The T2-FLAIR mismatch sign as an imaging marker for non-enhancing IDH-mutant, 1p/19q-intact lower-grade glioma: a validation study

Neuro Oncol. 2018 Sep 3;20(10):1393-1399. doi: 10.1093/neuonc/noy048.


Background: The purpose of this study was to assess the reproducibility of the previously described T2-fluid attenuated inversion recovery (FLAIR) mismatch sign as a specific imaging marker in non-enhancing isocitrate dehydrogenase (IDH) mutant, 1p/19q non-codeleted lower-grade glioma (LGG), encompassing both diffuse and anaplastic astrocytoma.

Methods: MR scans (n = 154) from 3 separate databases with genotyped LGG were evaluated by 2 independent reviewers to assess (i) presence/absence of "T2-FLAIR mismatch" sign and (ii) presence/absence of homogeneous signal on T2-weighted images. Interrater agreement with Cohen's kappa (κ) was calculated, as well as diagnostic test performance of the T2-FLAIR mismatch sign to identify IDH-mutant astrocytoma.

Results: There was substantial interrater agreement for the T2-FLAIR mismatch sign [κ = 0.75 (0.64-0.87)], but only fair agreement for T2 homogeneity [κ = 0.38 (0.25-0.52)]. The T2-FLAIR mismatch sign was present in 38 cases (25%) and had a positive predictive value of 100%, negative predictive value of 68%, a sensitivity of 51%, and a specificity of 100%.

Conclusions: With a robust interrater agreement, our study confirms that among non-enhancing LGG the T2-FLAIR mismatch sign represents a highly specific imaging marker for IDH-mutant astrocytoma. This non-invasive marker may enable a more informed patient counsel and can aid in the treatment decision processes in a significant proportion of patients presenting with non-enhancing, LGG-like lesions.

Publication types

  • Multicenter Study
  • Validation Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Neoplasms / diagnostic imaging
  • Brain Neoplasms / genetics
  • Brain Neoplasms / pathology*
  • Chromosomes, Human, Pair 1 / genetics
  • Chromosomes, Human, Pair 19 / genetics
  • Female
  • Follow-Up Studies
  • Glioma / diagnostic imaging
  • Glioma / genetics
  • Glioma / pathology*
  • Humans
  • Image Processing, Computer-Assisted / methods
  • Isocitrate Dehydrogenase / genetics*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Mutation*
  • Neoplasm Grading
  • Retrospective Studies
  • Young Adult


  • Isocitrate Dehydrogenase
  • isocitrate dehydrogenase 2, human
  • IDH1 protein, human