Abstract: A method for reconstructing an image of a subject with a medical imaging system, such as a magnetic resonance imaging system, is provided. Medical image data is acquired from the subject with the medical imaging system, and one or more images of the subject are reconstructed from the medical image data while constraining the one or more images to be consistent with a signal model that relates image intensity values in the image to a free parameter that is associated with a physical property of the subject. The signal model may be an analytical signal model or an approximate signal model learned from acquired medical image data. The model consistency condition may be enforced using an operator that projects an image estimate onto the space of all functions satisfying the signal model.

Abstract: A method for reconstructing an image of a subject with a medical imaging system, such as a magnetic resonance imaging system, is provided. Medical image data is acquired from the subject with the medical imaging system, and one or more images of the subject are reconstructed from the medical image data while constraining the one or more images to be consistent with a signal model that relates image intensity values in the image to a free parameter that is associated with a physical property of the subject. The signal model may be an analytical signal model or an approximate signal model learned from acquired medical image data. The model consistency condition may be enforced using an operator that projects an image estimate onto the space of all functions satisfying the signal model.

Abstract: A method for reconstructing a motion-compensated image depicting a subject with a magnetic resonance imaging (MRI) system is provided. An MRI system is used to acquire a time series of k-space data from the subject by sampling k-space along non-Cartesian trajectories, such as radial, spiral, or other trajectories at a plurality of time frames. Those time frames at which motion occurred are identified and this information used to segment the time series into a plurality of k-space data subsets. For example, the k-space data subsets contain k-space data acquired at temporally adjacent time frames that occur between those identified time frames at which motion occurred. Motion correction parameters are determined from the k-space data subsets. Using the determined motion correction parameters, the k-space data subsets are corrected for motion. The corrected data subsets are combined to form a corrected k-space data set, from which a motion-compensated image is reconstructed.

Abstract: A method for reconstructing a motion-compensated image depicting a subject with a magnetic resonance imaging (MRI) system is provided. An MRI system is used to acquire a time series of k-space data from the subject by sampling k-space along non-Cartesian trajectories, such as radial, spiral, or other trajectories at a plurality of time frames. Those time frames at which motion occurred are identified and this information used to segment the time series into a plurality of k-space data subsets. For example, the k-space data subsets contain k-space data acquired at temporally adjacent time frames that occur between those identified time frames at which motion occurred. Motion correction parameters are determined from the k-space data subsets. Using the determined motion correction parameters, the k-space data subsets are corrected for motion. The corrected data subsets are combined to form a corrected k-space data set, from which a motion-compensated image is reconstructed.

Abstract: An image reconstruction method includes reconstructing a composite image of a subject using a conventional reconstruction method. The composite image employs the best information available regarding the subject of the scan and this information is used to constrain the reconstruction of a highly undersampled image frames or improve the SNR of image frames. A blurred and normalized weighting image is produced from image frame data, and this normalized weighting image is multiplied by the composite image.

Abstract: Mask projection views are obtained prior to the arrival of a contrast agent during a dynamic contrast enhanced MRA study. After the arrival of the contrast agent, a set of undersampled contrast enhanced projection views are obtained for each of a plurality of time frames. Corresponding mask projection views are subtracted from the contrast enhanced projection views to provide sparse contrast enhanced projection view sets. A phase contrast scan of a region of interest is performed prior to or after the arrival of the contrast agent. The phase contrast image is used as a composite image in a HYPR reconstruction of the sparse projection view sets to produce first pass contrast enhanced images. Iterative HYPR reconstructions can also be performed to remove venous information from the reconstructed images.

Abstract: Mask projection views are obtained prior to the arrival of a contrast agent during a dynamic contrast enhanced MRA study. After the arrival of the contrast agent, a set of undersampled contrast enhanced projection views are obtained for each of a plurality of time frames. Corresponding mask projection views are subtracted from the contrast enhanced projection views to provide sparse contrast enhanced projection view sets. A phase contrast scan of a region of interest is performed prior to or after the arrival of the contrast agent. The phase contrast image is used as a composite image in a HYPR reconstruction of the sparse projection view sets to produce first pass contrast enhanced images. Iterative HYPR reconstructions can also be performed to remove venous information from the reconstructed images.

Abstract: A series of velocity encoded MR image frames are acquired. To increase the temporal resolution of the acquired image frames radial projections are acquired and each image frame is highly undersampled. The radial projections for each velocity encoding direction are interleaved throughout the scan and a composite phase image is reconstructed from these and used to reconstruct a velocity image for each image frame in a highly constrained backprojection method.

Abstract: Projection views of the moving heart and stationary background tissues are acquired and processed to provide corresponding moving tissue projection views. An average image is reconstructed in a conventional manner and a moving tissue image is reconstructed using a highly constrained backprojection method and a composite image formed from selected moving tissue projection views. The average image is then combined with the moving tissue image. The method is disclosed in a cardiac gated MRI scan.

Abstract: An image reconstruction method includes reconstructing a composite image of a subject using a conventional reconstruction method. The composite image employs the best information available regarding the subject of the scan and this information is used to constrain the reconstruction of a highly undersampled image frames or improve the SNR of image frames. A blurred and normalized weighting image is produced from image frame data, and this normalized weighting image is multiplied by the composite image.

Abstract: Projection views of the moving heart and stationary background tissues are acquired and processed to provide corresponding moving tissue projection views. An average image is reconstructed in a conventional manner and a moving tissue image is reconstructed using a highly constrained backprojection method and a composite image formed from selected moving tissue projection views. The average image is then combined with the moving tissue image. The method is disclosed in a cardiac gated MRI scan.

Abstract: A series of velocity encoded MR image frames are acquired. To increase the temporal resolution of the acquired image frames radial projections are acquired and each image frame is highly undersampled. The radial projections for each velocity encoding direction are interleaved throughout the scan and a composite phase image is reconstructed from these and used to reconstruct a velocity image for each image frame in a highly constrained backprojection method.