title: Assessment of irradiated brain metastases by means of arterial spin-labeling and dynamic susceptibility-weighted contrast-enhanced perfusion MRI: initial results.
abstract: OBJECTIVE
  To assess if preradiation and early follow-up measurements of relative regional cerebral blood flow (rrCBF) can predict treatment outcome in patients with cerebral metastases and to evaluate rrCBF changes in tumor and normal tissue after stereotactic radiosurgery using arterial spin-labeling (ASL) and first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MRI.
  
  
  METHODS
  In 25 patients with a total of 28 brain metastases, DSC MRI and ASL perfusion MRI using the Q2TIPS sequence were performed with a 1.5-T unit. Measurements were performed prior to and at 6 weeks, 12 weeks, and 24 weeks after stereotactic radiosurgery. Follow-up examinations were completely available in 25 patients for Q2TIPS and 17 patients with 18 metastases for DSC MRI. The rrCBF of the metastases and the normal brain tissue was determined by a region-of-interest analysis. rrCBF values were correlated with the treatment outcome that was classified according to tumor volume changes at 6 months.
  
  
  RESULTS
  The alteration of the rrCBF at the 6-week follow-up was highly predictive for treatment outcome. A decrease of the rrCBF value predicted tumor response correctly in all metastases for Q2TIPS and in 13 of 16 metastases for DSC MRI. The pretherapeutic rrCBF was not able to predict treatment outcome. The rrCBF values in normal brain tissue affected by radiation doses less than 0.5 Gy remained unchanged after therapy.
  
  
  CONCLUSIONS
  These preliminary results suggest that ASL and DSC MRI techniques determining rrCBF changes in brain metastases after stereotactic radiosurgery allow the prediction of treatment outcome.
authors.affiliation: Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany. m.a.weber@dkfz.de
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Weber
authors.forename: Christoph
authors.initials: C
authors.lastname: Thilmann
authors.forename: Matthias P
authors.initials: MP
authors.lastname: Lichy
authors.forename: Matthias
authors.initials: M
authors.lastname: Günther
authors.forename: Stefan
authors.initials: S
authors.lastname: Delorme
authors.forename: Ivan
authors.initials: I
authors.lastname: Zuna
authors.forename: André
authors.initials: A
authors.lastname: Bongers
authors.forename: Lothar R
authors.initials: LR
authors.lastname: Schad
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Marco
authors.initials: M
authors.lastname: Essig
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schlemmer
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D002536:Cerebral Arteries / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D017352:Echo-Planar Imaging; D005260:Female; D005500:Follow-Up Studies; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016634:Radiosurgery; D012039:Regional Blood Flow; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media