Toward accessible MRI: SDR4MR, a simple RF pulse monitoring technique using an inexpensive software-defined radio.

Objective: This study evaluated the applicability and performance of the SDR4MR method at 1.5 T and 3 T across different acquisition scenarios in a clinical environment.

Materials and methods: The SDR4MR hardware consists of a broadband receiver coil connected to a software-defined radio (SDR) via optional RF attenuators. The SDR stick is plugged into the computer's USB port, which runs the SDR software and a Mathematica script to decode the RF pulse sequence. Several MRI pulse sequences were recorded: (i) a multi-echo multi-slice spin echo sequence to check the SDR4MR configuration on a well-known simple sequence; (ii) 2D and 3D sequences for which detailed information is not available in the user interface.

Results: The measured RF pulse sequences have been drawn in the style of illustrations found in MRI textbooks. Sequence times and amplitudes were estimated, and sequence details not described in the MRI user interface were retrieved.

Conclusion: The present study demonstrated the implementation of SDR4MR on clinical scanners. This easy-to-use configuration enables precise monitoring of RF pulse sequences. This method could be further improved by taking advantage of advances in SDR hardware and software.