Encoding of non-MR signals in scanner recordings

Scanners can measure more than you think, and often better than dedicated systems.

Versatile hardware and methods for recording, processing and encoding non-MR signals in scanner recordings were developed by the DRCMR Acquisition Technology group and collaborators. This page provides details of this so-called "Magstripe encoding" named after a similar method earlier used to encode soundtracks in motion pictures as magnetic stripes outside the field-of-view (see figure).Figure from Wikipedia

New in July 2019:  A paper by J. O. Pedersen et al entitled Inductive measurement and encoding of k-space trajectories in MR raw data is accepted for publication in Magn Reson Mater Phy (MAGMA). We demonstrate that the hardware described here can encode accurate k-space trajectories in MR raw data during EPI and spiral imaging. A preprint is available.

Versatile open-source hardware is described in a paper in Concepts of Magnetic Resonance part B. It is designed to record time-critical non-MR signals during scanning, e.g. gradient activity and RF power (4 inputs in total). These are processed in real time using an FPGA (fast programmable chip), and the results are transferred to the scanner as a modulated RF signal that is recorded together with MRI raw data ("Magstripe encoding"). As an example of use, an electronic phantom is implemented. Additional fast USB signal transfer to a PC is also possible.

Related hardware: The above-mentioned new hardware opens for other applications than an earlier developed "multi-frequency amplitude modulator" that features amplitude modulation of 8 analog inputs to different carrier frequencies near the demodulation frequency of an MR scanner: