Virtual endoscopy of the tympanic cavity based on high-resolution multislice computed tomographic data

Objective: This study was designed to assess the value of high-resolution m ultislice computed tomography (MSCT) data of the petrous bone for the virtu al endoscopic visualization of the tympanic cavity. Background: The recently introduced MSCT technology has improved spatial re solution in the z axis as well as scan speed in computed tomography. Three- dimensional rendering of high-resolution MSCT data of the petrous bone may be expected to provide endoluminal views of superior image quality, thus co mpeting with transtympanic endoscopy (otoendoscopy). Setting: This study was conducted at a university teaching hospital. Materials and Methods: Cadaveric phantom studies in a MSCT scanner were per formed to define a data acquisition protocol, combining adequate detail res olution with low tube current. Subsequently, the cadaveric phantom underwen t otoendoscopy. The postprocessing parameters of the three-dimensional rend ering protocol were chosen to produce views closely resembling the correspo nding otoendoscopic images. High-resolution data from 18 patients with path ologic conditions of the middle ear, as suggested by clinical findings and assessment of cross-sectional data, were postprocessed using the volume ren dering technique to generate standardized virtual endoscopic views. A total of 36 virtual endoscopic scans of the tympanic cavity were generated. Results: With regard to intermediate and high-density structures, virtual e ndoscopic images, based on MSCT data, yielded endoluminal views closely res embling corresponding otoendoscopic views. Virtual endoscopy seems useful f or imaging ossicular pathologic conditions such as dysplasia and chain disr uption as well as for assessing patient status before and after otosurgery. Conclusion: MSCT data sets allow for generating virtual endoscopic views cl osely resembling otoendoscopic images. The technique is especially useful w hen ossicular pathologic changes are present as well as for preoperative an d postoperative imaging of otologic procedures.