For patients with symptoms, vestibular and auditory dysfunction and suspected SSCD, high-resolution CT is helpful for diagnosis (Figure 33-2). CT should take horizontal and coronal positions, and the display rate of three-dimensional reconstruction is the highest. High resolution CT can reduce the misdiagnosis rate. It is reported that 6 cases were diagnosed as SSCD by CT scan with a thickness of 65438±0.0mm, while spiral CT showed a complete thin bone layer at the top of the upper semicircular canal with a thickness of 0.5 mm, denying the fracture of the bone canal. Branstetter et al. (2006) examined 27 cases of suspected SSCD and 27 cases of control group, and considered that coronal multi-slice oblique reconstruction CT of temporal bone was enough to show SSCD. Krombach et al. (2006) performed high-resolution MRI examination on 26 cases of superior and posterior semicircular canal fissure, showing that T2-weighted 3D reconstruction, maximum density projection and volume imaging can clearly show the location of semicircular canal fissure. CT scanning SSCD can be combined with other features: ① The bone thickness at the top of the contralateral upper semicircular canal in patients with unilateral SSCD is thinner than that in normal people. ② The bone of the affected side ②SSCD and asymptomatic contralateral temporal bone tympanic lid and tympanic sinus lid may be stunted or missing. Krombach et al. (2004) compared the sensitivity and specificity of high-resolution CT and MRI in displaying SSCD. The sensitivity and specificity of MRI were 96% and 98% respectively, slightly lower than that of CT.