Frequency calibration for MRI scanner
First Claim
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1. 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 (fcor );
locating the peaks in the transformed NMR signal;
selecting one of the located peaks positioned to one side of the correlation frequency (fcor) as the Larmor frequency of water;
selecting one of the located peaks positioned to the other side of the correlation frequency (fcor) 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.
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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.
22 Citations
5 Claims
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1. A method for automatically adjusting the RF frequency of a transceiver in an NMR system, which comprises:
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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 (fcor ); locating the peaks in the transformed NMR signal; selecting one of the located peaks positioned to one side of the correlation frequency (fcor) as the Larmor frequency of water; selecting one of the located peaks positioned to the other side of the correlation frequency (fcor) 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. - View Dependent Claims (2, 3, 4, 5)
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Specification