US5327086A — Multiple-quantum NMR with frequency-modulated chi…

Claim 1

Independent Claim 259 words

In a method which includes the step of exciting a multiple quantum coherence in an NMR pulse experiment, said exciting step including the steps of subjecting a nuclear spin system to a magnetic field and irradiating said nuclear spin system, while subjected to said magnetic field, with a first sequence of RF pulses which includes a basic sequence having a first π/ 2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a π/2-pulse generated after another time interval τ following the first π-pulse, said method further including the step of reconverting said excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, said reconverting step including the step of irradiating said nuclear spin system with a second sequence of RF pulses; the improvement comprising wherein said step of irradiating with said first sequence of RF pulses includes the step of generating each of the three RF pulses of said basic sequence as a chirp pulse having a duration t p by sweeping the frequency of the exciting RF field in a monotonic fashion with respect to time during said duration t p between a lower limit frequency ω RFmin and an upper limit frequency ω RFmax ; and wherein said step of irradiating with said second sequence of RF pulses includes the step of generating as one of the pulses of said second sequence a fourth chirp pulse with a duration t p /2 and an amplitude between 2 and 4 times the amplitude of said first π/2-pulse.

Claim 2

Dependent Claim 259 words

In a method which includes the step of exciting a multiple quantum coherence in an NMR pulse experiment, said exciting step including the steps of subjecting a nuclear spin system to a magnetic field and irradiating said nuclear spin system, while subjected to said magnetic field, with a first sequence of RF pulses which includes a basic sequence having a first π/ 2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a π/2-pulse generated after another time interval τ following the first π-pulse, said method further including the step of reconverting said excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, said reconverting step including the step of irradiating said nuclear spin system with a second sequence of RF pulses; the improvement comprising wherein said step of irradiating with said first sequence of RF pulses includes the step of generating each of the three RF pulses of said basic sequence as a chirp pulse having a duration t p by sweeping the frequency of the exciting RF field in a monotonic fashion with respect to time during said duration t p between a lower limit frequency ω RFmin and an upper limit frequency ω RFmax ; and wherein said step of irradiating with said second sequence of RF pulses includes the step of generating as one of the pulses of said second sequence a fourth chirp pulse with a duration t p /2 and an amplitude between 2 and 4 times the amplitude of said first π/2-pulse.

Claim 3

Dependent Claim 13 words

The method according to claim 1, applied to one of NMR-imaging and NMR-in-vivo-spectroscopy.

Claim 4

Dependent Claim 11 words

The method according to claim 1, applied to heteronuclear correlation spectroscopy.

Claim 5

Dependent Claim 222 words

In a method which includes the step of exciting a multiple quantum coherence in an NMR pulse experiment, said exciting step including the steps of subjecting a nuclear spin system to a magnetic field of high field strength and irradiating said nuclear spin system, while subjected to said magnetic field of high field strength, with a first sequence of RF pulses which includes a basic sequence having a first π/2-pulse, a first π-pulse generated after a time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, said method further including the step of reconverting said excited multiple quantum coherence into a transverse magnetization for inducing a spin echo, said reconverting step including the step of irradiating said nuclear spin system with a second sequence of RF pulses; the improvement comprising wherein said step of irradiating with said second sequence of RF pulses includes the steps of generating, a dephasing time interval τ 1 following the spin echo, a chirp refocusing π-pulse having a duration t p /2 by sweeping the frequency of the RF field monotonically with respect to time during said duration t p /2 between a lower limit frequency ω RFmin and an upper limit frequency ω RFmax and generating a subsequent chirp π/2-pulse of furation t p .

Claim 6

Dependent Claim 222 words

In a method which includes the step of exciting a multiple quantum coherence in an NMR pulse experiment, said exciting step including the steps of subjecting a nuclear spin system to a magnetic field of high field strength and irradiating said nuclear spin system, while subjected to said magnetic field of high field strength, with a first sequence of RF pulses which includes a basic sequence having a first π/2-pulse, a first π-pulse generated after a time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, said method further including the step of reconverting said excited multiple quantum coherence into a transverse magnetization for inducing a spin echo, said reconverting step including the step of irradiating said nuclear spin system with a second sequence of RF pulses; the improvement comprising wherein said step of irradiating with said second sequence of RF pulses includes the steps of generating, a dephasing time interval τ 1 following the spin echo, a chirp refocusing π-pulse having a duration t p /2 by sweeping the frequency of the RF field monotonically with respect to time during said duration t p /2 between a lower limit frequency ω RFmin and an upper limit frequency ω RFmax and generating a subsequent chirp π/2-pulse of furation t p .

Claim 7

Dependent Claim 79 words

The method according to claim 4, wherein said step of irradiating with said second sequence of RF pulses includes the step of generating as one of the pulses of said second sequence of RF pulses a further chirp π-pulse of duration τ.sub.π =t p /2 a time delay τ 2 following said subsequent chirp π/2-pulse, and the step of detecting a spin echo resulting from said further chirp π-pulse a final delay τ 3 following said further chirp π-pulse.

Claim 8

Dependent Claim 33 words

The method according to claim 5, including the steps of selecting said time delay τ 2 so that τ 2 ≈0, and selecting said final delay τ 3 so that τ 3 ≈τ.sub.π.

Claim 9

Dependent Claim 59 words

The method according to claim 5, including the steps of selecting said time delay τ 2 so that τ 2 ≈(2J AM ) -1 , and selecting said final delay τ 3 so that τ 2 +τ.sub.π +τ 3 ≈J AM -1 , where J AM designates a scalar coupling constant for coupling between spin A and spin M.

Claim 10

Dependent Claim 60 words

The method according to claim 5, including the steps of selecting said time delay τ 2 so that τ 2 ≈(4J AM ) -1 , and selecting said final delay τ 3 so that τ 2 +τ.sub.π +τ 3 ≈(2J AM ) -1 , where J AM designates a scalar coupling constant for coupling between spin A and spin M.

Claim 11

Dependent Claim 239 words

In a method which includes the steps of exciting a multiple quantum coherence in an NMR pulse experiment, said exciting step including the steps of subjecting a nuclear spin system to a magnetic field of high field strength and irradiating said nuclear spin system, while subjected to said magnetic field of high field strength, with a first sequence of RF pulses which includes a basic sequence having a first π/2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, said method further including the step of reconverting said excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, said reconverting step including the step of irradiating said nuclear spin system with a second sequence of RF pulses; the improvement comprising wherein said step of irradiating with said first sequence of RF pulses includes the steps of generating each of the three RF pulses of said basic sequence as a chirp pulse having a duration t p by sweeping the frequency of the exciting RF field in a monotonic fashion with respect to time during said duration t p between a lower limit frequency ω RFmin and an upper limit frequency ω RFmax and then generating, after an evolution interval t 1 , an additional sequence which is an exact time reversed version of said basic sequence.

Claim 12

Dependent Claim 239 words

In a method which includes the steps of exciting a multiple quantum coherence in an NMR pulse experiment, said exciting step including the steps of subjecting a nuclear spin system to a magnetic field of high field strength and irradiating said nuclear spin system, while subjected to said magnetic field of high field strength, with a first sequence of RF pulses which includes a basic sequence having a first π/2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, said method further including the step of reconverting said excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, said reconverting step including the step of irradiating said nuclear spin system with a second sequence of RF pulses; the improvement comprising wherein said step of irradiating with said first sequence of RF pulses includes the steps of generating each of the three RF pulses of said basic sequence as a chirp pulse having a duration t p by sweeping the frequency of the exciting RF field in a monotonic fashion with respect to time during said duration t p between a lower limit frequency ω RFmin and an upper limit frequency ω RFmax and then generating, after an evolution interval t 1 , an additional sequence which is an exact time reversed version of said basic sequence.

Claim 13

Dependent Claim 21 words

The method according to claim 9, including the step of selecting said evolution time t 1 so that t 1 ≈0.

Claim 14

Dependent Claim 38 words

The method according to claim 10, including the step of generating immediately after said basic sequence a fourth chirp pulse having an amplitude which is about 3.3 times the amplitude of said first π/2-pulse in said basic sequence.

Claim 15

Dependent Claim 63 words

The method according to claim 9, wherein said step of irradiating with said second sequence of RF pulses includes the step of generating as two of the pulses of said second sequence of RF pulses a chirp π/2-pulse followed by a chirp π-pulse having half the duration and between 2 and 4 times the amplitude of the chirp π/2-pulse of said second sequence.

Claim 16

Dependent Claim 196 words

In a method for exciting, by means of a first sequence of RF pulses, at least one of a multiple quantum coherence and a double quantum coherence in an NMR pulse experiment by irradiating a nuclear spin system, subjected to a magnetic field, with the first pulse sequence which includes a first π/2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, and for reconverting, by irradiating the nuclear spin system with a second sequence of RF-pulses, the excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, the improvement comprising wherein the three RF pulses of the first pulse sequence are chirp pulses each having a duration t p during which the frequency of the exciting RF field is swept in a monotonic fashion with respect to time between a lower frequency ω RFmin and an upper frequency ω RFmax and the second sequence of RF pulses includes a fourth chirp pulse with a duration t p /2 and an amplitude between 2 and 4 times the amplitude of the first π/2-pulse.

Claim 17

Dependent Claim 196 words

In a method for exciting, by means of a first sequence of RF pulses, at least one of a multiple quantum coherence and a double quantum coherence in an NMR pulse experiment by irradiating a nuclear spin system, subjected to a magnetic field, with the first pulse sequence which includes a first π/2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, and for reconverting, by irradiating the nuclear spin system with a second sequence of RF-pulses, the excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, the improvement comprising wherein the three RF pulses of the first pulse sequence are chirp pulses each having a duration t p during which the frequency of the exciting RF field is swept in a monotonic fashion with respect to time between a lower frequency ω RFmin and an upper frequency ω RFmax and the second sequence of RF pulses includes a fourth chirp pulse with a duration t p /2 and an amplitude between 2 and 4 times the amplitude of the first π/2-pulse.

Claim 18

Dependent Claim 10 words

The method of claim 13, applied to heteronuclear correlation spectroscopy.

Claim 19

Dependent Claim 14 words

The method of claim 13, applied to at least one of NMR-imaging and NMR-in-vivo-spectroscopy.

Claim 20

Dependent Claim 182 words

In a method for exciting, by means of a first sequence of RF-pulses, at least one of a multiple quantum coherence and a double quantum coherence in an NMR pulse experiment by irradiating a nuclear spin system, subjected to a magnetic field of high field strength, with the first pulse sequence which includes a first π/2-pulse, a first π-pulse generated after a time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, and for reconverting, by irradiating the nuclear spin system with a second sequence of RF-pulses, the excited multiple quantum coherence into a transverse magnetization for inducing a spin echo, the improvement wherein the second sequence of RF pulses further includes, after a dephasing time interval τ 1 following the spin echo, a chirp refocusing π-pulse having a duration t p /2 during which the frequency of the RF field is monotonically swept with respect to time between a lower frequency ω RFmin and an upper frequency ω RFmax , and a subsequent chirp π/2-pulse of duration t p .

Claim 21

Dependent Claim 182 words

In a method for exciting, by means of a first sequence of RF-pulses, at least one of a multiple quantum coherence and a double quantum coherence in an NMR pulse experiment by irradiating a nuclear spin system, subjected to a magnetic field of high field strength, with the first pulse sequence which includes a first π/2-pulse, a first π-pulse generated after a time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, and for reconverting, by irradiating the nuclear spin system with a second sequence of RF-pulses, the excited multiple quantum coherence into a transverse magnetization for inducing a spin echo, the improvement wherein the second sequence of RF pulses further includes, after a dephasing time interval τ 1 following the spin echo, a chirp refocusing π-pulse having a duration t p /2 during which the frequency of the RF field is monotonically swept with respect to time between a lower frequency ω RFmin and an upper frequency ω RFmax , and a subsequent chirp π/2-pulse of duration t p .

Claim 22

Dependent Claim 54 words

The method of claim 16, wherein the second sequence of RF pulses further includes a subsequent chirp π-pulse of duration τ.sub.τ =t p /2 irradiated after a time delay τ 2 following the subsequent chirp π/2-pulse to generate a spin echo for detection after a final delay τ 3 following the subsequent chirp π-pulse.

Claim 23

Dependent Claim 19 words

The method of claim 17, wherein the time delay τ 2 ≈0 and the final delay τ 3 ≈τ.sub.π.

Claim 24

Dependent Claim 50 words

The method of claim 17, wherein the time delay τ 2 ≈(2J AM ) -1 and the final delay τ 3 is chosen such that τ 2 +τ.sub.π +τ 3 ≈J AM -1 , where J AM designates a scalar coupling constant for coupling between spin A and spin M.

Claim 25

Dependent Claim 51 words

The method of claim 17, wherein the time delay τ 2 ≈(4J AM ) -1 and the final delay τ 3 is chosen such that τ 2 +τ.sub.π +τ 3 ≈(2J AM ) -1 , where J AM designates a scalar coupling constant for coupling between spin A and spin M.

Claim 26

Dependent Claim 197 words

In a method for exciting, by means of a first pulse sequence of RF pulses, at least one of a multiple and a double quantum coherence in an NMR pulse experiment by irradiating a nuclear spin system, subjected to a magnetic field of high field strength, with the first pulse sequence which includes a first π/2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, and for reconverting, by irradiating the nuclear spin system with a second sequence of RF pulses, the excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, the improvement wherein the three RF pulses of said first pulse sequence are chirp pulses each having a duration t p during which the frequency of the exciting RF field is swept in a monotonic fashion with respect to time between a lower frequency ω RFmin and an upper frequency ω RFmax and the first pulse sequence is followed, after an evolution interval t 1 , by an additional pulse sequence which is a time reversed version of said first pulse sequence.

Claim 27

Dependent Claim 197 words

In a method for exciting, by means of a first pulse sequence of RF pulses, at least one of a multiple and a double quantum coherence in an NMR pulse experiment by irradiating a nuclear spin system, subjected to a magnetic field of high field strength, with the first pulse sequence which includes a first π/2-pulse, a first π-pulse generated after a defocusing time interval τ following the first π/2-pulse, and a second π/2-pulse generated after another time interval τ following the first π-pulse, and for reconverting, by irradiating the nuclear spin system with a second sequence of RF pulses, the excited multiple quantum coherence into a transverse magnetization for inducing a free induction decay, the improvement wherein the three RF pulses of said first pulse sequence are chirp pulses each having a duration t p during which the frequency of the exciting RF field is swept in a monotonic fashion with respect to time between a lower frequency ω RFmin and an upper frequency ω RFmax and the first pulse sequence is followed, after an evolution interval t 1 , by an additional pulse sequence which is a time reversed version of said first pulse sequence.

Claim 28

Dependent Claim 9 words

The method of claim 21, wherein t 1 ≈0.

Claim 29

Dependent Claim 35 words

The method of claim 21, wherein the first pulse sequence is immediately followed by a fourth chirp pulse having an amplitude about 3.3 times the amplitude of the first π/2-pulse in the first pulse sequence.

Claim 30

Dependent Claim 40 words

The method of claim 21, wherein the additional sequence of RF pulses includes an additional chirp π/2-pulse followed by an additional chirp π-pulse having half the duration and between 2 and 4 times the amplitude of the additional chirp π/2-pulse.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-07-04	1998-01-03	1998-07-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-07-04	2002-01-03	2002-07-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-07-04	2006-01-03	2006-07-05	$7700.00	Window Closed / Lapsed

Multiple-quantum NMR with frequency-modulated chirp pulses

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