Objective The radiological characteristics of World Health Organization grade III oligodendroglial tumours in relation to chromosome 1p and 19q deletions were analysed.

Methods 56 patients recently diagnosed with anaplastic oligodendroglioma (AO, n=49) or anaplastic oligoastrocytoma (AOA, n=7) were studied. Their preoperative magnetic resonance images were examined. Deletions of chromosome 1p and 19q were determined using the fluorescence in situ hybridisation method. Both 1p and 19q chromosomes had deletions (1p19q codeletion) in 39 patients (36 AO and 3 AOA).

Results Tumors associated with the 1p19q codeletion were predominantly located in the frontal lobe (p=0.044). The magnetic resonance image characteristics of indistinct tumour borders (p=0.005 on T1, p=0.036 on T2) and a heterogeneous intratumoural signal intensity (p=0.033 on T1, p=0.041 on T2) were significantly correlated with the 1p19q codeletion. Analysis of patient survival showed those with the 1p19q-codeleted tumours survived significantly longer than those lacking the 1p19q codeletion (p=0.042). The presence of a heterogeneous signal intensity in T2-weighted images, a characteristic significantly related to the 1p19q codeletion, indicated a favourable prognosis for patients' survival (HR; 0.125, 95% CI, 0.016 to 0.963, p=0.046) based on multivariate analysis.

Conclusion A relationship between radiological characteristics and molecular signatures in AO/AOAs was shown. It is believed that radiological characteristics have prognostic value as a surrogate marker for molecular characteristics.