title: Genetically Defined Oligodendroglioma Is Characterized by Indistinct Tumor Borders at MRI.
abstract: In 2016, the World Health Organization revised the brain tumor classification, makingIDHmutation and 1p/19q codeletion the defining features of oligodendroglioma. To determine whether imaging characteristics previously associated with oligodendroglial tumors are still applicable, we evaluated the MR imaging features of genetically defined oligodendrogliomas.
  
  
  
  One hundred forty-eight adult patients with untreated World Health Organization grade II and III infiltrating gliomas with histologic oligodendroglial morphology, known 1p/19q status, and at least 1 preoperative MR imaging were retrospectively identified. The association of 1p/19q codeletion with tumor imaging characteristics and ADC values was evaluated.
  
  
  
  Ninety of 148 (61%) patients had 1p/19q codeleted tumors, corresponding to genetically defined oligodendroglioma, and 58/148 (39%) did not show 1p/19q codeletion, corresponding to astrocytic tumors. Eighty-three of 90 (92%) genetically defined oligodendrogliomas had noncircumscribed borders, compared with 26/58 (45%) non-1p/19q codeleted tumors with at least partial histologic oligodendroglial morphology (P< .0001). Eighty-nine of 90 (99%) oligodendrogliomas were heterogeneous on T1- and/or T2-weighted imaging. In patients with available ADC values, a lower mean ADC value predicted 1p/19q codeletion (P= .0005).
  
  
  
  Imaging characteristics of World Health Organization 2016 genetically defined oligodendrogliomas differ from the previously considered characteristics of morphologically defined oligodendrogliomas. We found that genetically defined oligodendrogliomas were commonly poorly circumscribed and were almost always heterogeneous in signal intensity.
authors.affiliation: From the Departments of Radiology (D.R.J., F.E.D., T.J.K.).
authors.forename: D R
authors.identifier: 0000-0002-4217-5517
authors.initials: DR
authors.lastname: Johnson
authors.affiliation: From the Departments of Radiology (D.R.J., F.E.D., T.J.K.).
authors.forename: F E
authors.identifier: 0000-0001-9458-8017
authors.initials: FE
authors.lastname: Diehn
authors.affiliation: Pathology (C.G., R.B.J.).
authors.forename: C
authors.identifier: 0000-0003-2757-6782
authors.initials: C
authors.lastname: Giannini
authors.affiliation: Pathology (C.G., R.B.J.).
authors.forename: R B
authors.identifier: 0000-0002-4049-694X
authors.initials: RB
authors.lastname: Jenkins
authors.affiliation: Health Sciences Research (S.M.J.).
authors.forename: S M
authors.identifier: 0000-0002-4157-8066
authors.initials: SM
authors.lastname: Jenkins
authors.affiliation: Neurosurgery (I.F.P.), Mayo Clinic, Rochester, Minnesota.
authors.forename: I F
authors.identifier: 0000-0002-9702-8047
authors.initials: IF
authors.lastname: Parney
authors.affiliation: From the Departments of Radiology (D.R.J., F.E.D., T.J.K.) Kaufmann.Timothy@mayo.edu.
authors.forename: T J
authors.identifier: 0000-0001-7483-1569
authors.initials: TJ
authors.lastname: Kaufmann
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000235:genetics* / Q000473:pathology; D002878:Chromosomes, Human, Pair 1; D002888:Chromosomes, Human, Pair 19; D005260:Female; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009837:Oligodendroglioma / Q000000981:diagnostic imaging* / Q000235:genetics* / Q000473:pathology; D012189:Retrospective Studies
chemical_list: D007521:Isocitrate Dehydrogenase