Peritumoral edema on magnetic resonance imaging predicts a poor clinical outcome in malignant glioma

Abstract

Peritumoral edema (PTE), one of the main characteristics of malignant glioma, is a significant contributor to the morbidity and mortality from glioma, however, a recent systematic review suggested that controversy remains with regard to its prognostic value. To further determine whether PTE was a potential prognostic factor on routine pre-operative magnetic resonance imaging (MRI) for malignant glioma, the association between survival and PTE was investigated in the present retrospective review of 109 patients with newly diagnosed supratentorial malignant glioma using MRI data from these routine scans. The Kaplan-Meier method was used to calculate overall survival (OS) in univariate analysis, and COX proportional hazards model was applied to evaluate the effect of pre-operative MRI features on OS in multivariate analysis. The PTE extent, edema shape, degree of necrosis, enhancement extent, pathological grade, patient age, Karnofsky performance status (KPS) and post-operative chemoradiotherapy were associated with OS in the patients with malignant glioma on univariate analysis. Multivariate analysis indicated that the extent of PTE and degree of necrosis shown by pre-operative MRI were independent predictors of OS, in addition to pathological grade, patient age, KPS and post-operative chemoradiotherapy. Moreover, patients with two unfavorable factors (major edema and severe necrosis) exhibited a poorer OS compared with the remainder. In summary, PTE and degree of necrosis, which are easily determined from routine MRI, can be useful for predicting a poor clinical outcome in patients with newly diagnosed malignant glioma.

Keywords: glioblastoma; magnetic resonance imaging; malignant glioma; peritumoral edema; prognosis; survival.

Figure 1.

Example of classification of imaging features (arrows). (A) Minor edema (<1 cm) and the rounded edema shape shown by T2-W MRI. (B) Major edema (≥1 cm) and the irregular shape of edema shown by T2-W MRI. (C-H) Contrast-enhanced T1-W images showing (C) mild necrosis (≤50%), (D) severe necrosis (>50%), (E) no marked enhancement, (F) marked enhancement, (G) a small cyst and (H) a large cyst. T2-W MRI, T2-weighted magnetic resonance imaging.

Figure 2.

Correlations between (A) PTE, (B) necrosis, (C) enhancement, (D) edema shape, (E) major PTE and severe necrosis, (F) age, (G) grade and (H) chemoradiotherapy, and overall survival in the entire cohort (Kaplan-Meier curves). (E) a, the group with two unfavorable factors (major PTE and severe necrosis); b, the group with only one unfavorable factor (major PTE or severe necrosis); c, the group without major PTE and severe necrosis. PTE, peritumoral edema.