Magnetic Resonance Spectroscopy (MRS)

MRS measures metabolism in the brain or in other parts of the body including the liver, heart, prostate or breast.

Detection of site-specific binding and co-binding of ligands to human serum albumin using 19F NMR

Binding and co-binding of various 19F-labeled ligands to human serum albumin (HSA) has been studied using 19F NMR. Specifically shifted resonances in slow exchange with the free resonances are detected for many of the ligands. These specifically shifted resonances can be studied to yield accurate estimates of site-specific binding constants and stoichiometries. In addition, the use of two different 19F-labeled ligands can directly reveal competition for a given site or independent binding at different sites.

Publication Type: 
Journal Articles
Journal: 
Mol Pharmacol

Detection of site-specific binding and co-binding of ligands to macromolecules using 19F NMR

Study of ligand-macromolecular interactions by 19F nuclear magnetic resonance (NMR) spectroscopy affords many opportunities for obtaining molecular biochemical and pharmaceutical information. This is due to the absence of a background fluorine signal, as well as the relatively high sensitivity of 19F NMR. Use of fluorine-labeled ligands enables one to probe not only binding and co-binding phenomena to macromolecules, but also can provide data on binding constants, stoichiometries, kinetics, and conformational properties of these complexes.

Publication Type: 
Journal Articles
Journal: 
Life Sci

A localized double-quantum filter for the in vivo detection of brain glucose

A double-quantum filter (DQF) sequence with PRESS localization was developed for in vivo detection of the glucose resonances in the 3.85-ppm region of the brain proton spectrum. The efficiency and spectral editing characteristics were studied in phantom and animal experiments. Approximately 45% detection efficiency was achieved at 4.7 T with TE = 68 ms. Since the efficiency of the DQF method is dependent on the relative phases of the RF pulses, a phase calibration procedure was used to correct for phase shifts induced by the spatial localization.

Publication Type: 
Journal Articles
Journal: 
Magn Reson Med

Evidence for impairment of energy metabolism in vivo in Huntington's disease using localized 1H NMR spectroscopy

The Huntington's disease (HD) gene mutation has recently been found; however, the biochemical defect that leads to neurodegeneration is still unknown. A progressive impairment of neuronal energy metabolism is a possible etiologic factor. We tested this possibility using localized proton nuclear magnetic resonance (NMR) spectroscopy in 18 patients at high risk for, or suffering from, HD as compared with normal controls.

Publication Type: 
Journal Articles
Journal: 
Neurology

The application of porous-media theory to the investigation of time-dependent diffusion in in vivo systems

Recent developments in solid-boundary porous-media theory have shown that useful structural information can be extracted from the time-dependent diffusion coefficient, D(t), of the fluid filling the interstitial space. This theoretical framework provides a basis from which to understand the results from diffusion experiments performed in other types of systems (e.g. biological). Structural information about porous media can be obtained from the short-time behavior of D(t) in the form of the ratio of the surface area to pore volume, S/V.

Publication Type: 
Journal Articles
Journal: 
NMR Biomed

Determination of focal ischemic lesion volume in the rat brain using multispectral analysis

Multispectral (MS) analysis was used to determine the ischemic lesion volume in the rat brain after permanent middle cerebral arterial occlusion. MS analysis used a four-dimensional MS model consisting of an estimate of the average apparent diffusion coefficient of water (ADC(av)), T2, proton density, and perfusion. Four classification methods were investigated: (a) multivariate gaussian (MVG); (b) k-nearest neighbor (k-NN); (c) k-means (KM); and (d) fuzzy c-means (FCM). MVG and k-NN classifiers are supervised methods requiring labeled training data to characterize the stroke lesion.

Publication Type: 
Journal Articles
Journal: 
J Magn Reson Imaging

Dephasing of Hahn echo in rocks by diffusion in susceptibility-induced field inhomogeneities

The decay of the Hahn spin echo of water in the pore space of many porous media is dominated by the dephasing of spins in internal-field inhomogeneities, produced by susceptibility contrasts, rather than surface or bulk relaxation. This is particularly the case for measurements at moderate and high fields in samples such as fluid-saturated sedimentary rocks and some biological materials. Here, we study the behavior of the Hahn-echo decay in rocks with grains much larger and smaller than the average dephasing length, which is typically of the order of a few microns.

Publication Type: 
Journal Articles
Journal: 
Magn Reson Imaging

Changes in ADC caused by tensile loading of rabbit achilles tendon: evidence for water transport

Water diffusion measurements were performed on rabbit Achilles tendons during static tensile loading and tendons in an unloaded state. The apparent diffusion coefficient (ADC) was measured along two directions: parallel and perpendicular to the long axis of the tendon. Tendons were studied after being prepared in two ways: (a) after being stored frozen in phosphate-buffered saline (PBS) and (b) freshly isolated. Statistically significant directional anisotropy was observed in the ADC in all tendons.

Publication Type: 
Journal Articles
Journal: 
J Magn Reson

On the correlation between the water diffusion coefficient and oxygen tension in RIF-1 tumors

Water diffusion-coefficient mapping was used in conjunction with 19F inversion-recovery echo-planar imaging (IR-EPI) of a sequestered perfluorocarbon (PFC) emulsion to investigate the spatial correlation between the diffusion coefficient of water and the tissue oxygen tension (pO2) in radiation-induced fibrosarcoma (RIF-1) tumors (n = 11). The diffusion-time-dependent apparent diffusion coefficient, D(t), was determined by acquiring diffusion coefficient maps at 20 different diffusion times.

Publication Type: 
Journal Articles
Journal: 
NMR Biomed

Pages

Subscribe to RSS - Magnetic Resonance Spectroscopy (MRS)