UCLA

We present two cases in which MR exams revealed unusual, low signal intensity lines in the marrow space of epiphyses. These epiphyseal lines were smooth and regular, creating a bone-in-bone appearance. These lines were much more conspicuous on MR than on radiographs, partly because of adjacent alterations in trabecular architecture. A history of prolonged immobilization during childhood in both cases suggests that these lines represent growth arrest lines persisting in the epiphyses.