Comparison of plain radiographs and magnetic resonance images in the evaluation of periosteal reaction and osteoid matrix in osteosarcomas.

To determine the relationship and the degree of agreement between radiographs and MR images for the existence of osteoid matrix and periosteal reactions in the initial diagnosis of osteosarcomas, the plain radiographs and MR studies of 54 patients with proven osteosarcoma were retrospectively evaluated. In each tumor the visualization and type of osseous matrix, periosteal reaction and Codman angle were recorded independently for both techniques and by consensus between two radiologists. In 37 tumors agreement existed regarding osteoid matrix and in 31 cases regarding periosteal reactions. The Kappa statistic showed a significant relationship between both tests (0.49 and 0.44, respectively). Both techniques were also not statistically different in the proportion of findings with the McNemar test. Therefore, the ability of MR images seems important in reporting the MR features of bone tumors. Identification of osteoid mineralization and periosteal reaction can also be used with MR in the diagnosis of osteosarcoma.