NIMG-01. T2WI-FLAIR MISMATCH SIGN IN LOWER GRADE GLIOMA AND DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR

Abstract

Abstract 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 lower grade glioma (LGG). The purpose of this study is to explore the T2-FLAIR mismatch sing in supratentorial non-enhancing tumor including LGG and dysembryoplastic neuroepithelial tumor (DNET) and to unveil the exception rules of the sign. METHODS Forty-four patients of non-enhancing LGG and DNET were included in this study. LGG（diffuse astrocytoma with IDH mutant (IDHmut-Noncodel), oligodendroglioma with IDH-mutant and 1p19q codeletion (IDHmut-Codel), diffuse astrocytoma with IDH wildtype (IDHwt)）and DNET were diagnosed based on WHO 2016 classification. The tumors were evaluated MRI by 2 independent reviewers to assess presence or absence of T2-FLAIR mismatch sign. CT was also performed to evaluate the localized thinning of the skull bone. Inter-reviewer agreement with Cohen’s kappa (κ) was calculated. RESULT: Ten out of 18 cases (55.6%) of IDHmut-Noncodel presented T2-FLAIR mismatch sign. None of the other LGG (IDHmut-Codel and IDHwt) presented T2-FLAIR mismatch. Eight out of 11 cases (72.7%) of DNET also present the T2-FLAIR mismatch. The overlying part of the skull bone thinning was observed in 5 cases of DNET, but none of LGG presented the localized skull bone thinning. The inter-rater agreement for the T2-FLAIR mismatch and the localized thinning of the skull bone were excellent (κ= 1.00). CONCLUSION The T2-FLAIR mismatch sign was specific marker for IDHmut-Noncodel among LGG. However, DNET also presented the T2-FLAIR mismatch sign. The localized skull bone thinning could be useful for differentiating between IDHmut-Noncodel and DNET