Abstract: A composite image is produced for use in HYPR processing a current image frame. The amount of a priori data used to form the composite is determined by the amount of subject motion. The current composite image may be spatially registered with the current image frame to offset subject motion before being used to form an updated composite image. Subject motion may be analyzed on a frame-by-frame basis, a region-by-region basis or a pixel-by-pixel basis to optimize the SNR of the updated composite image.

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: A series of image frames are acquired in which an MR parameter such as echo time (TE) is changed and the resulting image frames are employed to produce an MRS image of a metabolite. Scan time is reduced without sacrificing image quality by reconstructing a composite image from data acquired for a plurality of the image frames and using a highly constrained image reconstruction method with the composite image to produce each image frame.

Abstract: Highly undersampled diffusion weighted image data sets are acquired for a plurality of different directions using a projection reconstruction pulse sequence. The acquired projection views are interleaved and are combined to form a more highly sampled data set that is used to reconstruct a composite image. A DWI image is reconstructed from each undersampled data set for each direction using a highly constrained backprojected method that employs the composite image. Diffusion tensor values are calculated from the DWI images.

Abstract: An x-ray computed tomography system uses a broad area x-ray emitter and detector to allow both in plane and out of plane x-ray projections not restrained to spiral or helical scans.

Abstract: Acquisition of MR data during a fMRI study employs a hybrid PR pulse sequence to acquire projection views from which multi-slice image frames may be reconstructed that depict the BOLD response to an applied stimulus or performed task. Composite images are reconstructed at each slice using the combined interleaved projection views from all the acquired image frames. The composite images are used to reconstruct the highly undersampled image frames.

Abstract: A series of image frames are acquired in which an MR parameter such as echo time (TE) is changed and the resulting image frames are employed to produce an MRS image of a metabolite. Scan time is reduced without sacrificing image quality by reconstructing a composite image from data acquired for a plurality of the image frames and using a highly constrained image reconstruction method with the composite image to produce each image frame.

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.

Abstract: Highly undersampled diffusion weighted image data sets are acquired for a plurality of different directions using a projection reconstruction pulse sequence. The acquired projection views are interleaved and are combined to form a more highly sampled data set that is used to reconstruct a composite image. A DWI image is reconstructed from each undersampled data set for each direction using a highly constrained backprojected method that employs the composite image. Diffusion tensor values are calculated from the DWI images.

Abstract: A cardiac gated acquisition of MR data during a breath-hold employs a hybrid PR pulse sequence to acquire projection views from which image frames may be reconstructed at a plurality of cardiac phases during each heartbeat. Composite images are reconstructed at each cardiac phase using interleaved projection views acquired during all the heartbeats. The composite images are used to reconstruct the highly undersampled image frames at the same cardiac phase using a highly constrained backprojection method.

Abstract: A generalized projection-slice theorem for divergent beam projections is disclosed. The theorem results in a method for processing the Fourier transform of the divergent beam projections at each view acquired by a CT system to the Fourier transform of the object function. Using this method, an inverse Fourier transform may be used to reconstruct tomographic images from the acquired divergent beam projections.

Abstract: Two-dimensional or three-dimensional, time-resolved MR frame images are acquired during a dynamic study of a subject. A composite MR image is produced and this is used to reconstruct each image frame by weighting the backprojection of each projection view acquired for that image frame. The composite image may be reconstructed from views acquired separately, or it may be produced by combining views acquired during the course of the dynamic study. A number of different clinical applications of the method are described.

Abstract: Two-dimensional or three-dimensional, time-resolved CT frame images are acquired during a dynamic study of a subject. A composite image is produced and this is used to reconstruct each CT frame image by weighting the backprojection of each projection view acquired for that image frame by the corresponding value in the composite image. This weighted backprojection enables artifact-free image frames to be produced with far fewer projection views of the subject. The composite image may be reconstructed from views acquired separately, or it may be produced by combining views acquired during the course of the dynamic study.

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 highly undersampled image frames. An image frame is reconstructed using limited acquired data and image quality is improved using a priori information of the subject by weighting pixel values therein by values of corresponding pixels in the composite image.

Abstract: A phase contrast image is produced using a 3D projection reconstruction pulse sequence. A high velocity-to-noise image is produced by using a LOW VENC motion encoding gradient. Phase wrap errors caused by high velocity flow is corrected using phase information in a HIGH VENC image produced from highly undersampled data acquired during the same scan.

Abstract: A phase contrast image is produced using a 3D projection reconstruction pulse sequence. A high velocity-to-noise image is produced by using a LOW VENC motion encoding gradient. Phase wrap errors caused by high velocity flow is corrected using phase information in a HIGH VENC image produced from highly undersampled data acquired during the same scan.

Abstract: A helical scan is performed with a fan beam or cone beam CT system to acquire a first set of sinogram data sets. The subject is injected with a contrast agent and the identical helical scan is performed to acquire a second set of sinogram data sets. Corresponding projection views are subtracted in the two data sets and a number of different images are reconstructed from the difference data set. One image is a tomographic image produced using a filtered backprojection method and a second image is a topograph produced by selecting and displaying projection views acquired at the same view angle in successive sinogram data sets.

Abstract: A contrast enhanced dynamic study of a subject is performed with a CT system. A series of undersampled image data sets are acquired during the study with successive data sets acquired at interleaved projection angles. More fully sampled image data sets are formed by transforming the x-ray attenuation projection data to k-space and then sharing peripheral k-space data between undersampled k-space data sets. Artifacts due to undersampling are thus reduced without significantly affecting the time resolution of a series of reconstructed images.

Abstract: An x-ray system for use with image-guided medical procedures is programmed to move in a first scan path to acquire cone beam attenuation data from which a three-dimensional digital subtraction angiogram of selected vasculature is reconstructed. The x-ray system is also programmed to move in a second scan path to acquire a series of tomosynthesis images during the inflow of a contrast agent into the selected vasculature. Parametric images are produced from information in the tomosynthesis images which indicate blood perfusion physiology of the tissues served by the vasculature.