BACKGROUND: Prolonged bed rest results in a loss of leg lean body mass. Previous studies using bed rest as a model for microgravity have shown decreases in leg mass after 12 and 14 d, 5 and 17 wk. HYPOTHESIS: As magnetic resonance imaging (MRI) can provide a precise and non-invasive means of determining muscle volume, we sought to determine if changes in leg muscle volume could be detected in bed rest periods as short as 7 d. METHODS: Five young, healthy, male volunteers were subjected to 7 d of absolute bed rest. Each subject underwent MRI quantitation of segmental muscle volumes of the calves and thighs before and after bed rest. Eleven (calf) and nine (thigh) contiguous 1-cm thick transaxial images were generated over prescribed regions using a Technicare MRI imager with a 0.6T superconducting magnet and body coil. Image processing was performed using a generalized 8-bit medical image analysis package developed at University of Texas Medical Branch. Images were analyzed for muscle and non-muscle volumes (including fat, blood vessel, and bone marrow volumes). RESULTS: The MRI quantitation demonstrated bed rest-induced significant decreases in segmental thigh muscle (approximately 3.0%, p < 0.05) volume. CONCLUSIONS: We conclude that computerized image analysis of MRI images provides a sensitive tool capable of detecting leg volume changes of as little as 3.0% over a 7-d period of strict bed rest.
BACKGROUND: Prolonged bed rest results in a loss of leg lean body mass. Previous studies using bed rest as a model for microgravity have shown decreases in leg mass after 12 and 14 d, 5 and 17 wk. HYPOTHESIS: As magnetic resonance imaging (MRI) can provide a precise and non-invasive means of determining muscle volume, we sought to determine if changes in leg muscle volume could be detected in bed rest periods as short as 7 d. METHODS: Five young, healthy, male volunteers were subjected to 7 d of absolute bed rest. Each subject underwent MRI quantitation of segmental muscle volumes of the calves and thighs before and after bed rest. Eleven (calf) and nine (thigh) contiguous 1-cm thick transaxial images were generated over prescribed regions using a Technicare MRI imager with a 0.6T superconducting magnet and body coil. Image processing was performed using a generalized 8-bit medical image analysis package developed at University of Texas Medical Branch. Images were analyzed for muscle and non-muscle volumes (including fat, blood vessel, and bone marrow volumes). RESULTS: The MRI quantitation demonstrated bed rest-induced significant decreases in segmental thigh muscle (approximately 3.0%, p < 0.05) volume. CONCLUSIONS: We conclude that computerized image analysis of MRI images provides a sensitive tool capable of detecting leg volume changes of as little as 3.0% over a 7-d period of strict bed rest.
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NASA Discipline Regulatory Physiology; Non-NASA Center
Authors: Michelle E Kho; Alexander D Truong; Roy G Brower; Jeffrey B Palmer; Eddy Fan; Jennifer M Zanni; Nancy D Ciesla; Dorianne R Feldman; Radha Korupolu; Dale M Needham Journal: Phys Ther Date: 2012-03-15
Authors: Bette J Caan; Jeffrey A Meyerhardt; Candyce H Kroenke; Stacey Alexeeff; Jingjie Xiao; Erin Weltzien; Elizabeth Cespedes Feliciano; Adrienne L Castillo; Charles P Quesenberry; Marilyn L Kwan; Carla M Prado Journal: Cancer Epidemiol Biomarkers Prev Date: 2017-05-15 Impact factor: 4.254