MR imaging correlates of survival in patients with high-grade gliomas

Abstract

Background and purpose: For patients with malignant gliomas, clinical data-including age, perioperative Karnofsky Performance Status (KPS), and tumor resection-and tumor imaging features-including necrosis and edema-have been found to correlate with survival. The purpose of this study was to assess the validity of these results and determine whether other imaging features are useful in predicting survival.

Methods: We analyzed the relationship between 15 imaging variables obtained from contrast-enhanced MR imaging scans and survival in patients with grade III (n = 43) and grade IV (n = 110) glioblastoma multiforme (GBM) gliomas. Image analysis was performed by 2 neuroradiologists who were blinded to clinical data. The Kaplan-Meier method was used to estimate survival probabilities. Univariable Cox models were used to assess the impact of imaging features on survival. A recursive partitioning analysis also was performed.

Results: As expected, age and KPS scores had significant prognostic value for both tumor grades. The extent of resection was not a statistically meaningful predictor of survival. For GBM, univariable analysis revealed the following imaging features to be significant, (hazard ratios in parentheses): noncontrast-enhancing tumor (nCET, 0.55), edema (1.62), satellites (1.74), and multifocality (4.34). For grade III tumors, the Cox hazard ratio for necrosis was 4.43 (P = .014) and correlated with a poor outcome and survival rates comparable to GBM patients. Lack of nCET, multifocality, and satellite lesions also were correlated with shortened survival.

Conclusion: Of 15 tumor imaging features in GBM patients, only nCET, edema, and multifocality/satellites are statistically significant prognostic indicators. The survival advantage of nCET is a novel finding.

Fig 1.

MR images of patients with GBM. A, Axial postcontrast T1-weighted images. There is an enhancing tumor with central, irregular hypoenhancement consistent with necrosis. B, Axial T2-weighted images of the same patient shown in panel A. High T2-weighted signal intensity surrounds the tumor, with signal intensity approaching that of CSF as seen in the lateral ventricles. The T2-weighted signal intensity change respects the cortical ribbon. The appearance is indicative of vasogenic edema (grade 2, extending more than 1 cm from the tumor, per definitions in Table 1). C, Axial postcontrast T1-weighted images of another GBM patient. As in the first case there is an enhancing tumor with irregular central hypoenhancement indicating necrosis. D, Axial T2-weighted images of the same patient shown in panel C. Adjacent to the enhancing portion of the tumor, there is increased T2-weighted signal intensity, which is significantly lower than that of CSF, which extends into the cortex and does not respect the cortical ribbon. The gray-white distinction is obscured. The region corresponds to areas of mildly low T1-weighted signal intensity. This appearance reflects the presence of nonenhancing tumor (nCET). There is also a sliver of higher T2-weighted signal intensity change at the medial margin of the tumor, which indicates a small amount of edema.

Fig 2.

Survival curves for glioblastoma. Favorable (n = 16) is tumors with nCET and without edema, satellites, and multifocal disease. Unfavorable (n = 17) is edema, and either satellites or multifocal disease, without nCET (n = 110 for all GBM patients).

Fig 3.

Recursive partitioning analysis. All 15 imaging features as described in the Methods section were entered into the recursive partitioning algorithm. The 95% confidence intervals are shown in parentheses.