الفهرس 
Introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
The temporal bone is complex with five developmentally different regions: the squamous, the petrous, the tympanic, the mastoid and the styloid. In the most general sense, the primary structure of the temporal bone is the ear. MSCT is presently the most accurate technique to study the temporal bone anatomy. MSCT offers excellent delineation of the bony walls of the external and middle ear. Also it can show the bony labyrinth, the bony facial nerve canal, the bony fossa of the geniculate ganglion and the bony internal auditory canal. Although in the past it was essential to position the patient for axial and/or coronal images, newer high-resolution multidetector spiral imaging systems can generate nearly isotropic voxels for multiplanar reconstructions, making the need for multiple series with direct imaging in several planes unnecessary. MSCT also provides new options as Three-dimensional reconstructions and multiplanar reformation (MPR) which were performed using the volume-rendering technique (VRT) on the workstation. MSCT data sets also allow for generating virtual endoscopic views closely resembling otoendoscopic images and can do accurate angiography (CTA or CTV). MSCT is important in diagnosis of congenital diseases of the external ear, the middle ear cavity, the ossicles and the bony labyrinth structures. MSCT can show with great precision the bony facial nerve canal involvement in congenital abnormalities of the middle car, the mastoid and the jugular bulb. In children with sensory neural hearing loss, MSCT performed with bone algorithms demonstrates inner ear dysplasias. Many of the anomalies of the vascular structures of the temporal bone that were previously visible only on angiograms are now readily recognizable on MSCT scans by CT angiography technique. In traumatic cases, MSCT is the method of choice in evaluation of the fractures of the temporal bone and ossicular injury as the ossicles may be fractured or dislocated. MSCT shows the fracture or dislocation more clearly. The availability of MSCT scanning as a diagnostic imaging modality has been a major advance in the management of inflammatory disease of the temporal bone. MSCT has many functions as demonstration of underlying anatomical variation when considering surgical treatment, it can demonstrate the extent of mastoid pneumatization and the position of carotid canal, jugular fossa, sigmoid sinus and the tegmen covering the middle fossa. Also it can diagnose the extent and nature of pathological changes. MSCT scanning in axial and coronal views with thin slice thickness and zooming is the imaging modality of choice in the assessment of inflammatory diseases of the temporal bone. In the presence of a retrotympanic mass that suggests the presence of a paraganglioma on otoscopy, labyrinthine or cochlear lesions, or if a mass is found localized within the tympanic cavity, non contrast MSCT is the initial investigation. In MSCT the characteristic diagnostic bony changes of the tumors can clearly appear such as glomus jugulare tumors, non contrast MSCT of the temporal bone showed the enlargement and erosion of the jugular foramen, with acoustic schwannoma, there is widening of the internal auditory canal and in patient with temporal bone metastases, there is extensive bone destruction. Post contrast MSCT showed the enhancement characteristics of the mass and the intracranial extension. In conclusion, temporal bone imaging remains at the forefront of the development of high-resolution imaging techniques of the body. The improved detection and understanding of temporal bone pathology provided by modern imaging methods as the MSCT for a very precise assessment of most pathologic entities. A thorough understanding of the anatomy is very important in correctly assessing pathology. The imaging of the temporal bone using MSCT allows a comprehensively assessing various pathological lesions through its high quality. MSCT excels in the evaluation of disorders that primarily affect air spaces or cortical bone.