title: MR imaging of bone marrow in children with osteosarcoma: effect of granulocyte colony-stimulating factor.
abstract: OBJECTIVE
  Granulocyte colony-stimulating factor (GCSF) is used to stimulate myeloid cell production and function in children undergoing chemotherapy for osteosarcoma. We hypothesize that GCSF can cause reconversion of marrow from fatty to hematopoietic and that this change can be detected by MR imaging at sites away from the primary tumor. This benign effect of treatment should not be confused with tumor spread.
  
  
  METHODS
  MR images of marrow of the affected and contralateral limbs were retrospectively reviewed for 16 patients with osteosarcoma of the femur or tibia; nine of these patients had received GCSF. A grade was assigned to marrow signal intensity at sites away from the tumor, and findings before and after treatment were compared. The validity of MR image interpretation was assessed by comparing the signal intensity of marrow with the histologic appearance of marrow at 19 resection margins.
  
  
  RESULTS
  Changes consistent with reconversion were seen on MR images in seven of nine patients who had received GCSF in addition to chemotherapy and in none of seven patients who had received chemotherapy alone. The difference in proportions was statistically significant (p = .006; Fisher's exact test, two tailed). The histologic appearance of marrow at the resection margins agreed with the interpretation of the short-Tl inversion recovery sequence in all cases (100%).
  
  
  CONCLUSIONS
  The findings suggest that GCSF causes changes in the MR imaging appearance of marrow. Histologic correlation supports the hypothesis that these changes are attributable to reconversion from fatty to hematopoietic marrow. Awareness of this finding is important to avoid false-positive diagnosis of marrow metastases.
authors.affiliation: Department of Radiology, Children's Hospital and Medical Center, Seattle, WA 98105, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Ryan
authors.forename: E
authors.initials: E
authors.lastname: Weinberger
authors.forename: K S
authors.initials: KS
authors.lastname: White
authors.forename: D W
authors.initials: DW
authors.lastname: Shaw
authors.forename: K
authors.initials: K
authors.lastname: Patterson
authors.forename: V
authors.initials: V
authors.lastname: Nazar-Stewart
authors.forename: J
authors.initials: J
authors.lastname: Miser
mesh_terms: D000293:Adolescent; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001853:Bone Marrow / Q000473:pathology*; D001859:Bone Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005266:Femoral Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000628:therapy; D016179:Granulocyte Colony-Stimulating Factor / Q000627:therapeutic use*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012516:Osteosarcoma / Q000175:diagnosis / Q000473:pathology* / Q000628:therapy; D013977:Tibia / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D016179:Granulocyte Colony-Stimulating Factor