US4536712A — Method and apparatus for examination by nuclear m…

Claim 1

Independent Claim 154 words

An examination method utilizing a nuclear magnetic resonance technique in which the body of a subject to be examined is placed in an uniform static magnetic field and subjected to an electromagnetic wave having a frequency which induces nuclear magnetic resonance, a magnetic field is also applied to the subject body to specify an area of the body from which nuclear magnetic resonance (NMR) signals are radiated, and such nuclear magnetic resonance signals from the specified body area are received, the method comprising the steps of: applying a first 90° pulse as the electromagnetic wave to the body to excite the same; then applying a 180° pulse to the body to produce an echo signal; applying a second 90° pulse to the body when said echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium; and thereafter repeating the foregoing sequence of the steps at prescribed intervals.

Claim 2

Dependent Claim 154 words

An examination method utilizing a nuclear magnetic resonance technique in which the body of a subject to be examined is placed in an uniform static magnetic field and subjected to an electromagnetic wave having a frequency which induces nuclear magnetic resonance, a magnetic field is also applied to the subject body to specify an area of the body from which nuclear magnetic resonance (NMR) signals are radiated, and such nuclear magnetic resonance signals from the specified body area are received, the method comprising the steps of: applying a first 90° pulse as the electromagnetic wave to the body to excite the same; then applying a 180° pulse to the body to produce an echo signal; applying a second 90° pulse to the body when said echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium; and thereafter repeating the foregoing sequence of the steps at prescribed intervals.

Claim 3

Dependent Claim 42 words

An examination method according to claim 1, wherein an NMR signal obtained in a single sequence and a signal obtained by inverting a time axis of the echo signal are averaged, and the average value is employed as data for one projection.

Claim 4

Dependent Claim 51 words

An examination method according to claim 1, wherein the difference between an NMR signal and a signal obtained by inverting a time axis of the echo signal is computed and employed as data for one projection, said data being computed according to prescribed arithmetic operations to provide a T 2 image.

Claim 5

Dependent Claim 38 words

An examination method according to claim 1, wherein a plurality of NMR signals and/or a plurality of echo signals generated in a plurality of sequences are averaged, and the average value is employed as data for one projection.

Claim 6

Dependent Claim 136 words

An examination method according to claim 1, wherein at least one of a time interval Ts 1 required after a first 90° pulse has been applied and before a 180° pulse is applied, a time interval Ts 2 required after the 180° pulse has ben applied and before a second 90° pulse is applied, and a time interval Td required after the second 90° pulse has been applied and before the first 90° pulse is applied, is varied in each sequence in measuring the intensity V of an NMR signal, and a plurality of such intensities V are obtained from each part of the subject body, at least one of a T 1 image, a T 2 image, and a proton-density image is obtained through arithmetic operations between images based on the plurality of intensities V.

Claim 7

Dependent Claim 190 words

An examination method utilizing a nuclear magnetic resonance technique in which the body of a subject to be examined is placed in an uniform static magnetic field and subjected to an electromagnetic wave having a frequency which induces nuclear magnetic resonance, a magnetic field is also applied to the subject body to specify an area of the body from which nuclear magnetic resonance (NMR) signals are radiated, and such nuclear magnetic resonance signals from the specified body area are received, the method comprising the steps of: applying a 180° pulse as the electromagnetic wave to the body; applying a 90° pulse to the body to excite the same a predetermined time interval after the 180° pulse has been applied; then applying a 180° pulse to the body to produce an echo signal; applying a 90° signal again to the body when said echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium; thereafter repeating the foregoing sequence of the steps at prescribed intervals; and effecting prescribed arithmetic operations on NMR signals obtained in the respective sequences for thereby producing a T 1 image.

Claim 8

Dependent Claim 190 words

An examination method utilizing a nuclear magnetic resonance technique in which the body of a subject to be examined is placed in an uniform static magnetic field and subjected to an electromagnetic wave having a frequency which induces nuclear magnetic resonance, a magnetic field is also applied to the subject body to specify an area of the body from which nuclear magnetic resonance (NMR) signals are radiated, and such nuclear magnetic resonance signals from the specified body area are received, the method comprising the steps of: applying a 180° pulse as the electromagnetic wave to the body; applying a 90° pulse to the body to excite the same a predetermined time interval after the 180° pulse has been applied; then applying a 180° pulse to the body to produce an echo signal; applying a 90° signal again to the body when said echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium; thereafter repeating the foregoing sequence of the steps at prescribed intervals; and effecting prescribed arithmetic operations on NMR signals obtained in the respective sequences for thereby producing a T 1 image.

Claim 9

Dependent Claim 174 words

An examination apparatus utilizing a nuclear magnetic resonance technique, comprising: means for applying a uniform static magnetic field to the body of a subject; means for producing magnetic fields to specify an area of the body from which a nuclear magnetic resonance (NMR) signal is to be radiated; excitation means for applying electromagnetic pulses to the body; control means for controlling signals to be fed to said excitation means; means for detecting the NMR signal from the body; arithmetic means for processing signals from said detecting means and effecting arithmetic operations on the signals to obtain a body-section image; and said control means being operable by applying a first 90° pulse as the electromagnetic wave to the body to excite the same, then applying a 180° pulse to the body to produce an echo signal, applying a second 90° pulse to the body when said echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium, and thereafter repeating the foregoing sequence of the steps at prescribed intervals.

Claim 10

Dependent Claim 174 words

An examination apparatus utilizing a nuclear magnetic resonance technique, comprising: means for applying a uniform static magnetic field to the body of a subject; means for producing magnetic fields to specify an area of the body from which a nuclear magnetic resonance (NMR) signal is to be radiated; excitation means for applying electromagnetic pulses to the body; control means for controlling signals to be fed to said excitation means; means for detecting the NMR signal from the body; arithmetic means for processing signals from said detecting means and effecting arithmetic operations on the signals to obtain a body-section image; and said control means being operable by applying a first 90° pulse as the electromagnetic wave to the body to excite the same, then applying a 180° pulse to the body to produce an echo signal, applying a second 90° pulse to the body when said echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium, and thereafter repeating the foregoing sequence of the steps at prescribed intervals.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1988-08-19	1989-02-18	1989-08-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1992-08-19	1993-02-18	1993-08-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1996-08-19	1997-02-18	1997-08-20	$7700.00	Window Closed / Lapsed

Method and apparatus for examination by nuclear magnetic resonance

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