Brain Quantitative MRI Metrics in Astronauts as a Unique Professional Group.

BACKGROUND AND PURPOSE: As part of its technological sophistication, the International Space Station (ISS) Program operates a robust medical surveillance schedule for its rotating 6-person crew to control the known health risks and to address knowledge gaps related to human health in space flight environment. Recent evidence on visual impairment in a subset of ISS crew has renewed the interest in the effects of long-duration space flight on the central nervous system (CNS). Through retrospective analysis in a sample of 10 healthy astronauts, we demonstrate the utility of multimodal quantitative magnetic resonance imaging (qMRI) with diffusion tensor imaging (DTI)-based customized brain templates to examine the structural attributes of various CNS compartments in this occupational group.

METHODS: The study included 10 healthy astronauts (45-55 years). All subjects had previous space flights with the median duration of 110 days. Multimodal quantitative structural imaging modalities performed and used in analyses.

RESULTS: A host of CNS features are presented, which are largely commensurate with the available normative data. Remarkably, some of our findings demonstrate statistically significant positive features suggestive of structural neuroplasticity conceivably associated with the professional activities of astronauts, and compensatory neurogenesis that counterweighs the expected normative volume loss with age.

CONCLUSIONS: The novelty of this exploratory report is in the demonstration of a qMRI toolset as a potential capability for characterization and surveillance of unique professional groups, and for future prospective examinations of the effects of various long-term exposures on CNS.