SURG-05. NAVIGATED INTRA-OPERATIVE 2-D ULTRASOUND VS STANDARD NEURONAVIGATION IN HIGH GRADE GLIOMA SURGERY

Maximizing extent of resection (EOR) and reducing residual tumor volume (RTV) while preserving neurological functions is the main goal in the surgical treatment of gliomas. Navigated Intra-operative ultrasound (N-ioUS) is a real-time imaging technique which, combining the advantages of ultrasound and conventional neuronavigation (NN), allows for overcoming the limitations of the latter. We evaluate the impact of real-time NN combining ioUS and pre-operative magnetic resonance imaging (MRI) on maximizing EOR in glioma surgery compared to standard NN. We retrospectively reviewed a series of 60 cases operated on for supratentorial gliomas, 31 operated under the guidance of N-ioUS and 29 resected with standard NN. Age, location of the tumor, pre- and post-operative Karnofsky Performance Status (KPS), EOR and, if any, post-operative complications were evaluated. Volumetric pre-operative and 48hours post-operative MRI was used to determine EOR. The rate of gross total resection (GTR) in NN group was 44.8% and EOR≤90% 10.3%, whereas in N-ioUS group a 61.2% GTR rate was obtained with a 6.4% rate of EOR≤90%. The rate of RTV> 1cc for GBMs was significantly lower for the N-ioUS group (p=0.01) compared to the NN. In 13/31 (42%) RTV was detected at the end of surgery with N-ioUS. In 8 of 13 cases (25.8% of the cohort) surgeons continued with the operation until complete resection. Specificity was greater in N-ioUS (42% vs 31%) and positive predictive value (73% vs 54%). At discharge the difference between pre and post-operative KPS was significantly higher for the N-ioUS (p=0.0008). Using N-ioUS-based real-time guidance in glioma surgery we obtained superior results in terms of both EOR and neurological outcome, in comparison to standard NN. N-ioUS has proven usefulness in detecting RTV> 1cc. In tumors located nearby eloquent areas the technique was successfully combined with cortical and subcortical mapping techniques.