Magnetic resonance perfusion-weighted imaging defines angiogenic subtypes of oligodendroglioma according to 1p19q and EGFR status

1p19q LOH has been shown to predict radio- and chemosensitivity and prolonged survival in oligodendrogliomas (OLs). We have recently shown that magnetic resonance perfusion-weighted imaging (MR-PWI) may be useful in predicting the histopathological grade or cytogenetic type of oligodendroglial neoplasms. MR-PWI allows noninvasive determination of relative tumor blood volume (rTBV), which may reflect the degree of neoplastic angiogenesis and metabolism. The present study was aimed to correlate rTBV to the angiogenic markers and EGFR expression in oligodendroglial tumors with 1p/19q LOH or 1p LOH (Group 1) and 1p19q intact alleles or 19q LOH (Group 2), respectively. In WHO grade II neoplasms, Group 1 showed significantly greater rTBV than Group 2 (P = 0.013). However, the differences between Group 1 and Group 2 were not significant in grade III tumors. Probe-based real-time RT-PCR analyses showed that 12% of Group 2 high-grade tumors with intact 1p19q exhibited dramatic EGFR overexpression (designated EGFR-high). Grade III neoplasms showed a significantly higher rTBV than grade II neoplasms. Group 1 tumors showed significantly higher rTBV than Group 2 tumors, independent of the EGFR-high subtype. Real-time RT-PCR analyses showed increased expression of VEGF, CD31 and CD105 in Group 1 tumors as compared to Group 2 tumors, excluding the EGFR-high subtype. Multivariable linear regression analysis showed a significant association of rTBV with 1p19q LOH, and expression of EGFR and VEGF. Therefore, the combined use of extensive molecular profiling and advanced MR imaging modalities may improve the accuracy of tumor grading, provide prognostic information, and has the potential to influence treatment decisions.