Specific Imaging Findings On CT, dysembryoplastic neuroepithelial tumor (DNT or DNET) appears as a low density cortico-subcortical supratentorial area. Calcifications are rare. Remodeling of the adjacent calvarium is frequent with superficially located tumors. On MRI, the classic appearance is of a well-demarcated pseudocystic lesion, strongly T2 hyperintense and T1 hypointense with variable signal on FLAIR images. Mass effect is minimal to absent, there is no surrounding vasogenic edema. DNTs may have a triangular-shaped pattern with the base along the cortical surface with preserved gyral pattern. Thin hyperintense signal on FLAIR images is visible both along the surface (bright rim) and as stripes along thin internal septa, resulting in a very characteristic multicystic, “bubbly” appearance. Additional small cysts, separated from the main mass, are often located in the neighboring cortex or subcortical white matter. Some lesionsmay show a more heterogeneous signal consistent with solid, cystic, or semiliquid structures. Solid components may either be solitary or form a multinodular pattern interspersed within a cystic frame. Contrast enhancement is rare, variable, and more often ringlike. Bleeding is also rare. Tumors show increased diffusivity with high ADC values and low rCBV on perfusion imaging. The MRS pattern is nonspecific with increase in mI/Cr and Cho/NAA ratios. Lactate and lipid peaks are usually absent.
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