Browsing by Author "McLeish, K"

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    Free-breathing radial acquisitions of the heart
    (2004) McLeish, K; Kozerke, S; Crum, WR; Hill, DLG
    There is considerable interest in performing free-breathing acquisitions of the heart in order to obtain high-quality images without the need for multiple, long breathholds. In this article a 3D motion-correction method is described that is based on image registration of in-plane data and through-plane slice tracking. A number of fast radial undersampled images are acquired, each of which is free of motion artifacts. Initially, in-plane translational and rotational motion between each image was corrected before combining the data to give a fully sampled image. At the next stage, correction of in-plane deformation, in addition to translations and rotations, was performed in the image domain. Through-plane translational motion was compensated using a navigator echo to move the acquisition plane. Using this method, information on the motion of the heart was captured at the same time as acquiring the image data. No motion model, assumptions about the motion, or training data are required. The method is demonstrated on phantom data and cardiac images acquired on free-breathing volunteers. Magn Reson Med 52:1127-1135, 2004. (C) 2004 WileyLiss, Inc.
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    Scan time reduction with an adaptive field of view
    (ELSEVIER SCIENCE INC, 2005) McLeish, K; Irarrazaval, P
    In magnetic resonance imaging (MRI), there is always a drive toward reducing the acquisition time. In volume imaging, time is often spent in acquiring data where there exists no signal because the imaging volume is larger than the object. In this paper, a method is presented for scan time reduction using an adaptive field of view (FOV). Multislice images are acquired with the FOV in the phase encoding direction of each slice determined by measurements made on the initial localization survey scan. Depending on the region of interest, an optimized FOV is also determined so that scan time is reduced in comparison to a normal scan while improving image resolution. The method is simple to implement and requires no additional hardware. Typical reductions in scan time are on the order 9-14%. (C) 2005 Elsevier Inc. All rights reserved.