====== Dysembryoplastic neuroepithelial tumor diagnosis ======

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According to Daumas-Duport and colleagues, the criteria for the diagnosis of [[Dysembryoplastic neuroepithelial tumor]] should include: 

(1) [[partial seizure]]s, with or without secondary generalization beginning before age 20 

(2) no [[neurological deficit]] or presence of a stable and likely congenital neurological deficit 

(3) cortical topography of the lesion as best demonstrated on MRI

(4) no mass effect on CT or MRI (except if related to a [[cyst]])
((Daumas-Duport C, Varlet P, Bacha S, Beuvon F, Cervera-Pierot P, Chodkiewicz JP. Dysembryoplastic neuroepithelial tumor: Nonspecific histological forms:A study of 40 cases. J Neurooncol 1999;41:267-80.)).

Radiographic features

DNETs are typically predominantly cortical and well circumscribed tumours.

CT

if cortical may scallop the inner table of of the skull vault (44-60%), but no erosion
the cranial fossa can be minimally enlarged at times
calcification in ~30% (more common histologically) 
low density
no enhancement
MRI

Typically seen as a cortical lesion with hardly any surrounding vasogenic oedema. 

T1

​generally hypointense c.f adjacent brain

T1 C+ (Gd)

may show enhancement in ~20-30% of cases,
enhancement may be heterogeneous or a [[mural nodule]]

T2
​generally high signal
high signal 'bubbly appearance'
FLAIR
​mixed signal intensity with bright rim sign
partial suppression of some of the "bubbles"
FLAIR is helpful in identifying the small peripheral lesions with similar intensity to CSF
T2* 
calcification relatively frequent
​haemosiderin staining uncommon as bleeding into DNETs is only occasional
DWI
​no restricted diffusion
MR spectroscopy
​non-specific although lactate may be present