High-resolution computed tomography of temporal bone: Part III: Axial postoperative anatomy

[Cochlear implants in isolated temporal bones: evaluation of electrode position with 64-slice computed tomography]

BACKGROUND

For the functional outcome after cochlear implant surgery, the electrode position is of essential importance. Therefore, radiological techniques to localize the electrode within the cochlea are becoming increasingly important. In our study, we used multi-slice computed tomography (CT) to find radiological criteria to allocate the electrode within the cochlea.

METHODS

Ten Nucleus 24 RCA electrodes were implanted into isolated human temporal bones using an extended cochleostomy and the Advance Off-Stylet technique. Five electrodes were implanted into the scala tympani and five into the scala vestibuli. After implantation, the temporal bones were blinded to the radiologist, and 64-slice CT scans were performed and analysed.

RESULTS AND CONCLUSIONS

In all 10 cases, the surgical positioning of the electrode was equal to the radiological analysis of the CT scans. Radiological criteria were found that permit correct identification of the electrode within the cochlea. We think that this technique is sufficient for most questions concerning quality control and is widely available.

The thin sectional anatomy of the temporal bone correlated with multislice spiral CT

The aim of this study was to explore the method for obtaining the thin sectional anatomy data of the adult temporal bone and study the fine structures using this method. Three fresh adult cadaveric heads were scanned with multi-slice computer tomography (MSCT) centered on petrous bones. The CT images of 0.6 mm were obtained by multi-planar reformation (MPR). The slices of 0.1 mm were shaved off the specimen in the axial direction with the numerical control milling machine after being embedded and frozen, pictures of which were taken by the digital camera and saved in the computer. The thin axial sectional anatomic structures of the intra-temporal were investigated and correlated with MPR images. Via the comparison, fifty micro-anatomic structures of the temporal bone that can't be delineated clearly or missed in the thick sections were evaluated. The anatomical details of the temporal bone can be clearly delineated in MSCT in sub-millimeter and were identical to those in sectional anatomy images. This method can supply anatomical details that had been missed or overlooked for imaging diagnosis and surgical anatomy.