A prospective trial of dynamic contrast-enhanced MRI perfusion and fluorine-18 FDG PET-CT in differentiating brain tumor progression from radiation injury after cranial irradiation

Neuro Oncol. 2016 Jun;18(6):873-80. doi: 10.1093/neuonc/nov301. Epub 2015 Dec 19.


Background: The aim of this study was to assess the effectiveness of fluorine-18 fluorodeoxyglucose (FDG) PET-CT and dynamic contrast-enhanced (DCE) MRI in differentiating tumor progression and radiation injury in patients with indeterminate enhancing lesions after radiation therapy (RT) for brain malignancies.

Methods: Patients with indeterminate enhancing brain lesions on conventional MRI after RT underwent brain DCE-MRI and PET-CT in a prospective trial. Informed consent was obtained. Lesion outcomes were determined by histopathology and/or clinical and imaging follow-up. Metrics obtained included plasma volume (Vp) and volume transfer coefficient (K(trans)) from DCE-MRI, and maximum standardized uptake value (SUVmax) from PET-CT; lesion-to-normal brain ratios of all metrics were calculated. The Wilcoxon rank sum test and receiver operating characteristic analysis were performed.

Results: The study included 53 patients (29 treated for 29 gliomas and 24 treated for 26 brain metastases). Progression was determined in 38/55 (69%) indeterminate lesions and radiation injury in 17 (31%). Vpratio (VP lesion/VP normal brain, P < .001), K(trans) ratio (P = .002), and SUVratio (P = .002) correlated significantly with diagnosis of progression versus radiation injury. Progressing lesions exhibited higher values of all 3 metrics compared with radiation injury. Vpratio had the highest accuracy in determining progression (area under the curve = 0.87), with 92% sensitivity and 77% specificity using the optimal, retrospectively determined threshold of 2.1. When Vpratio was combined with K(trans) ratio (optimal threshold 3.6), accuracy increased to 94%.

Conclusions: Vpratio was the most effective metric for distinguishing progression from radiation injury. Adding K(trans) ratio to Vpratio further improved accuracy. DCE-MRI is an effective imaging technique for evaluating nonspecific enhancing intracranial lesions after RT.

Keywords: 18F-FDG PET-CT; DCE MRI perfusion; radiation injury.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Brain / pathology*
  • Brain Neoplasms / diagnostic imaging*
  • Brain Neoplasms / pathology
  • Female
  • Fluorodeoxyglucose F18
  • Glioma / diagnostic imaging
  • Humans
  • Magnetic Resonance Imaging / methods
  • Male
  • Middle Aged
  • Multimodal Imaging / methods
  • Positron Emission Tomography Computed Tomography* / methods
  • Prospective Studies
  • Radiation Injuries / diagnosis
  • Radiation Injuries / pathology*


  • Fluorodeoxyglucose F18