Table 2.
Summary of key imaging features of glial and glioneuronal tumors.
| Tumor Type | Common Location | Key MRI Features |
|---|---|---|
| Diffuse high-grade gliomas | ||
| Diffuse midline glioma (H3K27 altered) | Ventral pons and thalami | Expansile, ill-defined mass No diffusion restriction Usually, non-enhancing at presentation Encasement of basilar artery without narrowing |
| Supratentorial high-grade glioma (H3 G34 mutant or H3 wild-type) |
Hemispheric or deep nuclei; most common in frontal and parietal lobes | Large, circumscribed tumor Diffusion restricting solid components Variable cysts/necrosis and hemorrhage |
| Circumscribed gliomas | ||
| Pilocytic astrocytoma | Cerebellum (most common), brainstem, optic chiasm/hypothalamus | Most commonly, cyst with enhancing mural nodule although cystic component can be variable, and may be completely solid |
| Ependymoma | ||
| Posterior fossa ependymoma | Fourth ventricle (PFB) or cerebellopontine angle (PFA) | Heterogeneous mass Calcifications common Intermediate diffusion (between medulloblastoma and pilocytic astrocytoma) Usually enhancing High myo-inositol on MRS |
| Supratentorial ependymoma | Frontal or parietal parenchyma | Large mass with necrosis Central chunky calcifications Diffusion restriction in two-thirds |
| Neuronal and glioneuronal tumors | ||
| Ganglioglioma | Temporal lobe | Variable, although commonly cystic with enhancing mural nodule No diffusion restriction |
| Dysembryoplastic neuroepithelial tumor (DNET) | Frontal or temporal lobes, cortically based | Well-circumscribed, triangular configuration, ‘bubbly’ appearance Absent or minimal enhancement May be associated with cortical dysplasia Scalloping of the overlying calvarium |
(Abbreviations: rCBV, relative cerebral blood volume; MRS, Magnetic Resonance Spectroscopy; NAA, N-acetylaspartate; PFA, posterior fossa A; PFB, posterior fossa B).