Age-related vascular changes in the epiphysis, physis, and metaphysis: normal findings on gadolinium-enhanced MRI of piglets.

OBJECTIVE: We sought to study the normal enhancement patterns seen on MRIs of the epiphysis, physis, and metaphysis and age-related vascular changes in piglets using gadoteridol, a nonionic gadolinium chelate.
MATERIALS AND METHODS: We quantitatively and qualitatively analyzed the normal changes on sequential T1-weighted images after the IV administration of gadoteridol. In an investigation approved by the research animal care committee at our hospital, we studied the proximal and distal femurs of 26 piglets 1-6 weeks old and correlated the enhanced images with findings on intermediate-weighted, T2-weighted, and gradient-recalled echo images and at histologic examination.
RESULTS: We observed early enhancement of the epiphyseal vascular canals, the main physis, the physis of the secondary ossification center, and a metaphyseal band adjacent to the physis. Enhancement of the epiphyseal and metaphyseal marrow and of the epiphyseal cartilage was slower. In the epiphyseal cartilage, we saw three phases of enhancement: vascular, canalicular, and cartilaginous. As the piglets matured, enhancement of the epiphyseal cartilage decreased, and the epiphyseal vascular canals were less conspicuous. Physeal enhancement was greatest during the first week of life, declined at 3 weeks, and subsequently increased again as the physis came to lie adjacent to a larger segment of the epiphyseal ossification center.
CONCLUSION: Gadoteridol-enhanced MRIs showed multiple cartilaginous and vascular structures of the growing skeleton. With maturity and progressive epiphyseal ossification, epiphyseal cartilage enhancement decreased, and physeal cartilage enhancement increased.