Non-Invasive Monitoring of Intracranial Pressure (ICP) with Volumetric Ophthalmic Ultrasound
Aaron Dentinger, Ph.D.
General Electric Company
Elevated levels of intracranial pressure (ICP), the pressure of the cerebrospinal fluid within skull, have been shown to be correlated with changes in ocular structures. Further research is still needed to understand the role elevated ICP plays in visual impairment observed during and following space missions.
The objective of this research is to non-invasively monitor ICP by detecting changes in the structure and functioning of the eye using 3-D ultrasound imaging. An ultrasound probe for ophthalmic scanning through a closed eyelid will be developed and integrated with a portable, high-resolution medical ultrasound scanner.
The new volumetric ultrasound system will provide user independent views of the entire ocular anatomy in a single scan with minimal crew time and ground guidance during image capture. Volumetric ultrasound data taken pre-flight, post-flight and in-flight will be aligned with pre-flight and post-flight magnetic resonance scans allowing in-flight changes in the ocular anatomy to be tracked over time. Sonographs of the optic nerve and globe will be extracted from the volumetric ultrasound data, and reliable measurement techniques for the size and shape of these structures will be developed to serve as indirect measures of ICP. Ultrasound ophthalmic scanning will also be used to measure fluctuations in the ICP and the blood flow in the retinal vessels to monitor the body's ability to compensate for changes in the ICP.
This research will lead to the development of tools to noninvasively monitor ICP and the body's ability to compensate for increases in ICP. The simplified ocular scan and new ocular metrics will provide the ability to track the short-term and long-term time course of ICP with minimal burden on the crew, to determine the correlation of ICP with visual acuity changes in response to microgravity, and to investigate effectiveness of potential treatments. In addition to in-flight monitoring of crew health during space missions, these techniques are applicable to many clinical applications where ICP plays a key role, such as monitoring patients with head trauma.