title: Evaluation of dynamic contrast-enhanced T1-weighted perfusion MRI in the differentiation of tumor recurrence from radiation necrosis.
abstract: BACKGROUND
  To investigate if perfusion measured with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can be used to differentiate radiation necrosis from tumor recurrence in patients with high-grade glioma.
  
  
  METHODS
  The study was approved by the institutional review board and informed consent was obtained from all subjects. 19 patients were recruited following surgery and radiation therapy for glioma. Patients had contrast enhancing lesions, which during the standard MRI examination could not be exclusively determined as recurrence or radiation necrosis. DCE-MRI was used to measure cerebral blood volume (CBV), blood-brain barrier (BBB) permeability and cerebral blood flow (CBF). Subjects also underwent FDG-PET and lesions were classified as either metabolically active or inactive. Follow-up clinical MRI and lesion histology in case of additional tissue resection was used to determine whether lesions were regressing or progressing.
  
  
  RESULTS
  Fourteen enhancing lesions could be classified as progressing (11) or regressing (three). An empirical threshold of 2.0 ml/100 g for CBV allowed detection of regressing lesions with a sensitivity of 100 % and specificity of 100 %. FDG-PET and DCE-MRI agreed in classification of tumor status in 13 out of the 16 cases where an FDG-PET classification was obtained. In two of the remaining three patients, MRI follow-up and histology was available and both indicated that the DCE-MRI answer was correct.
  
  
  CONCLUSIONS
  CBV measurements using DCE-MRI may predict the status of contrast enhancing lesions and give results very similar to FDG-PET with regards to differentiation between tumor recurrence and radiation necrosis.
authors.affiliation: Department of Radiology, Glostrup University Hospital, 57 Nordre Ringvej, 2600 Glostrup, Denmark. vibeke.andree.larsen@regionh.dk
authors.forename: Vibeke A
authors.initials: VA
authors.lastname: Larsen
authors.forename: Helle J
authors.initials: HJ
authors.lastname: Simonsen
authors.forename: Ian
authors.initials: I
authors.lastname: Law
authors.forename: Henrik B W
authors.initials: HB
authors.lastname: Larsson
authors.forename: Adam E
authors.initials: AE
authors.lastname: Hansen
mesh_terms: D001932:Brain Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D019786:Gadolinium DTPA; D005910:Glioma / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D009336:Necrosis / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000517:prevention & control; D011832:Radiation Injuries / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA