Method and apparatus for temperature-controlled application of radio frequency power in magnetic resonance imaging
First Claim
Patent Images
1. A method of operating a high field MRI system comprising the steps of:
- (a) acquiring NMR signals from a patient;
(b) extracting tissue temperature data from at least some of the NMR signals;
(c) extracting tissue image data from at least some of the NMR signals for the production of an MRI image; and
(d) repeating steps (a)-(c) while the tissue temperature measurements are below a safety threshold.
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Abstract
Temperature sensitive MRI measurements are used to monitor the effect of radio signals including the NMR signals themselves. In one embodiment, a closed loop MRI system maximizes acquisition speed without exceeding safety thresholds of tissue temperature by monitoring the tissue temperature using NMR signals in real-time.
14 Citations
28 Claims
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1. A method of operating a high field MRI system comprising the steps of:
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(a) acquiring NMR signals from a patient;
(b) extracting tissue temperature data from at least some of the NMR signals;
(c) extracting tissue image data from at least some of the NMR signals for the production of an MRI image; and
(d) repeating steps (a)-(c) while the tissue temperature measurements are below a safety threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A high field MRI system comprising:
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a polarizing magnet sized to receive at least a portion of a patient;
RF transceiver electronics for stimulating the patient tissue in the polarizing magnetic field to acquire NMR signals from a patient;
image processing electronics operating to;
(i) extracting tissue temperature data from at least some of the NMR signals;
(ii) extracting tissue image data from at least some of the NMR signals for the production of an MRI image; and
(iii) repeating collection of NMR signals for the production of an MRI image only while the tissue temperature measurements are below a safety threshold. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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23. A local coil comprising:
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an antenna array coupling to a region of interest in a patient;
a conductor for connecting the antenna array to signal processing circuitry of an MRI machine; and
a local oscillator producing a narrow band radiofrequency signal saturating tissue protons only when the tissue has reached a safety temperature limit. - View Dependent Claims (24)
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25. A computer program for execution on a MRI machine comprising the program steps of:
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(a) acquiring NMR signals from a patient;
(b) extracting tissue temperature data from at least some of the NMR signals;
(c) extracting tissue image data from at least some of the NMR signals for the production of an MRI image; and
(d) repeating steps (a)-(c) while the tissue temperature measurements are below a safety threshold. - View Dependent Claims (26, 27)
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28. A method of modeling the thermodynamic qualities of tissue comprising the steps of:
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(a) exposing the tissue to RF energy at least in part incident to the acquisition of NMR signals from a patient;
(b) extracting tissue temperature data from the NMR signals; and
(c) modeling the tissue based on the temperature change of the tissue as a function of deposited RF energy.
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Specification