MR VOLUME RENDERING OF THE LABYRINTH: WHEN IS IT NECESSARY?

PURPOSE Volume rendering (VR) is a 3D rendering methods widely used in CT and MR imaging. It helps in uderstanding complex anatomical conditions and is particularly useful in the evaluation of tiny structures of the body, as it is the membranous labyrinth. We aimed to verify the contribution of VR in the study of labyrinthine pathology. METHOD AND MATERIALS We performed 3D T2-weighted FSE MRI at 1.5 T, with a dedicated surface coil, at high resolution (0.5mm partition), in 89 patients candidate to cochlear implants. In each case data evaluation consisted in a primary axial viewing of the data sets, and a second reading with VR, at an high-end workstation (Dextroscope; VolumeInteractions/Bracco; Singapore). RESULTS MRI found pathology of the labyrinth in 29 cases: stenosis of the basal turn of the choclea (n=3), stenosis of the semicircular canals (n=12), common cavity deformity (n=4), agenesia of the semicircular canal (n=2), large vestibular aqueduct (n=8). Axial views alone were able to demonstrate labyrinthine pathology in 23/29 cases (sensitivity 79%); VR alone showed labyrinthine alterations in all cases. No differences were observed in the time efficiencey for reading axial images and for VR. CONCLUSION VR is essential in evaluating labyrinthine pathology and the use of axial images alone should not be recommended