BioSemi.nl

Hi,

Is there any safety reason (to the equipment as well as the subject) not to try use Biosemi in an MRI environment? The idea is not to do simultaneous EEG-fMRI acquisition but to alternate them (i.e. only collect EEG while the scanner is off). Some MRI compatible systems (eg. neuroscan) keep the ADC outside the scanner (but inside the scanner room) and run the electrode leads into the scanner. If the ActiveII setup is properly secured outside the scanner could it be damaged by the magnetic or RF fields? If the active electrodes & CMS/DRL are properly secured in the cap inside the scanner (and are proven to stay in situ during scanning), and the leads are also properly secured, is there prima facie reason to expect that they may be damaged by the electromagnetic fields?

Barak

The ActiveTwo system (AD-box and active electrodes) will not be damaged by the magnetic and RF fields. However, there is certainly an issue with respect to subject safety.

The RF fields during the scan may induce large currents in electrode wires inside the scanner (certain lengths of wire may act as an effective antenna). There have been incidents reported (with non-BioSemi systems) where this effect resulted in currents large enough to cause local skin burns on the subject. Therefore, MRI compatible system have to use carbon wires and safety resistors near the electrodes to prevent high current flow via the electrodes.

Since the ActiveTwo is not designed as an MRI compatible system, our standard active electrodes and wiring do not meet the special safety standards required for use in the MRI (we use copper wiring, and no additional safety resistors).

I don't immediately see dangers in case the actual scanner is turned off (just the large static magnetic field present, no RF fields). However, please regard this statement as a basis for further discussion, and certainly not as a declaration by the manufacturer that the ActiveTwo can be safely used in an non-scanning MRI

Best regards, Coen (BioSemi).