Correlation of the extent of tumor volume resection and patient survival in surgery of glioblastoma multiforme with high-field intraoperative MRI guidance

Abstract

Extent of resection (EOR) still remains controversial in therapy of glioblastoma multiforme (GBM). However, an increasing number of studies favor maximum EOR as being associated with longer patient survival. One hundred thirty-five GBM patients underwent tumor resection aided by 1.5T intraoperative MRI (iMRI) and integrated multimodal navigation. Tumor volume was quantified by manual segmentation. The influences of EOR, patient age, recurrent tumor, tumor localization, and gender on survival time were examined. Intraoperative MRI detected residual tumor volume in 88 patients. In 19 patients surgery was continued; further resection resulted in final gross total resection (GTR) for 9 patients (GTR increased from 47 [34.80%] to 56 [41.49%] patients). Tumor volumes were significantly reduced from 34.25 ± 23.68% (first iMRI) to 1.22 ± 16.24% (final iMRI). According to Kaplan-Meier estimates, median survival was 14 months (95% confidence interval [CI]: 11.7-16.2) for EOR ≥ 98% and 9 months (95% CI: 7.4-10.5) for EOR <98% (P< .0001); it was 9 months (95% CI: 7.3-10.7) for patients ≥ 65 years and 12 months (95% CI: 8.4-15.6) for patients <65 years (P < .05). Multivariate analysis showed a hazard ratio of 0.39 (95% CI: 0.24-0.63; P = .001) for EOR ≥ 98% and 0.61 (95% CI: 0.38-0.97; P < .05) for patient age <65 years. To our knowledge, this is the largest study including correlation of iMRI, tumor volumetry, and survival time. We demonstrate that navigation guidance and iMRI significantly contribute to optimal EOR with low postoperative morbidity, where EOR ≥ 98% and patient age <65 years are associated with significant survival advantages. Thus, maximum EOR should be the surgical goal in GBM surgery while preserving neurological function.

Fig. 1.

Workflow figure illustrating the surgical procedure in the setting of iMRI. (Gd: gadolinium).

Fig. 2.

Illustrative Case: MRI scans of a 60-year-old male patient with recurrent left parietal GBM during the surgical procedure. (A) Preoperative MRI, head already fixed, immediately before surgery (tumor volume: 57.3 mL). (B) First iMRI after estimated best possible tumor resection with a residual tumor mass of 2.32 mL. (C) Second iMRI after further tumor resection due to the first intraoperative scans, now showing gross total resection.

Fig. 3.

Kaplan–Meier estimates of survival in univariate analysis with respect to patient age (≥65 years/<65 years). Median survival: 9 months (95% CI: 7.3–10.7) for patients ≥65 years, 12 months (95% CI: 8.4–15.6) for patients <65 years (P < .04).

Fig. 4.

Kaplan–Meier estimates of survival in univariate analysis with respect to EOR (≥98%/<98%). Median survival: 14 months (95% CI: 11.7–16.2) for EOR ≥98%, 9 months (95% CI: 7.4–10.5) for EOR <98% (P < .001).

Fig. 5.

Cox proportional hazards model with respect to EOR (≥98%/<98%), (P < .0001).