[Bone marrow changes following radiotherapy. Results of MR tomography].

Magnetic resonance imaging (MRI) offers a new approach in the morphologic evaluation of the bone marrow. Physiologic and pathologic changes can be assessed with very high sensitivity. Radiotherapy induces acute depletion of the hematopoietic bone marrow, resulting in fatty degeneration. With MRI it is possible to evaluate the changes during irradiation and it also discloses the long-term fatty degeneration after radiotherapy. The irradiated bone marrow mostly exhibits a homogeneous hyperintense pattern on T1-weighted images. This allows clear recognition of the former target volumes. Our quantitative studies based on chemical shift imaging data reveal a lack of recovery of hematopoiesis after radiotherapy with 30 Gy or more. These results are independent of patients' age and of the interval after radiotherapy.