[High-resolution computerized tomography of the petrous bone with two-dimensional and three-dimensional reconstruction].

Fifty patients with various diseases of the petrous bone were examined by HR-CT with a 1024 x 1024 matrix. It is demonstrated that the improved spacial resolution results in a better discrimination of subtle anatomical structures and therefore leads to an expansion of the diagnostic possibilities in diseases of the auditory and vestibular organs. Evaluation of the two-dimensional reconstructed images shows that best quality is obtained with contiguous 1 mm, sections in the primary scans. In most cases these reconstructed images are diagnostically sufficient. In addition they help to reduce patient strain (no problem with patient positioning, no further x-ray exposure, time-saving). Three-dimensional reconstructions from the base of the skull allow a good visualization of complex and extensive osseous destructions of the temporal bone. The disadvantage of this method is on the one hand the lacking representation of soft tissue and the poor spacial resolution (no 3-D imaging of the ossicular chain), and on the other hand the smoothing of contours because of arithmetical filters. Thus tumor expansion and finer osseous erosions may not be distinguishable. Consequently, 2D primary or reconstructed images must continue to be the basis of diagnosis.