title: GRAPPA operator for wider radial bands (GROWL) with optimally regularized self-calibration.
abstract: A self-calibrated parallel imaging reconstruction method is proposed for azimuthally undersampled radial dataset. A generalized auto-calibrating partially parallel acquisition (GRAPPA) operator is used to widen each radial view into a band consisting of several parallel lines, followed by a standard regridding procedure. Self-calibration is achieved by regridding the central k-space region, where Nyquist criterion is satisfied, to a rotated Cartesian grid. During the calibration process, an optimal Tikhonov regularization factor is introduced to reduce the error caused by the small k-space area of the self-calibration region. The method was applied to phantom and in vivo datasets acquired with an eight-element coil array, using 32-64 radial views with 256 readout samples. When compared with previous radial parallel imaging techniques, GRAPPA operator for wider radial bands (GROWL) provides a significant speed advantage since calibration is carried out using the fully sampled k-space center. A further advantage of GROWL is its applicability to arbitrary-view angle ordering schemes.
authors.affiliation: Invivo Corporation, Philips Healthcare, Gainesville, Florida 32608, USA. wei.lin2@philips.com
authors.forename: Wei
authors.initials: W
authors.lastname: Lin
authors.forename: Feng
authors.initials: F
authors.lastname: Huang
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.forename: Arne
authors.initials: A
authors.lastname: Reykowski
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D002138:Calibration; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States