Cone-beam volumetric tomography for applications in the temporal bone

Hypothesis: Cone beam volumetric tomography (CBVT) has better spatial resolution compared with multi slice computed tomography (MSCT) in temporal bone imaging for superior canal dehiscence (SCD). Background: Imaging of SCD has traditionally used MSCT, but the ability to resolve thin bone next to low-radiodensity brain and inner ear fluids at the interface of the superior canal (SC) with the middle cranial fossa can be adversely affected by partial volume averaging, errors in registration of successive slices, and other factors. CBVT may offer advantages in these regards and may have better spatial resolution for this application. Methods: Five cadaveric temporal bones were scanned using both CBVT and MSCT. The information content at the interface of the SC and the middle cranial fossa was measured for each method using spatial differential transformations. The ability of each method to resolve progressively smaller interfaces between bone and fluid was measured by creating a spatial grating model from a human temporal bone. Results: The information content and spatial resolution were superior for CBVT compared with MSCT. Conclusion: The gold standard for diagnosis of SCD has been MSCT, but CBVT may offer improvements in information content and spatial resolution at the interface of the SC and the middle cranial fossa.