Sunday, 05 August 2018 16:37

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 August 2018: The "MR kit" is open-source versatile hardware described in an upcoming 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.

  • "MR kit" hardware layout. Details or changes may be added. Ask the developer Christian G. Hanson or brother Lars G. Hanson, who provide additional details.
  • A paper is upcoming: Jan Ole Pedersen et al, Concepts of Magnetic Resonance part B
  • The first ISMRM abstract based on the "MR kit" demonstrates proof of concept for a k-space sensor (proceedings of the ISMRM 25th Annual Meeting, p. 3906, 2017). The data quality improved much in the meantime, mostly due to regularization by a gradient coil current measure used to avoid noise accumulation over time.

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: