title: MRI of bone marrow oedema associated with focal bone lesions.
abstract: OBJECTIVE
  To quantify the volume of bone marrow oedema surrounding focal bone lesions and to identify its relevance relative to diagnosis.
  
  
  METHODS
  Three hundred and eighty-eight of 1456 patients included in the orthopaedic oncology database who underwent magnetic resonance imaging (MRI) demonstrated bone marrow oedema and were included in the study. There were 225 males and 163 females, age range 1-87 years (mean 29 years). MRI images were retrospectively reviewed and assessed for the extent of bone marrow oedema. The amount of oedema was graded: grade 1: oedema present but smaller than the lesion size; grade 2: oedema equivalent to the lesion size; grade 3: oedema greater than the lesion size.
  
  
  RESULTS
  There were 190 grade 1 lesions: 56% malignant, 33% benign, 11% non-neoplastic; 74 grade 2 lesions: 19% malignant, 50% benign, 31% non-neoplastic; and 124 grade 3 lesions: 10% malignant, 46% benign, 44% non-neoplastic. There was a significant relationship between oedema grade (i.e., volume of oedema) and final diagnosis (p<0.0005).
  
  
  CONCLUSIONS
  Bone marrow oedema may be associated with a wide range of focal bony lesions, including malignant, benign and non-neoplastic causes. As the volume of bone marrow oedema increases relative to the size of the underlying lesion, the probability that the underlying lesion is benign is increased.
authors.affiliation: Department of Radiology, The Royal Orthopaedic Hospital, Northfield, Birmingham, UK. steven.james@roh.nhs.uk
authors.forename: S L J
authors.initials: SL
authors.lastname: James
authors.forename: R J
authors.initials: RJ
authors.lastname: Hughes
authors.forename: K E
authors.initials: KE
authors.lastname: Ali
authors.forename: A
authors.initials: A
authors.lastname: Saifuddin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001847:Bone Diseases / Q000473:pathology*; D001855:Bone Marrow Diseases / Q000473:pathology; D001859:Bone Neoplasms / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D004487:Edema / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies