Abstract: Described here are systems and methods for reconstructing images from multi-level sampled data acquired with a magnetic resonance imaging (MRI) system. An alternating direction method-of multipliers (ADMM) strategy is implemented for sparse reconstruction of multi-level sampled data, and which decomposes the reconstruction problem into simpler subproblems and enables certain operations to be computed once offline and recycled during the reconstruction process rather than repeated at every iteration. As one example, the described reconstruction technique enables sparse reconstruction of 3D contrast-enhanced MR angiogram time-series in just several minutes rather than the several hours previously required.

Abstract: Systems and methods for super-resolution ultrasound imaging of microvessels in a subject are described. Ultrasound data are acquired from a region-of-interest in a subject who has been administered a microbubble contrast agent. The ultrasound data are acquired while the microbubbles are moving through, or otherwise present in, the region-of-interest. The region-of-interest may include, for instance, microvessels or other microvascuiature in the subject. By isolating, localizing, tracking, and accumulating the microbubbles in the ultrasound data, super-resolution images of the microvessels can be generated.

Abstract: Systems and methods for estimating acoustic properties in a region-of-interest in a subject or other object being imaged using a reference frequency method (“RFM”) is described. Using this RFM technique, ultrasound data acquired at a given frequency are normalized by ultrasound data acquired at different frequencies (e.g., adjacent frequencies or otherwise) in order to provide estimations of the acoustic properties (e.g., attenuation coefficient, a backscatter coefficient, or both) that are independent of the ultrasound system used to acquire the underlying data. For instance, the amplitude of each frequency component can be normalized by a different frequency in the power spectrum to cancel out the system-dependent effects. Because the methods described in the present disclosure are system independent, they can be applied to any transducer geometry (e.g., linear or curved arrays) and using any beam pattern (e.g., focused or unfocused).

Abstract: An asymmetric 3D shells k-space trajectory design with partial Fourier acceleration is described. A non-iterative homodyne reconstruction framework is also described.

Abstract: A system and method for generating a spatial map of parameters that describe the mechanically-induced harmonic motion information present within a magnetic resonance elastography (MRE) data set is provided. A first temporal harmonic signal is estimated using a graph-cut based optimization strategy, and can subsequently be used to generate a spatial map of mechanical parameters. The MRE data set is used to estimate the harmonic. The spatial map is of a mechanical parameter derived from the estimated harmonic.

Abstract: A system and method for simultaneously reconstructing magnetic resonance images and correcting those imaged for gradient nonlinearity effects are provided. As opposed to conventional methods for gradient nonlinearity correction where distortion is corrected after image reconstruction is performed, the model-based method described here prospectively accounts for the effects of gradient nonlinearity during reconstruction. It is a discovery of the inventors that the method described here can reduce the blurring effect and resolution loss caused by conventional correction algorithms while achieving the same level of geometric correction.

Abstract: A system and method for simultaneously reconstructing magnetic resonance images and correcting those imaged for gradient nonlinearity effects are provided. As opposed to conventional methods for gradient nonlinearity correction where distortion is corrected after image reconstruction is performed, the model-based method described here prospectively accounts for the effects of gradient nonlinearity during reconstruction and implements a spatial support constraint to reduce noise amplification effects.

Abstract: Systems and methods for simultaneous water-fat magnetic resonance imaging (“MRI”) and magnetic resonance elastography (“MRE”) using an integrated data acquisition and reconstruction scheme are described. This integrated acquisition and reconstruction technique can mitigate motion misregistration and provide improved image SNR relative to existing multiparametric acquisition techniques that require multiple separate acquisitions.

Abstract: Accelerated dynamic magnetic resonance imaging (“MRI”) methods in which low-rank matrix completion is implemented as a pre-processing step to fill undersampled accelerated k-space while retaining both spatial and temporal resolution are described. The undersampled k-space data are acquired using multilevel sampling, in which both uniform undersampling and non-uniform undersampling are combined to achieve high temporal resolution while retaining spatial resolution.

Abstract: An asymmetric 3D shells k-space trajectory design with partial Fourier acceleration is described. A non-iterative homodyne reconstruction framework is also described.

Abstract: A system and method for simultaneously reconstructing magnetic resonance images and correcting those imaged for gradient nonlinearity effects are provided. As opposed to conventional methods for gradient nonlinearity correction where distortion is corrected after image reconstruction is performed, the model-based method described here prospectively accounts for the effects of gradient nonlinearity during reconstruction and implements a spatial support constraint to reduce noise amplification effects.

Abstract: Systems and methods for efficiently generating MR images are provided. The method comprises acquiring k-space MR data, reconstructing an MR image from the k-space MR data, and generating the MR image. The MR image is reconstructed using an alternative-direction-method-of-multiplier (ADMM) strategy that decomposes an optimization problem into subproblems, and at least one of the subproblems is further decomposed into small problems. The further decomposition is based on Woodbury matrix identity and uses a diagonal preconditioner based on non-Toeplitz models.

Abstract: Described here are systems and methods for ultrasound clutter filtering to produce images of blood flow in a subject. In general, the clutter filtering is based on a singular value implementation, such as an accelerated singular value decomposition (“SVD”). In one example, the singular value-based clutter filtering can be accelerated by implementing a randomized SVD (“rSVD”). In another example, the singular value-based clutter filtering can be accelerated by implementing a randomized spatial downsampling. In still another example, singular value-based clutter filtering can be accelerated by implementing both an rSVD and a randomized spatial downsampling.

Abstract: Systems and methods for performing concomitant field corrections in magnetic resonance imaging (“MRI”) systems that implement asymmetric magnetic field gradients are provided, in general, the systems and methods described here can correct for the effects of concomitant fields of multiple orders, such as zeroth order, first order, and second order concomitant fields.

Abstract: Described here are systems and methods for reconstructing images from multi-level sampled data acquired with a magnetic resonance imaging (MRI) system. An alternating direction method-of multipliers (ADMM) strategy is implemented for sparse reconstruction of multi-level sampled data, and which decomposes the reconstruction problem into simpler subproblems and enables certain operations to be computed once offline and recycled during the reconstruction process rather than repeated at every iteration. As one example, the described reconstruction technique enables sparse reconstruction of 3D contrast-enhanced MR angiogram time-series in just several minutes rather than the several hours previously required.

Abstract: A method for reconstructing an image of a subject from multi-coil data acquired with an array of radio frequency (“RF”) receiver coils that form a part of a magnetic resonance imaging (“MRI”) system without the need for coil sensitivity calibration is provided. A coil data set is acquired for each of the RF receiver coils, for example, by undersampling k-space. A set of image blocks that defines the location and size of each of a plurality of image blocks in the image domain is then selected. The acquired coil data sets and selected image block set are then used to jointly estimate a coil image for each of the plurality of RF receiver coils while promoting locally-low rank structure in the coil images. These coil images are then combined to produce the target image of the subject.

Abstract: A system and method for simultaneously reconstructing magnetic resonance images and correcting those imaged for gradient nonlinearity effects are provided. As opposed to conventional methods for gradient nonlinearity correction where distortion is corrected after image reconstruction is performed, the model-based method described here prospectively accounts for the effects of gradient nonlinearity during reconstruction. It is a discovery of the inventors that the method described here can reduce the blurring effect and resolution loss caused by conventional correction algorithms while achieving the same level of geometric correction.

Abstract: Systems and methods for simultaneous water-fat magnetic resonance imaging (“MRI”) and magnetic resonance elastography (“MRE”) using an integrated data acquisition and reconstruction scheme are described. This integrated acquisition and reconstruction technique can mitigate motion misregistration and provide improved image SNR relative to existing multiparametric acquisition techniques that require multiple separate acquisitions.

Abstract: A system and method for estimating a physiological parameter from data acquired with a medical imaging system includes acquiring data with the medical imaging system. A physiological parameter is estimated from the acquired data using an iterative estimation in which a model of the medical imaging system is decoupled from a physics-based model of the acquired data.

Abstract: Systems and methods for efficiently generating MR images are provided. The method comprises acquiring k-space MR data, reconstructing an MR image from the k-space MR data, and generating the MR image. The MR image is reconstructed using an alternative-direction-method-of-multiplier (ADMM) strategy that decomposes an optimization problem into subproblems, and at least one of the subproblems is further decomposed into small problems. The further decomposition is based on Woodbury matrix identity and uses a diagonal preconditioner based on non-Toeplitz models.