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. As an example of use, an electronic phantom is implemented. The hardware 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 a programmable FPGA, and the results are transferred to the scanner as a modulated RF signal that is recorded together with MRI raw data ("Magstripe encoding"). 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: