Purpose: Methodological work was performed in the field of magnetic resonance imaging (MRI) and spectroscopy (MRS) in order to develop suitable tools for non-invasive characterization of hematopoietic bone marrow. The methods were applied for the assessment of normal values in healthy persons and to examine patients with generalized hematological diseases or to monitor effects of therapies influencing the composition of bone marrow.
Methods: Besides standard techniques of MRI as T1- or T2-weighted methods, chemical shift techniques for selective visualization of water or lipid components were applied. The method of magnetization transfer (MT) contrast was used with the intention to differentiate between multiple water containing tissue compartments (intra- vs. extracellular space). A further approach was the determination of the magnetic field distribution within spongy bone marrow. Besides investigations in healthy volunteers, prospective clinical studies were carried out in patients suffering from acute leukemia during their initial treatment and in patients who underwent high-dose therapy with following peripheral blood stem cell transplantation (PBSCT).
Results: Especially MR techniques for selective imaging of water of fat signals and proton spectroscopy yielded a high sensitivity to primarily pathological or therapeutically induced changes of hematopoietic bone marrow. Application of MT allowed an improved differentiation of the tissue compartments under PBSCT, which might result in temporary edema. Storage of hemosiderin in bone marrow after blood transfusions and simultaneous hematopoietic insufficiency could be revealed by methods sensitive to magnetic field inhomogeneities.
Conclusions: Methods of MRI and MRS allow to non-invasively characterize hematopoietic bone marrow in the course of hematological diseases and during therapy. Marked changes in the composition of hematological bone marrow are detectable for extensive marrow areas. The prognostic relevance of the findings has to be evaluated in future follow-up studies.