Size of the semicircular canals measured by multidetector computed tomography in different age groups.

PURPOSE: The purpose of the study was to obtain reference values for the sizes of the semicircular canals (SCCs) on multidetector computed tomographic (CT) images in different age groups. METHODS: Computed tomographic images of the temporal bone of 210 patients, a total of 420 ears without inner ear pathology, have been evaluated. These patients were divided into 4 groups by age: young children (<7 years), older children and adolescents (8-17 years), adults (18-59 years), and the elderly patients (>60 years). The inner diameter, maximum height, and width of the SCCs were measured. RESULTS: There was no significant difference in the size of SCC among the 4 age groups. The inner diameter measurements of the anterior SCC, lateral SCC, and posterior SCC were 0.101 ± 0.016, 0.135 ± 0.033, and 0.124 ± 0.021 cm, respectively. The height measurements of the anterior SCC, lateral SCC, and posterior SCC were 0.535 ± 0.086, 0.349 ± 0.090, and 0.490 ± 0.109 cm, respectively. The width measurements of the anterior SCC, lateral SCC, and posterior SCC were 0.567 ± 0.080, 0.302 ± 0.082, and 0.472 ± 0.099 cm, respectively. CONCLUSIONS: The size of SCCs remains constant from children to the elderly people, unlike the other human organs. The reference values provided by multidetector CT can serve as an aid for the interpretation of CT images.

Value of sliding-thin-slab maximum intensity projections in imaging of the auditory ossicles.

PURPOSE: To investigate the image quality with respect to ease of identifying fine structures of auditory ossicles delineated by multislice computed tomography with sliding-thin-slab (STS) maximum intensity projections (MIPs) and multiplanar reformations (MPR). METHODS: Fifty patients examined with a standardized protocol on a 16-slice multislice computed tomography were included in the study; the data were reformatted as STS MIP and MPR in 3 planes (axial, coronal, and sagittal) for each subject. Fifteen fine structures of auditory ossicles reformatted by 2 techniques were qualitatively assessed and rated with respect to ease of identifying fine structures of auditory ossicles by 2 blinded readers, and scores of STS MIP reformatted technique assessed by reviewers were compared with those of MPR. kappa Statistics were performed to determine how well the 2 readers agreed on each image; Paired t test was used to determine difference in images quality between MPR and STS MIP. RESULTS: The kappa values for qualitatively assessing 15 fine anatomical structures revealed high interobserver agreement, independent of the imaging modality (MPR or STS MIP images). Qualitative assessment of 15 fine anatomical structures, the STS MIP reformations were significantly superior to MPR (P < 0.05) in the delineation of 10 of 15 structures; whereas in delineation the remaining 5 of 15 structures, the MPR reformations were superior to STS MIP. CONCLUSIONS: Sliding-thin-slab MIP reformations were significantly superior to MPR with respect to ease of identity of most fine structures of auditory ossicles, but the rest of 5 fine structures (lenticular process of incus, head of stape, anterior crus of stapes, posterior crus of stapes, footplate of stapes) are suitable for visualization using MPR versus MIP.

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.