Bone marrow signal intensity on T1-weighted image of the lumbar spine related to age and sex

Measurements of signal intensity ratios of bone marrow/fat (BM/F) and bone marrow/cerebrospinal fluid (BM/CSF) on T1-weighted sagital image of the lumbar spine at 1.5-T were performed in 325 patients. The results were compared with the patients' age and sex. The regions of interest of bone marrow, fat, and cerebrospinal fluid were settled on L3 body, epidural fat, and intrathecal subarachnoid space, respectively. BM/F and BM/CSF ratios showed a progressive increase with age for both sexes and no sex difference in the ratios was noticed in any age groups. The progressive decrease in the hematopoietic marrow with replacement by fatty marrow would explain the increase in bone marrow signal intensity ratios. These normal values of BM/F and BM/CSF ratios may provide a base line for the evaluation of diseases involving the bone marrow of the lumbar spine diffusely. (author)