Diffusion tensor mode in imaging of intracranial epidermoid cysts: one step ahead of fractional anisotropy.
BACKGROUND
The signal characteristics of an epidermoid on T2-weighted imaging have been attributed to the presence of increased water content within the tumor. In this study, we explore the utility of diffusion tensor imaging (DTI) and diffusion tensor metrics (DTM) in knowing the microstructural anatomy of epidermoid cysts.


METHODS
DTI was performed in ten patients with epidermoid cysts. Directionally averaged mean diffusivity (D(av)), exponential diffusion, and DTM-like fractional anisotropy (FA), diffusion tensor mode (mode), linear (CL), planar (CP), and spherical (CS) anisotropy were measured from the tumor as well as from the normal-looking white matter.


RESULTS
Epidermoid cysts showed high FA. However, D(av) and exponential diffusion values did not show any restriction of diffusion. Diffusion tensor mode values were near -1, and CP values were high within the tumor. This suggested preferential diffusion of water molecules along a two-dimensional geometry (plane) in epidermoid cysts, which could be attributed to the parallel-layered arrangement of keratin filaments and flakes within these tumors.


CONCLUSIONS
Thus, advanced imaging modalities like DTI with DTM can provide information regarding the microstructural anatomy of the epidermoid cysts.
Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, 695011, India.
Milan
M
Jolapara
Chandrasekharan
C
Kesavadas
V V
VV
Radhakrishnan
Jitender
J
Saini
Satya Narayan
SN
Patro
Arun Kumar
AK
Gupta
Tirur Raman
TR
Kapilamoorthy
Narendra
N
Bodhey
D000328:Adult; D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004814:Epidermal Cyst / Q000175:diagnosis*; D020802:Epidural Abscess / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged