MRI safety of a programmable shunt assistant at 3 and 7 Tesla

Abstract

Objective. Several new shunt technologies have been developed to optimize hydrocephalus treatment within the past few years. Overdrainage, however, still remains an unresolved problem. One new technology which may reduce the frequency of this complication is the use of a programmable shunt assistant (proSA). Inactive in a horizontal position, it impedes CSF flow in a vertical position according to a prescribed pressure level ranging from 0 to 40 cm H₂O. Methods. We exposed the proSA valve in an ex vivo protocol to MR systems operating at 3 and 7 Tesla to investigate its MRI safety. Results. Following 3 Tesla exposure, no changes in valve settings were noted. Adjustment to any pressure level was possible thereafter. The mean deflection angle was 23 ± 3°. After exposure to 7 Tesla, however, there were unintended pressure changes, and the mechanism for further adjustment of the valves even disintegrated. Conclusion. According to the results of this study, proSA is safe with heteropolar vertical magnet alignment at 3 Tesla. Following 7 Tesla exposure, the valves lost their functional capability.

Keywords::

• anti-siphon device
• hydrocephalus
• shunt
• valve

Acknowledgments

We would like to thank Mr. Christoph Miethke and Jörg Knebel for the allowance of this pre-clinical, in vitro investigation and providing the valves for the MRI examination.

Disclosure

The authors have no conflict of interest to report concerning the materials or methods used in this study or the findings specified in this paper.

Dr. MJ Mirzayan received speaker's fee from Braun Company for lectures on treatment of hydrocephalus.

We have no personal or institutional financial interest in the investigated valve.