3D image of the middle ear ossicles: three protocols of post-processing based on multislice computed tomography.

ABSTRACT

The aim of this study was to examine and assess the comparative values of HRCT-based multiplanar reformation (MPR), volume rendering (VR) and virtual endoscope built on three-dimensional shaded-surface display (SSD-based CTVE) for evaluations of the ossicular chain. The normal pure tone audiograms, type-A tympanogram, and normal HRCT characteristics of 32 human ears of 18 patients were reviewed, whose ossicular chains were reconstructed with the three aforementioned protocols and assessed via the 3-point scoring system. The HRCT-based protocols could demonstrate a 3D image of the ossicular chain, except that of the footplate on the SSD-based CTVE. On the qualitative assessment, the efficacy of the MPR and VR, which were both superior to the SSD-based CTVE (P < 0.05), presented no statistical significance among the major and/or hyperdense structures (P > 0.05). As regards the lateral process of the malleus, VR was found to be significantly superior to the MPR and SSD-based CTVE (P < 0.05), both of which, however, showed no significant comparative differences (P > 0.05). Moreover, the three protocols in terms of efficacy were comparatively different in their representations of the anterior crus and footplates of the stapes, respectively (P < 0.05). On the MPR images, not all the images of the lenticular process were ideal; 20 of 32 cases were detected, but not defined. VR could be the more valuable protocol for the 3D reconstruction of the ossicular chain and ought to be more employed in future, especially for the education.