Pattern of use of intraoperative ultrasound in surgery for brain tumors influences outcomes in glial tumors.

Abstract

Background Intraoperative ultrasound (iUS) imaging has emerged as a promising adjunct in glioma surgery with both, 2-dimensional (2D) as well as navigated 3-dimensional (n3D), modes increasingly being used. Methods We analyzed our decade-long experience of 1075 brain tumor (807, 75% gliomas) cases operated using iUS. A retrospective chart and electronic records review was performed. The primary aim was to understand the patterns of use of iUS mode and its purpose of application (as a localizing tool or as a resection control modality) as well as to evaluate its impact on the extent of resection. Results The use of iUS increased over time, especially with the introduction of n3DUS though 2DUS remained the more commonly used mode (63%) overall during this period. For biopsies (156 cases), both 2D, as well as n3D iUS, were used as a localizing tool only. Lesion localization was the major purpose for use of iUS even for tumor resections (61%). Resection control was performed more often for gliomas (46.5% compared to 16.5% in non-glial tumors). n3DUS was the preferred modality as a resection control tool irrespective of histological class. GTR (gross total resection) was achieved in 53.1% cases overall, while in glial and non-glial tumors it was 44.7% and 80.7%, respectively. GTR was higher when iUS was used as a resection control modality. The US and MR defined EOR (extent of resection) showed substantial agreement (κ = 0.678) with high diagnostic accuracy of 84% for glial tumors. In glial tumors, iUS was used more often in eloquent tumors and GTR rates were slightly higher than when iUS was not used. Conclusion iUS is a versatile tool and is a useful surgical adjunct for glioma surgeons. Besides its proven benefit as a localizing tool, when used as a tool for resection control it improves the resection rates. n3DUS may offer benefits over 2DUS as a resection control modality, though the evidence is still evolving.