Introduction: Glioblastoma (GBM) extent of tumor resection (EOR) is difficult to precisely measure in a precise and consistent fashion due to the nonconformal shapes of MRI residual contrast enhancement present at the tumor margin as well as blood products present after surgery. An MRI signal-based approach for tumor segmentation was performed using an FDA 510k-approved software package. Our volume determination method was used to compare GBM EOR in newly diagnosed patients undergoing fluorescent-guided surgery (FGS) in a Phase II trial to patients who underwent standard resection without FGS.
Methods: Datasets consisted of high-resolution pre- and post-operative MR images (T1-weighted images pre- and post-gadolinium) from thirteen consecutive patients enrolled in a Phase II 5-ALA study and thirteen control patients matched for tumor location and size. A coarse region-of-interest (ROI) was drawn around the contrast-enhancing tumor and the software was used to segment volumes of hyper- and hypo-intensity on T1-weighted MR images within the ROI in an automated fashion. To estimate the residual tumor after surgery, image difference maps were produced by subtracting co-registered, pre- and post-gadolinium T1-weighted MR images to correct for postoperative blood accumulation.
Results: The average tumor EOR for those patients without FGS was 89.31 ± 7.45%, while those patients who underwent FGS was 95.15 ± 3.98%. These values were found to be significantly different at p<0.01 using the nonparametric Wilcoxon Rank-Sum Test. These results corroborate with those seen in the literature and support the use of this semi-automated method for the unbiased and reproducible generation of contrast-enhancing tumor volumes in GBM pre- and post-resection.
Conclusions: The comparison of our method with the current standard radiological orthogonal assessment is underway to illustrate precision in terms of inter-reader variability. The standardization of this method will permit quantitative analysis of GBM EOR, offering a highly precise tool for the longitudinal monitoring of patients in clinical trials.
Patient Care: The standardization of this method will permit quantitative analysis of GBM EOR as well as tumor response to chemo- and radiation therapies, offering a highly precise tool for the longitudinal monitoring of patients in clinical trials.
Learning Objectives: 1. Residual GBM tumor volume measurements after resection are difficult to consistently measure in a precise manner.
2. An FDA 510k-approved software package was used to determine extent of tumor resection (EOR) in a semi-automated method in newly diagnosed GBM patients enrolled in a Phase II clinical trial involving the fluorescent-guided surgery (FGS) with 5-ALA to patients who underwent standard resection without FGS.
3. A greater EOR was achieved in patients who undergent resection of their GBM with FGS in comparison to those without.
4. The standardization of this method will permit quantitative analysis of GBM EOR, offering a highly precise tool for the longitudinal monitoring of patients in clinical trials.