Visibility of epidermoid tumors on steady-state free precession images.
OBJECTIVE
To determine whether steady-state free precession sequences improve the MR visibility of epidermoid tumors in comparison with spin-echo images.


METHODS
Patients were four women and three men with epidermoid tumors in the subarachnoid spaces. MR was performed with a 1.5-T superconductive unit. For steady-state free precession imaging, three-dimensional Fourier transform fast imaging with steady-state free precession (FISP) images were used (20-40/7 [repetition time/echo time], flip angle of 25 degrees). The visualization and contrast-to-noise ratio were compared in FISP images and spin-echo images. In one case, the images of FISP and fast low-angle shot were obtained with variable repetition times and flip angles to evaluate the best pulse sequences for the visualization of epidermoid tumors.


RESULTS
The contrast-to-noise ratios between tumors and cerebrospinal fluid ranged from 7.9 to 17.5 (average was 12.9) on FISP images. The average of contrast-to-noise ratios on T1, T2, and proton density-weighted spin-echo images were 1.6, 2.0, and 4.2, respectively. Three-dimensional Fourier transform FISP images best showed central nervous system and demonstrated epidermoid tumors excellently.


CONCLUSIONS
Epidermoid tumors in the subarachnoid spaces were better demonstrated on steady-state free precession (three-dimensional Fourier transform FISP) than on conventional spin-echo images.
Department of Radiology, Kumamoto University School of Medicine, Japan.
Y
Y
Sakamoto
M
M
Takahashi
Y
Y
Ushio
Y
Y
Korogi
D000368:Aged; D001927:Brain Diseases / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D004814:Epidermal Cyst / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013346:Subarachnoid Space / Q000473:pathology