Fig. 2: Longitudinal modulation of 3 T quantitative magnetic resonance (MR) DIXON map of the sagittal lumbar spine preflight and 41, 184, and 363 days following a long-duration space mission.

a A male astronaut. b A female astronaut. In this male astronaut, the heat map displays decreased bone marrow adiposity (BMA) in lumbar vertebrae 41 days postflight (colder colour at L4; white asterisk) and recovery 1-year postflight compared to preflight. In this female astronaut, the heat map displays decreased BMA in lumbar vertebrae 41 days postflight and increased BMA 1-year postflight (warmer colour at L4; white pound symbol) compared to preflight. White arrows point to the L4 vertebra. c, d High resolution 1H-MRS spectra from the L4 vertebral body in (c) a male astronaut; and (d) a female astronaut preflight and 41 days, 184, and 363 days postflight. Shown are eight spectra with the corresponding LCModel fit as a red line over each spectrum. Above each spectrum, the residuum of the LCModel fit is displayed, showing low noise residua and excellent fitting results of the resonances. The lipid methylene group at 1.3 ppm is, relative to the water resonance, decreasing at 41 days postflight (black arrows) and gradually increasing at 184 days and 1-year postflight for both vertebrae shown.