Method for depiction of moving parts in a body by nuclear magnetic resonance experiment
US5007426A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 18, 1988 |
| Grant date | Apr 16, 1991 |
| Priority date | — |
| Expiry date | Jul 18, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/56308
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The acquisition of images of moving parts by NMR experiments requires the prolonged use of two series of excitation sequences. In the invention, only one sequence is enough. The radiofrequency electromagnetic excitation is itself modified to impose, from the very outset, a piece of information, representing the speed of the concerned moving parts, on the free precession signal. The imaging encodings which follow this particular excitation are standard ones. This particular excitation comprises, in principle, two excitations at 90.degree., having opposite directions, applied to one and the same axis and separated in time by a period during which a bipolar pulse of a magnetic field gradient is applied. It is shown that the magnetic moments of the fixed particles are re-aligned, at the end, with the orienting field while the magnetic moments of the moving particles are flipped with respect to this orientation, by an angle proportionate to their speed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.