Magnetic resonance investigation of bone marrow following priming and stem cell mobilization

Purpose: To evaluate application of MRI and magnetic resonance spectroscopy (MRS) to monitor bone marrow cellularity during pretransplant priming with chemotherapy and hematopoietic growth factor (HGF) administration. Materials and Methods: A total of 10 lymphoma and myeloma patients, in remission following induction therapy and considered eligible for high-dose therapy and autologous stem cell transplantation, were included in the study. MR investigation was scheduled four times: at study entry, and one, two, and four weeks following priming. Priming with cyclophosphamide and recombinant human granulocyte colony-stimulating factor (rhG-CSF) started the day after study entry. MR parameters studied in a region of interest were as follows: bone marrow intensity on short-time inversion-recovery (STIR) turbo spin-echo (TSE; thus STIRTSE) and on T1-weighted TSE (T1TSE) images, T2 value for fat component, T2 value for water component, water/fat ratio (W/F), T1 value for fat component, and T1 value for water component. Results: The results did not support the hypothesis that hematopoietic expansion quantitated and monitored by MR correlates to the level of mobilized progenitor cells. Conclusion: The results indicate that release of stem cells is a more complex phenomenon than hematopoietic expansion and reduction of fat tissue in bone marrow.