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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vivo NMR techniques are currently well established in pharmaceutical research and will likely become increasingly important in the future, as they procure noninvasively morphological, physiological, and biochemical information. The status of magnetic resonance imaging (MRI) and spectroscopy (MRS) in drug development is discussed on the basis of the characterization and evaluation of a rat model of ischemic stroke and the development and profiling of drugs for cerebral ischemia in this model. It can be concluded that MRI is well suited for drug screening (quantitative determination of lesion size), while dynamic MRI and MRS techniques provide relevant information on the mechanism of drug actions. The possibility to follow changes, pathological and therapeutic, in the same individual is important from two points of view. First, variations due to interindividual differences may be eliminated, increasing the statistical power of the results. Second, dose and/or time dependence of a drug can be explored in the same individual. As a result, the number of animals required for a study will be reduced, which from both ethical and economic aspects is highly desirable.
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PMID:In vivo NMR in pharmaceutical research. 146 Oct 65

A modified ISIS method, for image-selected localized proton magnetic resonance spectroscopy (1H MRS), was used to determine the ratios and T2 relaxation times of proton metabolites in normal subjects and in patients with chronic infarction and MRI white matter signal hyperintensities (WMSH). First, in patients with cerebral infarctions, increased concentrations of lactate were found in the majority of patients, and N-acetyl aspartate (NAA) was reduced to a significantly greater extent than choline (Cho) or creatine (Cre). For TE = 270 ms, the raw ratios of Cho/NAA, Cre/NAA, and Lac/NAA were significantly (P less than 0.05) increased from 0.23 +/- 0.02 (mean +/- SE), 0.20 +/- 0.01, and 0.05 +/- 0.01, respectively in the normal group to 0.39 +/- 0.08, 0.37 +/- 0.05, and 0.48 +/- 0.15 in the stroke group. Also, the T2 relaxation time of creatine was significantly (P = 0.007) increased from 136 ms in normal white matter to 171 ms in cerebral infarcts. Second, in patients with WMSH, no significant change of the proton metabolite concentrations could be detected with the exception of the choline which was significantly (P = 0.003) altered. The Cho/NAA ratio, after T2 and excitation profile correction, increased from 0.47 +/- 0.02 in the normal group to 0.64 +/- 0.05 in the WMSH group. Third, in normal white matter, the concentration of N-acetyl aspartate, choline, and lactate was estimated to 11.5, 2.0, and 0.6 mM, respectively, by assuming a total creatine concentration of 10 mM.
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PMID:Proton magnetic resonance spectroscopy of human brain: applications to normal white matter, chronic infarction, and MRI white matter signal hyperintensities. 151 53

MRI is becoming the imaging modality of choice in patients with ischemic cerebrovascular disease although CT is still the test of choice to exclude acute hemorrhagic stroke. We have briefly reviewed characteristic features of ischemic and hemorrhagic cerebrovascular disease as well as vascular anomalies as seen on MRI. In time MRS should provide useful noninvasive metabolic data to complement the anatomical data in patients with cerebrovascular disease.
Stroke 1989 Sep
PMID:Magnetic resonance and clinical cerebrovascular disease. An update. 267 30

Clinical studies using 31P and 1H MRS with a whole body 2.0 T MRI/MRS system are described. In most cases, techniques to quantitate absolute molar concentrations of metabolites in various organs were used. In the brain, AIDS, chronic stroke, and white matter lesions were associated with alterations of brain 31P metabolites. Epilepsy was associated with increased pH in the seizure focus. In the heart, dilated cardiomyopathy was associated with increased PDE/ATP while PCr/ATP was unchanged. In the liver, alcoholic hepatitis and cirrhosis were associated with diminished hepatic ATP while alcoholic hepatitis had increased pH and cirrhosis had decreased pH. This allowed differentiation of normal liver, alcoholic hepatitis, and alcoholic cirrhosis without biopsy. In the prostate, malignancy was associated with increased PME/ATP and decreased PCr/ATP. The PME/PCr was greatly increased in malignant prostate with no overlap in normals. Other cancers outside the brain had increased PME and effective treatment was often associated with diminished PME. 1H MRS of the brain was performed using ISIS and outer volume suppression pulses for volume localization. Excellent high resolution 1H water-suppressed spectra were obtained at echo times as short as 30 ms, showing well resolved peaks for lactate, N-acetylaspartate, glutamate, choline, creatinine, and inositol. 1H MRS demonstrated that the uptake of ethanol by the brain was slower than the rise of ethanol in blood. 31P spectroscopic imaging of the brain with resolution of 2.25 x 2.25 x 2.5 cm produced metabolic images and high resolution spectra from desired regions of interest.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinical magnetic resonance spectroscopy of brain, heart, liver, kidney, and cancer. A quantitative approach. 270 9

The invention of the Anger scintillation camera and the development of 99mTc tracers brought about a tenfold increase in nuclear brain scanning between 1963 and 1973, an increase that plateaued with the introduction of x-ray computed tomography. A second growth curve began in 1976 at which time there were four PET centers in the United States, a number that grew to 60 worldwide over the next decade. PET, SPECT, MRI, and MRS are leading us into a new era of in vivo brain chemistry, based on regional bioenergetics and neurotransmission. The immediate impact is in epilepsy, stroke, brain tumors and the dementias, with psychiatric diseases becoming a major focus of research. Receptivity has become a biochemical as well as a psychological approach to mental functions. The finding of elevated D2 dopamine receptors in schizophrenia in living patients may be the forerunner of a new biochemical approach to psychiatry.
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PMID:Images of the brain: past as prologue. 302 64

Familial hemiplegic migraine (FHM) is a rare autosomal dominant disorder of unknown pathogenesis characterized by migraine and transitory hemiplegic attacks. We describe a kindred fulfilling the diagnostic criteria for FHM in which: (1) brain phosphorus magnetic resonance spectroscopy (31P-MRS) showed a reduced phosphocreatine content accompanied by high [ADP], high percentage of V/Vmax of ATP biosynthesis and decreased phosphorylation potential; (2) muscle 31P-MRS showed a reduced rate of phosphocreatine recovery after exercise; (3) blood lactate was increased after effort; (4) muscle biopsy showed, in one patient, rare ragged red fibers succinate-dehydrogenase positive and cytochrome c oxidase negative; (5) genetic analysis of muscle mitochondrial DNA did not show any of the two point mutations in the tRNA(Leu(UUR)) associated with the MELAS syndrome (Mitochondrial myopathy, Encephalopathy with Lactic Acidosis and Stroke-like episodes). The defective energy metabolism of brain and muscle found in this pedigree suggests a multisystemic disorder of mitochondrial function in this FHM pedigree.
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PMID:Abnormal brain and muscle energy metabolism shown by 31P-MRS in familial hemiplegic migraine. 760 38

Neurospectroscopy measures a neuronal marker, energy and redox state, specific fuels of tissue respiration, maturation, and possibly myelination. It provides diagnostic patterns of altered neurochemistry. Current clinical uses range from intensive care in neonates to dementia in the elderly and include tumor and stroke management, prognosis in hemorrhage and trauma, white matter, inflammatory diseases, and AIDS. Inborn errors, metabolic and systemic diseases, subclinical hepatic encephalopathy, hyponatremia, and "coma" have been elucidated. Automation, single-voxel MRS, chemical shift imaging, quality control, and outcome analyses are discussed. With no remaining impediments to clinical use, neurospectroscopy has changed the way we look at diseases of the brain.
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PMID:Clinical applications of magnetic resonance spectroscopy. 787 53

We studied the reproducibility of metabolite signals (from N-acetyl aspartate [NAA], choline, and creatine) measured with a standard single-voxel proton magnetic resonance spectroscopy technique (PRESS, TE = 135 ms, 8 ml VOI) in vitro and in two groups of normal volunteers. Spectral peak areas were quantified both by integration and by curve-fitting. In the in vitro study, the "between-days" variability (coefficient of variation [CV]) of measurements ranged from 0.9% to 2.3%. In the first group of volunteers (n = 12), single voxel spectroscopic measurements (8 ml VOI, 256 acquisitions [ACQs]) were made from mirror-image parts of the right and left hemispheres on 2 separate days. The "between-days" CV of measurements ranged from 9% to 18% for metabolite areas, and from 10% to 26% for metabolite area ratios. There were no significant differences between quantification method or hemisphere. After checking and optimising the MR scanner performance (in fact, it was virtually optimal), the second group (n = 4) each had six sequential single voxel spectroscopic measurements (each of 64 ACQs) from the right hemisphere (without moving the voxel) on each of 4 separate days. Even when the metabolites were measured from the same place in the same hemisphere sequentially six times in a 20-min period, the "within-run" CVs ranged from 4.4% to 17.2% for metabolite areas and from 9.7% to 17.0% for metabolite area ratios. The between-days CVs for the subjects ranged from 7.7% to 25.8% (metabolite areas) and from 10.1% to 22.6% (metabolite area ratios). The variability is due to a combination of random noise, subject motion, baseline artefacts in the spectra, and uncertainties in repositioning the VOIs. It is likely to represent the best reproducibility possible with 8-ml VOIs in cooperative, healthy volunteers carefully positioned on each occasion in a standard clinical scanner. Changes in metabolite levels in individuals must therefore be of the order of 20-40% before we can be reasonably confident of measuring them. Reproducibility in patients, who may be less cooperative, will probably be no better, and this must be taken into account in the interpretation of MRS studies in patients with brain pathology; for example, stroke, head injury, and tumours.
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PMID:Reproducibility of metabolite peak areas in 1H MRS of brain. 920 88

The purpose of this study was to assess the relationship between morphological and metabolic changes in brain edema using proton magnetic resonance systems. The serial changes during the first 24 hours in the cold-injury trauma rat brain model were investigated by proton magnetic resonance imaging (1H MRI) and high-resolution proton MR spectroscopy (1H MRS). We also analyzed the efficacy of AVS 1,2-bis (nicotinamide)-propane which can scavenge free radicals to the edema in this experiment. The edema was developing extensively via the corpus callosum in ipsi- and contralateral hemispheres as shown by gradually increased signal intensity on 1H MRI. 1H MRS initially showed accumulation of acetate and lactate, and transient increasing of glutamine. After 24 hours, the increased glutamine decreased below the control, alanine increased, and N-acetyl asparatate decreased with the edema development. AVS-treatment significantly suppressed edema development, increases of lactate and alanine and decreases of N-acetyl asparatate. We suggest that the cold-induced lesion contains anaerobic glycolysis deterioration and results in severe brain tissue breakdown. AVS is proved valuable for the treatment of this edema lesion. Clinical 1H MRS showed prolonged lactate elevation and significant decreases of other metabolites in human ischemic stroke edema. In peritumoral edema, decreased N-acetyl asparatate gradually improved, and slightly elevated lactate disappeared after tumor removal. 1H MRS feasibly characterizes the ischemic and peritumoral edema and makes a quantitative analysis in human brain metabolism. We believe the combined 1H MRI and MRS study is a practical method to monitor the brain conditions and will make it easy and possible to find new therapeutic agents to some brain disorders.
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PMID:[Sequential observations of brain edema with proton magnetic resonance imaging and spectroscopy]. 872 79

MRS offers unique possibilities for non-invasive studies of biochemistry in the human brain in vivo. A growing body of evidence suggests that proton MRS may contribute to the clinical evaluation of a number of pathologies including ischaemia, tumours, epilepsy, metabolic and neuropaediatric disorders. In most cases results are expressed as ratios between metabolite signals obtained at certain experimental conditions. Presenting the results as metabolite signal ratios may lead to misinterpretation because such alterations can be due to changes in the content of either one of the metabolites or both, or may simply be due to changes in relaxation behaviour. Absolute quantitation of metabolite concentrations is therefore warranted. A number of studies using single volume proton MRS indicate that absolute quantitation of metabolite concentration is possible with respect to N-acetyl aspartate (NAA), total creatine, choline containing compounds, (Cho) and inositols (Ins). Internal standards (unsaturated water signal) as well as external standards have been used for signal calibration. Quality control with respect to signal linearity with concentration or with size of selected volume, selection efficiency, outer volume depression and signal contamination is essential for validation of the measurements. Furthermore, corrections for the influence of relaxation behavior are necessary. The results published so far indicate that the concentrations of NAA, total creatine, Cho and Ins in mmoles (kg wet weight)-1 range between 8.2 and 17.2 (mean 10.2), 5.9 and 11.6 (mean 7.2), 1.1 and 2.0 (mean 1.5) and 3.9 and 8.1 (mean 6.1), respectively. So far only a limited number of clinical studies has been published including studies of acute stroke, multiple sclerosis and Alzheimer's disease. The results are promising and encourage further exploitation of the utility of quantitative proton MRS in clinical practise.
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PMID:In vivo quantitation of metabolite concentrations in the brain by means of proton MRS. 877 Oct 88


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