| Autor: |
Andrew R. Bogdan, Peter M. Joseph |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Journal of Magnetic Resonance (1969). 91:527-538 |
| ISSN: |
0022-2364 |
| DOI: |
10.1016/0022-2364(91)90379-8 |
| Popis: |
A novel radiofrequency coil design which is especially useful for NMR imaging of sodium in small samples is described. The structure is neither a saddle nor a birdcage coil type, but rather consists of a series of tuned loops. In principle, the loops are not electrically connected to each other and the main interaction between them is by electromagnetic induction. The coil has approximate circular symmetry and uses much smaller capacitors than does the birdcage design. It is shown theoretically how a rotating held can be created by detuning two modes of the coil, and that the resulting impedance-frequency relationship differs substantially from that usually found in resonant circuits. It is shown that it is possible to use the coil simultaneously as both a transmitter and a receiver with no external phase-shifting networks, by using independent inductively coupled feed loops for transmitting and receiving. The behavior of the coil was studied in some detail using computer simulation, and a working model has been constructed and used for in vivo imaging of endogenous sodium in rats at 1.9 T. The theoretical analysis and experimental results indicate very high spatial homogeneity of the field and improved signal-to-noise ratio. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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