Correlation between diffusion tensor imaging parameters of the distal femoral physis and adjacent metaphysis, and subsequent adolescent growth

Background: Diffusion-tensor imaging (DTI) depicts the movement of water through columns of cartilage and newly formed bone and provides information about velocity of growth and growth potential. Objective: To determine the correlation between DTI tractography parameters of the distal femoral physis and metaphysis and the height change after DTI in pubertal and post-pubertal children. Materials and methods: We retrospectively analyzed DTI images of the knee in 47 children with a mean age of 14.1 years in a 2-year period. In sagittal echoplanar DTI studies, regions of interest were placed in the femoral physis. Tractography was performed using a fractional anisotropy threshold of 0.15 and a maximum turning angle of 40°. The sample was divided to assess short-term and long-term growth after DTI. Short-term growth (n=25) was the height change between height at MRI and 1 year later. Long-term growth (n=36) was the height gain between height at MRI and at the growth plateau. Results: For the short-term group, subjects with larger tract volume (R²=0.40) and longer track lengths (R²=0.38) had larger height gains (P<0.01). For the long-term group, subjects with larger tract volume (R²=0.43) and longer track lengths (R²=0.32) had a larger height gain at the growth plateau (P<0.01). Intra- and inter-observer variability were good–excellent. Conclusion: Follow-up data of growth 1 year after DTI evaluation and at skeletal maturity confirms that DTI parameters are associated with the amount of post-imaging growth.