Showing papers by "Jin Hyung Lee published in 2003"

Fast 3D imaging using variable‐density spiral trajectories with applications to limb perfusion

Abstract: Variable-density k-space sampling using a stack-of-spirals trajectory is proposed for ultra fast 3D imaging. Since most of the energy of an image is concentrated near the k-space origin, a variable-density k-space sampling method can be used to reduce the sampling density in the outer portion of k-space. This significantly reduces scan time while introducing only minor aliasing artifacts from the low-energy, high-spatial-frequency components. A stack-of-spirals trajectory allows control over the density variations in both the kx–ky plane and the kz direction while fast k-space coverage is provided by spiral trajectories in the kx–ky plane. A variable-density stack-of-spirals trajectory consists of variable-density spirals in each kx–ky plane that are located in varying density in the kz direction. Phantom experiments demonstrate that reasonable image quality is preserved with approximately half the scan time. This technique was then applied to first-pass perfusion imaging of the lower extremities which demands very rapid volume coverage. Using a variable-density stack-of-spirals trajectory, 3D images were acquired at a temporal resolution of 2.8 sec over a large volume with a 2.5 × 2.5 × 8 mm3 spatial resolution. These images were used to resolve the time-course of muscle intensity following contrast injection. Magn Reson Med 50:1276–1285, 2003. © 2003 Wiley-Liss, Inc.

Partial k-space reconstruction for radial k-space trajectories in magnetic resonance imaging

Abstract: A modified projection on convex sets (POCS) algorithm and method for partial k-space reconstruction using low resolution phase maps for scaling full sets of reconstructed k-space data. The algorithm can be used with partial k-space trajectories in which the trajectories share a common point such as the origin of k-space, including variable-density spiral trajectories, projection reconstruction trajectories with a semicircle region acquisition, and projection reconstruction trajectories with every other spike acquired.

Multi-coil reconstruction of MRI signals using linear phase multiplied data with separate demodulators for each coil

Abstract: Imaging time using PILS is reduced by using multiple coils with localized sensitivities with each coil having a separate demodulation channel thereby permitting parallel signal processing and image reconstruction. Images from the multiple coils are then combined to form an image with a larger field of view (FOV).