Separation of spectral components
AssigneeElscint Ltd.
InventorHanan Keren
Life of this patent
Estimating the term…
Abstract
Separation of spectral components is achieved by acquiring radio frequency (RF) signals using a two dimensional scan sequence wherein the bandwidth of at least one of the RF pulses is less than or equal to the Larmor frequency difference of the spectral components. The slice select gradient pulse applied during the application of the RF pulse of limited frequency is smaller than the slice select gradient pulses applied during application of the other Rf pulses.
Claims23
A method for separating spectral components in magnetic resonance imaging (MRI) systems, said method comprising the steps of:
- using a spin echo sequence including;
- applying a first radio frequency (RF) pulse to tip spins into a transverse plane where the spins dephase,
- applying a second RF pulse to rephase the spins to form an echo, said first and second RF pulses each having a bandwidth,
- applying a first slice selecting gradient pulse while applying said first RF pulse,
- applying a second slice selecting gradient pulse while applying said second RF pulse,
- limiting the bandwidth of at least one of the applied RF pulses in the spin-echo scan sequence,
- reducing the slice selecting gradient pulse applied while applying the at least one of the applied RF pulses to acquire separated RF signals from each of the spectral components;
- and
- using a 2-D fast Fourier transform operation for transforming the acquired separated RF signals into image values of a selected one of the spectral components.
A method for separating images of first and second spectral components using magnetic resonance imaging (MRI) systems, said method including the steps of:
- using a scan sequence,
- exciting the first and second spectral components with a first RF pulse in the presence of a first slice-selecting gradient pulse to cause the first and the second spectral components that are substantially at a same spatial two dimensional location to generate first and second RF signals,
- exciting the first and second spectral components with a second RF pulse in the presence of a second slice selecting gradient to cause the first and second spectral components to generate third and fourth RF signals of different frequencies, which are spatially separated, but wherein said first, second and third RF signals are substantially from the same location.
A system for separating images of spectral components using magnetic resonance imaging (MRI) systems, comprising:
- means for performing a scan sequence, including:
- magnet means for aligning spins in a subject,
- means for applying a first radio frequency (RF) pulse to tip the aligned spins into a transverse plane where the spins dephase,
- means for applying a second RF pulse to rephase said dephased spins to form an RF signal, said first and said second RF pulse each having a bandwidth.
- means for applying a first slice selecting gradient pulse at the time of applying the first RF pulse and a second slice selecting gradient pulse at the time of applying the second RF pulse,
- means for limiting the bandwidth of at least one of the applied RF pulse in the scan sequence,
- means for changing the slice selecting gradient during the application of the at least one of the applied RF pulses to acquire separate RF signals from the spectral components;
- and
- means for doing a 2-D fast Fourier transform operation for transforming the acquired separated RF signals of only one of the spectral components into separated image values.
A system for separating images of spectral components using MRI systems, said system including:
- means for exciting first and second spectral components to generate first and second RF signals which are from the same spatial location, and
- means for exciting said first and second spectral components to generate third and fourth RF signals which are spatially separated with said first, second and third RF signals being from the same spatial location.
Dependencies are inferred from the claim text.