Pulse sequence for operating a nuclear magnetic resonance tomography apparatus for producing images with different T2 contrast

Claim 1

A method for generating a pulse sequence for operating a nuclear magnetic resonance tomography apparatus for producing separate images having respectively different T 2 contrast comprising the steps of: (a) generating a first, selective radio-frequency pulse simultaneously with a gradient in the z-direction as a slice selection gradient; (b) generating a gradient in the y-direction with a directional sign for dephasing spins in the y-direction simultaneously with a gradient in the x-direction for phase coding spins in the x-direction, said gradient in the x-direction having characteristics from which an amplitude-time integral associated with said gradient in the x-direction can be calculated; (c) reversing the directional sign of said gradient in the y-direction thereby generating a first radio signal, and reading out said radio signal; (d) generating a second radio-frequency pulse with a flip angle of approximately 180°; (e) generating another gradient in the y-direction having the same operational sign as in step (c) thereby generating a second radio signal, and reading-out said second radio signal; (f) executing steps (a) through (e) a plurality of times and varying said characteristics of said gradient in said x-direction from execution-to-execution so that said amplitude-time integral varies from execution-to-execution, said plurality of said executions resulting in a data set of said first radio signals and a data set of said second radio signals; (g) constructing a first image having a T 2 contrast from said data set of said first radio signals; and (h) constructing a second image having a T 2 contrast differing from the T 2 contrast of said first image from said data set of said second radio signals, said x-, y- and z-directions being orthogonal.

Claim 2

A method for generating a pulse sequence for operating a nuclear magnetic resonance tomography apparatus for producing separate images having respectively different T 2 contrast comprising the steps of: (a) generating a first, selective radio-frequency pulse simultaneously with a gradient in the z-direction as a slice selection gradient; (b) generating a gradient in the y-direction with a directional sign for dephasing spins in the y-direction simultaneously with a gradient in the x-direction for phase coding spins in the x-direction, said gradient in the x-direction having characteristics from which an amplitude-time integral associated with said gradient in the x-direction can be calculated; (c) reversing the directional sign of said gradient in the y-direction thereby generating a first radio signal, and reading out said radio signal; (d) generating a second radio-frequency pulse with a flip angle of approximately 180°; (e) generating another gradient in the y-direction having the same operational sign as in step (c) thereby generating a second radio signal, and reading-out said second radio signal; (f) executing steps (a) through (e) a plurality of times and varying said characteristics of said gradient in said x-direction from execution-to-execution so that said amplitude-time integral varies from execution-to-execution, said plurality of said executions resulting in a data set of said first radio signals and a data set of said second radio signals; (g) constructing a first image having a T 2 contrast from said data set of said first radio signals; and (h) constructing a second image having a T 2 contrast differing from the T 2 contrast of said first image from said data set of said second radio signals, said x-, y- and z-directions being orthogonal.

Claim 6

A method for generating a pulse sequence for operating and NMR tomography apparatus for producing separate images having respectively different T 2 contrast comprising the steps of: (a) generating a first, selective radio-frequency pulse simultaneously with a gradient in the z-direction as slice selection gradient, said gradient in the z-direction having a directional sign; (b) reversing the directional sign of said gradient in the z-direction for rephasing spins in the z-direction, and simultaneously generating a gradient in the x-direction for pre-phasing spins in the x-direction; (c) generating a gradient in the y-direction having a directional sign and multiply reversing said directional sign of said gradient in the y-direction thereby generating a first radio-frequency signal at each directional sign reversal, and reading-out the respective first radio-frequency signals after each directional sign reversal, and simultaneously generating a further gradient in the x-direction having characteristics from which an amplitude-time integral of said further gradient in the x-direction can be calculated and varying said characteristics from directional sign reversal-to-directional sign reversal of said gradient in the y-direction to increase said amplitude-time integral from directional sign reversal-to-directional sign reversal; (d) generating a second radio-frequency pulse with a flip angle of approximately 180°; (e) generating a further gradient in the y-direction thereby generating a second radio-frequency signal, and reading out said second radio-frequency signal; (f) using said first radio signals to generate a first image having a T 2 contrast; and (g) using said second radio-frequency signal to generate a second image having a T 2 contrast different from said T 2 contrast of said first image, said x-, y- and z-directions being orthogonal.

Claim 7

A method for generating a pulse sequence for operating and NMR tomography apparatus for producing separate images having respectively different T 2 contrast comprising the steps of: (a) generating a first, selective radio-frequency pulse simultaneously with a gradient in the z-direction as slice selection gradient, said gradient in the z-direction having a directional sign; (b) reversing the directional sign of said gradient in the z-direction for rephasing spins in the z-direction, and simultaneously generating a gradient in the x-direction for pre-phasing spins in the x-direction; (c) generating a gradient in the y-direction having a directional sign and multiply reversing said directional sign of said gradient in the y-direction thereby generating a first radio-frequency signal at each directional sign reversal, and reading-out the respective first radio-frequency signals after each directional sign reversal, and simultaneously generating a further gradient in the x-direction having characteristics from which an amplitude-time integral of said further gradient in the x-direction can be calculated and varying said characteristics from directional sign reversal-to-directional sign reversal of said gradient in the y-direction to increase said amplitude-time integral from directional sign reversal-to-directional sign reversal; (d) generating a second radio-frequency pulse with a flip angle of approximately 180°; (e) generating a further gradient in the y-direction thereby generating a second radio-frequency signal, and reading out said second radio-frequency signal; (f) using said first radio signals to generate a first image having a T 2 contrast; and (g) using said second radio-frequency signal to generate a second image having a T 2 contrast different from said T 2 contrast of said first image, said x-, y- and z-directions being orthogonal.