Magnetic resonance imaging (MRI) can provide sensitive evaluation of neoplastic lesions or other pathologic conditions affecting the bone marrow. There is a gradual conversion of hematopoietic marrow to fatty marrow throughout the skeleton, reaching the adult appearance by 25 years of age. Lesions such as fractures will be evident on MRI due to the replacement of normal fatty elements by edema or blood; neoplastic processes will be evident due to the replacement of marrow elements with neoplastic cells.

Nonmalignant Marrow Signal Changes

There are nonneoplastic conditions that can also change the appearance of normal marrow. These include the administration of hematopoietic growth factors in healthy stem cell donors, anemia, low oxygen tension, and cigarette smoking, all of which create an appearance of greater hematopoietic marrow (i.e., less fatty marrow), which can simulate neoplastic involvement. In addition, children, young women, and athletes have marrow that is more hematopoietic.

Neoplastic and Therapy-Related Marrow Changes