To explore the change patterns in the lumbar vertebral bone marrow fat content with age, analyze the interactions between lumbar vertebral bone marrow fat content, bone mineral density (BMD), and age, and compare the difference of lumbar vertebral bone marrow fat content between males and females in the same age groups.

According to the statistical sample size requirements that the minimum sample size of each group was 18, thus, we prospectively recruited healthy volunteers who met the inclusion criteria. Among them, there were 139 males and females, with age range of 21-70 years old. According to age, the patients were divided into group 1 (21-30-yr), group 2 (31-40-yr), group 3 (41-50-yr), group 4 (51-60-yr), and group 5 (61-70-yr). Quantitative computed tomography (QCT) was used to measure the lumbar vertebral BMD, and MR mDIXON-Quant technique was used to measure the marrow fat content of L3 lumbar vertebra. We compared the difference of lumbar vertebral bone marrow fat content and BMD between different age groups in males and females using one-way ANOVA, and compared the difference of lumbar vertebral bone marrow fat content and BMD between males and females in the same age groups using t-test. Correlation analysis was conducted between bone marrow fat content, BMD and age.

Lumbar vertebral bone marrow fat content was generally increasing with the age. There were significant differences in the fat content of bone marrow at different age groups (male, F=13.598, P=0.000; female, F=73.419, P=0.000). Before the age of 50 years, lumbar vertebral bone marrow fat content in females was lower than one in males, and there was a significant difference between group 2 [females, (29.7±7.1) %- (36.1±6.6) %, males, (34.1±8.4) %- (39.9±5.9) %;21-30-yr, t=1.984, P=0.053;31-40-yr, t=5.699, P=0.000;41-50-yr, t=2.017, P=0.050]. Females older than 50 years had a higher marrow fat content than males, and there was a significant difference between group 5 [females, (48.3±8.8) %- (52.5±8.2) %, males, (45.5±8.1) %- (46.2±7.4) %;51-60-yr, t=-0.914, P=0.365;61-70-yr, t=-3.400, P=0.001]. For males, bone marrow fat content was positively correlated with age (r=0.527, P<0.05), and negatively correlated with BMD (r=-0.730, adjusted for age r=-0.584, P<0.05). For females, bone marrow fat content was positively correlated with age (r=0.761, P<0.05), and negatively correlated with BMD (r=-0.809, adjusted for age r=-0.473, P<0.05).

Lumbar vertebral bone marrow fat content was generally increasing with the age. Bone marrow fat content was positively correlated with age and negatively correlated with BMD for males and females.

Lumbar vertebrae; Bone density; Age distribution; Bone marrow fat; Imaging assessment