Abstract
A new class of NMR RF volume coils is being developed that permits improved tuning range, B1 homogeneity, tuning stability, and sensitivity compared to birdcages over a wide range of practical conditions, especially for microscopy and wraparound flexible applications. They are denoted litz coils, as their flux transparency and current distribution is obtained from woven foil patterns with insulated crossovers. Contrary to the design criteria of phased arrays, the parallel routes in litz coils use high coupling coefficients to achieve optimal current distribution, which is highly independent of tuning, balancing, and matching adjustments and is compatible with multiple capacitive segmentation. Magnetic filling factors, loaded Q, and inhomogeneity measurements and calculations are presented for a variety of litz coils with frequency-diameter products from 7 to 20 MHz-m and are compared to similar birdcages.
Original language | English |
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Pages (from-to) | 17-31 |
Number of pages | 15 |
Journal | Journal of Magnetic Resonance |
Volume | 140 |
Issue number | 1 |
DOIs | |
State | Published - Sep 1999 |
Externally published | Yes |
Funding
The authors thank the Center for Structural Biology at the University of Florida for the spinal cord image and Y. Kanazawa for the motivation to advance MRI coil technology. The authors also thank numerous technicians and engineers at (or formerly at) Doty Scientific, especially Xunming Chen, Andy Yang, David McCree, John Staab, Jiong Shao, Art Boman, Vince Cothran, and Mark Moore for their assistance in programming, experiments, calculations, analysis, and prototyping. This work was supported by Doty Scientific, Inc.
Keywords
- Birdcage
- Double-resonance
- Litz coil
- Multinuclear