Patent classifications
G01R33/56554
MAGNETIC RESONANCE IMAGING APPARATUS, CORRECTION METHOD, AND MEMORY MEDIUM
A magnetic resonance imaging apparatus according to an embodiment includes a processing circuitry. Regarding the k-space data obtained as a result of performing multi-shot imaging that includes a plurality of shots, the processing circuitry obtains a correction coefficient, based on first-type magnetic resonance images generated using the k-space data, the correction coefficient correcting phase shifting occurring in read out direction among the plurality of shots. Then, the processing circuitry corrects the k-space data based on the correction coefficients. Moreover, the processing circuitry generates a second-type magnetic resonance image using the corrected k-space data.
Free-Breathing MRI with Motion Compensation
A method for acquiring magnetic resonance imaging data with respiratory motion compensation using one or more motion signals includes acquiring a plurality of gradient-delay-corrected radial readout views of a subject using a free-breathing multi-echo pulse sequence, and sampling a plurality of data points of the gradient-delay-corrected radial readout views to yield a self-gating signal. The self-gating signal is used to determine a plurality of respiratory motion states corresponding to the plurality of gradient-delay-corrected radial readout views. The respiratory motion states are used to correct respiratory motion bias in the gradient-delay-corrected radial readout views, thereby yielding gradient-delay-corrected and motion-compensated multi-echo data. One or more images are reconstructed using the gradient-delay-corrected and motion-compensated multi-echo data.
IMPROVED WHOLE-BLADE ACQUISITION AND PHASE CORRECTION IN MAGNETIC RESONANCE IMAGING
Various embodiments of a system and associated method for whole-blade acquisition and phase correction for fast and robust MR imaging are disclosed herein. In particular, the system enables sampling of odd and even k-space echoes in the same k-space as well as a whole-blade phase correction strategy to achieve improved image quality at an accelerated imaging rate.
3D FLOW COMPENSATED INTERLEAVED EPI WITH A CENTRIC REORDERING SCHEME FOR FAST HIGH-RESOLUTION SUSCEPTIBILITY-WEIGHTED IMAGING
A method and apparatus for susceptibility-weighted imaging, and a magnetic resonance imaging system. The method includes, in planar echo imaging of a plurality of excitations, performing flow compensation in directions of layered encoding, phase encoding, and frequency encoding for echoes of each excitation; after determination of excitation each time, when a linear reordering mode is adopted, for excitation each time, collecting each echo towards space k in a positive direction or a negative direction from the central echo of the plurality of echoes, and collecting echoes of the current excitation in a direction opposite to a direction of collecting echoes of the previous excitation; and subjecting the collected echoes to susceptibility-weighted imaging. An aspect of the present disclosure allows a reduction of flow artifacts in an image created by susceptibility-weighted imaging based on a planar echo sequence.
Method for obtaining an operating parameter, storage medium, and magnetic resonance apparatus
A storage medium, a magnetic resonance apparatus, and a method for obtaining an operating parameter of a magnetic resonance apparatus are disclosed herein. The method includes generating of at least one echo train, wherein the generation of an echo train includes: setting a given set of parameters; applying at least one radio frequency excitation pulse; and applying a dephasing gradient in readout direction; and reading out the echo train having at least two echo signals, wherein a readout gradient is applied while reading out the echo signals. The method further includes acquiring at least two echo signals, wherein the set of parameters differs in at least one parameter being used for different echo signals; processing the echo signals line by line to projections; and obtaining the operating parameter using the projections.
Free-breathing MRI with motion compensation
A method for acquiring magnetic resonance imaging data with respiratory motion compensation using one or more motion signals includes acquiring a plurality of gradient-delay-corrected radial readout views of a subject using a free-breathing multi-echo pulse sequence, and sampling a plurality of data points of the gradient-delay-corrected radial readout views to yield a self-gating signal. The self-gating signal is used to determine a plurality of respiratory motion states corresponding to the plurality of gradient-delay-corrected radial readout views. The respiratory motion states are used to correct respiratory motion bias in the gradient-delay-corrected radial readout views, thereby yielding gradient-delay-corrected and motion-compensated multi-echo data. One or more images are reconstructed using the gradient-delay-corrected and motion-compensated multi-echo data.
Automatic determination of a correction factor for producing magnetic resonance images
Automatically determining a correction factor for producing MR images includes outputting a first readout gradient along a readout dimension, reading out a first MR signal from a subject during the output of the first readout gradient, and specifying a second readout gradient having a theoretically identical gradient moment to the first readout gradient. A temporal waveform that differs from a temporal waveform of the first readout gradient is specified for the second readout gradient. The second readout gradient is output along the readout dimension. A second MR signal is read out from the subject during the output of the second readout gradient. A first extent of a representation of the subject is determined based on the first MR signal. A second extent of a representation of the subject is determined based on the second MR signal. A correction factor is obtained from a ratio between the first and second extents.
Variable gain amplification for linearization of NMR signals
Various approaches of amplifying an NMR signal in response to a transmitted NMR pulse include estimating the characteristic time associated with the NMR signal; transmitting the NMR pulse to the sample and receiving the NMR signal therefrom; and applying a time-dependent amplifier gain to the received NMR signal based at least in part on the estimated characteristic time.
Phase correction for echo-planar imaging
Systems and methods include conversion of a first frame of k-space data acquired using a first initial readout polarity to first hybrid (k.sub.x, y)-space data, conversion of a second frame of k-space data acquired using a second initial readout polarity to second hybrid (k.sub.x, y)-space data, determination of a relationship between phase difference and y-position based on phase differences between a plurality of pixels located at k.sub.x=a of first hybrid (k.sub.x, y)-space data and a plurality of pixels at k.sub.x=b of second hybrid (k.sub.x, y)-space data, where a and b are constants, modification of the second hybrid (k.sub.x, y)-space data based on the relationship, conversion of the modified second hybrid (k.sub.x, y)-space data to a modified second frame of k-space data, generation of two single-polarity readout k-space frames based on the first frame of k-space data and the modified second frame of k-space data, and correction of a third frame of EPI image data based on the two single-readout polarity k-space frames.
Method for producing diffusion-weighted and non-diffusion-weighted measurement data by magnetic resonance
To acquire measurement data of an object, a first subsampled set of diffusion-weighted measurement data with switching of diffusion gradients for diffusion encoding of the measurement data, using a first echo spacing, and a second subsampled set of non-diffusion-weighted measurement data, using the first echo spacing, are acquired. The first and second subsampled sets of measurement data are supplemented using calibration data to produce first and second complete sets of measurement data. At least the first calibration data, acquired using the first echo spacing, may be used for supplementing the second subsampled set of measurement data to produce a second complete set of measurement data. By supplementing subsampled sets of measurement data with calibration data acquired according to the same echo spacing as the subsampled measurement data, noise signals in the supplemented measurement data are advantageously eliminated.