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Query: UNIPROT:Q9BWK5 (MRI)
 85,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The clinical application of positron emission tomography (PET) for the evaluation of brain tumours has proved clinically valuable. Amino acid and FDG-glucose PET provide information on the degree of malignancy and the prognosis during the initial evaluation. After therapy, the residual tumour can be visualized and recurrence can be differentiated from necrosis. Amino acids have advantages over FDG for these clinical applications. Blood flow, oxygen extraction and metabolism and blood-brain barrier permeability are of minor relevance in clinical situations. Comparison of PET with MRI and MRS will provide new data. The quantitative information of the unique information yielded by PET will lead to a more important clinical role, as will the extrapolation of this experience to the SPECT technique.
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PMID:[Evaluation of brain tumors using positron emission tomography]. 132 47

Magnetic resonance imaging and spectroscopy were performed in several types of muscular disorders. In acute stages, 31P spectra showed remarkable changes compared with normals, and T2-weighted MR images were most sensitive in delineating the pathology. Fatty degeneration of muscle in chronic diseases yielded high contrast in T1-weighted MRI and could be quantified by 1H-MRS including the chemically selective determination of proton T1 values. In order to evaluate true abundance rations of phosphorus metabolites, 31P relaxation times T1 of muscle were measured by localized inversion recovery.
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PMID:MRI and MRS of the skeletal muscle. 142 1

As clinical applications of MRS grow in number and complexity, there is a need for standardized methods for characterizing the performance of volume selection techniques. The results are presented of a thorough evaluation of a particular implementation of ISIS performed using a procedure which forms the basis of the method adopted by the European Community Concerted Action on MRS and MRI. We have found that ISIS localization is optimal when the volume of interest is slightly smaller than the region we wish to study. Contamination with extraneous signal has little T1 dependence so long as TR greater than T1 and the detection pulse angle is 90 degrees. However, a poorly optimized detection pulse results in T1-weighted contamination unless TR greater than 3T1. In the clinical context, this corresponds to a different degree of contamination for each peak in the spectrum. Adiabatic detection pulses were used in an attempt to overcome this problem without resorting to unacceptable TR values, but these were found to function less well than properly optimized rectangular pulses, even if the power was increased above the level determined by the system for B1 insensitivity. These detailed results pertain only to our system, but illustrate the importance of performing similar measurements as part of clinical spectroscopy programmes at other centres.
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PMID:Experimental characterization of the ISIS technique for volume selected NMR spectroscopy. 144 56

The potential role of MRS in studying the pharmacokinetics of anticancer drugs is reviewed. In vivo and ex vivo MRS has been used extensively in studies with fluoropyrimidines. Results from preclinical models have demonstrated that biochemical modulation of 5-fluorouracil metabolism can be demonstrated by MRS. The more general potential of MRS is illustrated by studies with the antifolate CB3988 (C2-desamino-C2-methyl-N10-propargyl-2'-trifluoromethyl-5,8-dideazafolic acid). Studies in mice and rats have shown that hepatobiliary clearance and renal elimination can be measured non-invasively by MRS. Comparison of half-lives derived from MRS and high performance liquid chromatography data gave reasonable agreement. In addition, MRI was used to localize drug-derived material within the abdominal cavity. The application of ex vivo MRS is illustrated by studies on the urinary excretion of platinum complexes. 1H-MRS has been used to demonstrate the presence of the cyclobutanedicarboxylate leaving group, both free and platinum bound, in the urine of patients treated with carboplatin. With iproplatin 195Pt NMR has been used to demonstrate in vivo reduction of this Pt(IV) complex to Pt(II) complexes. Finally, the application of MRS to the study of the molecular pharmacology of alkylating agents (a nitrogen mustard and N-methyl-N-nitrosourea) is discussed.
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PMID:In vivo and ex vivo magnetic resonance spectroscopy as applied to pharmacokinetic studies with anticancer agents: a review. 144 68

The first successful demonstrations of nuclear magnetic resonance (NMR) in bulk matter were reported in 1946 (Bloch, Hansen and Packard 1946; Purcell, Torrey and Pound 1946). Since then NMR has become a widespread technique for investigating matter of all kinds. In the 1970's NMR was applied to living systems, including man, in 2 distinct approaches. One application was in the production of images (Lauterbur 1973), called Magnetic Resonance Imaging or MRI, and the other in the production of NMR spectra (Moon and Richards 1973; Hoult et al. 1974), called Magnetic Resonance Spectroscopy or MRS. By appropriate manipulation of the NMR signal an NMR image may be generated. This can be a 2D image of a single slice, or a set of 2D images of parallel slices, or a 3D image. 2D images may be obtained directly in any orientation, axial, coronal, sagittal. The method uses no ionizing radiation and is inherently safe. It is non-invasive, although paramagnetic solutions may be injected intravenously to improve contrast. MRI images observed in normal clinical practice are maps of the NMR signals from water and fat in the tissues; they depend on proton density, but also significantly on the relaxation times T1 and T2. Images can be provided of flow (MR angiography) and diffusion (free, restricted or anisotropic). Images are typically 512 x 512 pixels with spatial resolution of about 0.5 mm. The images can be correlated with anatomical structures and indeed MRI is a primary source of such structures with localization precision of 0.5 mm as in CT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nuclear magnetic resonance and the brain. 148 41

The technique of magnetic resonance spectroscopy has been developed, and the study of high-energy phosphate metabolites in the liver using phosphorus 31 magnetic resonance spectroscopy (31P-MRS) has been reported in humans and animals, but few studies have used 31P-MRS for the evaluation of extracorporeal shock wave lithotripsy (ESWL) of the liver. In this study, 31P-MRS was used to evaluate the metabolic changes in hamster liver after ESWL and histological correlation was performed. Syrian golden hamsters were anesthetized and shock waves were irradiated to the left side of the liver. Hamsters were irradiated by LITHOSTAR-PLUS (SIEMENS) at a voltage of 19 KV. 31P-MRS was studied by JNM-GSX model 270 (6.34 Tesla). Typical peaks of 31P-spectra of hamster liver showed a tendency for PDE/beta-ATP, alpha-ATP/beta-ATP and gamma-ATP/beta-ATP to decrease among the irradiated group compared with the control group. However, there were no significant differences in PME/Pi, beta-ATP/Pi or (alpha-ATP-beta-ATP)/beta-ATP between the control group and irradiated group. With regard to intracellular pH and PDE/beta-ATP, a decreasing tendency was noted in the irradiated groups (p less than 0.05). There was no difference in the signal intensity of T1WI and T2WI on 1H-MRI, between these two groups. Pathologically, the irradiated group showed minor hemorrhage and edema in the liver, and subcapsular hematoma. The results obtained from 31P-MRS clearly showed the metabolic changes and were correlated well with the histological findings, but MRI was not capable of providing close visualization of post-ESWL liver damage.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Phosphorus 31-magnetic resonance spectroscopic studies of animal liver after extracorporeal shock wave lithotripsy]. 150 53

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

The goals of this study were to evaluate 31P MR spectroscopic imaging (MRSI) for clinical studies and to survey potentially significant spatial variations of 31P metabolite signals in normal and pathological human brains. In normal brains, chemical shifts and metabolite ratios corrected for saturation were similar to previous studies using single-volume localization techniques (n = 10; pH = 7.01 +/- 0.02; PCr/Pi = 2.0 +/- 0.4; PCr/ATP = 1.4 +/- 0.2; ATP/Pi = 1.6 +/- 0.2; PCr/PDE = 0.52 +/- 0.06; PCr/PME = 1.3 +/- 0.2; [Mg2+]free = 0.26 +/- 0.02 mM.) In 17 pathological case studies, ratios of 31P metabolite signals between the pathological regions and normal-appearing (usually homologous contralateral) regions were obtained. First, in subacute and chronic infarctions (n = 9) decreased Pi (65 +/- 12%), PCr (38 +/- 6%), ATP (55 +/- 6%), PDE (47 +/- 9%), and total 31P metabolite signals (50 +/- 8%) were observed. Second, regions of decreased total 31P metabolite signals were observed in normal pressure hydrocephalus (NPH, n = 2), glioblastoma (n = 2), temporal lobe epilepsy (n = 2), and transient ischemic attacks (TIAs, n = 2). Third, alkalosis was detected in the NPH periventricular tissue, glioblastoma, epilepsy ipsilateral ictal foci, and chronic infarction regions; acidosis was detected in subacute infarction regions. Fourth, in TIAs with no MRI-detected infarction, regions consistent with transient neurological deficits were detected with decreased Pi, ATP, and total 31P metabolite signals. These results demonstrate an advantage of 31P MRSI over single-volume 31P MRS techniques in that metabolite information is derived simultaneously from multiple regions of brain, including those outside the primary pathological region of interest. These preliminary findings also suggest that abnormal metabolite distributions may be detected in regions that appear normal on MR images.
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PMID:Phosphorus-31 MR spectroscopic imaging (MRSI) of normal and pathological human brains. 156 92

A three-dimensional (3D) phase-encoding proton spectroscopic imaging method is presented for a whole body MRI/MRS system. Metabolite images at 2 T of choline, creatine, and N-acetyl aspartate (NAA) of normal brain were obtained with a spatial resolution of 1.5 cc. With PRESS volume preselection and outer volume suppression pulses, brain regions close to the skull could be studied without significant contamination by lipid and water signals.
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PMID:3D phase encoding 1H spectroscopic imaging of human brain. 156 98

Surface coil MRI combined with spatially localized spectroscopy was used to noninvasively detect 1H signals from metabolites within an intracerebral malignant glioma in rats. The MRS pulse sequence was based upon two-dimensional ISIS, which restricted 1H signals to a column-shaped volume, combined with one-dimensional spectroscopic imaging, which further resolved the signals into 8 or 16 slices along the major axis of the column. All experiments were executed with adiabatic pulses which induced uniform spin excitation despite the inhomogeneous radiofrequency field distribution produced by the surface coil transmitter. Surface coil MRI and MRS experiments were performed on phantom samples, normal rat brains, and rat brains harboring malignant gliomas. Spatially resolved in vivo 1H spectra of intracerebral gliomas revealed significantly decreased concentrations of N-acetyl-aspartate and creatine and increased lactic acid (or lipids) as compared to the contralateral hemisphere. These results demonstrate that metabolic abnormalities in intracerebral rat gliomas can be spatially resolved in a noninvasive manner using localized in vivo 1H MRS.
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PMID:Spatially localized in vivo 1H magnetic resonance spectroscopy of an intracerebral rat glioma. 173 86


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