A systematic technique for comprehensive evaluation of the temporal bone by computed tomography.

Abstract

A systematic method for comprehensive visualization of the temporal bone structures using thin-section, high-resolution computed tomography (CT) was developed. In relation to the anthropologic baseline (0 degrees), four separate tomographic planes of 0 degrees, 30 degrees, 70 degrees, and 105 degrees were each found to optimize different aspects of temporal bone evaluation with significant reduction in the radiation dose to the lens. Virtually all patients were able to maintain the necessary head positioning that allows for both direct coronal and axial sections. It is concluded that in the majority of cases, thin-section, high-resolution CT can replace polytomography, although the examinations may be complementary in the evaluation of certain abnormalities.

Which temporal bone anatomical structures and pathologies could be best visualized by applying reconstruction to cross-sections obtained on an axial plane?

“…The recommended tube angulation during assessment of the temporal bone varies depending on the region examined, but in daily use, standard techniques include axial and coronal projections. [1,5] To visualize the anatomical structures, improved additional projections were developed. These projections, which are not orthogonal, were supported by temporal bone politomography pioneers.…”

“…These projections, which are not orthogonal, were supported by temporal bone politomography pioneers. [1,[5][6][7] Other planes known in classical otologic radiology were investigated for the first time by Zonneveld in 1983. [7] This report discussed observations of classical autoradiological planes using proper patient positioning techniques in direct CT. [6,7] Autoradiological planes used with direct CT include transverse (Hirtz), coronal, sagittal, semiaxial (Guillen), semilongitudinal (Zonneveld), axiopetrosal (Pöschl), and longitudinal (Stenvers).…”

“…Thus, a detailed evaluation of temporal bone anatomical structures (ossicle chain, the stapes oval window complexes, round window, cochlea, vestibular aqueduct, semi-circular canal, and facial nerve canal) and pathologies, as well as the increased accuracy of CT for diagnosis, was provided. [1,4,5,[12][13][14][15][16][17] With the introduction of high-resolution CT (HRCT) algorithms, studies have been performed with a spatial resolution of less than 1 millimeter; these are known as thin-section thicknesses with 'edge enhanced' filters. In addition, reconstruction programs can be applied to these studies.…”

“…In addition, reconstruction programs can be applied to these studies. [1,4,5,7,8] In recent years, three-dimensional (3D) multiplanar reformatted imaging obtained from conventional cross-sectional CT data has been used at an increasing frequency.…”

“…[3,[18][19][20][21] In addition, many patients cannot maintain the position in which the head is brought to backward flexion in the prone position, which is required to obtain coronal images. [1,3,5] Since the dental region is within the field, there will be artefacts in the direct coronal sections of patients with a dental apparatus. [3] To eliminate these restrictions, instead of direct coronal imaging, the concept of obtaining coronal reconstructions from the axial images using thin-slice thickness has been proposed.…”