Method and apparatus for regulating radio frequency pulse
AssigneesHitachi, Ltd., Hitachi Instrument Engineering Co., Ltd.
InventorsMakoto Yoshida, Naoki Satoh, Hidehiko Asoh, Tuyosi Shudo, Ryuzaburo Takeda, Jun'ichi Taguchi
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Abstract
When image information obtained on the basis of an NMR signal, e.g. MRI, is acquired, a radio frequency pulse is set so that a strong signal can be obtained particularly from a portion of interest among the sample. To accomplish this object, the occurrence of signals from portions of the sample other than the selected portion of interest is inhibited in advance of obtaining information (an image) of the sample. Various radio frequency pulses are then irradiated to the sample and a suitable radio frequency pulse is determined on the basis of the resulting signal.
Claims14
For a sample placed inside a static magnetic field in which a radio frequency pulse is irradiated to said sample and an image on the status of said sample is obtained on the basis of a nuclear magnetic resonance signal obtained thereby from said sample, a method of regulating said radio frequency pulse to be executed for obtaining the image, associated with said sample, comprising the steps of:
- inhibiting occurrence of nuclear magnetic resonance signals from portions in a slice of said sample other than a selected portion of said slice including when said selected portion is associated with a relatively weaker NMR signal than NMR signals from other than said selected portion of said slice, said slice corresponding to a selected cross-section of said sample,
- wherein said selected portion of said slice is defined by a grid portion thereof corresponding to a plan view area of said slice surrounded by rectangular grid portions of said slice disposed to become saturated such that when said radio frequency pulse is irradiated to said sample the image to be formed is comprised from said selected portion in said slice;
- generating said nuclear magnetic resonance signal from the selected portion in the slice of said sample under such a signal occurrence inhibition state;
- and
- regulating at least one of the irradiation time and amplitude of said radio frequency pulse so as to set a flip angle of a spin of said selected portion to a desired angle on the basis of said nuclear magnetic resonance signal generated from said selected portion.
In an apparatus for obtaining image information on a sample placed in a static magnetic field by irradiating a radio frequency pulse to said sample, in which the apparatus regulates said radio frequency pulse on the basis of a nuclear magnetic resonance signal obtained thereby from said sample, said apparatus comprising:
- means for inhibiting occurrence of nuclear magnetic resonance signals from portions in a slice of said sample other than from a selected portion in said slice including when said selected portion is associated with a relatively weaker NMR signal than NMR signals from other than said selected portion of said slice, said slice corresponding to a selected cross-section of said sample,
- wherein said selected portion of said slice is defined by a grid portion corresponding to a plan view area of said slice surrounded by rectangular grid portions of said slice disposed to become saturated such that when said radio frequency pulse is irradiated to said sample the image to be formed is comprised from said selected portion in said slice;
- means for generating said nuclear magnetic resonance signal from said selected portion in said slice under such a signal occurrence inhibition state;
- and
- means for regulating at least one of the irradiation time and amplitude of said radio frequency pulse on the basis of said nuclear magnetic resonance signal so as to set a flip angle of a spin of said selected portion to a desired angle.
Dependencies are inferred from the claim text.