Case Western Reserve University

Other

Magnetic Resonance of Bavacia

Martin Blaimer

Mark A Griswold

Candice Bookwalter

Kestutis J Barkauskas

Felix Breuer

Randall Kroeker

Herbert Koestler

Example systems, methods, and apparatus control a pMRI apparatus to produce a pulse sequence having an extended acquisition window, and overlapping phase-encoding gradients and read gradients. One example method controls a pMRI apparatus to produce a trajectory having Cartesian and non-Cartesian segments that sample in a manner that satisfies the Nyquist criterion in at least one region of a volume to be imaged. The pMRI apparatus is controlled to apply radio frequency energy to the volume according to the pulse sequence and following the trajectory and to acquire MR signal from the volume in response to the application of the RF energy. The MR signal includes a first component associated with the Cartesian segment of the trajectory and a second component associated with the non-Cartesian segment of the trajectory. The example method includes calibrating a reconstruction process using Nyquist-satisfying data from the second component.

Calibrating parallel MRI with cartesian continuous sampling

Example systems, methods, and apparatus associated with determining a phase-encoding direction for parallel MRI are described. One example, method includes selecting a set of projection directions along which an MRI apparatus is to apply RF energy to an object to be imaged. The method includes controlling the MRI apparatus to selecting a set of projection directions and to acquire MR signal from the object through a set of detectors. The method includes analyzing the MR signal to identify individual sensitivities for members of the set of detectors and selecting a phase-encoding direction for a pMRI session based on the individual sensitivities for the members. The method produces a concrete, tangible, and useful result by controlling the MRI apparatus to perform the pMRI session based on the selected phase-encoding direction.

Determining phase-encoding direction for parallel MRI

Example methods, apparatus, and systems associated with dynamic parallel magnetic resonance imaging (DpMRI) are presented. One example system facilitates separating data associated with a dynamic portion of a dynamic magnetic resonance image from data associated with a static portion of the dynamic magnetic resonance image. The system computes reconstruction parameters for a DpMRI reconstruction processes for both the dynamic portion of the image and the static portion of the image. The example system produces a DpMRI image based on separate reconstructions of the dynamic portion of a dynamic magnetic resonance image and the static portion of a dynamic magnetic resonance image. The separate reconstructions may depend on separate sets of reconstruction parameters and on separated static data and dynamic data.

Dynamic parallel magnetic resonance imaging(DpMRI) with sparse data

Example systems, methods, and apparatus facilitate providing a k-space line that is missing in an under-sampled time frame. The missing line is computed by applying a GRAPPA-operator to a known k-space line in the under-sampled time frame. One example method includes controlling a dynamic parallel magnetic resonance imaging (DpMRI) apparatus to acquire a first under-sampled time interleaved frame having at least one first k-space line and controlling the DpMRI apparatus to acquire a second under-sampled time interleaved frame having at least one second k-space line that neighbors the first k-space line. The method includes assembling a reference data set from the first under-sampled time frame and the second under-sampled time frame and then determining the GRAPPA-operator from neighboring k-space lines in the reference data set.

Dynamic pMRI using GRAPPA-operator with under-sampled time interleaved frames

Example systems, methods, and apparatus control a pMRI apparatus to produce a pulse sequence having an extended acquisition window, and overlapping phase-encoding gradients and read gradients. One example method controls a pMRI apparatus to produce a trajectory having Cartesian and radial segments that sample in a manner that satisfies the Nyquist criterion in at least one region of a volume to be imaged. The pMRI apparatus is controlled to apply radio frequency energy to the volume according to the pulse sequence and following the trajectory and to acquire MR signal from the volume in response to the application of the RF energy. The MR signal includes a first component associated with the Cartesian segment of the trajectory and a second component associated with the radial segment of the trajectory. The example method includes calibrating a reconstruction process using Nyquist-satisfying data from the second component.

Calibrating pMRI with cartesian continuous sampling

Example systems, methods, and apparatus associated with conjugate symmetry in parallel imaging are provided. One example method includes controlling a parallel magnetic resonance imaging (pMRI) apparatus to acquire a first magnetic resonance (MR) signal from a first point in k-space using a phased array of receiving coils. The method also includes identifying a second point in k-space that is related to the first point by a conjugate symmetry relation. The relation may be, for example, a reflection, a rotation, and so on. The method also includes determining a second MR signal associated with the second point based, at least in part, on the first MR signal and the conjugate symmetry relation and then reconstructing an MR image based, at least in part, on both the first MR signal and the second MR signal.

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Cleveland Heights, OH, United States of America

Martin Blaimer