Parallel RF Transmission: RF Shimming GUI

Parallel transmission experiments require knowledge of the B₁⁺ distributions of individual coil transmit elements in order to tailor the RF excitation as desired. In addition to B₁⁺ distributions, B₀ maps and, if needed, power correlation matrices must be measured / calibrated before designing parallel transmission RF pulses. Even after scanner-related-measurements are acquired, RF pulse design requires inputs such as the desired excitation profile, the choice of RF pulse design method, the excitation k-space trajectory and so on. Since parallel transmit systems are still in the development stage, the workflow of obtaining the abovementioned inputs and designing parallel transmission RF pulses is not yet supported with intuitive graphical user interfaces (GUIs) of the sort used in clinical MRI scans. The lack of application specific GUIs for parallel transmit systems results in inefficiencies in the MRI scan workflow, e.g. longer experiments and operator errors. In order to increase the efficiency and accuracy of parallel transmit experiments, we developed and used custom-designed GUIs in the Matlab programming environment.

The GUIs provided here can be used not only for parallel transmit experiments but also for transmit coil design (e.g. using electromagnetic simulation results as inputs to test the suitability of prospective coil designs) and for educational purposes (e.g. for practice in RF pulse design).

RF Shimming GUI

RF shimming GUI (RFShimGUI) was developed for and used in the maximum efficiency RF shimming study which was published here. The download includes Matlab executable files for 64bit Windows.

Brief details of the implementation and the workflow of the RFShimGUI was extracted from Cem M. Deniz's PhD thesis and can be found here.

Example dataset as an input to RFShimGUI:

• 4-channel in vivo hip B₁⁺ maps used in the manuscript can be found here and the measured Φ-matrix with 20V calibration voltage.
• 8-channel in vivo brain flip angle maps from 7T scanner can be found here.

Note: You need the Matlab Compiler Runtime (MCR) version 8.5 in order to run executable files. If you don't have it installed please download and install it from Matlab website using this link

Please let me know if you had any problems installing GUIs or find any bugs of the software (cemmurat.deniz@nyumc.org).