212 Continuous Mapping of Brain Tumor Resection Progression During Surgery

Abstract

INTRODUCTION: Maximal safe extent of resection extends survival for gliomas. Surgical adjuncts including neuronavigation, intraoperative MRI (iMRI), intraoperative ultrasonography (iUS), and fluorescence imaging can help surgeons minimize unintentional residual tumor; each with associated limitations including cost, availability, susceptibility to brain shift and complex tumor shapes. METHODS: During tumor resection, surgical instruments, including navigation pointer, ultrasonic aspirator, suction, and bipolar forceps, were optically tracked. Data was streamed to 3D Slicer (https://www.slicer.org/) via OpenIGTLink (http://openigtlink.org/) and 3D maps of the resection cavity were computed using instrument tip locations. iMRI was performed after substantial resection and used to evaluate the resection maps. RESULTS: In 25 of 28 cases where residual tumor was identified on iMRI, the ‘difference map’ obtained by subtracting the resection map from the preoperative tumor contour correctly ascertained the location of residual. In 18 of these 25, the difference map reliably predicted the extent of residual as well. In 3 cases, false-positive overlap >30% of the contoured residual volume was noted and likely attributable to brain shift or collapse of the resection cavity during surgery. Even in these cases, surgeons reported that the general shape of the resection map helped them mentally compensate for brain shift and identify potential residual in visually inaccessible regions. Additionally, we present solutions to overcome line-of-sight challenges in optical tracking during dynamic resection. CONCLUSION: Our real-time navigated tracking system reliably maps resection progress during surgery and can direct attention to residual. It operates synergistically with commercial neuronavigation without disruption to surgical flow and can, in conjunction with iUS, compensate for brain shift and resection cavity collapse.