NI-17 T2-FLAIR MISMATCH SIGN IN DIFFUSE GLIOMA AND DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR

BACKGROUND: T2-FLAIR mismatch sign was reported as a specific imaging marker for diffuse astrocytoma with IDH-mutant and 1p/19q non-codeletion. However, most of the previous studies for T2-FLAIR mismatch were confirmed only among low grade glioma. The purpose of this study is to assess the T2-FLAIR mismatch sign in supratentorial diffuse glioma, diffuse midline glioma and dysembryoplastic neuroepithelial tumor (DNT) to unveil the exception rules of the sign. METHODS: In total, 51 patients were included in this study; 33 supratentorial diffuse glioma (18 diffuse astrocytoma with IDH mutant (IDHmut-Noncodel), 12 oligodendroglioma with IDH-mutant and 1p19q codeletion (IDHmut-Codel), 3 diffuse astrocytoma with IDH wildtype (IDHwt)), 18 diffuse midline glioma and 11 DNT. The tumors were evaluated by 2 independent reviewers to assess presence or absence of T2-FLAIR mismatch sign. RESULT: Ten out of 18 cases of IDHmut-Noncodel presented T2-FLAIR mismatch sign. None of the other supratentorial diffuse glioma (IDHmut-Codel and IDHwt) presented T2-FLAIR mismatch. The T2-FLAIR mismatch sign for IDHmut-Noncodel presented 100% positive predictive values among supratentorial diffuse glioma. However, 8 out of 18 cases of diffuse midline glioma and 8 out of 11 cases of DNT also presented the T2-FLAIR mismatch. CONCLUSION: The T2-FLAIR mismatch sign was specific marker for IDHmut-NonCodel among supratentorial diffuse glioma. Physicians need to be aware that diffuse midline glioma and DNT could present the T2-FLAIR mismatch sign.