10036- MNG-3 EVALUATION OF THE CORRELATION BETWEEN PET STUDIES AND PATHOLOGICAL FINDINGS IN MENINGIOMAS, AND THEIR IMPACT ON RECURRENCE

Abstract OBJECTIVE Meningiomas are the most common primary brain tumors, typically following a benign course. However, some cases recur after surgery, necessitating further treatment or reoperation. This study aims to examine the relationship between PET studies and pathological findings, and their impact on recurrence. METHODS We included cases of newly diagnosed meningiomas treated surgically in our department from August 2008 to August 2022. The correlation between preoperative FDG-PET and methionine-PET accumulations with pathological findings (WHO grade, Ki-67 index), as well as the impact on recurrence, was investigated. RESULTS The study included 55 cases (22 males, 33 females), aged 17-87 years (median 61.8). The WHO grade was grade 1 in 34 cases and grade 2 in 21 cases, with no grade 3 cases observed. Recurrence occurred in 20 cases during follow-up, necessitating additional treatment. A significant correlation was observed between the tumor T/N ratio and the Ki-67 index for both tracers. Regarding WHO grade, the T/N ratio for FDG was 0.64 in the grade 1 group and 1.04 in the grade 2 group (p<0.01), while for MET, it was 4.8 in the grade 1 group and 6.39 in the grade 2 group (p<0.01), with both tracers showing significantly higher values in the grade 2 group. For postoperative recurrence, the T/N ratio for FDG was 0.97 in the recurrence group and 0.69 in the non-recurrence group (p=0.01), while for MET, it was 6.38 in the recurrence group and 4.66 in the non-recurrence group (p<0.01), with both tracers showing significantly higher values in the recurrence group. CONCLUSION The study demonstrated a significant correlation between preoperative PET studies and pathological findings in meningiomas, as well as an association with recurrence. PET studies were significantly correlated with the tumor malignancy and were considered predictors of postoperative recurrence.