Method for increasing resolution in a NMR solids imaging system
AssigneeBruker Instruments, Inc.
InventorDavid G. Cory
Life of this patent
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Abstract
A multiple-pulse RF pulse sequence applied to abundant nuclei after excitation and in the presence of a spatial magnetic field gradient significantly reduces the resonant line width thereby increasing image resolution relative to other known pulse sequences. The RF pulse sequence is constructed from selected sets of known six-pulse cycles called dipolar decoupled inversion pulses. The dipolar decoupled inversion pulses are, in turn, constructed from standard solid echo pulse pairs. The magnetic field gradient is periodically varied during application of the RF pulses to preserve imaging information.
Claims20
In an NMR imaging experiment for obtaining spatial spin density data of abundant nuclei in a solid object in which said nuclei are placed in a magnetic field having a spatial gradient and excited with a radio frequency pulse and output magnetization is subsequently detected, a method for improving image resolution comprising the steps of:
- A. irradiating said nuclei with at least one radio-frequency pulse sequence after said nuclei are excited and before said output magnetization is detected, said pulse sequence being composed of at least two radio-frequency composite inversion pulses, each of said composite inversion pulses having a predetermined non-zero effective field in the same direction and wherein the sign of the effective field in the first pulse is different from the sign of the effective field in the second pulse;
- and
- B. varying the strength of said magnetic field gradient during step A.
An NMR imaging method for obtaining spatial spin density data of abundant nuclei in a solid object, said method comprising the steps of:
- A. placing said nuclei in a magnetic field having a spatial gradient;
- B. exciting said nuclei with a radio frequency pulse;
- C. irradiating said nuclei with at least one radio-frequency pulse sequence composed of at least two radio-frequency composite inversion pulses, each of said composite inversion pulses having a predetermined non-zero effective field in the same direction and wherein the sign of the effective field in the first pulse is different from the sign of the effective field in the second pulse;
- D. varying the strength of said magnetic field gradient during step C;
- and
- E. detecting output magnetization.
Dependencies are inferred from the claim text.