NIMG-12. EVALUATING THE SUPER T2-FLAIR MISMATCH SIGN IN OLIGODENDROGLIOMA, IDH-MUTANT AND 1P/19Q CODELETED

Abstract BACKGROUND We reported the super T2-FLAIR mismatch sign as a prognostic imaging biomarker for non-enhanced astrocytoma, IDH-mutant, CNS WHO grade 2 or 3. However, it remains unclear whether this novel imaging biomarker is applicable for oligodendroglioma, IDH-mutant and 1p/19q codeleted. METHODS We conducted a retrospective evaluation of non-enhanced oligodendroglioma, IDH-mutant and 1p/19q codeleted, including 14 cases from at our institute and 15 cases from TCGA/TCIA database. We defined “super T2-FLAIR mismatch sign” positivity as having a significantly strong low signal comparable to cerebrospinal fluid, rather than just a pale FLAIR low-signal tumor region as in regular T2-FLAIR mismatch. We evaluated the presence or absence of T2-FLAIR mismatch sign and super T2-FLAIR mismatch sign using preoperative MRI and statistically analyzed the progression-free survival (PFS) and overall survival (OS) using log-rank test. RESULTS The median age of this patient group was 47 (ranging 20-77) years and consisted with 16 males and 13 females. There were 27 cases of grade 2 and two cases of grade 3. The regular T2-FLAIR mismatch sign was observed in three cases (10%) (grade 2: 2 cases, grade 3: 1 case). While the super T2-FLAIR mismatch sign was observed in three cases (10%) (grade 2: 2 cases, grade 3: 1 case). One case had both regular and super T2-FLAIR mismatch signs. The mean follow-up period was 33.4 months, during which there were 3 cases of progression and 1 death. Both regular and super T2-FLAIR mismatch sign were not associated with PFS, OS. CONCLUSIONS The presence of the super T2-FLAIR mismatch sign was not associated with prognosis in oligodendroglioma, IDH-mutant and 1p/19q codeleted. Because the sample size was insufficient, further larger investigation through is needed to assess the utility of this sign.