2021年 · 第101卷第47期

Otosclerosis is one of the causes of progressive hearing loss in people aged 20 to 50 years. High-resolution CT (HRCT) is the first imaging method of choice for preoperative diagnosis of otosclerosis. In order to improve the detection rate of otosclerosis, this study proposed a systematic flow chart based on HRCT: whether there is a density reduction area in the anterior vestibular window area (0~3 points, where 0 points are no density reduction areas and 3 points are significant density reduction areas); Whether there is new bone formation in the vestibular window and the round window, which is manifested as bone thickening, stenosis or obstruction of both windows; Whether there are areas of reduced density in bone around cochlea, semicircular canal and internal auditory canal; Superior semicircular canal fracture, ossicular chain deformity, volute widening or hammer head fixation were excluded. To verify the diagnostic efficacy of this flow chart, the study retrospectively included 17 laterals with otosclerosis confirmed by middle ear surgery from 2010 to 2016 as the test group, and 21 laterals with cochlear implant and no otosclerosis confirmed as the control group. Systematic evaluation of preoperative HRCT images of both groups by a radiologist using a blinded method accurately diagnosed otosclerosis in all 17-side test groups and excluded otosclerosis in 21-side control groups. In the test group, the density reduction was observed in the anterior area of the vestibular window on 17 sides, of which 9 sides (53.0%) had new bone formation, and 8 sides (47.1%) showed the density reduction around the cochlea. When bone density is reduced in the anterior vestibular window area, physicians have increased confidence in diagnosing the reduced density area around the cochlea. HRCT images evaluated by a systematic flow chart are a tool for highly accurate assessment of otosclerosis and improve the diagnosis rate of otosclerosis by physicians.

The key structures of temporal bone are mostly hidden in bone, so CT is the first imaging tool for diagnosing temporal bone lesions. With the development of imaging technology, CT with higher spatial resolution (ultra-high resolution CT) has been used in clinical practice. The study was based on a 128-slice spiral CT instrument with Z-axis resolution scale of 0.25 mm and X-axis resolution scale of 0.125 mm and Y-axis resolution scale of 0.125 mm. The visibility of 27 tiny structures in 18 normal temporal bones was evaluated by an otologist and a radiologist, respectively, into clear display, display and non-display, and the evaluation results were compared transversely with previous studies. The results showed an inter-observer assessment agreement of 89% for ultra-high resolution CT of the temporal bone. The CT can clearly show the protrusion of the malleus, the lenticular process of the incus, the anterior and posterior arch of the stapes, the floor plate of the stapes, the volute axis, the vestibular aqueduct, the superficial petrous nerve and the anterior malleus ligament, etc., and can partially show the stapes tendon, the cord tympanic nerve, the cochlear bone spiral plate, etc. Compared with previous studies, the overall display ability of this CT on the microstructure of temporal bone is similar to that of cone beam CT, and is higher than that of previous spiral CT. Ultra-high resolution CT provides good visualization of the microstructures of the temporal bone in normal subjects.