FIG 6. A case of a 2-mm intracanalicular acoustic schwannoma. A small filling defect in the CSF of the left internal auditory canal was depicted on both 1.5-T images (imaging time, 12 minutes) (A) and 0.35-T images (imaging time, 11 minutes) (B) (arrows).

A, The imaging parameters at 1.5 T were as follows: field of view, 16 cm; section thickness, 0.8 mm; 4000/240 (TR/TE); four shots; echo train length, 79; matrix, 512 x 512 x 40; echo spacing, 15.0 milliseconds; and imaging time, 11 minutes 48 seconds.

B, The imaging parameters for 0.35 T were the same as those presented in the legend to figure 5B. Our protocol for "the screening brain and internal auditory canal" included T2-weighted images for whole-brain and MR cisternography with 3D fast asymmetry spin-echo images obtained in 2 minutes 45 seconds. The protocol for "screening internal auditory canal only" for the patients who had finished their whole-brain study was MR cisternography with 3D fast asymmetric spin-echo images obtained in 12 minutes. For this image, the latter protocol was applied to compare the image quality between the 0.35- and 1.5-T images obtained during comparable imaging time. Note the considerable difference in the image quality between the 0.35- and 1.5-T images when obtained during comparable imaging time, although the pathologic findings can be appreciated on either image.