Vol.98 No.10 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 98 No. 10 October 2005
CT Diagnosis of the Ossicular Lesion Using
Multiplanar Reconstruction
Nozomu Mori
(Kagawa University)
It has been widely pointed out that multislice CT (MSCT) is useful in middle ear disease. The evaluation of the pathological state of the middle ear using 3D CT imaging has been reported on up to now. It is well known that 3D CT imaging is susceptible to post-processing artifacts, whereas multiplanar reconstruction (MPR) is less susceptible to these artifacts. The usefulness of 2D CT imaging using MPR in the evaluation of ossicular lesions in middle ear diseases is discussed.
MSCT imaging was performed by Aquilion? (Toshiba Medical Systems, Tokyo, Japan). The axial spiral scans were obtained. Dosimetric measurements using a head calibration phantom were performed for evaluating the radiation exposure of the lenses. The acquired high-resolution data were transferred to a workstation (ALATO VIEW, Toshiba).
In approximately 90％ of ears, MPR image findings of the malleus handle, the incus long process, incudostapedial joint and the superstructure of the stapes were compatible with their operative findings. Ninety-five to 100％ of ears without soft tissue shadows around the ossicles showed agreement between the findings of MPR imaging and the operation. The footplate of the stapes in 7 of 48 ears showed a "sclerotic" finding. Five ears had an "erosive" finding. There was no correlation between MPR image findings and the mobility of the stapedial footplate. The results suggest that MPR imaging is valuable for providing information on the ossicles except the stapes footplate.
MPR images showed abnormal findings in 29 of 32 ears (91％) with clinical otosclerosis, which showed demineralization located at the region anterior to the oval window corresponding to the fissula antefenestram, whereas the conventional axial images showed abnormal findings in 22 of 32 ears (69％). The results suggest that MPR imaging can detect small lesions in otosclerosis.
Key words : ossicular lesions, multiplanar reconstruction, multislice CT, middle ear