetic resonance imaging combined with diffusion tensor imaging and magnetic resonance spectroscopy study

Neuroimaging findings in 1,2-dichloroethane (1,2-DCE) encephalopathy have seldom been reported. We present the comprehensive neuroimaging findings, conventional magnetic resonance imaging (MRI) combined with diffusion tensor imaging (DTI) and 1 H-magnetic resonance spectroscopy ( 1 H-MRS), in a case of 1,2-DCE encephalopathy. On day-4 the signal intensity of the lesions on diffusion-weighted imaging (DWI) was higher than that with T2-weighted imaging (T2WI); mean apparent diffusion coefficient (ADC) values for lesions were lower than control values. On day-20, the mean ADC value was increased gradually, whereas the mean fractional anisotropy (FA) of the lesions was significantly reduced. 1 H-MRS showed reduced ratios of N-acetyl aspartate to creatinine (NAA/Cr) and NAA to choline (NAA/Cho) on day-20 as compared with the control values. Combining conventional MRI with DTI and MRS is valuable in the early diagnosis and prognosis of 1,2-DCE-induced encephalopathy.     

Magnetic resonance imaging and proton magnetic resonance spectroscopy of megalencephaly and dilated Virchow-Robin spaces

Megalencephaly with dilated Virchow-Robin spaces has been suggested to represent a new clinical entity. This report describes two males and a female who have been monitored from pregnancy. The patients manifest a relatively normal psychomotor development with some minor neurologic symptoms such as mild muscle hypotonia and clumsy motor performance. Biochemical and electrophysiologic tests were normal. In the white matter of the brain, a prominent dilatation of the Virchow-Robin spaces with some adjacent signal alterations could be demonstrated by magnetic resonance imaging. Magnetic resonance spectroscopy revealed normal metabolite concentrations in the cortical and deep gray matter and normal-appearing white matter. Affected white matter was characterized by mildly reduced to normal levels of myo-inositol and a decrease of all other metabolites including total N-acetyl moieties, choline-containing compounds, and total creatine. These data indicate that the dilatation of Virchow-Robin spaces reflects an underlying brain pathology causing neuroaxonal damage. Possible differential diagnoses are discussed.     

Prolonged survival and serial magnetic resonance imaging/magnetic resonance spectroscopy changes in infantile krabbe disease

Krabbe disease may present during infancy, late infancy, or adulthood. Earlier-onset disease is associated with shorter survival times. We present a case of infantile onset Krabbe disease with prolonged survival, initial intracranial optic nerves and optic chiasm hypertrophy, and serial changes on cranial magnetic resonance imaging and magnetic resonance spectroscopy.     

Characterization of untreated gliomas by magnetic resonance spectroscopic imaging

Although there are trends in the morphologic, metabolic, hemodynamic, and structural properties of untreated gliomas that are reflected in MR measurements, there is considerable heterogeneity both within and between lesions of the same histologic grade. The spatial extent of the abnormality in ADC and RA images is similar to the T2 lesion, but there is no obvious difference in intensity between grades. The rCBV is significantly increased in the enhancing volume of grade 4 lesions but is similar or reduced in intensity for most grade 3 lesions. There are clear differences between the enhancing volumes and the regions with increased Cho that may be highly significant for planning focal therapy. The location and intensity of the Lac/Lip peaks are consistent with those representing regions of necrosis for grade 4 lesions. The fact that small Lac/Lip peaks can also be seen in grade 2 and grade 3 lesions suggests that their presence may be indicative of regions that are likely to progress to a higher grade. If this were the case, it would be valuable for directing biopsies. The correlations between rCBV, Cho, and ADC suggest that cellularity, membrane turnover, and vascularity are linked in grade 4 lesions. It is not clear whether there is any relationship between these parameters regions in grade 2 or grade 3 gliomas. While further work is required to optimize the methodology associated with these MR parameters, it seems likely that combining the information from such measurements may be valuable for predicting outcome and tailoring therapy to individual patients.     

肌萎缩侧索硬化38例弥散张量成像及磁共振波谱表现

目的 研究肌萎缩侧索硬化(ALS)的弥散张量成像(DTI)和磁共振波谱(MRS)特点,并对ALs的病理生理机制进行初步探讨.方法 ALS患者38例,单纯下运动神经元受累疾病患者8例,混合型颈椎病5例和健康对照34名,行常规头颅MRI、DTI和1H-MRS测定.结果 21%(8/38)的ALS患者可见T2 FLAIR序列双侧锥体束走行异常高信号,强度高于皮质灰质.ALS组和健康对照组相比,中央前回(ALS组0.492±0.059,健康对照组0.552 4-0.045,F=17.150,P<0.01)、内囊后肢(分别为0.679 ±0.048、0.727±0.031,F=19.481,P<0.01)、大脑脚(左侧0.740±0.038、0.761±0.024,F=4.290;右侧0.720±0.044、0.746±0.034,F=3.264,均P<0.01)的部分各向异性(FA值)显著降低;ALS组上述部位的N-乙酰大冬氨酸/肌酸(NAA/Cr)值和健康对照组相比亦存在显著降低.AKS组各部位FA值降低百分率分别为10.9%、6.6%、2.8%～3.5%,以中央前回处最为显著;内囊前肢、枕叶处的FA值亦有不同程度降低.结论 DTI和MRS枪测不仪有助于ALS患者:运动神经元高位受累的确认和ALS的诊断和鉴别诊断,而且还可促进对ALS病理机制和病损分布的了解.     

Hippocampal pathology in schizophrenia: magnetic resonance imaging and spectroscopy studies

The hippocampus is a site of previously reported structural and functional abnormalities in schizophrenia. We used magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) to measure gray matter volumes, the neuronal marker N-acetylaspartate (NAA), and the combination of glutamate (Glu), glutamine (Gln), and gamma-aminobutyric acid (GABA), designated Glx. Measurements were obtained of the medial temporal lobe, centered on the hippocampus, in 10 male patients with schizophrenia (3 neuroleptic-medicated and 7 medication-free), and 10 matched normal volunteers. MRI volumetric measurements and MRS data obtained with short echo time (TE=20 ms) one-dimensional STEAM chemical shift imaging (CSI) on a GE 1.5 Tesla Signa system were analyzed. A laterality index ?(L-R)/(L+R) was generated from the ratio of Glx to choline-containing compounds (Cho) to test asymmetry changes. Reliability of the MRS measures was assessed with five test-retest studies of healthy volunteers and showed coefficients of variation (CV) in the range of 36-44% for the MRS ratios and standard deviations (S.D.) of 0.15-0.17 for the laterality indices. The Glx/Cho laterality index showed a relative right-sided excess in this region in the patients (-0.23+/-0.20) compared to the controls (+0.06+/-0.20), which was not confounded by tissue composition or placement variability of the MRS voxels. Hippocampal volume deficit and asymmetry were not significant, and other MRS measures showed no differences between patients and controls. The preliminary finding of a lateralized abnormality in Glx is consistent with postmortem findings of asymmetric neurochemical temporal lobe abnormalities in schizophrenia.