Age-related apparent diffusion coefficients of lumbar vertebrae in healthy children at 1.5 T.

BACKGROUND: Diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient (ADC) calculation is important for detecting bone marrow pathologies. OBJECTIVE: To investigate age-related differences of lumbar vertebral body ADC to establish normal values for healthy children. MATERIALS AND METHODS: Forty-nine healthy children without any history of oncological or hematological diseases (10.2±4.7 years, range: 0-20 years) were included in this retrospective study. All magnetic resonance imaging (MRI) examinations were performed at 1.5 T and with similar scan parameters. The diffusion-weighted sequences were performed with b values of 50, 400 and 800 s/mm2. ADC values were measured by placing regions of interest at three different levels within each lumbar vertebral body (L1 to L5). ADC values were analyzed for different age groups (0-2 years, 3-6 years, 7-11 years, 12-14 years, 15-20 years), for each vertebral and intravertebral level. RESULTS: The mean ADC of the whole study group was 0.60±0.09 × 10-3 mm2/s. Children between the ages of 12 and 14 years had significantly higher ADC compared to the other age groups (P≤0.0003). ADC values were significantly higher in the 1st lumbar vertebral body compared to the other levels of the lumbar spine (P<0.005) with the exception of L5, and in the upper third of the vertebral bodies compared to the middle or lower thirds (P≤0.003). CONCLUSION: The age-, vertebral- and intravertebral level-dependent differences in ADC suggest a varying composition and cellularity in different age groups and in different locations.