Method for 2D magnetic resonance imaging, corresponding MRI device, computer program, and computer-readable storage medium
The present disclosure relates to a method and a magnetic resonance imaging device for two-dimensional (2D) magnetic resonance (MR) imaging of a subject. The disclosure further relates to a corresponding computer program and a corresponding computer-readable storage medium. In one exemplary method, a k-space dataset of the subject is acquired using a simultaneous multi-slice technique. Therein, a blipped phase-encoding gradient is applied in a pseudo-random manner to achieve an incoherent undersampling at least in a k-space direction perpendicular to a slice select direction. A compressed sensing reconstruction is then performed based on the acquired k-space dataset to generate an MR image of the subject.
1. A method for two-dimensional (2D) magnetic resonance imaging of a subject, the method comprising:
acquiring an undersampled k-space dataset for the subject using a simultaneous multi-slice technique, wherein, to achieve an incoherent undersampling in at least one k-space direction, an encoding for selecting the respective k-space points to be sampled for the k-space dataset is created by applying a blipped phase-encoding gradient in a slice direction in a pseudo-random manner and/or by pseudo-randomly impressing a phase on radio-frequency (RF) pulses used in acquiring the k-space dataset; and
performing a compressed sensing reconstruction based on the acquired undersampled k-space dataset to generate a magnetic resonance image of the subject,
wherein the blipped phase-encoding gradient is varied in the slice direction within each echo train so that different echoes in a specific echo train are configured to sample k-space points from different k-space coordinates in the at least one k-space direction, and
wherein, as a boundary condition for the incoherent undersampling, a k-space center is sampled at a same relative time within all of the echo trains.
2. A magnetic resonance imaging device comprising:
an imaging system configured to acquire an undersampled k-space dataset for a subject using a simultaneous multi-slice technique, wherein, to achieve an incoherent undersampling in at least one k-space direction, an encoding for selecting the respective k-space points to be sampled for the k-space dataset is created by applying a blipped phase-encoding gradient in a slice direction in a pseudo-random manner and/or by pseudo-randomly impressing a phase on radio-frequency (RF) pulses used in acquiring the k-space dataset; and
a processor for processing the acquired undersampled k-space data by a compressed sensing reconstruction based on the acquired undersampled k-space dataset to generate a magnetic resonance image of the subject,
wherein the blipped phase-encoding gradient is varied in the slice direction within each echo train so that different echoes in a specific echo train are configured to sample k-space points from different k-space coordinates in the at least one k-space direction, and
wherein, as a boundary condition for the incoherent undersampling, a k-space center is sampled at a same relative time within all of the echo trains.
3. A non-transitory computer readable medium comprising instructions configured to cause a magnetic resonance imaging device to:
acquire an undersampled k-space dataset for a subject using a simultaneous multi-slice technique, wherein, to achieve an incoherent undersampling in at least one k-space direction, an encoding for selecting the respective k-space points to be sampled for the k-space dataset is created by applying a blipped phase-encoding gradient in a slice direction in a pseudo-random manner and/or by pseudo-randomly impressing a phase on radio-frequency (RF) pulses used in acquiring the k-space dataset; and
perform a compressed sensing reconstruction based on the acquired undersampled k-space dataset to generate a magnetic resonance image of the subject,
wherein the blipped phase-encoding gradient is varied in the slice direction within each echo train so that different echoes in a specific echo train are configured to sample k-space points from different k-space coordinates in the at least one k-space direction, and
wherein, as a boundary condition for the incoherent undersampling, a k-space center is sampled at a same relative time within all of the echo trains.
4. The method of claim 1 , wherein, as a boundary condition for the incoherent undersampling, a sampling probability is provided for k-space points in a the k-space center that is higher than for k-space points in a k-space periphery or closer to the k-space periphery that the k-space points in the k-space center.
5. The method of claim 4 , wherein the undersampled k-space dataset is acquired using a GeneRalised Auto calibrating Partial Parallel Acquisition (GRAPPA) technique for parallel imaging, and
wherein k-space data of the k-space points in the k-space center is used as reference data for the GRAPPA technique.
6. The method of claim 5 , wherein, for the incoherent undersampling, different numbers of sampled k-space points are allowed for different coordinates in the at least one k-space direction.
7. The method of claim 1 , wherein, for the incoherent undersampling, different numbers of sampled k-space points are allowed for different coordinates in the at least one k-space direction.
8. The method of claim 1 , wherein multiple different image contrasts are acquired and the incoherent undersampling is also performed in a corresponding additional sampling dimension that depends on types of the different image contrasts.
9. The method of claim 8 , wherein an echo time is used as the additional sampling dimension so that echo times are at least pseudo-randomized across the acquisitions of the different image contrasts.
10. The method of claim 9 , wherein a Dixon technique is used, and
wherein the additional sampling dimension is spanned by a phase state of different signals so that differently pseudo-randomized sampling patterns are used for in-phase echoes and out-of-phase echoes.
11. The method of claim 8 , wherein a Dixon technique is used, and
wherein the additional sampling dimension is spanned by a phase state of different signals so that differently pseudo-randomized sampling patterns are used for in-phase echoes and out-of-phase echoes.