Lin C, LeBlanc AD, Evans HJ, Shackelford L, Organov V, Driscoll T, Hedrick T.

J Bone Miner Res. 1999 Sep; 14 Suppl 1: S265.

Baylor College of Medicine, Houston, TX, USA.

Magnetic resonance relaxation time (T2) changes in the cellular component of vertebral (L3) bone marrow (mT2) were observed in the crewmembers following a 17-day shuttle mission. The purpose of this study was to determine mT2 changes in L3 after long duration space flight and bedrest and to correlate changes in mT2 with the changes in spine BMD. Using localized magnetic resonance spectroscopy with a Siemens 1.5T MRI system and a Hologic DEXA bone densitometer, we measured mT2 in L3 vertebra and spine BMD (L1-L4) of 7 MIR space station crew who spent 4-6 months in microgravity and in 15 subjects in an ongoing 17week bed rest study. Among the 15 bed rest subjects, 6 were enrolled in a 1hr daily exercise program, 5 were given 10mg Alendronate per day as potential countermeasures against disuse bone loss and 4 were controls with no countermeasure. In addition, mT2 was measured in 7 ambulatory normal controls over a 2 year period. For the long-duration space flights, we found that the mT2 was below pre-flight baseline immediately post-flight (-12.5%, P=0.02) and quickly increased to a level above baseline (23.5%, P=0.010). It remained elevated for several months before gradually returning to pre-flight level. For bed rest subjects with countermeasures, mT2 increased during bed rest (9.5%, P=0.025) and remained elevated (17.3%, P=0.006) after bed rest for several months before returning to baseline. There was no significant change in mT2 for the control group during bedrest (3.0%, P=0.22), however, it increased after bed rest, (10.5%, P=0.016). For the ambulatory controls, mT2 did not change. There was no correlation between baseline mT2, the age of the subjects or baseline spine BMD. However, the correlation of the change in mT2 and the change in BMD during bed rest and space flight was highly significant (R=0.6, p<0.003). These results suggest that the observed changes in mT2 are related to the regional bone density changes in the spine.

Publication Types:

• Meeting Abstracts

Keywords:

• Bed Rest
• Bone Density
• Bone Marrow
• Exercise
• Lumbar Vertebrae
• Magnetic Resonance Imaging
• Space Flight
• Weightlessness
• Weightlessness Countermeasures
• NASA Center JSC
• NASA Discipline Musculoskeletal
• Non-NASA Center

Other ID:

• 20604052

UI: 102194996

From Meeting Abstracts