Normal gadolinium-enhanced MR images of the developing appendicular skeleton: Part I. Cartilaginous epiphysis and physis.

OBJECTIVE: We have used gadolinium-enhanced MR imaging to define the expected normal appearance of the developing cartilaginous epiphyses and physes in neonates, infants, and children and to define the changes with maturity in epiphyseal vascular pattern. MATERIALS AND METHODS: We analyzed gadolinium-enhanced MR images of 80 normal epiphyses in 48 neonates, infants, and children who were 1 month to 15.5 years old. We studied the differences in enhancement ratios for the epiphyses and physes and the epiphyseal vascular pattern at various development stages. We correlated the MR imaging findings with histologic and injection studies of immature epiphyses. RESULTS: Gadolinium enhancement allowed differentiation between physeal and epiphyseal cartilage and revealed epiphyseal vascular canals. Enhancement proved to be greater in the physeal than in the epiphyseal cartilage (p < .001). In the unossified epiphysis, the vascular canals were mainly parallel. After the development of the secondary ossification center, these canals came to have a radial pattern (p < .0001). Comparison with cadaveric specimens confirmed how, with age, the arrangement of these canals changed. Also, physeal enhancement decreased with physeal closure. CONCLUSION: Gadolinium-enhanced MR imaging reveals differential enhancement of the physis, epiphyseal vascular canals, and epiphyseal cartilage. The pattern of epiphyseal vessels and degree of enhancement of the physis change with maturity.