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Effects of RF amplifier distortion on selective excitation and their correction by prewarping

✍ Scribed by Frandics Chan; John Pauly; Albert Macovski

Publisher: John Wiley and Sons
Year: 1992
Tongue: English
Weight: 736 KB
Volume: 23
Category: Article
ISSN: 0740-3194
DOI: 10.1002/mrm.1910230204

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✦ Synopsis

Abstract

In a magnetic resonance imaging system, an RF power amplifier is employed to boost an RF pulse to sufficient strength to excite the nuclear spins in a subject. The nonideal behavior of this amplifier distorts a selective‐excitation pulse, and this distortion in turn degrades the slice profile. We have found two types of nonideal behavior particularly troublesome: nonlinearity and incidental phase modulation. One of their effects is the introduction of an unwanted “skirt” in the out‐of‐slice region of a slice profile. We present an effective method of correction in which a selective‐excitation pulse is prewarped to compensate for the distortion. © 1992 Academic Press, Inc.

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