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US 5,309,102 AGranted
Frequency calibration for MRI scanner
AssigneeGeneral Electric Company
InventorTodd W. Deckard
Life of this patent
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Abstract
An NMR scanner performs a prescan before each NMR scan sequence in which the optimal RF excitation frequency is automatically determined and applied to the scanner's transceiver. The prescan sequence includes a pair of NMR measurements which provide data that allows the precise RF excitation frequency to be determined.
Claims5
A method for automatically adjusting the RF frequency of a transceiver in an NMR system, which comprises:
- performing an NMR measurement in which an NMR signal is produced and acquired;
- transforming the acquired NMR signal to the frequency domain;
- defining a correlation model which depicts expected fat and water peaks;
- correlating the correlation model with the transformed NMR signal to produce a correlation frequency (f.sub.cor );
- locating the peaks in the transformed NMR signal;
- selecting one of the located peaks positioned to one side of the correlation frequency (f.sub.cor) as the Larmor frequency of water;
- selecting one of the located peaks positioned to the other side of the correlation frequency (f.sub.cor) as the Larmor frequency of fat;
- and
- outputting to the transceiver on the NMR system an RF frequency command (CF) which is based on the determined water or fat Larmor frequency.
6 more elements
Dependencies are inferred from the claim text.