Method of and device for determining a nuclear magnetization distribution in a region of a body

Claim 1

A method of determining a nuclear magnetic distribution in a region of a body, a steady, homogeneous magnetic field being generated in which the region of the body is situated, and a) a high-frequency electromagnetic pulse is generated in order to cause a precessional motion of the magnetization of nuclei in the body, thus generating a resonance signal, b) after which, after a preparation period, a number of signal samples is periodically extracted from the resonance signal (FID signal) during a measurement period which is divided into a number of sampling intervals, c) after which, each time after a waiting period, the steps a) and b) are repeated a number of times (n') in order to obtain a group of signal samples wherefrom an image of the distribution of the induced nuclear magnetization is determined, characterized in that, after the extraction of thesampling signals, a high-frequency 180 0 pulse is generated in order to generate a nuclear spin echo signal and an effect (phase shift) exerted on the nuclear magnetization by a gradient field is cancelled, after which a further high-frequency excitation pulse is generated during the nuclear spin echo signal.

Claim 2

A method of determining a nuclear magnetic distribution in a region of a body, a steady, homogeneous magnetic field being generated in which the region of the body is situated, and a) a high-frequency electromagnetic pulse is generated in order to cause a precessional motion of the magnetization of nuclei in the body, thus generating a resonance signal, b) after which, after a preparation period, a number of signal samples is periodically extracted from the resonance signal (FID signal) during a measurement period which is divided into a number of sampling intervals, c) after which, each time after a waiting period, the steps a) and b) are repeated a number of times (n') in order to obtain a group of signal samples wherefrom an image of the distribution of the induced nuclear magnetization is determined, characterized in that, after the extraction of thesampling signals, a high-frequency 180 0 pulse is generated in order to generate a nuclear spin echo signal and an effect (phase shift) exerted on the nuclear magnetization by a gradient field is cancelled, after which a further high-frequency excitation pulse is generated during the nuclear spin echo signal.

Claim 8

A method as claimed in any one of the Claims 1 to 6, wherein either a first or a first and a second gradient magnetic field are applied during the preparation period, the gradient directions thereof being mutually perpendicular, during the measurement period a further gradient field being applied whose gradient direction extends perpendicularly to the gradient direction of a gradient field present during the preparation period, the integral over the intensity of at least one gradient field during the preparation period each time having a different value when the steps a) and b) are repeated, a nuclear spin density distribution being derived from the group of signal samples after Fourier transformation thereof.

Claim 9

A method as claimed in any one of the Claims 1 to 6, wherein during the preparation period at least one gradient magnetic field is applied whose integral over the intensity during the preparation period each time has a different value during the repetition of the steps a) and b), location-dependent nuclear spin resonance spectra being derived from the group of signal samples after Fourier transformation thereof.

Claim 12

A device for determining the nuclear magnetization distribution in a region of a body, comprising a) means for generating a steady homogeneous magnetic field, b) means for generating high-frequency electromagnetic radiation, c) means for generating a gradient magnetic field, d) sampling means for sampling a resonance signal generated by the means specified sub a) and b), e) processing means for processing the signals provided by the sampling means in order to form a nuclear magnetization distribution, and f) control means for controlling at least the means specified sub b) to e) for generating, conditioning, sampling and processing a number of resonance signals, characterized in that the control means comprise preprogrammed computer means for generating and supplying control signals to the means for generating high-frequency electromagnetic radiation, said control signals being capable of generating an adjustable pulse sequence of 90° and 180 0 excitation pulses, a period of time expiring between two 180 0 excitation pulses last generated being twice as long as the period of time expiring between the last 180° pulse and a subsequent further 90° excitation pulse.

Claim 13

A device for determining the nuclear magnetization distribution in a region of a body, comprising a) means for generating a steady homogeneous magnetic field, b) means for generating high-frequency electromagnetic radiation, c) means for generating a gradient magnetic field, d) sampling means for sampling a resonance signal generated by the means specified sub a) and b), e) processing means for processing the signals provided by the sampling means in order to form a nuclear magnetization distribution, and f) control means for controlling at least the means specified sub b) to e) for generating, conditioning, sampling and processing a number of resonance signals, characterized in that the control means comprise preprogrammed computer means for generating and supplying control signals to the means for generating high-frequency electromagnetic radiation, said control signals being capable of generating an adjustable pulse sequence of 90° and 180 0 excitation pulses, a period of time expiring between two 180 0 excitation pulses last generated being twice as long as the period of time expiring between the last 180° pulse and a subsequent further 90° excitation pulse.