Variations of CT-based trunk muscle attenuation by age, sex, and specific muscle.
BACKGROUND
Fat accumulation in muscle may contribute to age-related declines in muscle function and is indicated by reduced attenuation of x-rays by muscle tissue in computed tomography scans. Reduced trunk muscle attenuation is associated with poor physical function, low back pain, and increased hyperkyphosis in older adults. However, variations in trunk muscle attenuation with age, sex and between specific muscles have not been investigated.


METHODS
A cross-sectional examination of trunk muscle attenuation in computed tomography scans was performed in 60 younger (35-50 years) and 60 older (75-87 years) adults randomly selected from participants in the Framingham Heart Study Offspring and Third Generation Multidetector Computed Tomography Study. Computed tomography attenuation of 11 trunk muscles was measured at vertebral levels T8 and L3, and the effects of age, sex, and specific muscle on computed tomography attenuation of trunk muscles were determined.


RESULTS
Muscle attenuation varied by specific muscle (p < .001), was lower in older adults (p < .001), and was generally lower in women than in men (p < .001), although not in all muscles. Age-related differences in muscle attenuation varied with specific muscle (p < .001), with the largest age differences occurring in the paraspinal and abdominal muscles.


CONCLUSIONS
Trunk muscle attenuation is lower in older adults than in younger adults in both women and men, but such age-related differences vary widely between muscle groups. The reasons that some muscles exhibit larger age-related differences in fat content than others should be further explored to better understand age-related changes in functional capacity and postural stability.
Beth Israel Deaconess Medical Center, 330 Brookline Ave, RN115, Boston, MA 02215, USA. danders7@bidmc.harvard.edu
Dennis E
DE
Anderson
John M
JM
D'Agostino
Alexander G
AG
Bruno
Serkalem
S
Demissie
Douglas P
DP
Kiel
Mary L
ML
Bouxsein
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D061330:Multidetector Computed Tomography; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D012494:Sampling Studies; D012737:Sex Factors; D060726:Torso