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

Proton magnetic resonance imaging (1H MRI) has emerged as a clinically useful tool for the diagnosis of intraocular tumors. During the last four years 1H MRI characteristics, including spin-lattice relaxation times (T1) and spin-spin relaxation times (T2), have been established for several types of tumors. The introduction of surface coils to the imaging process has significantly improved the quality of intraocular MR images, leading some clinicians to suggest that 1H MR images are preferable to CT scans. Another MRI technique, in which sodium-23 (23Na) is imaged rather than protons, is now under development as tool for intraocular diagnosis. The potential of 23Na MRI depends upon the high concentration and "visibility" of sodium in the vitreous body, and upon the apparent differences in sodium behavior in normal cells vs. tumor cells. The metabolism of normal ocular tissues and intraocular tumors may be probed noninvasively with phosphorus-31 MR spectroscopy (31P MRS). Much progress has been made during the last few years in understanding the appearance of 31P MR spectra of many types of healthy and diseased cells and tissues. Clinical application of this technique to the diagnosis and monitoring of intraocular tumors following conservative treatment will be dependent upon the development of spectroscopy techniques that collect information from the volume of interest (tumor) only.
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PMID:Magnetic resonance imaging and spectroscopy of intraocular tumors. 254 92

The authors have made use of an integrated magnetic resonance imaging/spectroscopy (MRI/MRS) examination to study seven patients with a variety of bone tumors. The spatial localization method used in the 31P portion of the examination was surface coil localization and a one-dimensional chemical shift imaging method (3 cases). The authors found that the precision of spatial localization was critical in many of these cases, since most of these bone tumors were surrounded by muscle tissue that contained high concentrations of phosphocreatine (PCr). For this reason, they suggest that the metabolite ratios should be referenced to the adenosine triphosphate (beta-NTP) resonance rather than PCr. The phosphate monoester (PME) to beta-NTP ratio was elevated as compared with normal muscle in all of the bone tumors studied. The authors found that all of these tumors exhibited pHs between 7.0 and 7.2, which are similar to the values found for normal muscle. They also show the feasibility of using a line-selective proton chemical shift imaging sequence with high spatial resolution for investigating changes in the fatty composition of bone marrow. This method is illustrated in an example of a patient with advanced avascular necrosis in the femoral heads.
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PMID:Magnetic resonance imaging and magnetic resonance spectroscopy of bone tumors and bone marrow disease. 260 29

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.
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PMID:Magnetic resonance and clinical cerebrovascular disease. An update. 267 30

Nuclear magnetic resonance (NMR) and positron emission tomography (PET) are among the most advanced methodologies providing, with different physical approaches, diagnostic images of the body. In this framework, NMR and PET are particularly well known, not only for the high quality of their present results, but also for the expectations of further developments at clinical and diagnostic level. Common feature of NMR and PET is the capability of associating the anatomical image with information on the physico-chemical and/or biochemical properties of tissues. NMR imaging (MRI) is in fact based upon the acquisition of signals, whose intensities indirectly but closely depend upon particular physico-chemical and biophysical properties of biological tissues. NMR spectroscopy (MRS) and PET allow, on the other hand, quantitative studies on metabolic reactions, as they occur in intact tissues, in vivo and in situ. This review is aimed at summarizing the basic principles of tissue characterization by NMR and PET and discussing their perspectives of clinical application. Emphasis will be given to the special requirements of tissue characterization by these methodologies, referring to the need of improving accuracy and precision of measurements, as well as at evaluating, on a quantitative basis, the performance of the equipment.
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PMID:[Nuclear magnetic resonance and positron emission tomography: diagnostic potential in tissue characterization]. 268 6

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

Magnetic resonance imaging and spectroscopy have the potential for supporting clinical hyperthermia advances in the treatment of deep tumors. Current spectroscopic techniques can monitor treatment delivery and effectiveness through changes in metabolism and blood flow. Spectra can be obtained in vivo, repetitively and noninvasively; furthermore, current techniques have been implemented to give spatially resolved information. Further advances in MRI/MRS techniques may make it possible to obtained the information necessary for individualized treatment planning, for qualitative monitoring and assessment of treatment results, and for the measurement of thermal fields in vivo.
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PMID:Applications of magnetic resonance techniques to deep tumor hyperthermia. 281 11

Overview on informations which are necessary to interpret MRI and MRS. The approach is related rather to application than it is a physical one. The central steps in comprehending MR are presented, e.g. frequency decomposition in order to obtain local information with MRI or chemical information with MRS, the spin echo in order to differentiate instrumental dephasation from dephasation by molecular interference, perfusion in MRI, and the components of sensitivity in measuring different nuclei etc. The report terminology is based on the description of grey scale pictures, but one has to consider that the information is not one-dimensional but multiparametric. Therefore new terms have to be developed, a problem similar to that of describing scintigraphic time sequences in nuclear medicine.
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PMID:[Checklist for understanding magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS)]. 298 87

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

Because of the complexity and cost of clinical investigations and the virtual lack of pharmacological leads, drugs for the treatment of strokes have to be tested extensively in animal models closely mimicking the human disorder. With the recent introduction of in vivo NMR imaging (MRI) and spectroscopy (MRS), it is now possible to evaluate the consequences of strokes and to monitor the effects of therapeutic interventions in animals with the same methodology as in humans. The appearance and evolution of brain infarcts in spontaneously hypertensive rats (SHR), after occlusion of the middle cerebral artery (MCA), were detected with MRI. In coronal sections through the rat brain, regions with increased MRI signal started to become discernible after 6 h and turned out to be largely necrotic already after 24 h, as revealed by histology. The location (fronto-parietal cortex, caudate-putamen) and total infarct size, as determined from MR images or histology, were highly reproducible. Posttreatment with the dihydropyridine calcium antagonist isradipine (PN 200-110), at a daily dose of 3 X 0.3 mg/kg sc, reduced the total infarct size by 30-40%, determined by quantitative MRI and confirmed by histology. Biochemical markers of necrosis, such as the increased brain wet wt, the levels of sodium, potassium, dopamine, and noradrenaline, were changed toward normal values. The functional consequences of these morphological effects of isradipine were reflected by the parallel improvement of a neurological score. Follow-up observations made by MRI and histology indicated that the morphological differences between treated and control animals were still present to the same extent after 2 wk and, therefore, seem to be permanent. In order to elucidate the putative mechanisms involved, the influence of calcium antagonists on cerebral blood flow (CBF) and high energy phosphates (HEPs) was investigated. CBF was measured quantitatively with [14C] iodoantipyrine in MCA-occluded SHRs. Although isradipine had no effect on CBF in the contralateral hemisphere, at a dose reducing infarct size, it increased the reduced blood flow in the lesioned hemisphere toward normal values. HEPs (PCr and ATP) as well as inorganic phosphate (Pi) and intracellular pH were measured noninvasively in the rat brain by 31P MRS using a surface coil. Under normal conditions, calcium antagonists had no effect on these parameters.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Reduction of neural damage in irreversible cerebral ischemia by calcium antagonists. 307 31

In summary, then, the major strength of MRI in evaluating cerebral ischemia is in the sensitivity that this methodology provides for detection of the disease process. However, it must be realized that edema is a nonspecific event related to various insults affecting the brain. There is still an uncertain capability of MRI in separating acute hemorrhagic from acute ischemic events. The superior sensitivity of MRI should help in investigations aimed at evaluating various forms of intervention in acute ischemia. Because some of these acute changes are at the biochemical rather than morphologic level, proton MRI alone probably will be insufficient to explore numerous variables. For this reason, the potential offered by MRS in cerebral ischemia research and in clinical settings is important. Vascular imaging is relatively complex. Several techniques show promising results but at the present time have poor resolution in comparison to ultrasound and angiography. For the immediate future, they will remain investigational.
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PMID:Magnetic resonance imaging of cerebral ischemia and infarction. 307 44


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