Extent and time course of morphological changes of bone marrow induced by granulocyte-colony stimulating factor as assessed by magnetic resonance imaging of healthy blood stem cell donors

The aim of this study was to assess the time course and extent of signal alterations of red bone marrow after short-term stimulation by recombinant human granulocyte-colony stimulating factor (rHuG-CSF) in healthy peripheral blood stem cell donors using magnetic resonance imaging (MRI) at low-field strength. Twelve healthy blood stem cell donors without evidence of bone marrow disorders were prospectively investigated and underwent four MRI studies of their lumbar spine. Sagittal T1- and T2-weighted spin-echo sequences and a gradient-echo (GE) sequence with an echo time for out-of-phase imaging were performed prior to rHuG-CSF application (baseline MRI), on the day of first stem cell harvest (after 70 microg/kg body weight rHuG-CSF, second MRI) followed by two studies 9-18 days (median 14.5 days, third MRI) and 26-48 days (median 39.5 days, fourth MRI) after discontinuation of rHuG-CSF application. Baseline MRI showed normal marrow signal in all patients. The second MRI revealed a decrease of quantified bone marrow signal relative to nucleus pulposus in T1- and T2-weighted images and an increase of relative signal in out-of-phase GE sequences. The greatest changes of relative marrow signal were observed at the third MRI. Compared to baseline MRI, relative marrow signal was diminished by 12% in T1-weighted images and increased by 59% in GE sequences, consistent with a rise in marrow cellularity simulating diffuse marrow disease. At the fourth MRI quantified relative marrow signal returned to baseline levels in all sequences. In healthy individuals rHuG-CSF application leads to significant signal changes of bone marrow in lumbar vertebra that are maximal about 2 weeks after discontinuation of rHuG-CSF application. In patients with underlying marrow disorders who receive hematopoietic growth factors during treatment, these changes should not be confused with disease progression.