title: MRI to quantify early radiation-induced changes in the salivary glands.
abstract: OBJECTIVE
  We investigated radiation-induced changes in the salivary glands, 6 weeks after RT, using MRI.
  
  
  METHODS
  Eighteen oropharyngeal cancer patients were treated with salivary gland sparing IMRT. All patients received a 3T MRI exam before and 6 weeks after the end of RT, including a T(1)-weighted (T(1)w), a T(2)-weighted (T(2)w), and a dynamic contrast-enhanced (DCE) MRI. For both time points separately, the parotid and submandibular glands were delineated on the MR images. Differences in median signal intensity and signal variation within the glands were tested for significance. Correlations were studied between the MR changes and the planned RT dose.
  
  
  RESULTS
  The volume of the glands reduced significantly by 25%. The T(1)w signal decreased by 10% and the T(2)w signal increased by 23%. The k(ep) value decreased, while the v(e) increased. A correlation of the changes in T(2)w signal with the mean dose was found in both glands.
  
  
  CONCLUSIONS
  Overall radiation-induced changes and volume loss were observed in the parotid and submandibular gland using MR. The observed differences indicated an increased water content such as found in oedema. The overall changes could be related to the mean dose, with a slightly greater impact in the high dose area.
authors.affiliation: Department of Radiotherapy, University Medical Center, Utrecht, The Netherlands.
authors.forename: Antonetta C
authors.initials: AC
authors.lastname: Houweling
authors.forename: Tim
authors.initials: T
authors.lastname: Schakel
authors.forename: Cornelis A T
authors.initials: CA
authors.lastname: van den Berg
authors.forename: Marielle E P
authors.initials: ME
authors.lastname: Philippens
authors.forename: Judith M
authors.initials: JM
authors.lastname: Roesink
authors.forename: Chris H J
authors.initials: CH
authors.lastname: Terhaard
authors.forename: Cornelis P J
authors.initials: CP
authors.lastname: Raaijmakers
mesh_terms: D003287:Contrast Media; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009929:Organ Size / Q000528:radiation effects; D009942:Organometallic Compounds; D009959:Oropharyngeal Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D012469:Salivary Glands / Q000473:pathology / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol