Role of High Resolution Computed Tomography in Evaluation of Pathologies of Temporal Bone

Abstract

Background: High Resolution Computed Tomography (HRCT), a modification of routine CT, provides a direct visual window in the temporal bone providing minute structural details. Purpose of the present study was to evaluate the normal variations, pathological processes (infections and congenital anomalies) and their extent involving the temporal bone along with their complications on HRCT and to correlate these imaging findings surgically, wherever available.

Materials and methods: The prospective study included 50 patients who were referred to the radiology department with clinically suspected temporal bone or ear pathologies. After detailed clinical examination, the patients were subjected to high resolution computed tomography (HRCT) examination. The imaging findings were correlated with the surgical findings wherever available. The surgical findings were considered as final.

Results: From a total of 50 cases, 83.33% had cholesteatoma. The surgical and radiological findings showed a high level of sensitivity (89.29%) in the identification of cholesteatoma. HRCT provides a good sensitivity of 80.65% in the identification of changes to the ossicular chain despite the presence of surrounding soft tissue. HRCT was highly informative in identification of erosion of lateral semicircular canal. In diagnosis of facial canal dehiscence HRCT had a low sensitivity of 33.33%. In the evaluation of any congenital abnormality of the ear HRCT proved to be beneficial in depicting the anatomical details.

Conclusion: The clinical and radiological findings showed a high level sensitivity with intraoperative findings as regards to the presence of cholesteatoma, changes of the ossicular chain and erosion of the lateral semicircular canal. HRCT findings, in the treatment of any congenital abnormality of the ear were a good guide to the surgeon for planning and management.

Keywords: Asom; Cholesteatoma; Chronic suppurative otitis media; Csom; Otitis media.

[Table/Fig-2]:

Clinical symptoms of patients studied

[Table/Fig-3]:

HRCT findings

[Table/Fig-5]:

Axial HRCT image showing soft tissue density mass in the left middle ear cavity and is extending into the mastoid antrum through the aditus (white square). Erosion of left sided ossicles and lateral cortical wall of mastoid is also seen (white arrow)

[Table/Fig-6]:

Axial HRCT image showing soft tissue density mass lesion causing erosion of the wall of the external auditory canal (white arrows), ear ossicles are absent and erosion of the tympanic segment of the facial nerve (black arrow)

[Table/Fig-7]:

Left extensive cholesteatoma. HRCT. axial cuts showing soft tissue density mass completely opacifying middle ear cavity. Mass is eroding ossicular chain, causing bony defect in the postero-lateral mastoid wall. The anterior limb of the left lateral semicircular canal is eroded

[Table/Fig-8]:

Congenital microtia with external auditory canal atresia with fused ossicles. HRCT. Axial cut showing soft tissue density in middle ear cavitywith fused, laterally pushed ear ossicles and eac stenosis