MRI of the central nervous system in rats following heliox saturation decompression

Aims: The main objectives of the present study was to establish an animal model of decompression sickness (DCS) after heliox saturation diving, and to use this model to evaluate possible morphological changes in the CNS induced by DCS using structural MRI. Methods: Two groups of rats were pressurized with heliox to 5 bar (pO(2')=50 kPa). The saturation time was three hours; decompression rate was 1 bar/10 seconds or 1 bar/20 seconds. A 7.0 Tesla small animal MRI scanner was used for detection of possible morphological changes in the brain and spinal cord, two hours and one week after the dive, compared to one week prior to the dive. Results: Neurological symptoms of DCS were observed in seven out of 10 animals. MRI of the brain and spinal cord did not reveal any morphological CNS injuries. Conclusion: This diving procedure was successful in causing DCS in a large proportion of the animals. However, despite massive neurological signs of DCS, no visible CNS injuries were observed in the MRI scans.