title: Hit the mark with diffusion-weighted imaging: metastases of rhabdomyosarcoma to the extraocular eye muscles.
abstract: BACKGROUND
  Rhabdomyosarcoma is the most frequent malignant intraorbital tumour in paediatric patients. Differentiation of tumour recurrence or metastases from post-therapeutic signal alteration can be challenging, using standard MR imaging techniques. Diffusion-weighted MRI (DWI) is increasingly considered a helpful supplementary imaging tool for differentiation of orbital masses.
  
  
  METHODS
  We report on a 15-year-old female adolescent of Caucasian ethnicity who developed isolated bilateral thickening of extraocular eye muscles about two years after successful multimodal treatment of orbital alveolar rhabdomyosarcoma. Intramuscular restricted diffusion was the first diagnostic indicator suggestive of metastatic disease to the eye muscles. DWI subsequently showed signal changes consistent with tumour progression, complete remission under chemoradiotherapy and tumour recurrence.
  
  
  CONCLUSIONS
  Restricted diffusivity is a strong early indicator of malignancy in orbital tumours. DWI can be the key to correct diagnosis in unusual tumour manifestations and can provide additional diagnostic information beyond standard MRI and PET/CT. Diffusion-weighted MRI is useful for monitoring therapy response and for detecting tumour recurrence.
authors.forename: Nicole
authors.initials: N
authors.lastname: Hassold
authors.forename: Monika
authors.initials: M
authors.lastname: Warmuth-Metz
authors.forename: Beate
authors.initials: B
authors.lastname: Winkler
authors.forename: Michael C
authors.initials: MC
authors.lastname: Kreissl
authors.forename: Karen
authors.initials: K
authors.lastname: Ernestus
authors.forename: Meinrad
authors.initials: M
authors.lastname: Beer
authors.affiliation: Department of Paediatric Radiology, Institute of Diagnostic and Interventional Radiology, Josef-Schneider-Straße 2, Wuerzburg 97080, Germany. neubauer_h@ukw.de.
authors.forename: Henning
authors.initials: H
authors.lastname: Neubauer
mesh_terms: D000293:Adolescent; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D019042:Muscle Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D009801:Oculomotor Muscles; D009918:Orbital Neoplasms / Q000473:pathology; D012208:Rhabdomyosarcoma / Q000175:diagnosis* / Q000556:secondary*