Abstract
OBJECTIVE: Implementation of a decoupling method for isolation of transmit and receive radio frequency (RF) coils for concurrent excitation and acquisition (CEA) MRI in samples with ultra-short T2*.
MATERIALS AND METHODS: The new phase and amplitude (PA) decoupling method is implemented in a clinical 3T-MRI system equipped with a parallel transmit array system. For RF excitation, two transmit coils are used in combination with a single receive coil. The transmit coil is geometrically decoupled from the receive coil, and the remaining B 1-induced voltages in the receive coil during CEA are minimized by the second transmit coil using a careful adjustment of the phase and amplitude settings in this coil. Isolation of the decoupling scheme and transmit noise behavior are analyzed for different loading conditions, and a CEA MRI experiment is performed in a rubber phantom with sub-millisecond T2* and in an ex vivo animal.
RESULTS: Geometrical (20 dB) and PA decoupling (50 dB) provided a total isolation of 70 dB between the transmit and receive coils. Integration of a low-noise RF amplifier was necessary to minimize RF transmit noise. CEA MR images could be reconstructed from a rubber phantom and an ex vivo animal.
CONCLUSION: CEA MRI can be implemented in clinical MRI systems using active decoupling with parallel transmit array capabilities with minor hardware modifications.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 565-576 |
| Number of pages | 12 |
| Journal | Magma (New York, N.Y.) |
| Volume | 28 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 1 2015 |
| Externally published | Yes |
Keywords
- Concurrent excitation and acquisition
- Continuous-wave NMR
- Geometrical decoupling
- Phase amplitude decoupling
- Transmit array
ASJC Scopus subject areas
- Radiological and Ultrasound Technology
- Biophysics
- Radiology Nuclear Medicine and imaging