Depth and refocusing pulses for use with inhomogeneous radiofrequency coils in nuclear magnetic resonance spectroscopy
US4486709A · kind A · utility
Inventor
Key dates
| Filing date | Nov 22, 1982 |
| Grant date | Dec 4, 1984 |
| Priority date | — |
| Expiry date | Nov 22, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/465
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a pulsed nuclear magnetic resonance method of analysis, in which a single radiofrequency pulse is applied using an irradiation coil which provides an inhomogeneous radiofrequency field across the sample volume, the inhomogeneity of this field ensures that some sample regions experience a radiofrequency pulse which is closer to a .pi./2 pulse angle than for other regions, resulting in a larger signal intensity from the former regions as compared to the latter. If a second pulse is applied after the first, prior to acquisition of the signal, and if the phase of this pulse is alternated through the four phases: 0.degree., 90.degree., 180.degree. and 270.degree., during a series of transients, then, provided the receiver phase is changed by 180.degree. when the second pulse phase is changed by 90.degree., the signal intensity will accumulate from regions where the second pulse angle is .pi. radians and there will be discrimination against regions where the second pulse angle differs markedly from .pi. radians. This discrimination towards certain sample regions can be improved by adding further pulses after the second pulse provided the phase of each additional pulse is alternated th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.