Contructive Interference in Steady State(CISS) 3DFT MR Imaging of the Inner Ear and Adjacent Structures

ABSTRACT

PURPOSE: To assess the value of 3 dimensional fourier transformation interference in steady state magnetin resonance imaging(3 DFT CISS1 MRI) in depicting the inner ear and vascular structures. MATERIALS AND METHODS: Using 3DFT CISS axial and coronal MRI scans of both ears with 17.1 msec/8.0 msec/50 degree(TR/TE/FA) and 0.9mm in nominal thickness, we studied 68 normal ears of 34 volunteers aged between 15 and 54 years. We assessed the visualization of the membranous labyrinth, and of cranial nerves VII and VIII in the inner ear canal. We analyzed the location of the vascular loop of the anterior inferior cerebellar artery in relation to cranial nerves VII and internal auditory canal. To define the three-dimensional images of the membranous labyrinth, MIP reconstruction of axial images was carried out. RESULTS: The very high signal of the intralabyrinth fluid enabled one hundred percent of the membranous labrynth to be seen. There was a lack of contrast between soft tissue and bone such as the facial nerve canal, vestibular aqueduct and canal of the subarcuate artery. In 25% of cases, the vascular loop was recognized in the porus acusticus, and in 6% of cases, inside the internal auditory canal. CONCLUSION: 3DFT CISS MRI is useful for determining the detailed anatomy of the inner ear and the nearby vascular loop. This special MR technique can be added as a routine protocol in the study of diseases of the inner ear.