Method and apparatus for measuring temperature of subject

A method of measuring a temperature distribution of a subject comprising:

• (a) a step of applying a static field to said subject;
• (b) a step of applying a radio frequency field for inducing magnetic resonance to said subject;
• (c) a step of applying a gradient field in a Z-axis direction of said subject in order to select a portion to be measured;
• (d) a step of applying a gradient field for phase encoding in a Y-axis direction of said subject;
• (e) a step of applying a gradient field for reading in an X-axis direction of said subject;
• (f) a step of applying a field for temperature measurement to said subject so as to change coherence o said nuclear spin in accordance with the temperature distribution of said portion of said subject to be measured;
• (g) a step of executing said steps (b) through (f) while changing at least said gradient field for phase encoding, and emitting a large number of NMR signals from said portion to be measured;
• and
• (h) a step of reading said NMR signals and obtaining the temperature distribution of said portion to be measured from the intensity of said NMR signals corresponding to the change of coherence of said nuclear spin and the frequency corresponding to the position of said nuclear spin.

A method of measuring a temperature of a subject comprising:

• (a) a step of applying a static field to said subject;
• (b) a step of applying a first field to said subject so as to excite a nuclear spin at a portion of said subject to be measured;
• (c) a step of applying a second field to said subject so as to generate NMR signals from said portion to be measured;
• (d) a step of applying a third field to said subject so as to change coherence of said nuclear spin in accordance with a temperature distribution of said portion to be measured;
• (e) a step of reading said NMR signals and obtaining the temperature state of said portion to be measured from the change of intensity of said NMR signals corresponding to the change of coherence of said nuclear spin;
• (f) a step of executing said steps (b) through (e) for a second portion of said subject whose temperature is known and serves as a reference portion, and obtaining a relation between the change of intensity of said NMR signals and the temperature;
• and
• (g) a step of comparing the change of intensity of said NMR signals obtained from said portion to be measured with said relation, and expressing the temperature of said portion to be measured in an absolute unit.

A method of measuring a perfusion rate of a body fluid of a subject, comprising:

• a step of obtaining in advance a relation between a temperature state of a portion of said subject to be measured, for which measurement of the perfusion rate of the body liquid is required, and the perfusion rate of the body fluid;
• a step of applying a static field to said subject;
• a step of applying a first field to said subject so as to excite a nuclear spin at the portion of said subject to be measured;
• a step of applying a second field to said subject so as to generate NMR signals from said portion to be measured;
• a step of applying a third field to said subject so as to change coherence of said nuclear spin in accordance with a temperature distribution of said portion to be measured;
• a step of reading said NMR signals and obtaining the temperature state of said portion to be measured from the change of intensity of said NMR signals corresponding to the change of coherence of said nuclear spin;
• and
• a step of comparing said temperature state with said relation and obtaining the perfusion rate of the body fluid of said portion to be measured.

An apparatus for measuring a subject, comprising:

• means for applying a static field to said subject;
• means for applying a first field to said subject so as to excite a nuclear spin at a portion of said subject to be measured;
• means for applying a second field to said subject so as to generate NMR signals from said portion to be measured;
• means for applying a third field to said subject so as to change coherence of said nuclear spin in accordance with a temperature distribution of said portion to be measured;
• and
• means for obtaining the temperature state of said portion to be measured from the change of intensity of said NMR signals in accordance with the change of coherence of said nuclear spin.

An apparatus for measuring a temperature distribution of a subject, comprising:

• (a) means for applying a static field to said subject;
• (b) means for applying a radio frequency field for inducing magnetic resonance to said subject;
• (c) means for applying a gradient field for selecting a portion to be measured in a Z-axis direction of said subject;
• (d) means for applying a gradient field for phase encoding to a Y-axis of said subject;
• (e) means for applying a gradient field for reading in an X-axis direction of said subject;
• (f) means for applying a field for temperature measurement to said subject so as to change coherence of a nuclear spin in accordance with a temperature distribution of said portion to be measured;
• (g) means for executing the operations of said means (b) through (f) while changing at least said gradient field for phase encoding, and emitting a large number of NMR signals from said portion to be measured;
• and
• (h) means for reading said NMR signals and obtaining the temperature distribution of said portion to be measured from the intensity of said NMR signals corresponding to the change of coherence of said nuclear spin and from its frequency corresponding to the position of said nuclear spin.

An apparatus for measuring a temperature of a subject, comprising,

• (a) means for applying a static field to said subject;
• (b) means for applying a first field to said subject so as to excite a nuclear spin at a portion of said subject to be measured;
• (c) means for applying a second field to said subject so as to generate NMR signals from said portion to be measured;
• (d) means for applying a third field to said subject so as to change coherence of said nuclear spin in accordance with a temperature distribution of said portion to be measured;
• (e) means for reading said NMR signals, and acquiring the temperature state of said portion to be measured from the change of intensity of said NMR signals corresponding to the change of coherence of said nuclear spin;
• (f) means for executing the operations of said means (b) through (f) for a second portion of said subject whose temperature is known and serves as a reference portion, and acquiring a relation between the intensity change of said NMR signal and the temperature;
• and
• (g) means for comparing the intensity change of said NMR signal obtained from said portion to be measured with said relation, and expressing the temperature of said portion to be measured in an absolute unit.

An apparatus for measuring a perfusion rate of a body fluid of a subject, comprising:

• means for obtaining in advance a relation between a temperature state of a portion of a subject to be measured, for which the perfusion rate of the body fluid must be measured, and the perfusion rate of said body fluid;
• means for applying a static field to said subject;
• means for applying a first field to said subject so as to excite a nuclear spin at said portion of said subject to be measured;
• means for applying a second field to said subject so as to generate NMR signals from said portion to be measured;
• means for applying a third field to said subject so as to change coherence of said nuclear spin in accordance with a temperature distribution of said portion to be measured;
• means for reading said NMR signals and obtaining the temperature state of said portion to be measured from the change of intensity of said NMR signals corresponding to the change of coherence of said nuclear spin;
• and
• means for acquiring the perfusion rate of the body fluid of said portion to be measured by comparing said temperature state with said relation.