US4716367A — Creation and use of a moving reference frame for …

Claim 1

Independent Claim 149 words

A method for measuring movement of nuclei in a sample using a nuclear magnetic resonance technique, comprising the steps of: exciting a nuclear magnetic resonance signal; measuring said nuclear magnetic resonance signal emitted by said nuclei; and determining the nuclei moving in a given range of velocities; wherein a moving reference frame adjustment parameter is effectively varied over time to provide a moving reference frame to which the motion of said nuclei is effectively compared in said measuring and determining steps so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 2

Independent Claim 149 words

A method for measuring movement of nuclei in a sample using a nuclear magnetic resonance technique, comprising the steps of: exciting a nuclear magnetic resonance signal; measuring said nuclear magnetic resonance signal emitted by said nuclei; and determining the nuclei moving in a given range of velocities; wherein a moving reference frame adjustment parameter is effectively varied over time to provide a moving reference frame to which the motion of said nuclei is effectively compared in said measuring and determining steps so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 3

Independent Claim 191 words

A method of measuring the velocity of flow of a fluid, comprising the steps of: selecting a particular fluid velocity range to be studied; applying a radio frequency excitation signal to said fluid; applying a time varying magnetic field to a sample, said time varying magnetic field varying at a rate such that a reference frame moving at a velocity equal to the velocity of the fluid to be studied is created so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary, wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled; detecting a nuclear magnetic resonance (NMR) signal from said sample; and using said NMR signal to generate an image of fluid flowing in said velocity range, whereby static nuclei are prevented from making as great a contribution to the NMR signal as the nuclei flowing in the velocity range to be studied.

Claim 4

Independent Claim 191 words

A method of measuring the velocity of flow of a fluid, comprising the steps of: selecting a particular fluid velocity range to be studied; applying a radio frequency excitation signal to said fluid; applying a time varying magnetic field to a sample, said time varying magnetic field varying at a rate such that a reference frame moving at a velocity equal to the velocity of the fluid to be studied is created so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary, wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled; detecting a nuclear magnetic resonance (NMR) signal from said sample; and using said NMR signal to generate an image of fluid flowing in said velocity range, whereby static nuclei are prevented from making as great a contribution to the NMR signal as the nuclei flowing in the velocity range to be studied.

Claim 5

Independent Claim 133 words

A method for selectively imaging flowing nuclei using nuclear magnetic resonance (NMR) techniques, comprising the steps of: selecting a velocity for study; defining a frame of reference moving with a velocity substantially equal to the velocity to be studied so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and applying successive pulses of radio frequency excitation energy and recording an NMR signal emitted by excited nuclei in intervals between applications of said radio frequency energy; wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 6

Independent Claim 133 words

A method for selectively imaging flowing nuclei using nuclear magnetic resonance (NMR) techniques, comprising the steps of: selecting a velocity for study; defining a frame of reference moving with a velocity substantially equal to the velocity to be studied so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and applying successive pulses of radio frequency excitation energy and recording an NMR signal emitted by excited nuclei in intervals between applications of said radio frequency energy; wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 7

Independent Claim 112 words

A method for measuring movement of flowing nuclei using nuclear magnetic resonance (NMR) techniques, comprising the steps of: selecting a velocity range for study; defining a reference frame moving with a velocity within the velocity range for study; exciting nuclei so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and detecting the NMR response; wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 8

Independent Claim 112 words

A method for measuring movement of flowing nuclei using nuclear magnetic resonance (NMR) techniques, comprising the steps of: selecting a velocity range for study; defining a reference frame moving with a velocity within the velocity range for study; exciting nuclei so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and detecting the NMR response; wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 9

Dependent Claim 68 words

The method of claim 4, further comprising the steps, in coordination with said exciting and detecting steps, of: controlling the phase of nuclei moving with the reference frame so that the phase precesses the same amount between each said detecting step; and controlling the precession frequency of nuclei moving with the moving reference frame so that said precession frequency is substantially the same for each said detecting step.

Claim 10

Dependent Claim 16 words

The method of claim 5, wherein said defining step comprises: varying a main applied magnetic field.

Claim 11

Dependent Claim 32 words

The method of claim 6, further comprising the step of: using an SSFP imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 12

Dependent Claim 33 words

The method of claim 6, further comprising the step of: using a spin echo imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 13

Dependent Claim 41 words

The method of claim 5, wherein said defining step comprises: controlling a phase and frequency of excitation energy used to excite said nuclei; and controlling a phase and frequency of a reference signal in a receiver for receiving said NMR response.

Claim 14

Dependent Claim 32 words

The method of claim 9, further comprising the step of: using an SSFP imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 15

Dependent Claim 33 words

The method of claim 9, further comprising the step of: using a spin echo imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 16

Dependent Claim 44 words

The method of claim 4, further comprising the step, in coordination with said exciting and detecting steps, of: controlling the precession frequency of nuclei moving with the moving reference frame so that said precession frequency is substantially the same for each said detecting step.

Claim 17

Dependent Claim 16 words

The method of claim 12, wherein said defining step comprises: varying a main applied magnetic field.

Claim 18

Dependent Claim 32 words

The method of claim 13, further comprising the step of: using an SSFP imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 19

Dependent Claim 33 words

The method of claim 13, further comprising the step of: using a spin echo imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 20

Dependent Claim 41 words

The method of claim 12, wherein said defining step comprises: controlling a phase and frequency of excitation energy used to excite said nuclei; and controlling a phase and frequency of a reference signal in a receiver for receiving said NMR response.

Claim 21

Dependent Claim 32 words

The method of claim 16, further comprising the step of: using an SSFP imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 22

Dependent Claim 33 words

The method of claim 16, further comprising the step of: using a spin echo imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 23

Dependent Claim 32 words

The method of claim 4, further comprising the step of: using an SSFP imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 24

Dependent Claim 33 words

The method of claim 4, further comprising the step of: using a spin echo imaging technique to form an image of the flowing nuclei based on NMR responses detected in said detecting step.

Claim 25

Dependent Claim 20 words

The method of claim 4, wherein said defining step comprises: varying the velocity at which the moving reference frame moves.

Claim 26

Dependent Claim 29 words

The method of claim 21, wherein said defining step comprises: varying the velocity at which the moving reference frame moves so as to measure pulsatile movement of said nuclei.

Claim 27

Dependent Claim 50 words

The method of claim 4, further comprising the steps of: selecting one or more different velocity ranges for study; performing said defining, exciting, and detecting steps one or more additional times; and compiling a velocity distribution based on quantities of nuclei flowing in said one or more different velocity ranges.

Claim 28

Dependent Claim 40 words

The method of claim 4, wherein said defining step comprises: selecting a velocity window which determines the contribution to the detected NMR response made by nuclei flowing near to, but not exactly at, the velocity of the moving reference frame.

Claim 29

Dependent Claim 25 words

The method of claim 24, wherein said step of selecting a velocity window comprises: changing a magnetization response's spatial periodicity established in said NMR technique.

Claim 30

Independent Claim 118 words

An apparatus for measuring movement of flowing nuclei using nuclear magnetic resonance (NMR) techniques, comprising: means for selecting a velocity range for study; means for defining a reference frame moving with a velocity within the velocity range for a study; means for exciting nuclei so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and means for detecting the NMR response; wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 31

Independent Claim 118 words

An apparatus for measuring movement of flowing nuclei using nuclear magnetic resonance (NMR) techniques, comprising: means for selecting a velocity range for study; means for defining a reference frame moving with a velocity within the velocity range for a study; means for exciting nuclei so as to cause nuclei moving with the reference frame to have an NMR response substantially the same as the nuclei would have if both the reference frame and the nuclei were stationary; and means for detecting the NMR response; wherein resolution of velocity is independent of the thickness, in the direction of motion of the reference frame, of a volume in which nuclei are excited and from which the NMR response is sampled.

Claim 32

Dependent Claim 87 words

The apparatus of claim 26, further comprising: means, acting in coordination with said exciting means and said detecting means, for controlling the phase of nuclei moving with the reference frame so that the phase precesses the same amount between each detection of the NMR response; and means, acting in coordination with said exciting means and said detecting means, for controlling the precession frequency of nuclei moving with the moving reference frame so that said precession frequency is substantially the same for each detection of the NMR response.

Claim 33

Dependent Claim 18 words

The apparatus of claim 27, wherein said defining means comprises: means for varying a main applied magnetic field.

Claim 34

Dependent Claim 45 words

The apparatus of claim 27, wherein said defining means comprises: means for controlling a phase and frequency of excitation energy used to excite said nuclei; and means for controlling a phase and frequency of a reference signal in a receiver for receiving said NMR response.

Claim 35

Dependent Claim 48 words

The apparatus of claim 26, further comprising: means, functioning in coordination with said exciting means and said detecting means, for controlling the precession frequency of nuclei moving with the moving referencesd frame so that said precession frequency is substantially the same for each detection of the NMR response.

Claim 36

Dependent Claim 18 words

The apparatus of claim 30, wherein said defining means comprises: means for varying a main applied magnetic field.

Claim 37

Dependent Claim 45 words

The apparatus of claim 30, wherein said defining means comprises: means for controlling a phase and frequency of excitation energy used to excite said nuclei; and means for controlling a phase and frequency of a reference signal in a receiver for receiving said NMR response.

Claim 38

Dependent Claim 22 words

The apparatus of claim 26, wherein said defining means comprises: means for varying the velocity at which the moving reference frame moves.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1990-12-28	1991-06-29	1991-12-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1994-12-28	1995-06-29	1995-12-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1998-12-28	1999-06-29	1999-12-29	$7700.00	Window Closed / Lapsed

Creation and use of a moving reference frame for NMR imaging of flow

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