Quantitative MR evaluation of intracranial epidermoid tumors by fast fluid-attenuated inversion recovery imaging and echo-planar diffusion-weighted imaging.
OBJECTIVE
Quantification of MR can provide objective, accurate criteria for evaluation of a given MR sequence. We quantitatively compared conventional MR sequences with fast fluid-attenuated inversion recovery (fast-FLAIR) and echo-planar diffusion-weighted (DW) MR imaging in the examination of intracranial epidermoid tumors.


METHODS
Eight patients with surgically confirmed intracranial epidermoid tumors were examined with T1-weighted MR sequences, fast T2- and proton density-weighted dual-echo sequences, fast-FLAIR sequences, and DW echo-planar sequences. We measured the MR signal intensity and apparent diffusion coefficient (ADC) of epidermoid tumors, normal brain tissue, and CSF and calculated the tumor-to-brain and tumor-to-CSF contrast ratios and contrast-to-noise ratios (CNR). Results were compared among the five MR methods.


RESULTS
On fast-FLAIR imaging, the mean signal intensity of epidermoid tumors was significantly higher than that of CSF but significantly lower than that of the brain; the contrast ratio and CNR of tumor-to-CSF were 4.71 and 9.17, respectively, significantly greater than the values with conventional MR imaging. On echo-planar DW imaging, epidermoid tumors showed a remarkably hyperintense signal relative to those of the brain and CSF; the mean contrast ratio and CNR of tumor-to-CSF were 13.25 and 19.34, respectively, significantly greater than those on fast-FLAIR or conventional MR imaging. The mean ADC of epidermoid tumors was 1.197 x 10(-3) mm(2)/s, significantly lower than that of CSF but higher than that of brain tissues.


CONCLUSIONS
Fast-FLAIR imaging is superior to conventional MR imaging in depicting intracranial epidermoid tumors. Echo-planar DW imaging provides the best lesion conspicuity among the five MR methods. The hyperintensity of epidermoid tumors on echo-planar DW imaging is not caused by the diffusion restriction but by the T2 shine-through effect.
Chen
S
S
Department of Neurosurgery, Hiroshima University School of Medicine, Hiroshima, Japan.
Ikawa
F
F
Kurisu
K
K
Arita
K
K
Takaba
J
J
Kanou
Y
Y
D000368:Aged; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000175:diagnosis*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis*; D003937:Diagnosis, Differential; D004058:Diffusion; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity