Accuracy of a miniature intracranial pressure monitor, its function duringmagnetic resonance scanning, and assessment of image artifact generation

OBJECTIVE: We examined the accuracy and repeatability of an intracranial pr essure (ICP) monitor (Codman MicroSensor; Johnson & Johnson Professional, I nc., Raynham, MA) in a nonmagnetic environment and during magnetic resonanc e imaging (MRI). The resulting image artifact generation was calculated. JC P monitoring is essential in management of severe head injury, but few ICP monitoring devices are compatible with use in an MRI scanner. The use of MR I to assess head injury is increasing, and developing safe methods of conti nuously monitoring ICP may improve patient care. METHODS: A water manometer was used as the standard for comparison. We asse ssed pressure readings from the ICP monitor in a nonmagnetic environment us ing a standard and a long connector cable between the pressure transducer a nd display unit. This long cable permitted testing during MRI sequences bec ause the display unit could be distanced from the magnet. Accuracy was dete rmined during T2-weighted imaging, proton spectroscopy, and diffusion-weigh ted imaging, and artifact generation was assessed. RESULTS: We found a high degree of accuracy for repeated measurements over a clinical pressure range using both standard and long connector cables out side the MRI room. During MRI scanning, the ICP monitor was accurate during T2 and proton spectroscopy sequences. Accuracy during diffusion-weighted i maging, however, was clinically unacceptable. This ICP monitor creates a re duction in signal-to-noise ratio in the received signal during Ta-weighted imaging and proton spectroscopic imaging, with the obtained images still ra diologically interpretable. CONCLUSION: The Codman ICP monitor is sufficiently accurate and free of art ifact generation to be used during most clinical MRP applications. This cou ld enhance patient monitoring and safety.