Photon Counting Versus Energy-integrated Detector CT in Detection of Superior Semicircular Canal Dehiscence.

Abstract

Superior semicircular canal dehiscence (SSCD), an osseous defect overlying the SSC, is associated with aconstellation of audiovestibular symptoms. This study sought to compare conventional energy-integrated detector (EID) computed tomography (CT) to photon-counting detector (PCD)-CT in the detection of SSCD. Included patients were prospectively recruited to undergo atemporal bone CT on both EID-CT and PCD-CT scanners. Two blinded neuroradiologists reviewed both sets of images for 1)the presence or absence of SSCD (graded as present, absent, or indeterminate), and 2)the width of the bone overlying the SSC (if present). Any discrepancies in the presence or absence of SSCD were agreed upon by consensus. In the study 31patients were evaluated, for atotal of 60individual temporal bones (2were excluded). Regarding SSCD presence or absence, there was substantial agreement between EID-CT and PCD-CT (k = 0.76; 95% confidence interval, CI 0.54-0.97); however, SSCD was present in only 9(15.0%) temporal bones on PCD-CT, while EID-CT examinations were interpreted as being positive in 14(23.3%) temporal bones. This yielded afalse positive rate of 8.3% on EID-CT. The bone overlying the SSC was thinner on EID-CT images (0.66 mm; SD = 0.64) than on PCD-CT images (0.72 mm; SD = 0.66) (p < 0.001). The EID-CT examinations tend to overcall the presence of SSCD compared to PCD-CT and also underestimate the thickness of bone overlying the SSC.