2001 ASNR Annual Meeting Abstracts
01-S-434-ASNR
Multiplanar Reformation of Normal Middle Ear:
Relation between Slice Thickness and Visibility
Toyama, Y.
Kagawa Medical University, Kagawa, Japan
Purpose
To examine the relation between slice thickness and visibility of normal middle ear using helical
CT.
Materials & Methods
CT examinations on 27 normal middle ears in 22 patients were reviewed by two radiologists,
with special attention paid to malleus (head, neck, handle, lateral process), incus (short process,
body, long process), stapes (anterior crus, posterior crus), tendon of Tensor, stapedius, anterior
ligament of malleus, superior ligament of malleus, posterior ligament of incus, and facial canal.
CT scanning was performed with either an Aquilion scanner (Toshiba) or a Hispeed Advantage
scanner (GE). The scans were obtained by using 0.5 mm (10 ears:Aquilion with multidetector),
0.8 mm (12 ears:Aquilion) or 1.0 mm (5 ears:Hispeed Advantage) collimation. All examinations
were reviewed by using multiplanar reformation. Each examination was scored on a three-point
scale as follows: 2 =detected clearly, 1 =detected indistinctly, 0 =not detected.
Results
All structures of malleus, incus, and facial canal were detected clearly in each collimation (0.5,
0.8, 1.0 mm). In case of stapes and posterior ligament of incus, no significant difference was
found between the three collimations. In case of tendon of Tensor, stapedius and anterior
ligament of malleus, the scans with 0.5 and 0.8 mm collimation were clearer than those with 1.0
mm, with a significant difference (p < 0.05). The scans of superior ligament of malleus obtained
by using 0.5 mm collimation yielded significantly clear visibility compared with 1.0 mm
collimation (p < 0.05).
Conclusion
With regard to ossicles, there was no relation between slice thickness and visibility on CT
examination. However some tendons and ligaments in the middle ear showed a tendency to be
detected more clearly with thinner section CT.