Evaluation of Stapes Image Quality with Ultra-High-Resolution CT in Comparison with Conebeam CT and High-Resolution CT in Cadaveric Heads.

Background and purpose: Conventional CT imaging techniques are ineffective in adequately depicting the stapes. The purpose of this study was to evaluate the ability of high-resolution (HR), ultra-high-resolution (UHR) with and without deep learning reconstruction (DLR), and conebeam (CB)-CT scanners to image the stapes by using micro-CT as a reference.

Materials and methods: Eleven temporal bone specimens were imaged by using all imaging modalities. Subjective image analysis was performed by grading image quality on a Likert scale, and objective image analysis was performed by taking various measurements of the stapes superstructure and footplate. Image noise and radiation dose were also recorded.

Results: The global image quality scores were all worse than micro-CT (P ≤ .01). UHR-CT with and without DLR had the second-best global image quality scores (P > .99), which were both better than CB-CT (P = .01 for both). CB-CT had a better global image quality score than HR-CT (P = .01). Most of the measurements differed between HR-CT and micro-CT (P ≤ .02), but not between UHR-CT with and without DLR, CB-CT, and micro-CT (P > .06). The air noise value of UHR-CT with DLR was not different from CB-CT (P = .49), but HR-CT and UHR-CT without DLR exhibited higher values than UHR-CT with DLR (P ≤ .001). HR-CT and UHR-CT with and without DLR yielded the same effective radiation dose values of 1.23 ± 0.11 (1.13-1.35) mSv, which was 4 times higher than that of CB-CT (0.35 ± 0 mSv, P ≤ .01).

Conclusions: UHR-CT with and without DLR offers comparable objective image analysis to CB-CT while providing superior subjective image quality. However, this is achieved at the cost of a higher radiation dose. Both CB-CT and UHR-CT with and without DLR are more effective than HR-CT in objective and subjective image analysis.