Clinical history: 51-year old woman with episodic seizures for 20 years

Diagnosis: Oligodendroglioma (WHO grade II)

Imaging techniques:

(A) Sagittal T1-weighted TIRM*(TR/TE 2000/9ms), (B) axial T1-weighted TIRM (TR/TE 2000/9ms), (C) axial T2-weighted TSE (TR/TE 4800/99ms), (D) axial T2-weighted TIRM (TR/TE 8500/85ms), and (E) coronal T2-weighted TIRM (TR/TE 8500/85ms) images were acquired along with (F, G, H) axial EPI-DTI (TR/TE 3700/95ms; b-values= 0 and 1000; Diffusion Directions 20). Contrast-enhanced T1-weighted TSE (TR/TE 350-533/6.4) images were obtained in three orthogonal planes (I, J, K).

Imaging findings:

Pre-contrast MRI demonstrates a large right frontal mass involving the cortex and subcortical white matter. The lesion is predominantly solid with heterogeneity related to intratumoral cysts and chronic hemorrhage. On both T1 and T2WI, the tumor exhibits heterogenously hyperintense signal with moderate mass effect. No significant peritumoral edema is noted. Calcifications characteristic of oligodendroglioma are less evident on MRI appearing as small, non-specific low signal intensity foci. On post-contrast MR images, the solid components of the tumor exhibit mild enhancement, which makes the cysts more conspicuous. DTI shows increased ADC values and decreased FA values within the lesion, as well as involvement of the subcortical arcuate fibers and the corticospinal tracts of the right frontal lobe (DTI Tractography).

Oligodendrogliomas account for approximately 15% of intracranial gliomas and 5% of all intracranial tumors. Calcification is frequent, ranging from microcalcifications to large areas of conglomerate calcification.

* TIRM: Turbo Inversion Recovery Magnitude