Bone Marrow Maturation in Healthy and Diseased States

The bone marrow is a dynamic organ that changes composition throughout life; however, the conversion from red to yellow bone marrow is not definitive and irreversible; under particular conditions a re-conversion may be occur, in which inactive “yellow” marrow can be reactivated into the hematologically active “red” form. MR is the best imaging technique for assessing normal and pathologic bone marrow, to evaluate response during and after treatment, and for the diagnosis of bone marrow relapse and complications. MRI may be a useful tool for the primary diagnosis of disease and to assist anatomopathologic investigation such as biopsies and bone marrow aspirates, to detect the most abnormal/diseased site. Marrow disorders may be categorized into marrow hyperplasia/reconversion, marrow infiltration/deposition, and marrow depletion/failure; each of these shows characteristic imaging findings on MRI.