Field of the Invention
The present invention concerns the reconstruction of a magnetic resonance (MR) image from radial collection of MR data in a manner that avoids artifacts (in particular, artifacts caused by metal parts).
Description of the Prior Art
In magnetic resonance imaging, raw data (magnetic resonance measurement data) are acquired from a subject by the operation of a magnetic resonance scanner in which the subject is situated. The acquired raw data are entered as complex numbers at respective data points of a memory. This collection of raw data in the memory is known as k-space data. The entry of the raw data at the respective data points of the memory is known as “scanning” k-space, or scanning a k-space memory. The path composed of data points along which the raw data are successively entered in k-space is known as a “k-space trajectory.”
The k-space data are then transformed into image data, typically by operation of a Fourier transform on the k-space data. The k-space trajectory that is used to enter the raw data into k-space may have an influence on the type or degree of artifacts that may occur in the image represented by the image data. Trajectories such as a Cartesian trajectory, which proceeds along a rectilinear path, and a radial trajectory, which proceeds radially outwardly from a center of k-space to a periphery of k-space, are among the known types of k-space trajectories.
The radial scanning of k-space, which is also referred to as the radial collection of MR data, is a known method, for obtaining T1-weighted MR data, for example, which is used for musculoskeletal imaging (imaging of the musculoskeletal system.
Compared with the traditional Cartesian collection of MR data, the radial collection of MR data has the advantage of being less sensitive to movement. However, the radial collection of MR data is more sensitive to system failures such as gradient delays and off-resonance effects. For example, sensitivity with regard to artifacts caused by metal parts is more pronounced in the case of the radial collection of MR data than in the case of the Cartesian collection of MR data.