MR imaging of epiphyseal marrow in infancy

The purposes of this paper are determination of the signal characteristics of marrow in the developing secondary ossification center and reevaluation of prior reports that the epiphyseal marrow is always fatty. Various epiphyses of 25 patients undergoing MR imaging within 1 y of the expected radiographic appearance of the ossification center were studied retrospectively. In addition, in 14 rabbits, 1 d--6 wk of age, and in five newborn lambs the MR signal of the ossification center was compared with its appearance on histologic or gross pathologic studies. The ossified epiphyses were classified as having signal intensity lower or higher than that of adjacent cartilage on T1-weighted images