NIMG-40. SUPER T2-FLAIR MISMATCH SIGN AS PROGNOSTIC IMAGING BIOMARKER FOR NON-ENHANCED ASTROCYTOMA, IDH-MUTANT

Abstract

Abstract BACKGROUND The T2-FLAIR mismatch sign has been established as a highly specific diagnostic imaging biomarker for astrocytoma, IDH-mutant. However, prognostic imaging biomarker for this tumor has not been well established. METHODS We retrospectively reviewed 31 cases of non-enhanced astrocytoma, IDH-mutant, WHO grade 2 and 3 treated at our hospital. 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 40 (ranging 19-75) years, and consisted with 21 males and 10 females., with 21 males and 10 females. There were 25 cases of grade 2 and six cases of grade 3. T2-FLAIR mismatch sign was observed in 17 cases (54.8%) (grade 2: 16 cases, grade 3: 1 case), and super T2-FLAIR mismatch sign was observed in eight cases (25.8%) (grade 2: 8 cases). The presence or absence of T2-FLAIR mismatch sign was not associated with both PFS (46.8 months vs. 33.6 months, p=0.2526) and OS (not reached vs. 152 months, p=0.2087). Positive super T2-FLAIR mismatch sign cases have propensity to show longer PFS (112.7 months vs. 36.0 months, p=0.0710), and significantly longer OS (not reached vs. 152 months, p=0.0392). When super T2-FLAIR mismatch sign-positive cases were compared to negative cases in patients who did not accomplish entire removal, the PFS was significantly longer (p=0.0045) and there was a propensity for a longer OS (p=0.0543). CONCLUSIONS Super T2-FLAIR mismatch sign can be considered as a prognostic imaging biomarker for non-enhanced astrocytoma, IDH-mutant.