A post-processing protocol for three-dimensional visualization of the inner ear using the volume-rendering technique based on a standard magnetic resonance imaging protocol

Abstract

A superior diagnostic quality compared to other post-processing (PP) techniques for three-dimensional (3D) inner ear imaging has been attributed to volume rendering (VR). We defined and assessed a VR protocol for 3D visualization of the inner ear in a routine imaging setting. Following definition of a VR protocol by using lower threshold values, surface shading, perspective views and related parameters, standardized 3D views of the inner ear were generated and evaluated in 32 patients suffering from sensorineural or combined hearing loss. Comprehensive inner ear visualization was achieved in 28 patients by means of two 3D shaded-surface views. Incomplete data acquisition (1/32), motion and pulsation artefacts (2/32) and interposed fluid-retaining mastoid cells (1/32) were responsible for non-diagnostic image quality in 4/32 patients. In 5/32 patients modifications of the PP protocol involving the threshold value and depth-cueing parameters helped to establish diagnostic image quality. Mean post-processing time amounted to 5.8 min per site. 3D imaging with the VR technique is suitable for routine inner ear assessment if direct VR, predefined PP protocols and standardized labyrinthine views are used.