Alright - the images from top to bottom - CT, FLAIR, GRE/T2*, ADC, DWI, postcon T1, precon T1 and T2
This case represents a Dysembryoplastic Neuroepithelial Tumor (DNET).
1. Benign tumor of neuroepithelial tissue arising from cortical or deep grey matter.
2. Virtually always in patients with refractory partial seizures
3. Majority - younger (in 20's or younger) and male
4. Neurologic deficits are not common
5. temporal (often amygdala/hippocampus) > frontal > parietal; can also be seen in caudate, pons, and cerebellum
6. Cerebellar - present with vertigo, ataxia and gait disturbances
7. Tend to be stable, recurrence is rare but malignant degeneration has occured - therefore long term follow up is recommended.
9. Imaging - similar to low-grade gliomas - can be difficult do differentiate from diffuse astrocytoma, ganglioglioma and oligodendroglioma
10. CT - hypoattenuating mass with occasional calcifications, may see remodeling of inner table; minimal or no mass effect; may resemble a stroke but no evolution over time
11. MR - low signal on T1, high on T2 without surrounding edema; 1/3 enhance and usually peripheral or nodular (i.e. 2/3 don't); if enhancing - may be something more ominous
12. Some have a "soap bubble" appearance; some appear like an enlarged gyrus; can have multicystic appearance
13. Often when cortical - wedge shaped with point toward ventricle
14. FLAIR - mixed hypo/iso with bright rim; GRE - occasionally bleed and can be confused with cavernoma (rare); PD - hyperintense rim; No restricted diffusion
15. HMPAO - hypoperfusion (ictal may have uptake); No uptake on Thallium-201; PET - hypometabolism
16. DDX - Taylor Dysplasia (single Tubersous sclerosis lesion - expand gyrus, nonenhancing, looks like a tuber), Neuorepithelial cyst (nonenhancing single or complex cyst, no bright rim), ganglioglioma (strong enhancement, calcs, cyst), PXA (enhancing nodule adjacent to pia and look for dural tail)
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