Thermal imaging of fat and muscle using a simultaneous phase and magnitude double echo sequence
First Claim
1. A method for thermal magnetic resonance imaging, comprising:
- generating a first two echo sequence before heating a tissue region within a patient, the first two echo sequence having a first echo optimized for temperature contrast from fat tissue and a second echo optimized for temperature contrast from water-based tissue;
heating the tissue region;
generating a second two echo sequence after heating the tissue region, the second two echo sequence having a third echo optimized for temperature contrast from fat tissue and a fourth echo optimized for temperature contrast from water-based tissue;
comparing the first echo to the third echo to obtain a temperature shift in fat tissue; and
comparing the second echo to the fourth echo to obtain a temperature shift in water-based tissue.
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Abstract
A method for magnetic resonance imaging includes applying a first two echo gradient echo sequence to a tissue region, the first two echo sequence generating a first echo and a subsequent second echo. A second two echo gradient echo sequence is applied after heating the tissue region, the second two echo sequence generating a third echo and a subsequent fourth echo. A magnitude difference between the third echo and the first echo is measured and correlated to a temperature shift for fat tissue, and a phase difference between the fourth echo and the second echo is measured and correlated to a temperature shift for water-based tissue. A thermal image is generated of the tissue region based upon the temperature shift for both fat and water-based tissue.
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Citations
20 Claims
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1. A method for thermal magnetic resonance imaging, comprising:
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generating a first two echo sequence before heating a tissue region within a patient, the first two echo sequence having a first echo optimized for temperature contrast from fat tissue and a second echo optimized for temperature contrast from water-based tissue;
heating the tissue region;
generating a second two echo sequence after heating the tissue region, the second two echo sequence having a third echo optimized for temperature contrast from fat tissue and a fourth echo optimized for temperature contrast from water-based tissue;
comparing the first echo to the third echo to obtain a temperature shift in fat tissue; and
comparing the second echo to the fourth echo to obtain a temperature shift in water-based tissue. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
measuring a magnitude difference between the third echo and the first echo; and
correlating the magnitude difference to the temperature shift in fat tissue.
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3. The method of claim 1, wherein the step of comparing the second echo to the fourth echo comprises:
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measuring a phase difference between the fourth echo and the second echo; and
correlating the phase difference to the temperature shift in water-based tissue.
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4. The method of claim 1, further comprising generating a thermal image of the tissue region based upon the temperature shifts in fat and water-based tissue.
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5. The method of claim 1, wherein the step of generating a first two echo sequence comprises using a gradient echo sequence to generate the first and second echoes.
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6. The method of claim 1, wherein the step of generating a second two echo sequence comprises using a gradient echo sequence to generate the third and fourth echoes.
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7. The method of claim 1, wherein the step of generating a first two echo sequence comprises generating a single radio frequency (RF) excitation pulse to generate both the first echo and the second echo.
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8. The method of claim 7, wherein the RF excitation pulse is configured for generating a low angle flip of less than about ninety degrees.
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9. The method of claim 1, further comprising focusing ultrasonic energy towards the tissue region between the steps of generating the first and second two echo sequences.
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10. A method for thermal magnetic resonance imaging, comprising:
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generating a first two echo sequence before heating a tissue region within a patient, the first two echo sequence having a first echo optimized for temperature contrast from fat tissue and a second echo optimized for temperature contrast from water-based tissue;
directing thermal energy towards the tissue region;
generating a second two echo sequence after directing the thermal energy towards the tissue region, the second two echo sequence having a third echo optimized for temperature contrast from fat tissue and a fourth echo optimized for temperature contrast from water-based tissue;
comparing the third echo and the first echo to obtain a first difference;
comparing the fourth echo and the second echo to obtain a second difference; and
combining a complex difference between the first difference and the second difference to identify a location of the thermal energy. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for thermal magnetic resonance imaging, comprising:
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applying a first two echo gradient echo sequence to a tissue region of a patient, the first two echo sequence generating a first echo and a subsequent second echo within the tissue region;
directing thermal energy towards the tissue region;
applying a second two echo gradient echo sequence after directing the thermal energy towards the tissue region, the second two echo sequence generating a third echo and a subsequent fourth echo within the tissue region;
comparing the first echo to the third echo to obtain temperature shift data attributable substantially to fat tissue within the tissue region; and
comparing the second echo to the fourth echo to obtain temperature shift data attributable substantially to water-based tissue within the tissue region. - View Dependent Claims (17, 18, 19, 20)
measuring a magnitude difference between the third echo and the first echo; and
correlating the magnitude difference to the temperature shift for fat tissue.
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18. The method of claim 16, wherein the step of comparing the second echo to the fourth echo comprises:
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measuring a phase difference between the fourth echo and the second echo; and
correlating the phase difference to the temperature shift for water-based tissue.
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19. The method of claim 16, further comprising generating a thermal image of the tissue region based upon the temperature shift data for both fat and water-based tissue.
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20. The method of claim 16, further comprising combining a complex difference between the temperature shift data for the fat tissue and the water-based tissue to identify a location of the thermal energy.
Specification