Berry P, Berry I, Manelfe C
MRI Unit, Hôpital Purpan, Toulouse, France.
Aviat Space Environ Med. 1993 Mar;64(3 Pt 1):212-8.
Head-down (-6 degrees) bed rest, a microgravity simulation model in humans, leads to muscular atrophy of the lower limbs. Magnetic Resonance Imaging (MRI) at 0.5 tesla was performed at 1 year intervals on the same six volunteers (except one) before and after 1 month bed rest. Three of the six subjects were daily exposed in a lying position to LBNP (lower body negative pressure), a countermeasure to cardiovascular deconditioning (LBNP group). The groups were exchanged the second year. After bed rest, the quadriceps of the thigh lost uniformly 11% of its cross section area (CSA) and the triceps of the leg 10.5%, with 12.8% lost from the deeper soleus versus 8.5% from the gastrocnemius (p < 0.05). LBNP produced no effect on these changes. The MRI signal intensity of muscles exhibited a trend toward higher values after bed rest although without statistical significance. MRI allowing for noninvasive and reliable quantification of muscle fibers of the lower limbs is an excellent procedure for the assessment of muscle disuse and countermeasures.
头低位（-6度）卧床休息是一种人体微重力模拟模型，会导致下肢肌肉萎缩。在6名志愿者（除1人外）卧床休息1个月前后，每隔1年使用0.5特斯拉的磁共振成像（MRI）进行检查。6名受试者中有3人每天以躺卧姿势接受下体负压（LBNP），这是一种针对心血管功能失调的对策（LBNP组）。第二年两组进行了交换。卧床休息后，大腿股四头肌的横截面积（CSA）平均减少了11%，小腿三头肌减少了10.5%，比目鱼肌深部减少了12.8%，腓肠肌减少了8.5%（p<0.05）。LBNP对这些变化没有影响。卧床休息后，肌肉的MRI信号强度呈升高趋势，但无统计学意义。MRI能够对下肢肌肉纤维进行无创且可靠的量化，是评估肌肉废用及相应对策的极佳方法。
