MRI-Based Investigation into the Effects of Simulated Microgravity on Cerebrospinal Fluid and Vascular Flow
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National Aeronautics and Space Administration (NASA) astronauts have reported decrease in visual acuity due to Microgravity Ocular Syndrome (MOS) after returning from long duration space missions. It is hypothesized that MOS results from a head-ward fluid shift induced by the effects of microgravity. This shift increases intracranial pressure (ICP) resulting in optic nerve damage and visual impairment (Gerlach et al., 2017). Previous studies on MOS have examined Magnetic Resonance Imaging (MRI) scans of subjects on earth under simulation of microgravity. These studies have utilized the proportionality between posture and intracranial pressure in the Head Down Tilt (HDT) protocol for simulating the effects of microgravity. The protocol consists of two scans: a baseline scan in the supine position (0°) and a head down tilted scan at a specific angle for comparison. We used the MRI scans conducted at Emory University’s Center for Systems Imaging to analyze changes in arterial and venous blood flow under simulations of microgravity. Ten healthy volunteers underwent two MRI scans: one scan at a HDT of -15° to simulate the effects of microgravity and another scan in the supine position (0°) to serve as a baseline for comparison. Results from the scans showed a decrease in arterial blood flow in the HDT position but no change in venous blood flow in the HDT position.