Irina Brote1,2, Klaus Solbach3, Stephan Orzada1,2, Oliver Kraff1,2, Stefan Maderwald1,2, Mark E. Ladd1,2, Andreas K. Bitz1,2
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany; 2Department of Diagnostic & Interventional Radiology & Neuroradiology, University Hospital Essen, Essen, Germany; 3High Frequency Engineering, University Duisburg-Essen, Duisburg, Germany
RF real time monitoring is a major concern for multi-channel transmit systems. Here an approach is proposed which incorporates online monitoring of both the RF phase and amplitude by use of directional couplers and I/Q demodulators; the forward and reflected signals can be monitored. Furthermore, this set-up enables the direct assessment of the complex scattering matrix of the loaded coil array in just 10 s for an 8-channel system. The implemented monitoring system can be utilized for transmit SENSE applications to monitor the full waveform (phase and amplitude) of the multi-dimensional pulses.