NIMG-75. POSTOPERATIVE68GA-DOTATATE/PET-CT IMAGING IS PROGNOSTIC FOR PROGRESSION-FREE SURVIVAL IN MENINGIOMA WHO GRADE 1: A PROSPECTIVE SINGLE-CENTER STUDY

Abstract PURPOSE Microsurgical tumor resection represents the first-line treatment for symptomatic meningiomas, and extent of resection has been shown to be of prognostic importance. Assessment of tumor remnants with somatostatin receptor PET proves to be superior to intraoperative estimation with Simpson grading or MRI. However, prognostic relevance of postoperative PET for progression-free survival in meningiomas remains unclear. METHODS We conducted a prospective study including patients with surgically removed meningioma WHO grade 1 and collected clinical and imaging data. All patients received postoperative MRI and 68Gallium-DOTATATE/PET, and were followed regularly with MRI surveillance scans for detection of tumor recurrence/progression. RESULTS We included 46 patients with 49 tumors. Mean age at diagnosis was 57.8 ± 1.7 years with a male-to-female ratio of 1:1.7. Local tumor progression occurred in 7/49 patients (14%) after a median follow-up of 52 months. Positive PET was associated with an increased risk for progression (*p = 0.015) and a lower progression-free survival (*p = 0.029) whereas MRI was not. 20/20 patients (100%) with negative PET findings remained recurrence-free. Location of recurrence/progression on MRI was adjacent to regions where postoperative PET indicated tumor remnants in all cases. Gross tumor volumes were higher on PET compared to MRI (*p = 0.032). CONCLUSION Our data show that 68Ga-DOTATATE/PET is highly sensitive in revealing tumor remnants in patients with meningioma WHO grade 1. Negative PET findings were associated with a higher progression-free survival, thus improving surveillance. In patients with tumor remnants, additional PET can optimize adjuvant radiotherapy target planning of surgically resected meningiomas.