title: Diffusion-weighted MRI for detection and differentiation of musculoskeletal tumorous and tumor-like lesions in pediatric patients.
abstract: BACKGROUND
  MRI is the diagnostic mainstay for detection and differentiation of musculoskeletal tumors. However, a projection regarding the biological dignity of lesions based on standard MRI sequences remains difficult and uncertain. This study was undertaken to analyse whether diffusion-weighted MRI (DWI) can distinguish between benign and malignant musculoskeletal tumorous and tumor-like lesions in pediatric patients.
  
  
  METHODS
  MR examinations of 44 consecutive pediatric patients (26 girls, mean age 11±6 years) including standard sequences and DWI (b=50/800 s/mm(2)) at 1.5 or 3 Tesla were retrospectively evaluated. The study group contained 10 patients with non-treated malignant tumors and 34 patients with benign lesions. Size, relative signal intensity and apparent diffusion coefficient (ADC, unit ×10(-3) mm(2)/s) were determined in one lesion per patient.
  
  
  RESULTS
  Mean ADC was 0.78±0.45×10(-3) mm(2)/s in patients with malignant tumors and 1.71±0.75 ×10(-3) mm(2)/s in patients with benign lesions (P<0.001). Relative operating characteristics (ROC) analysis showed a sensitivity of 90% and a specificity of 91% for malignancy, based on an ADC cut-off value of ≤1.03. On logistic regression, mean ADC and lesion size accounted for 62% of variability in benign vs. malignant tumors. For malignant tumors, the signal intensity ratio was higher on DWI than on T1w post-contrast images (P<0.002). Two cases of local tumor recurrence were diagnosed by DWI only.
  
  
  CONCLUSIONS
  DWI shows promising results for determination of biological dignity in musculoskeletal tumors. Mean ADC ≤1.03×10(-3) mm(2)/s is a strong indicator of malignancy at the first diagnosis. The use of DWI for early diagnosis of tumor recurrence in comparison with standard MRI sequences should be evaluated in prospective studies.
authors.affiliation: Department of Pediatric Radiology, Institute of Radiology, University of Wuerzburg, Josef-Schneider-Straße 2, Wuerzburg, 97080, Germany. neubauer@roentgen.uni-wuerzburg.de
authors.forename: Henning
authors.initials: H
authors.lastname: Neubauer
authors.forename: Laura
authors.initials: L
authors.lastname: Evangelista
authors.forename: Nicole
authors.initials: N
authors.lastname: Hassold
authors.forename: Beate
authors.initials: B
authors.lastname: Winkler
authors.forename: Paul Gerhardt
authors.initials: PG
authors.lastname: Schlegel
authors.forename: Herbert
authors.initials: H
authors.lastname: Köstler
authors.forename: Dietbert
authors.initials: D
authors.lastname: Hahn
authors.forename: Meinrad
authors.initials: M
authors.lastname: Beer
mesh_terms: D000293:Adolescent; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D019042:Muscle Neoplasms / Q000175:diagnosis*; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D012372:ROC Curve; D012512:Sarcoma, Ewing / Q000175:diagnosis; D055815:Young Adult