EFFECT OF HEMATOPOIETIC GROWTH-FACTORS ON MR-IMAGES OF BONE-MARROW IN CHILDREN UNDERGOING CHEMOTHERAPY

PURPOSE: To evaluate the effects of hematopoietic growth factors on magnetic resonance (MR) image signal intensity (SI) of bone marrow in children undergoing neoadjuvant chemotherapy for musculoskeletal malignancies. MATERIALS AND METHODS: Blinded evaluations were performed of T1-weighted and short inversion time inversion recovery images of the pelvis and/or lower extremities of 15 patients undergoing chemotherapy, with or without granulocyte or granulocyte-macrophage colony-stimulating factor. RESULTS: Four of the 11 patients who received growth factors initially had hematopoietic marrow SI that did not change during therapy. All seven with initially fatty marrow had SI changes consistent with reconversion to hematopoietic marrow that coincided temporally with increases in absolute neutrophil counts from minimums of 0-2,580/mm(3) to maximums of 10,858-45,880/mm(3). The four patients who did not receive growth factors had no MR imaging changes in initially hematopoietic (n = 1) or fatty (n = 3) marrow. CONCLUSION: Hematopoietic activity induced by growth factors can produce changes in bone marrow SI that may simulate bone marrow involvement by musculoskeletal tumors.