WO2017167937A1 - Imagerie par résonance magnétique dynamique à résolution temporelle et spatiale accrue - Google Patents

Imagerie par résonance magnétique dynamique à résolution temporelle et spatiale accrue Download PDF

Info

Publication number
WO2017167937A1
WO2017167937A1 PCT/EP2017/057637 EP2017057637W WO2017167937A1 WO 2017167937 A1 WO2017167937 A1 WO 2017167937A1 EP 2017057637 W EP2017057637 W EP 2017057637W WO 2017167937 A1 WO2017167937 A1 WO 2017167937A1
Authority
WO
WIPO (PCT)
Prior art keywords
image
time series
acquisition
images
acquisition step
Prior art date
Application number
PCT/EP2017/057637
Other languages
English (en)
Inventor
Hua Guo
Xuesong Li
Bida Zhang
Original Assignee
Koninklijke Philips N.V.
Tsinghua University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips N.V., Tsinghua University filed Critical Koninklijke Philips N.V.
Publication of WO2017167937A1 publication Critical patent/WO2017167937A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/563—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution of moving material, e.g. flow contrast angiography
    • G01R33/56308—Characterization of motion or flow; Dynamic imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/4818—MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space
    • G01R33/4824—MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space using a non-Cartesian trajectory
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5611—Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
    • G01R33/56509—Correction of image distortions, e.g. due to magnetic field inhomogeneities due to motion, displacement or flow, e.g. gradient moment nulling

Definitions

  • the invention relates to the field of magnetic resonance (MR) imaging. It concerns a method of MR imaging of a body of a patient placed in the examination volume of a MR device.
  • the invention also relates to a MR device and to a computer program to be run on a MR device.
  • Image-forming MR methods which utilize the interaction between magnetic fields and nuclear spins in order to form two-dimensional or three-dimensional images are widely used nowadays, notably in the field of medical diagnostics, because for the imaging of soft tissue they are superior to other imaging methods in many respects, do not require ionizing radiation and are usually not invasive.
  • the body of the patient to be examined is arranged in a strong, uniform magnetic field Bo whose direction at the same time defines an axis (normally the z-axis) of the co-ordinate system to which the measurement is related.
  • the magnetic field Bo produces different energy levels for the individual nuclear spins in dependence on the magnetic field strength which can be excited (spin resonance) by application of an electromagnetic alternating field (RF field) of defined frequency (so-called Larmor frequency, or MR frequency).
  • the distribution of the individual nuclear spins produces an overall magnetization which can be deflected out of the state of equilibrium by application of an electromagnetic pulse of appropriate frequency (RF pulse) while the corresponding magnetic field Bi of this RF pulse extends perpendicular to the z-axis, so that the magnetization performs a precessional motion about the z-axis.
  • the precessional motion describes a surface of a cone whose angle of aperture is referred to as flip angle.
  • the magnitude of the flip angle is dependent on the strength and the duration of the applied electromagnetic pulse.
  • 90° pulse the magnetization is deflected from the z axis to the transverse plane (flip angle 90°).
  • the magnetization relaxes back to the original state of equilibrium, in which the magnetization in the z direction is built up again with a first time constant Ti (spin lattice or longitudinal relaxation time), and the
  • magnetization and its variation can be detected by means of receiving RF coils which are arranged and oriented within an examination volume of the MR device in such a manner that the variation of the magnetization is measured in the direction perpendicular to the z-axis.
  • the decay of the transverse magnetization is accompanied by dephasing taking place after RF excitation caused by local magnetic field inhomogeneities facilitating a transition from an ordered state with the same signal phase to a state in which all phase angles are uniformly distributed.
  • the dephasing can be compensated by means of a refocusing RF pulse (for example a 180° pulse). This produces an echo signal (spin echo) in the receiving coils.
  • time-varying magnetic field gradients extending along the three main axes are superposed on the uniform magnetic field B 0 , leading to a linear spatial dependency of the spin resonance frequency.
  • the signal picked up in the receiving coils then contains components of different frequencies which can be associated with different locations in the body.
  • the signal data obtained via the receiving coils correspond to the spatial frequency domain and are called k-space data.
  • the k-space data usually include multiple lines acquired of different phase encoding. Each line is digitized by collecting a number of samples. A set of k-space data is converted to an MR image by means of Fourier transformation.
  • Dynamic (time-resolved) MR imaging is a challenging topic that opens up a wide field in medical diagnosis, such as, for example, contrast-enhanced MR angiography, perfusion imaging, interventional imaging and functional brain imaging (fMRI).
  • medical diagnosis such as, for example, contrast-enhanced MR angiography, perfusion imaging, interventional imaging and functional brain imaging (fMRI).
  • fMRI is a technique used to determine the dynamic brain function, often based on echo planar imaging, but can also be performed by using contrast agents and observing their first pass effects through brain tissue.
  • Functional magnetic resonance imaging allows insights in a dysfunctional brain as well as into the basic workings of the brain.
  • the most frequently used effect in fMRI to assess brain function is the blood oxygenation level dependent contrast (BOLD) effect, in which differential changes in brain perfusion and their resultant effect on the regional distribution of oxyhaemoglobin and deoxyhaemoglobin are observable because of the different 'intrinsic contrast media' effects of the two haemoglobin forms.
  • BOLD blood oxygenation level dependent contrast
  • Increased brain activity causes an increased demand for oxygen, and the vascular system actually overcompensates for this, increasing the amount of oxygenated haemoglobin. Because deoxygenated haemoglobin attenuates the MR signal, the vascular response leads to a signal increase that is related to the neural activity.
  • Functional imaging relates body function or thought to specific locations in the brain where the neural activity is taking place.
  • the brain In fMRI, the brain has to be scanned at a fast rate and at a sufficient spatial resolution that are matched to the neural activity of interest, for example in response to an external stimulus. Due to the nature of MR signal acquisition, however, improving temporal resolution while maintaining spatial resolution is a conflict of goals.
  • Xu et al. Magnetic Resonance in Medicine, vol. 69(2), p. 370-381 propose a time-resolved MR imaging technique for the diagnosis of liver lesions.
  • the method is called temporal resolution acceleration with constrained evolution reconstruction (TRACER). It is characterized by a three-dimensional volume coverage and a high-temporal frame rate. Data is acquired using a stack of spirals sampling trajectory combined with a golden ratio view order using an eight-channel coil array for parallel MR signal acquisition. Temporal frames are reconstructed from vastly undersampled data sets using a nonlinear inverse algorithm assuming that the temporal changes are small at short time intervals.
  • a method of MR imaging of a body of a patient placed in the examination volume of a MR device comprises the steps of:
  • - generating MR signals by subjecting at least a portion of the body to a MR imaging sequence comprising a number of RF pulses and switched magnetic field gradients;
  • each MR image is reconstructed from the MR signals acquired in the respective acquisition step using the MR image attributed to the respectively preceding acquisition step as a regularization constraint of each reconstruction;
  • each MR image is reconstructed from the MR signals acquired in the respective acquisition step using the MR image attributed to the respectively succeeding acquisition step as a regularizaiton constraint of each reconstruction;
  • MR signals are acquired in a number of successive acquisition steps, preferably using a high degree of undersampling and parallel signal acquisition via an array of RF receiving coils having different spatial sensitivity profiles. In this way, the time required for a single acquisition step (forming a time frame of the dynamic imaging) is minimized.
  • the known TRACER approach (see above) is adopted to reconstruct the first time series of MR images from the acquired undersampled MR signals.
  • the MR images of the first time series are reconstructed one by one in the temporal order of the acquisition steps.
  • Each MR image (frame) of the first time series is reconstructed by solving a linear problem using the particular conjugate gradient approach of the TRACER technique, wherein the MR image attributed to the respectively preceding acquisition step
  • each reconstruction step (i.e., the respective temporally preceding frame) is used as a regularization constraint in each reconstruction step.
  • the reconstruction of the first time series does not necessarily have to commence with the MR signals acquired in the first acquisition step. Any acquisition step may be selected at the starting point of the
  • the reconstruction of the second time series does not necessarily have to commence with the MR signals acquired in the last acquisition step.
  • any acquisition step may be selected at the starting point of the reconstruction of the second time series.
  • the starting point of the reconstruction of the second time series constitutes the end point of the reconstruction of the first time series and vice versa. For example, if the first reconstruction of the first time series commence with the MR signals acquired in the acquisition step tk, the reconstructions corresponding to acquisition steps tk+1, tk+2 impart tN, tl, t2... will follow until the final reconstruction ends with the MR signals acquired in the acquiition step tk-1.
  • the reconstruction of the first time series is in the order of acquistion steps (tk, tk+1, ..tN, tl, t2,...tk-1) .
  • the reconstruction of the second time series is in the reverse order of the acquisition steps (tk, tk+1, ..tN, tl, t2,...tk-1), starting with the acquitions step tk-1 and ending with the acquisition step tk.
  • a drawback of the known TRACER scheme is that errors are accumulated along the time series. To suppress this error accumulation, the reconstruction is executed one more time according to the invention to reconstruct the second time series of MR images, wherein the order of the reconstruction is reversed.
  • the TRACER reconstruction is preferably employed again to reconstruct the second time series of MR images from the acquired MR signals.
  • the MR images of the second time series are reconstructed one by one in the reverse temporal order of the acquisition steps.
  • Each MR image of the second time series is reconstructed by solving a linear problem using the approach of the TRACER technique, wherein the MR image attributed to the respectively succeeding acquisition step (i.e., the respective temporally succeeding frame) is used as a regularization constraint in each reconstruction step.
  • a third time series of MR images is computed from the first and second series, wherein each pair of MR images of the first and second time series attributed to the same time frame is combined into a MR image of the third time series for the respective time frame.
  • the combination may be performed by simply averaging the corresponding MR images of the first and second time series. Error accumulation is effectively avoided in this way.
  • MR signals are acquired in a number of successive acquisition steps and corresponding (first/second/third) time series of MR images are reconstructed.
  • the duration of a single acquisition step should take less than, e.g., 500 ms such that the MR signals acquired in a single acquisition step can be attributed to a single motion state of the body of the patient (wherein no motion is assumed to take place during a single acquisition step). If the typical time scale of the relevant motion is known, the number of k-space profiles acquired per acquisition step can be determined accordingly.
  • the method of the invention may thus advantageously comprise the step of estimating and correcting motion-induced displacements and phase errors in the MR signals and/or in the MR images attributed to the individual acquisition steps.
  • displacements (translation and/or rotation) and phase errors which are caused by patient motion, can be derived from the comparison of the MR signals and/or the MR images attributed to different acquisition steps.
  • the invention thus provides a MR imaging method that is robust with respect to motion of the examined patient during MR signal acquisition.
  • the MR signals are acquired in each acquisition step as a set of undersampled spiral k-space profiles from a number of parallel slices arranged at different positions along a slice direction.
  • the spiral k- space profiles have a varying k-space density.
  • k-space is sampled with a three-dimensional stack of variable density spirals to achieve a high-temporal frame rate with whole volume coverage.
  • One temporal frame is reconstructed in the first and second time series for each spiral k-space leaf sampled across all slices in the stacked spiral 3D acquisition.
  • the spiral k-space trajectories should have a variable density such that k-space is oversampled in the center, whereas undersampling occurs in the periphery of k-space.
  • spiral leaves of the k-space profiles may advantageously be rotated by the Golden Angle in consecutive acquisition steps.
  • each new spiral k-space leaf is sampling a substantially different part of k-space compared to the immediately preceding leaf.
  • a full set of slice encodings is preferably acquired according to the invention.
  • a high-quality first MR base image is formed from a fully sampled MR signal dataset, after which subsequent MR images of the first time series are reconstructed from the highly undersampled stack of spiral k-space trajectories according to the TRACER scheme by limiting the amount of change that can occur in the images from one temporal frame to the next.
  • the first MR image of the first time series is reconstructed from the MR signals acquired in two or more initial acquisition steps, wherein the MR signals of the two or more initial acquisition steps form a fully sampled MR signal data set.
  • This first MR image is then used as a constraint in the reconstruction of the next MR image of the first time series which is reconstructed from the (undersampled) MR signals attributed to the respective next time frame.
  • the high-quality first MR base image initializes the step by step reconstruction and serves as an initial guess in the reconstruction of the first time series of MR images according to the TRACER method.
  • a high-quality final MR base image may advantageously be formed from a fully sampled MR signal dataset as well, after which preceding MR images of the second time series are reconstructed in the reverse order of the acquisition steps.
  • the last MR image of the second time series is reconstructed from the MR signals acquired in the last acquisition steps, wherein the MR signals of these last acquisition steps form a fully sampled MR signal data set.
  • This last MR image is then used as a constraint in the reconstruction of the preceding MR image of the second time series which is
  • the high-quality final MR base image initializes the reverse step by step
  • the method of the invention described thus far can be carried out by means of a MR device including at least one main magnet coil for generating a uniform, steady magnetic field Bo within an examination volume, a number of gradient coils for generating switched magnetic field gradients in different spatial directions within the examination volume, at least one body RF coil for generating RF pulses within the examination volume and/or for receiving MR signals from a body of a patient positioned in the examination volume, a control unit for controlling the temporal succession of RF pulses and switched magnetic field gradients, and a reconstruction unit for reconstructing MR images from the received MR signals.
  • the method of the invention can be implemented by a corresponding programming of the reconstruction unit and/or the control unit of the MR device.
  • the method of the invention can be advantageously carried out on most MR devices in clinical use at present. To this end it is merely necessary to utilize a computer program by which the MR device is controlled such that it performs the above-explained method steps of the invention.
  • the computer program may be present either on a data carrier or be present in a data network so as to be downloaded for installation in the control unit of the MR device.
  • Figure 1 shows a MR device for carrying out the method of the invention
  • Figure 2 schematically illustrates the dual TRACER MR image acquisition and reconstruction scheme according to the invention
  • Figure 3 a block diagram illustrating the image acquisition and reconstruction process of the invention
  • Figure 4 a block diagram illustrating the software design of the reconstruction processor of the MR device shown in Figure 1 ;
  • Figure 5 fMRI images reconstructed according to the invention in comparison to fMRI images reconstructed conventionally using CS.
  • a MR device 1 is shown as a block diagram.
  • the device comprises superconducting or resistive main magnet coils 2 such that a substantially uniform, temporally constant main magnetic field Bo is created along a z-axis through an examination volume.
  • the device further comprises a set of (1 st , 2 nd , and - where applicable - 3 rd order) shimming coils 2', wherein the current flow through the individual shimming coils of the set 2' is controllable for the purpose of minimizing Bo deviations within the examination volume.
  • a magnetic resonance generation and manipulation system applies a series of RF pulses and switched magnetic field gradients to invert or excite nuclear magnetic spins, induce magnetic resonance, refocus magnetic resonance, manipulate magnetic resonance, spatially and otherwise encode the magnetic resonance, saturate spins, and the like to perform MR imaging.
  • a gradient amplifier 3 applies current pulses or waveforms to selected ones of whole-body gradient coils 4, 5 and 6 along x, y and z-axes of the examination volume.
  • a digital RF frequency transmitter 7 transmits RF pulses or pulse packets, via a send/receive switch 8, to a body RF coil 9 to transmit RF pulses into the examination volume.
  • a typical MR imaging sequence is composed of a packet of RF pulse segments of short duration which, together with any applied magnetic field gradients, achieve a selected manipulation of nuclear magnetic resonance signals.
  • the RF pulses are used to saturate, excite resonance, invert magnetization, refocus resonance, or manipulate resonance and select a portion of a body 10 positioned in the examination volume.
  • the MR signals are also picked up by the body RF coil 9.
  • a set of local array RF coils 1 1 , 12, 13 are placed contiguous to the region selected for imaging.
  • the array coils 1 1 , 12, 13 can be used to receive MR signals induced by body-coil RF transmissions.
  • the resultant MR signals are picked up by the body RF coil 9 and/or by the array RF coils 1 1 , 12, 13 and demodulated by a receiver 14 preferably including a preamplifier (not shown).
  • the receiver 14 is connected to the RF coils 9, 1 1 , 12 and 13 via send/receive switch 8.
  • a host computer 15 controls the shimming coils 2' as well as the gradient pulse amplifier 3 and the transmitter 7 to generate any of a plurality of MR imaging sequences, such as echo planar imaging (EPI), echo volume imaging, gradient and spin echo imaging, fast spin echo imaging, and the like.
  • EPI echo planar imaging
  • the receiver 14 receives a single or a plurality of MR data lines in rapid succession following each RF excitation pulse.
  • a data acquisition system 16 performs analog-to-digital conversion of the received signals and converts each MR data line to a digital format suitable for further processing. In modern MR devices the data acquisition system 16 is a separate computer which is specialized in acquisition of
  • the digital raw image data are reconstructed into an image representation by a reconstruction processor 17 which applies an appropriate reconstruction algorithm (see below).
  • the MR image may represent a planar slice through the patient, an array of parallel planar slices, a three-dimensional volume, or the like.
  • the image is then stored in an image memory where it may be accessed for converting slices, projections, or other portions of the image representation into appropriate format for visualization, for example via a video monitor 18 which provides a man-readable display of the resultant MR image.
  • step 31 spatial sensitivity maps 21 of the used RF receiving coils
  • step 32 MR signals are acquired in parallel via the RF receiving coils 11, 12, 13 in a number of successive acquisition steps forming time frames tl, t2, t3,... tN.
  • the MR signals are acquired in each time frame tl, t2, t3,... tN as a stack of
  • Each time frame comprises MR signal data sampled across all slices in the three-dimensional stacked spiral acquisition.
  • a first base image reconstructor 41 reconstructs a high-quality MR base image 22 from a fully sampled MR signal dataset comprising the MR signals acquired in the first acquisition steps.
  • This high-quality MR base image 22 is used as an initial guess in the further reconstruction of a first time series of MR images 23 according to the invention.
  • the MR images of the first time series 23 are reconstructed by first time series reconstructor 42 in step 34 one by one in the temporal order of the acquisition steps.
  • Each MR image (frame) of the first time series 23 is reconstructed by solving a linear problem using the particular conjugate gradient approach of the TRACER technique, wherein the MR image attributed to the respectively preceding acquisition step (i.e., the respective temporally preceding frame) is used as a regularization constraint in each reconstruction step.
  • the high-quality base image 22 is used as a constraint.
  • x n arg min ⁇
  • x n is the MR image of the first time series attributed to time frame n
  • y n denotes the MR signals acquired in step n
  • S describes the spatial encoding according to the sensitivity maps 21.
  • F is the Fourier transform operator
  • P is the k- space projection onto the respective spiral sampling trajectory.
  • ⁇ ⁇ - is the MR image attributed to the respectively preceding acquisition step n— 1.
  • ⁇ is the regularization parameter.
  • a further high-quality MR base image 24 is reconstructed by second base image reconstructor 43 from a fully sampled MR signal dataset comprising the MR signals acquired in the last acquisition steps.
  • This high-quality MR base image 24 is used as an initial constraint in the further reconstruction of a second time series of MR images 25 according to the invention.
  • the TRACER reconstruction is employed by a second time series reconstructor 44 in step 36 again to reconstruct the MR images of the second time series 25 one by one in the reverse temporal order of the acquisition steps.
  • Each MR image of the second time series 25 is reconstructed by solving a linear problem using the approach of the TRACER technique, wherein the MR image attributed to the respectively succeeding acquisition step (i.e., the respective temporally succeeding frame) is used as a regularization constraint in each reconstruction step.
  • the high-quality base image 25 is used as an initial constraint.
  • x n arg min ⁇
  • x n+1 is the MR image attributed to the respectively succeeding acquisition step n + 1.
  • a third time series of MR images 26 is computed by third time series reconstructor 45 from the first and second series 23, 25, wherein each pair of MR images of the first and second time series 23, 25 attributed to the same time frame tl, t2, t3,... tN is combined into a MR image of the third time series 26 by averaging the corresponding MR images of the first and second time series 23, 25.
  • Figure 5 a shows experimental BOLD contrast fMRI images acquired by the dual TRACER approach according to the invention. A visual stimulus was provided to the patient. 14-fold undersampling was applied in each single acquisition step. The MR signals were acquired using the above-described variable density spiral Golden Angle strategy.
  • Figure 5b shows the same BOLD fMRI images reconstructed using the conventional CS approach. It can be seen that the sensitivity of the neural activity mapping is significantly higher in the fMRI images reconstructed according to the invention ( Figure 5 a).
  • the described approach of the invention is particularly advantageous for BOLD fMRI situations because the differences in the MR images between adjacent time frames tl, t2, t3,... tN are typically small, so that the MR images can be reconstructed at a high image quality even in combination with a high degree of undersampling as required to obtain a correspondingly high temporal resolution.
  • the TRACER reconstruction scheme adopted according to the invention ensures high image fidelity to the acquired MR signal data of the respective current time frame. Image quality is maintained to a particularly high degree by imposing consistency with both the temporally preceding and succeeding time frames tl, t2, t3,... tN.

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Vascular Medicine (AREA)
  • General Health & Medical Sciences (AREA)
  • Radiology & Medical Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

L'invention concerne un procédé d'imagerie par résonance magnétique du corps (10) d'un patient. L'invention concerne en particulier un procédé permettant une imagerie par résonance magnétique dynamique dotée d'une haute résolution spatiale et temporelle. Le procédé selon l'invention consiste : à générer des signaux de résonance magnétique (RM) par soumission d'au moins une partie du corps à une séquence d'imagerie RM comprenant plusieurs impulsions RF et des gradients de champ magnétique commutés ; à acquérir les signaux RM en plusieurs étapes d'acquisition successives ; à reconstruire une première série temporelle d'images RM dans l'ordre des étapes d'acquisition, chaque image RM ultérieure étant reconstruite à partir des signaux RM acquis lors de l'étape d'acquisition respective au moyen de l'image RM attribuée à l'étape d'acquisition respectivement précédente comme contrainte de régularisation de chaque reconstruction, la première image RM de la première série temporelle (23) étant reconstruite à partir des signaux RM acquis en au moins deux étapes d'acquisition initiales ; à reconstruire une deuxième série temporelle d'images RM dans l'ordre inverse des étapes d'acquisition, chaque image RM précédente étant reconstruite à partir des signaux RM acquis lors de l'étape d'acquisition respective au moyen de l'image RM attribuée à l'étape d'acquisition respectivement suivante comme contrainte de régularisation de chaque reconstruction, la dernière image RM de la deuxième série temporelle (25) étant reconstruite à partir des signaux RM acquis en au moins deux étapes d'acquisition finales ; et à calculer une troisième série temporelle d'images RM, chaque paire d'images RM des première et deuxième séries temporelles attribuées à la même étape d'acquisition étant moyennée pour générer une image RM de la troisième série temporelle pour l'étape d'acquisition respective. L'invention concerne en outre un dispositif RM (1) et un programme informatique destiné à être exécuté sur le dispositif RM (1).
PCT/EP2017/057637 2016-03-31 2017-03-30 Imagerie par résonance magnétique dynamique à résolution temporelle et spatiale accrue WO2017167937A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CN2016078026 2016-03-31
CNPCT/CN2016/078026 2016-03-31
EP16174308 2016-06-14
EP16174308.3 2016-06-14

Publications (1)

Publication Number Publication Date
WO2017167937A1 true WO2017167937A1 (fr) 2017-10-05

Family

ID=58488984

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2017/057637 WO2017167937A1 (fr) 2016-03-31 2017-03-30 Imagerie par résonance magnétique dynamique à résolution temporelle et spatiale accrue

Country Status (1)

Country Link
WO (1) WO2017167937A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3517988A1 (fr) * 2018-01-29 2019-07-31 Koninklijke Philips N.V. Imagerie par résonance magnétique au moyen d'une acquisition par empilement d'étoiles à correction de mouvement intrinsèque
CN116538949A (zh) * 2023-07-03 2023-08-04 湖南大学 一种基于时域超分辨的高速动态过程dic测量装置与方法

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
BO XU ET AL: "Fast 3D contrast enhanced MRI of the liver using temporal resolution acceleration with constrained evolution reconstruction", MAGNETIC RESONANCE IN MEDICINE., vol. 69, no. 2, 22 March 2012 (2012-03-22), US, pages 370 - 381, XP055322948, ISSN: 0740-3194, DOI: 10.1002/mrm.24253 *
JINGYUAN LYU ET AL: "Highly accelerated 3D dynamic contrast enhanced MRI from sparse spiral sampling using integrated partial separability model and JSENSE", OPTICAL SENSING II, vol. 9109, 23 May 2014 (2014-05-23), 1000 20th St. Bellingham WA 98225-6705 USA, pages 91090N, XP055322951, ISSN: 0277-786X, ISBN: 978-1-62841-971-9, DOI: 10.1117/12.2053194 *
LI FENG ET AL: "Golden-angle radial sparse parallel MRI: Combination of compressed sensing, parallel imaging, and golden-angle radial sampling for fast and flexible dynamic volumetric MRI", MAGNETIC RESONANCE IN MEDICINE., vol. 72, no. 3, 18 October 2013 (2013-10-18), US, pages 707 - 717, XP055322954, ISSN: 0740-3194, DOI: 10.1002/mrm.24980 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3517988A1 (fr) * 2018-01-29 2019-07-31 Koninklijke Philips N.V. Imagerie par résonance magnétique au moyen d'une acquisition par empilement d'étoiles à correction de mouvement intrinsèque
WO2019145527A1 (fr) * 2018-01-29 2019-08-01 Koninklijke Philips N.V. Imagerie par rm utilisant une acquisition par empilement d'étoiles à correction de mouvement intrinsèque
CN116538949A (zh) * 2023-07-03 2023-08-04 湖南大学 一种基于时域超分辨的高速动态过程dic测量装置与方法
CN116538949B (zh) * 2023-07-03 2023-09-15 湖南大学 一种基于时域超分辨的高速动态过程dic测量装置与方法

Similar Documents

Publication Publication Date Title
US9746539B2 (en) MR imaging with suppresion of flow artifacts
EP3635425B1 (fr) Imagerie par résonance magnétique au moyen d'une acquisition par empilement d'étoiles à contraste variable
EP2800980A1 (fr) Irm dotée d'une séparation eau/graisse de type dixon et connaissance préalable de l'inhomogénéité du champ magnétique principal
US11415655B2 (en) Reduced field-of-view perfusion imaging with high spatiotemporal resolution
JP2019522513A (ja) ディクソン法による水／脂肪分離を用いたｍｒ撮像
EP3003144A1 (fr) Imagerie par résonance magnétique ayant un contraste de sensibilité amélioré
JP7446328B2 (ja) ソフト動きゲーティングによる３ｄラジアル又はスパイラル収集を用いたｍｒ画像
CN106796274B (zh) 具有伪迹抑制的propeller-mr成像
JP2023109791A (ja) 並列マルチスライスｍｒ撮像
WO2018224653A1 (fr) Imagerie rm à séparation eau/graisse de type dixon à double écho
US9316711B2 (en) System and method for accelerated magnetic resonance imaging using spectral sensitivity
US10859652B2 (en) MR imaging with dixon-type water/fat separation
US11543482B2 (en) Magnetic resonance imaging using motion-compensated image reconstruction
WO2018114554A1 (fr) Imagerie rm à séparation eau/graisse de type dixon
WO2017167937A1 (fr) Imagerie par résonance magnétique dynamique à résolution temporelle et spatiale accrue
US11815582B2 (en) Dual echo steady state MR imaging using bipolar diffusion gradients
US11269037B2 (en) MR imaging using motion-dependent radial or spiral k-space sampling
EP3185029A1 (fr) Imagerie par résonance magnétique avec acquisition d'hélice t2 utilisant une correction de décroissance
WO2020173688A1 (fr) Imagerie rm epi à correction de distorsion
WO2018001759A1 (fr) Imagerie par résonance magnétique (rm) pondérée par diffusion utilisant une image de plan épipolaire (epi) multi-prise avec détection de mouvement et reconstruction de détection modifiée
US20240069136A1 (en) Mr mammography
EP3118643A1 (fr) Imagerie par résonance magnétique d'hélice dynamique
EP4291913A1 (fr) Imagerie par résonance magnétique à séparation eau/graisse de type dixon

Legal Events

Date Code Title Description
NENP Non-entry into the national phase

Ref country code: DE

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17715439

Country of ref document: EP

Kind code of ref document: A1

122 Ep: pct application non-entry in european phase

Ref document number: 17715439

Country of ref document: EP

Kind code of ref document: A1