Traumatic ossicular chain separation: sliding-thin-slab maximum-intensity projections for diagnosis.

OBJECTIVES

To retrospectively determine, by using multislice computed tomography (MSCT), whether additional interpretation of sliding-thin-slab maximum-intensity projection (MIP) reformation images improve diagnostic accuracy when compared with the diagnostic interpretation of conventional sliding-thin-slab multiplanar reformation (MPR) CT images for traumatic ossicular chain separation.

MATERIALS AND METHODS

Twenty-nine patients with pathologically or clinically confirmed unilateral traumatic ossicular chain separation who underwent temporal bone MSCT were retrospectively identified from electronic medical records. An additional 29 control subjects, who underwent temporal bone MSCT for other reasons, were retrospectively selected from the same period. Two neuroradiologists independently reviewed the 116 temporal bones twice. One review was restricted to MPR ("MPR only") images. The other review used MIP images and MPR ("all reformations") images. The observers were blinded to clinical history, and the 2 reviews took place 8 weeks apart to avoid recall bias. The chi2 test was performed for diagnostic accuracy between MPR images and all reformation images. Cohen kappa statistics was used to evaluate interobserver variability.

RESULTS

With "all reformations" images, observer 1 diagnosed traumatic ossicular chain separation in 28 (24.1%) of 116 temporal bones, which is significantly higher than that with MPR (16.4%, 19/116 temporal bones, P < 0.05); Observer 2 diagnosed traumatic ossicular chain separation in 27 (23.3%) of 116 temporal bones, which is also significantly higher than that with MPR (17.2.0%, 20/116 bones, P < 0.05). The kappa values were 0.89 and 0.96, respectively, on the basis of MPR and "all reformations" images that revealed high interobserver agreement, independent of the imaging modality (MPR or "all reformations" images).

CONCLUSIONS

Additional interpreting MIP images provided more accurate diagnoses than interpreting MPR images alone for diagnosis of traumatic ossicular chain separation.