Xiaowei Zou

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Despite rigid-body realignment to compensate for head motion during an echo-planar imaging time-series scan, nonrigid image deformations remain due to changes in the effective shim within the brain as the head moves through the B(0) field. The current work presents a combined prospective/retrospective solution to reduce both rigid and nonrigid components of(More)
MR contrast agents are used to improve the detectability of pathologic conditions. In this study we clarify the mechanism of action of a newly developed superparamagnetic agent (AMI-25, Advanced Magnetics Inc., Cambridge, MA). Transverse relaxation rates were measured from segments of rat brain, heart, and liver using a CPMG pulse sequence. Relaxation rates(More)
Two types of artifacts--a mirror-reversed image about the phase-encode direction and a wave-like intensity variation across the image--may appear when using a conventional multiecho spin-echo sequence. We describe and demonstrate a new method, which eliminates such artifacts, using only one excitation per phase-encoding step and without the need for spoiler(More)
PURPOSE A novel longitudinal relaxation time (T1 ) measurement method using complex amplitude modulation is presented. THEORY The method applies a series of inversion pulses to the imaged region in accordance with a binary modulation sequence. The longitudinal magnetization acquired in a given pulse repetition time (TR) interval is the sum of the(More)
A new NMR method for producing angiograms with strong suppression of the static spin signal and without the need for subtraction is described and demonstrated. A velocity-selective pulse sequence was implemented whereby the magnetization of all stationary spins is driven to the -z axis and is not detected, while maximizing the signal intensity of the moving(More)
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