Electron and Nuclear Spin Resonance

Shulman, R. G.

doi:10.1146/annurev.pc.13.100162.001545

Cited by 8 publications

(2 citation statements)

References 64 publications

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“…The importance of this tool was not lost on biochemists, molecular biologists and physiologists, and the biological implications of NMR spectroscopy were already understood more than 20 years ago (6,7). In the intervening years, NMR spectroscopy has been used in-vitro and in-vivo to study enzymatic reactions (8,9); measure intracellular pH (10,11); study cell membranes (12)(13)(14); follow metabolic pathways in normal, ischemic and neoplastic states (15)(16)(17)(18); and monitor pharmaceutical interventions (19,20).…”

Section: Thank Youmentioning

confidence: 99%

NMR chemical shift imaging

Brink

Buschmann

Rosen

1989

Computerized Medical Imaging and Graphics

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Medical Engineering and Medical PhysicsI. ABSTRACT Methods of obtaining nuclear magnetic resonance (NMR) images containing chemical shift information are presented. Using a three-dimensional Fourier Transform approach (two spatial axes and one resonance frequency axis), proton chemical shift images were acquired in phantoms and in-vivo using both spin echo and free induction decay (FID) pulse sequences. A proton resonance frequency of 61.5 MHz, corresponding to a magnetic field strength of 1.44 tesla, was used. In simple phantoms, chemical shift images indicate that spectral resolution of 0.7 parts per million (ppm) is readily achieved at all locations within the image matrix, even when using a magnet not specifically designed for chemical shift spectroscopy. In-vivo images of normal human forearms and cat heads yield separable signals from water and lipid protons. In the cat brain, no appreciable NMR signal originates from membrane lipids (e.g., myelin); images acquired using FID pulse sequences imply T 2 relaxation times less than 2 msec for these protons. The measurement of magnetic susceptibility using this technique is also demonstrated. The effect of susceptibility variations in-vivo appears in general to be less than 1 ppm.Proton chemical shift imaging was used to study fatty liver change in the rat. The correlation between lipid group signal intensity from chemical shift images i'n-viv and liver triglyceride levels measured in-vitro was good (r = .97). In-vivo T 1 relaxation time measurements were made on lipid and water protons separately. Values calculated were corrected for the influence of gaussian plane selection and spin echo data acquisition, and demonstrate different T 1 times reflecting two distinct populations of non-exchanging protons. Proton chemical shift imaging offers enhanced sensitivity over conventional NMR imaging techniques in characterizing fatty liver disease.Selective saturation (solvent suppression) techniques were used in an imaging context in both phantoms and in-vivo. Using a three-dimensional chemical shift imaging approach, data presented demonstrate the feasibility of imaging proton metabolites at low concentration. Phantom studies without solvent suppression failed to detect lactate at 80 mM; however with solvent suppression, lactate at 40 mM was imaged in a reasonable time (approximately 50 minutes). Using a conventional two-dimensional NMR imaging technique preceded by a selective (saturating) pulse, signal from water or lipid protons were eliminated (>95% reduction in signal intensity), resulting in images of -CH 2 -or H 2 0 proton distribution with resolution and imaging times equivalent to conventional proton images. With improvements in imaging systems, these techniques may play an important role in the non-invasive evaluation of tissue ischemia using proton NMR. where Y is the gyromagnetic ratio (defined as the ratio of the nuclear magnetic moment to the spin angular momentum) and B is the magnetic field seen by the nucleus (5). This B field is traditionally rewritte...

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Section: Thank Youmentioning

confidence: 99%

NMR chemical shift imaging

Brink

Buschmann

Rosen

1989

Computerized Medical Imaging and Graphics

View full text Add to dashboard Cite

show abstract

“…In early years, the reviews (8)(9)(10)(11)(12) (21) in 1977. In the last several years, specialized reviews of several different topics have become not only the standard but the only way to cover the broad diversity and widespread research in NMR.…”

Section: Nmr-a Rapidly Expanding Fieldmentioning

confidence: 99%