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 September 2018: The "MR kit" is open-source versatile hardware described in a new 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 can provide additional details.
  • A paper is published: 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: