The circuit described in this study is intended for Magnetic Resonance Imaging
(MRI) application. The function of this circuit is to transmit RF energy to the sample
and then receive the RF energy. The circuit that does this is called a birdcage coil. This
coil is capable of producing a very homogenous B1 field over a large volume; it is this
aspect of birdcage coils that make them very favorable for animal/human studies as it is
necessary that all nuclei in the volume of the coil are excited by uniform RF energy. At
high-field (4.7T) when the power is fed to the coil at a single port the coil unable to
produce a homogenous B1 field. However when power is fed at multiple ports the
performance of the coil improves. In this paper a study is carried out comparing the
performance of the coil when power is fed at a single port and two ports. The advantage
of feeding at two ports is that there is sqrt(2) improvement in SNR and the RF power
efficiency is doubled. In this work strategies are presented for matching, tuning and
isolating the two ports. Also, an attempt is made to fabricate a mechanically rigid coil
and interfacing the coil with some additional features that will make the coil easy to use.
The homogeneity and SNR of a birdcage coil in linear and quadrature mode loaded with
saline, oil and CuSO4 phantom was measured on the bench and the scanner. The coil performance was compared to two other birdcage coils in the lab. It was found that the
unshielded trombone coil that was 3 times smaller in volume than the coil presented has
140% higher SNR than the coil presented but the homogenous region of the coil
presented is 48% higher than the smaller coil. Lastly on the bench; the SNR of the
quadrature coil was 30% higher than the coil in the linear mode.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85902 |
| Date | 10 October 2008 |
| Creators | Kampani, Vishal Virendra |
| Contributors | Wright, Steven M. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, born digital |
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