Chemical analysis by ultrahigh-resolution nuclear magnetic resonance in the earth's magnetic field

High-resolution NMR spectroscopy is a powerful tool for non-destructive structural investigations of matter(1). EM Typically, expensive and immobile superconducting magnets are required for chemical analysis by high-resolution NMR spectroscopy. Here we present the feasibility of liquid-state proton (H-1), lithium (Li-7) and fluorine (F-19) ultrahigh-resolution NMR spectroscopy' in the Earth's magnetic field. We show that in the Earth's field the transverse relaxation time T, of the Li-7 nucleus is very sensitive to its mobility in solution. The J-coupling constants(3) of silicon-containing (Si-29) and fluorine-containing molecules are measured with just a single scan. The accuracy of the measured H-1-Si-29 and H-1-F-19 J-coupling constants is between a few millihertz up to 20 mHz. This is at least one order of magnitude better than the precision obtained with superconducting magnets. The high precision allows the discrimination of similar chemical structures of small molecules as well as of macromolecules

Two-dimensional MR spectroscopy of healthy and cancerous prostates in vivo

OBJECTIVES: A major goal of this article is to summarize the current status of evaluating prostate metabolites non-invasively using spatially resolved two-dimensional (2D) MR Spectroscopy (MRS). MATERIALS AND METHODS: Due to various technical challenges, the spatially resolved versions of 2D MRS techniques are currently going through the developmental stage. During the last decade, four different versions of 2D MRS sequences have been successfully implemented on 3T and 1.5T MRI scanners manufactured by three different vendors. These sequences include half and maximum echo sampled J-resolved spectroscopy (JPRESS), S-PRESS and L-COSY, which are single volume localizing sequences, and the multi-voxel based JPRESS sequence. RESULTS: Even though greater than 1ml voxels have been used, preliminary evaluations of 2D JPRESS, S-PRESS and L-COSY sequences have demonstrated unambiguous detection of citrate, creatine, choline, spermine and more metabolites in human prostates. ProFIT-based quantitation of JPRESS and L-COSY data clearly shows the superiority of 2D MRS over conventional one-dimensional (1D) MRS and more than six metabolites have been successfully quantified. These sequences have been evaluated in a small group of prostate pathologies and pilot investigations using these sequences show promising results in prostate pathologies. CONCLUSION: Implementation of the state-of-the-art 2D MRS techniques and preliminary evaluation in prostate pathologies are discussed in this review. Even though these techniques are going through developmental and early testing phases, it is evident that 2D MRS can be easily added on to any clinical Magnetic Resonance Imaging (MRI) protocol to non-invasively record the biochemical contents of the prostate