ROLE OF CT AND MRI IN DIAGNOSIS OF HEARING LOSS

Abstract

The type of hearing loss determines the imaging strategy. Initially, the radiological study of the temporal bony labyrinth was restricted to conventional radiographic studies, later improved with polytomographic techniques. This essay is organized on the basis of the three types of hearing loss. SNHL, CHL, and MHL. SNHL indicates dysfunction of the cochlea, cochlear nerve, or brain. MRI became the method of choice to study the pathologic inner ear. No other radiological technique can detect so much pathology in patients with SNHL. But the Success of the MR technique depends on the sequences that are chosen. Unenhanced T 1 - weighted spin-echo Images and especially Gd- enhanced T1 - weighted spin-echo Images and good quality gradient-echo images (3DFT-CISS), are necessary to recognize all inner ear pathology. Therefore these three MR sequences should always be included in the routine inner ear protocol. • Additional T1-weighted Images are not necessant in the study of the inner ear or internal auditmy canal, but they can detect lesions in the brain stem or cerebral cortex, potentially explaining sensorineural heaning loss.