title: Correlation of non-mass-like abnormal MR signal intensity with pathological findings surrounding pediatric osteosarcoma and Ewing's sarcoma.
abstract: OBJECTIVE
  The aim of this work was to determine the role of MRI in interpreting abnormal signals within bones and soft tissues adjacent to tumor bulk of osteosarcoma and Ewing's sarcoma in a pediatric population by correlating MR findings with histopathology.
  
  
  METHODS
  Thirty patients met the inclusion criteria, which included (1) osteosarcoma or Ewing's sarcoma, (2) MR studies no more than 2 months prior to surgery, (3) presence of abnormal MR signal surrounding the tumor bulk, (4) pathological material from resected tumor. The patients received standard neoadjuvant chemotherapy. Using grid maps on gross pathology specimens, the abnormal MR areas around the tumor were matched with the corresponding grid sections. Histopathology slides of these sections were then analyzed to determine the nature of the regions of interest. The MR/pathological correlation was evaluated using Mann-Whitney U test and Fisher's exact test.
  
  
  RESULTS
  Twenty-seven patients had osteosarcoma and three patients had Ewing's sarcoma. Of the studied areas, 17.4% were positive for tumor (viable or necrotic). There was no statistically significant correlation between areas positive for tumor and age, gender, signal extent and intensity on MRI, or tissue type. There was, however, a statistically significant correlation between presence of tumor and the appearance of abnormal soft tissue signals. A feathery appearance correlated with tumor-negative areas whereas a bulky appearance correlated with tumor-positive regions.
  
  
  CONCLUSIONS
  MR imaging is helpful in identifying the nature of abnormal signal areas surrounding bone sarcomas that are more likely to be tumor-free, particularly when the signal in the soft tissues surrounding the tumor is feathery and edema-like in appearance.
authors.affiliation: Department of Surgery, American University of Beirut Medical Center, PO Box 11-0236, Riad El Solh, Beirut 1107 2020, Beirut, Lebanon. km34@aub.edu.lb
authors.forename: Karim Z
authors.initials: KZ
authors.lastname: Masrouha
authors.forename: Khaled M
authors.initials: KM
authors.lastname: Musallam
authors.forename: Alexis Bou
authors.initials: AB
authors.lastname: Samra
authors.forename: Ayman
authors.initials: A
authors.lastname: Tawil
authors.forename: Rachid
authors.initials: R
authors.lastname: Haidar
authors.forename: Zaher
authors.initials: Z
authors.lastname: Chakhachiro
authors.forename: Said
authors.initials: S
authors.lastname: Saghieh
authors.forename: Abeer
authors.initials: A
authors.lastname: Abdallah
authors.forename: Raya
authors.initials: R
authors.lastname: Saab
authors.forename: Samar
authors.initials: S
authors.lastname: Muwakkit
authors.forename: Miguel R
authors.initials: MR
authors.lastname: Abboud
authors.forename: Nabil J
authors.initials: NJ
authors.lastname: Khoury
mesh_terms: D000293:Adolescent; D001859:Bone Neoplasms / Q000473:pathology* / Q000628:therapy; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020360:Neoadjuvant Therapy; D012516:Osteosarcoma / Q000473:pathology* / Q000628:therapy; D012189:Retrospective Studies; D012512:Sarcoma, Ewing / Q000473:pathology* / Q000628:therapy; D018709:Statistics, Nonparametric; D055815:Young Adult