Accuracy of the neurosurgeons estimation of extent of resection in glioblastoma

Abstract

Background The surgeons' estimate of the extent of resection (EOR) shows little accuracy in previous literature. Considering the developments in surgical techniques of glioblastoma (GBM) treatment, we hypothesize an improvement in this estimation. This study aims to compare the EOR estimated by the neurosurgeon with the EOR determined using volumetric analysis on the postoperative MR scan. Methods Pre-and post-operative tumor volumes were calculated through semi-automatic volumetric assessment by three observers. Interobserver agreement was measured using intraclass correlation coefficient (ICC). A univariate general linear model was used to study the factors influencing the accuracy of estimation of resection percentage. Results ICC was high for all three measurements: pre-operative tumor volume was 0.980 (0.969-0.987), post-operative tumor volume 0.974 (0.961-0.984), and EOR 0.947 (0.917-0.967). Estimation of EOR by the surgeon showed moderate accuracy and agreement. Multivariable analysis showed a statistically significant effect of operating neurosurgeon (p = 0.01), use of fluorescence (p < 0.001), and resection percentage (p < 0.001) on the accuracy of the EOR estimation. Conclusion All measurements through semi-automatic volumetric analysis show a high interobserver agreement, suggesting this to be a reliable assessment of EOR. We found a moderate reliability of the surgeons' estimate of EOR. Therefore, (early) postoperative MRI scanning for evaluation of EOR remains paramount.

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“…Calculation of tumor volume from multiple slices, however, as reported by Johnson et al in head and neck cancer, may yield an even more accurate estimation of the volume but is less accessible to the clinician 20 . An even better estimate of tumor's volume by volume calculation with MRI as was already reported in Glioblastomas 21 …”

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