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

Abstract

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. 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. We retrospectively analyzed DTI images of the knee in 47 children with a mean age of 14.1years 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 1year later. Long-term growth (n=36) was the height gain between height at MRI and at the growth plateau. 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. Follow-up data of growth 1year after DTI evaluation and at skeletal maturity confirms that DTI parameters are associated with the amount of post-imaging growth.