Medical imaging in microgravity.

Microgravity environment induces significant pathophysiological changes in humans. As long-term space habitation and interplanetary missions become commonplace in the next century, researchers and imaging specialists must embrace the unique challenges of microgravity research in developing innovative uses of imaging technology. Microgravity results in cephalad fluid shift, loss of electrolytes, loss of muscle and bone mass, anemia, reduced immune response, variability in gastric emptying and hepatic metabolism, increased bowel transit, and development of space motion sickness. Medical imaging is uniquely capable of assessing all of these physiologic adaptations to weightlessness. The imaging information will also aid in identifying those changes which are potentially beneficial and those which are harmful to humans living in space. Interventions may then be employed to capitalize on the benefits and prevent the harmful effects. This article reviews the physiological adaptations to weightlessness and outlines ways in which medical imaging techniques may provide insight into these adaptations.