JPWO2020183000A5

JPWO2020183000A5 -

Info

Publication number: JPWO2020183000A5
Application number: JP2021553803A
Authority: JP
Publication date: 2023-03-17
Anticipated expiration: 2040-03-13

Claims

A method of MR imaging of an object positioned within an examination volume of an MR apparatus, comprising:
generating MR signals by subjecting the object to an imaging sequence comprising RF pulses and switching magnetic field gradients;
acquiring the MR signals using a 3D radial or spiral acquisition scheme with oversampling of a central portion of k-space;
detecting motion-induced displacement and/or deformation of the object during acquisition of MR signals and assigning each of the acquired MR signals to a motion state;
reconstructing an MR image from the weighted MR signals in the central portion of k-space, wherein stronger weighting is applied to MR signals acquired in more frequent motion states, and weaker weighting is applied to applied to MR signals acquired in less frequent motion states.

2. The method of claim 1, wherein the frequency of occurrence of each motion state is determined based on a histogram reflecting the number of MR signals acquired per motion state.

3. Method according to claim 1 or 2, wherein the weighting of the MR signals in the central part of k-space is adapted every time frame.

4. The method of any one of claims 1-3, wherein the 3D radial or spiral acquisition scheme comprises a radial sampling density that gradually decreases in k-space from the central slice to a lower radial sampling density in the peripheral slices. .

5. The method of claims 1-4, wherein a broader range of weighting factors is applied to the MR signals in the central portion of the k-space and less pronounced weighting is applied to the MR signals in the peripheral portions of the k-space. A method according to any one of paragraphs.

6. The method of any one of claims 1-5, wherein the weighting applied to the MR signals during reconstruction of the MR image is derived from a user-specific gating percentage.

7. The method of any one of claims 1-6, wherein the MR signals are acquired in parallel via several RF receive coils with different spatial sensitivity profiles.

8. A method according to any preceding claim, wherein the MR images are reconstructed using a parallel image reconstruction algorithm such as compressed sensing or SENCE.

9. A method according to any preceding claim, wherein a time sequence of MR images is reconstructed from the acquired MR signals.

10. The MR signal of any one of claims 1-9, wherein the MR signal is acquired as a radial or spiral k-space profile, and the rotation angle of the k-space profile is incremented according to the golden angle scheme during acquisition of successive k-space profiles. The method described in section.

At least one main magnet coil for generating a uniform and stable magnetic field B0 within an examination volume, several gradient coils for generating switching magnetic field gradients in different spatial directions within said examination volume, and said examination volume. at least one RF coil for generating RF pulses within and/or receiving MR signals from an object located within said examination volume, and for controlling the time sequence of RF pulses and switching magnetic field gradients and a reconstruction unit for reconstructing an MR image from the received MR signals, the MR apparatus comprising:
generating MR signals by subjecting the object to an imaging sequence comprising RF pulses and switching magnetic field gradients;
acquiring the MR signals using a 3D radial or spiral acquisition scheme with oversampling of a central portion of k-space;
detecting motion-induced displacement and/or deformation of the object during acquisition of the MR signals and assigning each of the MR signals to a motion state;
reconstructing an MR image from the weighted MR signals in the central portion of k-space, wherein stronger weighting is applied to MR signals acquired in more frequent motion states, and weaker weighting is applied to An MR apparatus configured to perform steps applied to MR signals acquired in less frequent motion states.

A computer program executed on an MR apparatus, the computer program comprising:
generating an imaging sequence comprising RF pulses and switching magnetic field gradients;
acquiring the MR signals using a 3D radial or spiral acquisition scheme with oversampling of a central portion of k-space;
detecting motion-induced displacement and/or deformation from an object during acquisition of the MR signals and assigning each of the MR signals to a motion state;
reconstructing an MR image from the weighted MR signals in the central portion of k-space, wherein stronger weighting is applied to MR signals acquired in more frequent motion states, and weaker weighting is applied to A computer program having instructions for steps to be applied to MR signals acquired in less frequent motion states.