B1 transmit phase gradient coil for single-axis TRASE RF encoding
| Autor: | Jonathan C. Sharp, Scott B. King, Boguslaw Tomanek, Vyacheslav Volotovskyy, Qunli Deng |
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| Rok vydání: | 2013 |
| Předmět: |
diode
Image quality Acoustics Transducers Biomedical Engineering Biophysics Phase (waves) Sensitivity and Specificity mathematical analysis process model Magnetics Nuclear magnetic resonance signal detection image analysis process optimization process technology Image Interpretation Computer-Assisted image quality Radiology Nuclear Medicine and imaging nuclear magnetic resonance imaging Linear phase Physics process design Phantoms Imaging Reproducibility of Results Equipment Design Transmit Array Spatial Encoding magnetic resonance imaging Image Enhancement Magnetic Resonance Imaging image processing Equipment Failure Analysis Amplitude Transducer Electromagnetic coil Radio frequency Radiofrequency coil |
| Zdroj: | Magnetic Resonance Imaging. 31:891-899 |
| ISSN: | 0730-725X |
| DOI: | 10.1016/j.mri.2013.03.017 |
| Popis: | Purpose TRASE (Transmit Array Spatial Encoding) MRI uses RF transmit phase gradients instead of B 0 field gradients for k-space traversal and high-resolution MR image formation. Transmit coil performance is a key determinant of TRASE image quality. The purpose of this work is to design an optimized RF transmit phase gradient array for spatial encoding in a transverse direction (x- or y- axis) for a 0.2 T vertical B 0 field MRI system, using a single transmitter channel. This requires the generation of two transmit B 1 RF fields with uniform amplitude and positive and negative linear phase gradients respectively over the imaging volume. Materials and Methods A two-element array consisting of a double Maxwell-type coil and a Helmholtz-type coil was designed using 3D field simulations. The phase gradient polarity is set by the relative phase of the RF signals driving the simultaneously energized elements. Results Field mapping and 1D TRASE imaging experiments confirmed that the constructed coil produced the fields and operated as designed. A substantially larger imaging volume relative to that obtainable from a non-optimized Maxwell-Helmholtz design was achieved. Conclusion The Maxwell (sine)–Helmholtz (cosine) approach has proven successful for a horizontal phase gradient coil. A similar approach may be useful for other phase-gradient coil designs. |
| Databáze: | OpenAIRE |
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