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Virtual Labyrinthoscopy: Visualization of the Inner Ear with Interactive Direct Volume Rendering¹

¹ From the Division of Neuroradiology (B.F.T., K.E.W.E., W.J.H.), Computer Graphics Group (P.H., C.R.S.), Department of Neurosurgery (R.N., U.N.), and Institute of Diagnostic Radiology (H.G.), University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received March 8, 1999; revision requested April 28 and received June 2; accepted June 11. Address reprint requests to B.F.T. (e-mail: bernd.tomandl@stud.uni-erlangen.de).

View larger version (213K): [in a new window]   Figure 1a.   Visualization process based on high-resolution spiral CT data on the structures of the temporal bone. (a) Section image shows a volume of interest selected for 3D visualization (yellow square). (b) Anterolateral opaque 3D representation based on direct volume rendering shows the selected volume of interest. (c) Anterolateral view of the right labyrinth shows an intermediate step, during which color and opacity values are adjusted interactively. (d) Anterolateral semitransparent view shows the bony labyrinth.

View larger version (175K): [in a new window]   Figure 1b.   Visualization process based on high-resolution spiral CT data on the structures of the temporal bone. (a) Section image shows a volume of interest selected for 3D visualization (yellow square). (b) Anterolateral opaque 3D representation based on direct volume rendering shows the selected volume of interest. (c) Anterolateral view of the right labyrinth shows an intermediate step, during which color and opacity values are adjusted interactively. (d) Anterolateral semitransparent view shows the bony labyrinth.

View larger version (165K): [in a new window]   Figure 1c.   Visualization process based on high-resolution spiral CT data on the structures of the temporal bone. (a) Section image shows a volume of interest selected for 3D visualization (yellow square). (b) Anterolateral opaque 3D representation based on direct volume rendering shows the selected volume of interest. (c) Anterolateral view of the right labyrinth shows an intermediate step, during which color and opacity values are adjusted interactively. (d) Anterolateral semitransparent view shows the bony labyrinth.

View larger version (183K): [in a new window]   Figure 1d.   Visualization process based on high-resolution spiral CT data on the structures of the temporal bone. (a) Section image shows a volume of interest selected for 3D visualization (yellow square). (b) Anterolateral opaque 3D representation based on direct volume rendering shows the selected volume of interest. (c) Anterolateral view of the right labyrinth shows an intermediate step, during which color and opacity values are adjusted interactively. (d) Anterolateral semitransparent view shows the bony labyrinth.

View larger version (145K): [in a new window]   Figure 2a.   Direct volume rendering of a normal left labyrinth and facial canal. (a) Anterolateral view shows the relationship of the mastoid and labyrinthine segments of the facial nerve (arrows) to the bony labyrinth. (b) Anterolaterocaudal view shows the relationship of the bony labyrinth to the facial canal.

View larger version (172K): [in a new window]   Figure 2b.   Direct volume rendering of a normal left labyrinth and facial canal. (a) Anterolateral view shows the relationship of the mastoid and labyrinthine segments of the facial nerve (arrows) to the bony labyrinth. (b) Anterolaterocaudal view shows the relationship of the bony labyrinth to the facial canal.

View larger version (144K): [in a new window]   Figure 3a.   Direct volume rendering of a normal left labyrinth including clip planes, which suppress disturbing structures within the 3D representation. (a) Superior view clearly shows the semicircular canals, ampullae, vestibule, cochlea, and inner auditory canal (arrow). (b) Anterolateral view shows the turns of the cochlea and the orthogonal semilunar canals. Arrow = inner auditory canal. (c) Anterolateral view shows the cochlea in detail and allows measurement of its diameter in a given clip plane.

View larger version (176K): [in a new window]   Figure 3b.   Direct volume rendering of a normal left labyrinth including clip planes, which suppress disturbing structures within the 3D representation. (a) Superior view clearly shows the semicircular canals, ampullae, vestibule, cochlea, and inner auditory canal (arrow). (b) Anterolateral view shows the turns of the cochlea and the orthogonal semilunar canals. Arrow = inner auditory canal. (c) Anterolateral view shows the cochlea in detail and allows measurement of its diameter in a given clip plane.

View larger version (192K): [in a new window]   Figure 3c.   Direct volume rendering of a normal left labyrinth including clip planes, which suppress disturbing structures within the 3D representation. (a) Superior view clearly shows the semicircular canals, ampullae, vestibule, cochlea, and inner auditory canal (arrow). (b) Anterolateral view shows the turns of the cochlea and the orthogonal semilunar canals. Arrow = inner auditory canal. (c) Anterolateral view shows the cochlea in detail and allows measurement of its diameter in a given clip plane.

View larger version (140K): [in a new window]   Figure 4a.   Chondrosarcoma of the temporal bone. (a) Gadolinium-enhanced axial T1-weighted MR image shows a partly cystic, enhancing tumor (short arrows). There is effusion in the temporal bone (long arrow). (b) Shaded surface display (SSD) image shows bone destruction in the apex of the pyramid (arrow). (c) Anterolateral view obtained with direct volume rendering shows the destruction caused by the tumor (arrow). (d) Anterosuperior view obtained with direct volume rendering does not show the inner ear clearly due to effusion within the temporal bone. Still, it is possible to see the mastoid segment of the facial canal (arrows).

View larger version (177K): [in a new window]   Figure 4b.   Chondrosarcoma of the temporal bone. (a) Gadolinium-enhanced axial T1-weighted MR image shows a partly cystic, enhancing tumor (short arrows). There is effusion in the temporal bone (long arrow). (b) Shaded surface display (SSD) image shows bone destruction in the apex of the pyramid (arrow). (c) Anterolateral view obtained with direct volume rendering shows the destruction caused by the tumor (arrow). (d) Anterosuperior view obtained with direct volume rendering does not show the inner ear clearly due to effusion within the temporal bone. Still, it is possible to see the mastoid segment of the facial canal (arrows).

View larger version (165K): [in a new window]   Figure 4c.   Chondrosarcoma of the temporal bone. (a) Gadolinium-enhanced axial T1-weighted MR image shows a partly cystic, enhancing tumor (short arrows). There is effusion in the temporal bone (long arrow). (b) Shaded surface display (SSD) image shows bone destruction in the apex of the pyramid (arrow). (c) Anterolateral view obtained with direct volume rendering shows the destruction caused by the tumor (arrow). (d) Anterosuperior view obtained with direct volume rendering does not show the inner ear clearly due to effusion within the temporal bone. Still, it is possible to see the mastoid segment of the facial canal (arrows).

View larger version (175K): [in a new window]   Figure 4d.   Chondrosarcoma of the temporal bone. (a) Gadolinium-enhanced axial T1-weighted MR image shows a partly cystic, enhancing tumor (short arrows). There is effusion in the temporal bone (long arrow). (b) Shaded surface display (SSD) image shows bone destruction in the apex of the pyramid (arrow). (c) Anterolateral view obtained with direct volume rendering shows the destruction caused by the tumor (arrow). (d) Anterosuperior view obtained with direct volume rendering does not show the inner ear clearly due to effusion within the temporal bone. Still, it is possible to see the mastoid segment of the facial canal (arrows).

View larger version (152K): [in a new window]   Figure 5a.   Schwannoma of the glossopharyngeal nerve inside the jugular foramen. (a) Fusion of MR and CT images shows a contrast-enhanced tumor (arrow) in relation to the skull base. (b) Fusion image after application of clip planes shows that the tumor has been eliminated to provide a view of the enlarged jugular foramen (arrow). (c, d) Superoposterior (c) and posteromedial (d) semitransparent views show the spatial relationship of the inner ear and the tumor. Interactive measurement of distances assists in therapy planning.

View larger version (147K): [in a new window]   Figure 5b.   Schwannoma of the glossopharyngeal nerve inside the jugular foramen. (a) Fusion of MR and CT images shows a contrast-enhanced tumor (arrow) in relation to the skull base. (b) Fusion image after application of clip planes shows that the tumor has been eliminated to provide a view of the enlarged jugular foramen (arrow). (c, d) Superoposterior (c) and posteromedial (d) semitransparent views show the spatial relationship of the inner ear and the tumor. Interactive measurement of distances assists in therapy planning.

View larger version (161K): [in a new window]   Figure 5c.   Schwannoma of the glossopharyngeal nerve inside the jugular foramen. (a) Fusion of MR and CT images shows a contrast-enhanced tumor (arrow) in relation to the skull base. (b) Fusion image after application of clip planes shows that the tumor has been eliminated to provide a view of the enlarged jugular foramen (arrow). (c, d) Superoposterior (c) and posteromedial (d) semitransparent views show the spatial relationship of the inner ear and the tumor. Interactive measurement of distances assists in therapy planning.

View larger version (155K): [in a new window]   Figure 5d.   Schwannoma of the glossopharyngeal nerve inside the jugular foramen. (a) Fusion of MR and CT images shows a contrast-enhanced tumor (arrow) in relation to the skull base. (b) Fusion image after application of clip planes shows that the tumor has been eliminated to provide a view of the enlarged jugular foramen (arrow). (c, d) Superoposterior (c) and posteromedial (d) semitransparent views show the spatial relationship of the inner ear and the tumor. Interactive measurement of distances assists in therapy planning.

View larger version (65K): [in a new window]   Figure 6a.   Enlarged vestibular aqueduct. (a) Section images (presented from superior [left] to inferior [right]) show an enlarged vestibular aqueduct (arrows). (b) Superior view obtained with direct volume rendering shows the spatial relationship of the funnel-like enlarged vestibular aqueduct (arrow) to the other structures of the inner ear. (c) Posterior view obtained with direct volume rendering shows the inside of the "funnel" (arrow).

View larger version (56K): [in a new window]   Figure 6b.   Enlarged vestibular aqueduct. (a) Section images (presented from superior [left] to inferior [right]) show an enlarged vestibular aqueduct (arrows). (b) Superior view obtained with direct volume rendering shows the spatial relationship of the funnel-like enlarged vestibular aqueduct (arrow) to the other structures of the inner ear. (c) Posterior view obtained with direct volume rendering shows the inside of the "funnel" (arrow).

View larger version (79K): [in a new window]   Figure 6c.   Enlarged vestibular aqueduct. (a) Section images (presented from superior [left] to inferior [right]) show an enlarged vestibular aqueduct (arrows). (b) Superior view obtained with direct volume rendering shows the spatial relationship of the funnel-like enlarged vestibular aqueduct (arrow) to the other structures of the inner ear. (c) Posterior view obtained with direct volume rendering shows the inside of the "funnel" (arrow).

View larger version (168K): [in a new window]   Figure 7a.   Complex deformity of inner ear structures. (a) Section images (presented from inferior [top left] to superior [bottom right]) show a small, irregular cochlea (short arrow); a short inner auditory canal (long arrow); a long labyrinthine segment of the facial nerve (arrowhead); and deformity of the temporal bone. (b) SSD image (posterosuperior view) of the skull base shows winglike deformity of the petrous parts of the temporal bones (arrows). (c) Superior view obtained with direct volume rendering shows the deformities. (d) Anterior view obtained with direct volume rendering shows only one turn of the cochlea (arrow).

View larger version (138K): [in a new window]   Figure 7b.   Complex deformity of inner ear structures. (a) Section images (presented from inferior [top left] to superior [bottom right]) show a small, irregular cochlea (short arrow); a short inner auditory canal (long arrow); a long labyrinthine segment of the facial nerve (arrowhead); and deformity of the temporal bone. (b) SSD image (posterosuperior view) of the skull base shows winglike deformity of the petrous parts of the temporal bones (arrows). (c) Superior view obtained with direct volume rendering shows the deformities. (d) Anterior view obtained with direct volume rendering shows only one turn of the cochlea (arrow).

View larger version (187K): [in a new window]   Figure 7c.   Complex deformity of inner ear structures. (a) Section images (presented from inferior [top left] to superior [bottom right]) show a small, irregular cochlea (short arrow); a short inner auditory canal (long arrow); a long labyrinthine segment of the facial nerve (arrowhead); and deformity of the temporal bone. (b) SSD image (posterosuperior view) of the skull base shows winglike deformity of the petrous parts of the temporal bones (arrows). (c) Superior view obtained with direct volume rendering shows the deformities. (d) Anterior view obtained with direct volume rendering shows only one turn of the cochlea (arrow).

View larger version (147K): [in a new window]   Figure 7d.   Complex deformity of inner ear structures. (a) Section images (presented from inferior [top left] to superior [bottom right]) show a small, irregular cochlea (short arrow); a short inner auditory canal (long arrow); a long labyrinthine segment of the facial nerve (arrowhead); and deformity of the temporal bone. (b) SSD image (posterosuperior view) of the skull base shows winglike deformity of the petrous parts of the temporal bones (arrows). (c) Superior view obtained with direct volume rendering shows the deformities. (d) Anterior view obtained with direct volume rendering shows only one turn of the cochlea (arrow).

View larger version (130K): [in a new window]   Figure 8a.   Commonly used visualization techniques. (a) SSD image (anteromedial view) shows the inner ear. Only parts of the structures are seen. (b) MIP image (anterolateral view) from high-resolution MR imaging data shows the inner ear.

View larger version (84K): [in a new window]   Figure 8b.   Commonly used visualization techniques. (a) SSD image (anteromedial view) shows the inner ear. Only parts of the structures are seen. (b) MIP image (anterolateral view) from high-resolution MR imaging data shows the inner ear.