Effects of end-ring/shield configuration on homogeneity and signal-to-noise ratio in a birdcage-type coil loaded with a human head
✍ Scribed by Wanzhan Liu; Christopher M. Collins; Pamela J. Delp; Michael B. Smith
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 203 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
We modeled four different end‐ring/shield configurations of a birdcage coil to examine their effects on field homogeneity and signal‐to‐noise ratio (SNR) at 64 MHz and 125 MHz. The configurations are defined as: 1) conventional: a conventional cylindrical shield; 2) surrounding shield: a shield with annular extensions to closely shield the end rings; 3) solid connection: a shield with annular extensions connected to the rungs; and 4) thin wire connection: a shield with thin wires connected to the rungs. At both frequencies, the coil with conventional end‐ring/shield configuration produces the most homogeneous RF magnetic (B~1~) field when the coil is empty, but produces the least homogeneous B~1~ field when the coil is loaded with a human head. The surrounding shield configuration results in the most homogeneous B~1~ and highest SNR in the coil loaded with the human head at both frequencies, followed closely by the solid connection configuration. Magn Reson Med 51:217–221, 2004. © 2003 Wiley‐Liss, Inc.