Automatic tuning and matching of a small multifrequency saddle coil at 4.7 T
✍ Scribed by Rigoberto Pérez de Alejo; Carlos Garrido; Palmira Villa; Ignacio Rodriguez; Juan José Vaquero; Jesús Ruiz-Cabello; Manuel Cortijo
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 221 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
A new circuit design for automatically tuning and matching a saddle coil for small animal imaging is presented. This design allows working at ^1^H, ^19^F, and ^3^He resonance frequencies in a 4.7 T spectrometer. It is based on a balanced circuit with commercial variable capacity diodes controlled by a computer using digital potentiometers. The change between two different frequencies can be accurately performed in a few seconds. System Q is compared, between 140–210 MHz, to the same coil tuned and matched with high Q variable capacitors. Differences lower than 5% were found with a loaded coil. The proposed design has initially been evaluated in ^19^F and ^1^H NMR images acquired with a five‐tube phantom. An application is also shown for the acquisition of ^3^He, ^19^F, and ^1^H lung images in a control rat. Magn Reson Med 51:869–873, 2004. © 2004 Wiley‐Liss, Inc.