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DOI: 10.1148/rg.26si065502
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Role of 3D CT in the Evaluation of the Temporal Bone1

Girish M. Fatterpekar, MD, Amish H. Doshi, MD, Mohit Dugar, MD, Bradley N. Delman, MD, Thomas P. Naidich, MD and Peter M. Som, MD

1 From the Department of Radiology, Mount Sinai Medical Center, One Gustave L. Levy Place, New York, NY 10029. Presented as an education exhibit at the 2005 RSNA Annual Meeting. Received January 26, 2006; revision requested March 7 and received March 23; accepted April 6. All authors have no financial relationships to disclose.

Figure 1
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  		Figure 1a.  Normal anatomy of the auditory apparatus. (a) Oblique coronal 3D VR CT image (anterior view) shows the pinna (P); the EAC, including the cartilaginous (CaEAC) and osseous (OsEAC) portions; the isthmus (Is); the middle ear cavity (ME); and the inner ear (IE). The middle ear is divided into the epitympanum (above dotted green line), mesotympanum (between dotted green and dotted yellow lines), and hypotympanum (below dotted yellow line). (b) Three-dimensional VR CT image (view from the dissected medial portion of the temporal bone) shows the inner ear, including the cochlea (Co), vestibule (Ve), superior semicircular canal (SSCC), lateral semicircular canal (LSCC), and posterior semicircular canal (PSCC). The internal auditory canal (IAC) and the bony canal for the facial nerve (FN) are also seen.

 

Figure 1
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  		Figure 1b.  Normal anatomy of the auditory apparatus. (a) Oblique coronal 3D VR CT image (anterior view) shows the pinna (P); the EAC, including the cartilaginous (CaEAC) and osseous (OsEAC) portions; the isthmus (Is); the middle ear cavity (ME); and the inner ear (IE). The middle ear is divided into the epitympanum (above dotted green line), mesotympanum (between dotted green and dotted yellow lines), and hypotympanum (below dotted yellow line). (b) Three-dimensional VR CT image (view from the dissected medial portion of the temporal bone) shows the inner ear, including the cochlea (Co), vestibule (Ve), superior semicircular canal (SSCC), lateral semicircular canal (LSCC), and posterior semicircular canal (PSCC). The internal auditory canal (IAC) and the bony canal for the facial nerve (FN) are also seen.

 

Figure 2
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  		Figure 2a.  Normal anatomy of the malleus. (a) Posterior oblique 3D VR CT image shows the head of the malleus (HM) and, appearing as a narrow constriction inferiorly, the neck of the malleus (NM). The manubrium (M) lies inferior to the neck. The head of the malleus demonstrates a facet (F) on its posterior aspect that articulates with the body of the incus. (b) Anterior oblique 3D VR CT image shows two bony spicules arising from the upper portion of the manubrium, the anterior process (AP) and the lateral process (LP). The tip of the manubrium (TM) attaches to the tympanic membrane at the umbo.

 

Figure 2
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  		Figure 2b.  Normal anatomy of the malleus. (a) Posterior oblique 3D VR CT image shows the head of the malleus (HM) and, appearing as a narrow constriction inferiorly, the neck of the malleus (NM). The manubrium (M) lies inferior to the neck. The head of the malleus demonstrates a facet (F) on its posterior aspect that articulates with the body of the incus. (b) Anterior oblique 3D VR CT image shows two bony spicules arising from the upper portion of the manubrium, the anterior process (AP) and the lateral process (LP). The tip of the manubrium (TM) attaches to the tympanic membrane at the umbo.

 

Figure 3
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  		Figure 3.  Normal anatomy of the incus. Three-dimensional VR CT image (inferolateral view) shows the body of the incus (BI), which demonstrates a facet (F) on its anterior surface that articulates with the head of the malleus. The short process (SP) is directed posterolaterally, and the long process (LP) is directed inferiorly. The tip of the long process bends medially to end in a rounded projection, the lenticular process (LnP), which articulates with the head of the stapes.

 

Figure 4
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  		Figure 4a.  Normal anatomy of the stapes. (a) Three-dimensional VR CT image (inferior view) shows the head of the stapes (HS), which articulates with the lenticular process of the incus. Inferior to the head of the stapes is the stapes neck (NS), which provides attachment to the stapedius muscle. The anterior crus (AC) and posterior crus (PC) connect the stapes neck to the stapes footplate (FP). The stapes is a cartilaginous structure, unlike the bony malleus and incus. Therefore, the color rendering of the stapes on the 3D shaded-surface-display reformatted images was different from that of the malleus and incus (cf Figs 2, 3). (b, c) Three-dimensional VR CT images (view from the dissected tympanic cavity looking into the oval window) obtained with (b) and without (c) the stapes (St) present show that the stapes footplate (dotted blue line) sits on the oval window (dotted yellow line), attached to its margins by the annular ligament (AL).

 

Figure 4
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  		Figure 4b.  Normal anatomy of the stapes. (a) Three-dimensional VR CT image (inferior view) shows the head of the stapes (HS), which articulates with the lenticular process of the incus. Inferior to the head of the stapes is the stapes neck (NS), which provides attachment to the stapedius muscle. The anterior crus (AC) and posterior crus (PC) connect the stapes neck to the stapes footplate (FP). The stapes is a cartilaginous structure, unlike the bony malleus and incus. Therefore, the color rendering of the stapes on the 3D shaded-surface-display reformatted images was different from that of the malleus and incus (cf Figs 2, 3). (b, c) Three-dimensional VR CT images (view from the dissected tympanic cavity looking into the oval window) obtained with (b) and without (c) the stapes (St) present show that the stapes footplate (dotted blue line) sits on the oval window (dotted yellow line), attached to its margins by the annular ligament (AL).

 

Figure 4
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  		Figure 4c.  Normal anatomy of the stapes. (a) Three-dimensional VR CT image (inferior view) shows the head of the stapes (HS), which articulates with the lenticular process of the incus. Inferior to the head of the stapes is the stapes neck (NS), which provides attachment to the stapedius muscle. The anterior crus (AC) and posterior crus (PC) connect the stapes neck to the stapes footplate (FP). The stapes is a cartilaginous structure, unlike the bony malleus and incus. Therefore, the color rendering of the stapes on the 3D shaded-surface-display reformatted images was different from that of the malleus and incus (cf Figs 2, 3). (b, c) Three-dimensional VR CT images (view from the dissected tympanic cavity looking into the oval window) obtained with (b) and without (c) the stapes (St) present show that the stapes footplate (dotted blue line) sits on the oval window (dotted yellow line), attached to its margins by the annular ligament (AL).

 

Figure 5
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  		Figure 5.  Normal anatomy of the bony labyrinth. Three-dimensional VR CT image (anterolateral view) shows the normal bony labyrinth, which consists of the cochlea (Co), vestibule (Ve), and semicircular canals (SCC). FN = facial nerve canal, IAC = internal auditory canal, OW = oval window.

 

Figure 6
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  		Figure 6.  Normal anatomy of the cochlea. Three-dimensional VR CT image (inferolateral view after dissection of a portion of the inferior wall of the cochlea) shows the osseous spiral lamina (SL), which divides the bony canal for the cochlea into upper and lower passages, the scala vestibule (SV) and the scala tympani (ST), respectively. Dissection of the apical cochlear bony labyrinth shows the terminus of the spiral lamina as a conical projection, or hamulus (Ha), allowing free communication between the scala vestibule and the scala tympani at the helicotrema (He). OW = oval window, RW = round window.

 

Figure 7
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  		Figure 7.  Normal anatomy of the vestibule. Three-dimensional VR CT image (inferolateral view after dissection of the lateral wall of the vestibule) demonstrates the elliptical recess (ER) posteriorly and the spherical recess (SR) anteriorly, which house the utricle and saccule, respectively. A bony ridge, the vestibular crest (VC), lies between the elliptical and spherical recesses. The vestibular crest divides inferiorly into two limbs that form an inverted V and bound a small depression, the cochlear recess (CR). The cochlear recess houses the blind opening of the cochlear duct.

 

Figure 8
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  		Figure 8.  Sound transmission. Three-dimensional VR CT image demonstrates the anatomic structures involved in the transmission of sound. Sound vibrations transmitted through the tympanic membrane (TM) are amplified multifold across the middle ear cavity by the lever mechanism of the ossicles. In addition, the disproportionately larger size of the tympanic membrane allows sound waves to be concentrated onto the smaller oval window (OW), further contributing to sound augmentation. Inward deflection of the oval window by the footplate of the stapes (St) compresses the fluid in the scala vestibuli (wavy yellow line). This compression wave travels along the coils of the cochlea in the scala vestibuli to the helicotrema (He). It then spirals back through the scala tympani (wavy green line) to the round window (RW), which serves as a pressure-relief diaphragm. The vibrations in the scala vestibuli also stimulate the cochlear duct (lying adjacent to the osseous spiral lamina [SL]), where mechanical energy is converted into electrical impulses and transmitted via the cochlear nerve to the brainstem (not shown). In = incus, M = malleus.

 

Figure 9
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  		Figure 9.  Three-dimensional VR CT image (semiopaque windowing) shows the inner ear impressions produced on the medial wall of the tympanic cavity. The prominence produced by the anterior limb of the lateral semicircular canal (LSCC) is seen posteriorly, and the prominence produced by the facial nerve canal (FN) is seen anteriorly. The prominence produced by the curved terminus of the septum canalis musculotubari (SCM) is seen superior and anterior to the oval window (OW). The septum canalis musculotubari serves as the landmark for the geniculate ganglion. The prominence produced by the cochlear promontory (CoP) lies inferior and slightly anterior to the oval window.

 

Figure 10
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  		Figure 10.  Three-dimensional VR CT image (semiopaque windowing) shows two recesses on the posterior wall of the tympanic cavity: The sinus tympani (ST) lies medial to the facial nerve recess (FNR) and indicates the position of the ampulla of the posterior semicircular canal. The pyramidal eminence (PE) is a small conical projection located between the two recesses that gives rise to the stapedius muscle. Co = cochlea.

 

Figure 11
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  		Figure 11.  Normal IAC. Coronal (top left), sagittal (top right), and axial (bottom left) VR CT images show the normal IAC (arrow). Virtual IAC otoscopic image (bottom right) shows the fundus of the IAC, which is divided into upper and lower portions by the falciform crest (FCr). The Bill bar (BB) further subdivides the upper portion of the fundus into openings for the facial nerve (FN) anteriorly and the superior vestibular nerve (SV) posteriorly. The lower portion of the fundus contains an anterior opening for bundles of the cochlear nerve (CN) and a pinpoint posterior opening for the inferior vestibular nerve (IV).

 

Figure 12
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  		Figure 12.  Normal anatomy of the osseous neural canals for the facial and superior vestibular nerves. Three-dimensional VR CT image (superior view) shows the bony canal for the facial nerve (FN) dissected in its proximal portion at the anterosuperior aspect of the internal auditory canal (IAC). The bony canal for the superior vestibular nerve (SV) lies posterior to the facial nerve canal and extends to the vestibule (Ve).

 

Figure 13
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  		Figure 13.  Normal anatomy of the osseous neural canals for the facial and cochlear nerves. Three-dimensional VR CT image (medial view) shows that the cochlear nerve canal (CN) lies inferior to the facial nerve canal (FN) and courses to the cochlea. IAC = internal auditory canal.

 

Figure 14
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  		Figure 14.  Singular canal. Three-dimensional VR CT image (posteroinferior view) shows the singular canal (SC), through which courses a branch of the inferior vestibular nerve. The inferior vestibular nerve innervates the posterior semicircular canal (PSCC).

 

Figure 15
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  		Figure 15a.  Normal anatomy of the facial nerve canal. Three-dimensional VR CT images (posterior [a], superior [b], and lateral [c] views) show the course of the facial nerve through its bony canal as it exits the anterosuperior aspect of the fundus of the internal auditory canal (IAC). The labyrinthine segment of the facial nerve courses through the fallopian canal (fc) to the geniculate ganglion, where the nerve makes a hairpin turn known as the anterior genu (ag). The tympanic segment (ts) of the facial nerve canal runs below the lateral semicircular canal (LSCC) and above the oval window (OW) along the medial wall of the tympanic cavity. It then makes a gentle curve (the posterior genu [pg]) and heads vertically downward as the mastoid segment (ms) to exit the temporal bone at the stylomastoid foramen. The chorda tympani arises from the lateral aspect of the mastoid segment approximately 5 mm proximal to the stylomastoid foramen and courses superiorly within its own bony canal, the canaliculus chorda tympani (cct). Co = cochlea, In = incus, M = malleus.

 

Figure 15
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  		Figure 15b.  Normal anatomy of the facial nerve canal. Three-dimensional VR CT images (posterior [a], superior [b], and lateral [c] views) show the course of the facial nerve through its bony canal as it exits the anterosuperior aspect of the fundus of the internal auditory canal (IAC). The labyrinthine segment of the facial nerve courses through the fallopian canal (fc) to the geniculate ganglion, where the nerve makes a hairpin turn known as the anterior genu (ag). The tympanic segment (ts) of the facial nerve canal runs below the lateral semicircular canal (LSCC) and above the oval window (OW) along the medial wall of the tympanic cavity. It then makes a gentle curve (the posterior genu [pg]) and heads vertically downward as the mastoid segment (ms) to exit the temporal bone at the stylomastoid foramen. The chorda tympani arises from the lateral aspect of the mastoid segment approximately 5 mm proximal to the stylomastoid foramen and courses superiorly within its own bony canal, the canaliculus chorda tympani (cct). Co = cochlea, In = incus, M = malleus.

 

Figure 15
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  		Figure 15c.  Normal anatomy of the facial nerve canal. Three-dimensional VR CT images (posterior [a], superior [b], and lateral [c] views) show the course of the facial nerve through its bony canal as it exits the anterosuperior aspect of the fundus of the internal auditory canal (IAC). The labyrinthine segment of the facial nerve courses through the fallopian canal (fc) to the geniculate ganglion, where the nerve makes a hairpin turn known as the anterior genu (ag). The tympanic segment (ts) of the facial nerve canal runs below the lateral semicircular canal (LSCC) and above the oval window (OW) along the medial wall of the tympanic cavity. It then makes a gentle curve (the posterior genu [pg]) and heads vertically downward as the mastoid segment (ms) to exit the temporal bone at the stylomastoid foramen. The chorda tympani arises from the lateral aspect of the mastoid segment approximately 5 mm proximal to the stylomastoid foramen and courses superiorly within its own bony canal, the canaliculus chorda tympani (cct). Co = cochlea, In = incus, M = malleus.

 

Figure 16
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  		Figure 16a.  Large vestibular aqueduct syndrome in a 9-year-old girl with progressive sensorineural hearing loss. (a) CT scan shows a dilated vestibular aqueduct (arrowhead). The normal vestibular aqueduct should be approximately the same size as the posterior semicircular canal (arrow). (b) Corresponding 3D CT reformatted image again demonstrates the dilated vestibular aqueduct (arrowhead). The opening of the vestibular aqueduct (curved arrow) into the vestibule (Ve) is also seen. Straight arrow indicates the posterior semicircular canal. (c) Three-dimensional VR CT image (posterior view) shows the classic funnel-shaped deformity of the dilated vestibular aqueduct (*) resulting from an enlarged endolymphatic sac housed within the dorsal portion of the vestibular aqueduct. Ve = vestibule.

 

Figure 16
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  		Figure 16b.  Large vestibular aqueduct syndrome in a 9-year-old girl with progressive sensorineural hearing loss. (a) CT scan shows a dilated vestibular aqueduct (arrowhead). The normal vestibular aqueduct should be approximately the same size as the posterior semicircular canal (arrow). (b) Corresponding 3D CT reformatted image again demonstrates the dilated vestibular aqueduct (arrowhead). The opening of the vestibular aqueduct (curved arrow) into the vestibule (Ve) is also seen. Straight arrow indicates the posterior semicircular canal. (c) Three-dimensional VR CT image (posterior view) shows the classic funnel-shaped deformity of the dilated vestibular aqueduct (*) resulting from an enlarged endolymphatic sac housed within the dorsal portion of the vestibular aqueduct. Ve = vestibule.

 

Figure 16
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  		Figure 16c.  Large vestibular aqueduct syndrome in a 9-year-old girl with progressive sensorineural hearing loss. (a) CT scan shows a dilated vestibular aqueduct (arrowhead). The normal vestibular aqueduct should be approximately the same size as the posterior semicircular canal (arrow). (b) Corresponding 3D CT reformatted image again demonstrates the dilated vestibular aqueduct (arrowhead). The opening of the vestibular aqueduct (curved arrow) into the vestibule (Ve) is also seen. Straight arrow indicates the posterior semicircular canal. (c) Three-dimensional VR CT image (posterior view) shows the classic funnel-shaped deformity of the dilated vestibular aqueduct (*) resulting from an enlarged endolymphatic sac housed within the dorsal portion of the vestibular aqueduct. Ve = vestibule.

 

Figure 17
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  		Figure 17a.  Congenital ossicular malformation with oval window atresia in a 12-year-old boy with right-sided mixed hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show malformed ossicles with an associated soft-tissue mass (arrowhead) attached to the lateral wall of the right tympanic cavity. A suspicious platelike covering (arrow) is seen in the expected region of the right oval window. The left-sided ossicles (Os) and left oval window (OW) are normal. (c) Three-dimensional VR CT image (inferolateral view) shows a normal left bony labyrinth with the oval window (OW) and round window (RW) well depicted. (d) Three-dimensional VR CT image (inferolateral view) shows an abnormal right bony labyrinth with absence of the oval window (arrowhead). RW = round window.

 

Figure 17
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  		Figure 17b.  Congenital ossicular malformation with oval window atresia in a 12-year-old boy with right-sided mixed hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show malformed ossicles with an associated soft-tissue mass (arrowhead) attached to the lateral wall of the right tympanic cavity. A suspicious platelike covering (arrow) is seen in the expected region of the right oval window. The left-sided ossicles (Os) and left oval window (OW) are normal. (c) Three-dimensional VR CT image (inferolateral view) shows a normal left bony labyrinth with the oval window (OW) and round window (RW) well depicted. (d) Three-dimensional VR CT image (inferolateral view) shows an abnormal right bony labyrinth with absence of the oval window (arrowhead). RW = round window.

 

Figure 17
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  		Figure 17c.  Congenital ossicular malformation with oval window atresia in a 12-year-old boy with right-sided mixed hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show malformed ossicles with an associated soft-tissue mass (arrowhead) attached to the lateral wall of the right tympanic cavity. A suspicious platelike covering (arrow) is seen in the expected region of the right oval window. The left-sided ossicles (Os) and left oval window (OW) are normal. (c) Three-dimensional VR CT image (inferolateral view) shows a normal left bony labyrinth with the oval window (OW) and round window (RW) well depicted. (d) Three-dimensional VR CT image (inferolateral view) shows an abnormal right bony labyrinth with absence of the oval window (arrowhead). RW = round window.

 

Figure 17
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  		Figure 17d.  Congenital ossicular malformation with oval window atresia in a 12-year-old boy with right-sided mixed hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show malformed ossicles with an associated soft-tissue mass (arrowhead) attached to the lateral wall of the right tympanic cavity. A suspicious platelike covering (arrow) is seen in the expected region of the right oval window. The left-sided ossicles (Os) and left oval window (OW) are normal. (c) Three-dimensional VR CT image (inferolateral view) shows a normal left bony labyrinth with the oval window (OW) and round window (RW) well depicted. (d) Three-dimensional VR CT image (inferolateral view) shows an abnormal right bony labyrinth with absence of the oval window (arrowhead). RW = round window.

 

Figure 18
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  		Figure 18a.  Aberrant ICAs in a 26-year-old woman with bilateral tinnitus, which was more pronounced in the left ear. (a, b) CT scans of the right (a) and left (b) temporal bones show bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in b) was identified only retrospectively, after evaluation of the 3D VR CT images (cf c, d), as being in proximity to the aberrant left ICA. (c, d) Corresponding 3D VR CT images also demonstrate the bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in d) appears to be attached to the aberrant left ICA. On the contralateral side, the right malleus (arrowhead in c) is not as close to the aberrant right ICA. (e) Three-dimensional VR CT image (lateral view) shows the aberrant right ICA (*). There is no attachment of the malleus (M) to the artery. In = incus. (f) Three-dimensional VR CT image (lateral view) clearly demonstrates attachment of the abnormally long manubrium of the left malleus (M) to the aberrant left ICA (*) by a band of soft tissue (arrow). In = incus.

 

Figure 18
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  		Figure 18b.  Aberrant ICAs in a 26-year-old woman with bilateral tinnitus, which was more pronounced in the left ear. (a, b) CT scans of the right (a) and left (b) temporal bones show bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in b) was identified only retrospectively, after evaluation of the 3D VR CT images (cf c, d), as being in proximity to the aberrant left ICA. (c, d) Corresponding 3D VR CT images also demonstrate the bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in d) appears to be attached to the aberrant left ICA. On the contralateral side, the right malleus (arrowhead in c) is not as close to the aberrant right ICA. (e) Three-dimensional VR CT image (lateral view) shows the aberrant right ICA (*). There is no attachment of the malleus (M) to the artery. In = incus. (f) Three-dimensional VR CT image (lateral view) clearly demonstrates attachment of the abnormally long manubrium of the left malleus (M) to the aberrant left ICA (*) by a band of soft tissue (arrow). In = incus.

 

Figure 18
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  		Figure 18c.  Aberrant ICAs in a 26-year-old woman with bilateral tinnitus, which was more pronounced in the left ear. (a, b) CT scans of the right (a) and left (b) temporal bones show bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in b) was identified only retrospectively, after evaluation of the 3D VR CT images (cf c, d), as being in proximity to the aberrant left ICA. (c, d) Corresponding 3D VR CT images also demonstrate the bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in d) appears to be attached to the aberrant left ICA. On the contralateral side, the right malleus (arrowhead in c) is not as close to the aberrant right ICA. (e) Three-dimensional VR CT image (lateral view) shows the aberrant right ICA (*). There is no attachment of the malleus (M) to the artery. In = incus. (f) Three-dimensional VR CT image (lateral view) clearly demonstrates attachment of the abnormally long manubrium of the left malleus (M) to the aberrant left ICA (*) by a band of soft tissue (arrow). In = incus.

 

Figure 18
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  		Figure 18d.  Aberrant ICAs in a 26-year-old woman with bilateral tinnitus, which was more pronounced in the left ear. (a, b) CT scans of the right (a) and left (b) temporal bones show bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in b) was identified only retrospectively, after evaluation of the 3D VR CT images (cf c, d), as being in proximity to the aberrant left ICA. (c, d) Corresponding 3D VR CT images also demonstrate the bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in d) appears to be attached to the aberrant left ICA. On the contralateral side, the right malleus (arrowhead in c) is not as close to the aberrant right ICA. (e) Three-dimensional VR CT image (lateral view) shows the aberrant right ICA (*). There is no attachment of the malleus (M) to the artery. In = incus. (f) Three-dimensional VR CT image (lateral view) clearly demonstrates attachment of the abnormally long manubrium of the left malleus (M) to the aberrant left ICA (*) by a band of soft tissue (arrow). In = incus.

 

Figure 18
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  		Figure 18e.  Aberrant ICAs in a 26-year-old woman with bilateral tinnitus, which was more pronounced in the left ear. (a, b) CT scans of the right (a) and left (b) temporal bones show bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in b) was identified only retrospectively, after evaluation of the 3D VR CT images (cf c, d), as being in proximity to the aberrant left ICA. (c, d) Corresponding 3D VR CT images also demonstrate the bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in d) appears to be attached to the aberrant left ICA. On the contralateral side, the right malleus (arrowhead in c) is not as close to the aberrant right ICA. (e) Three-dimensional VR CT image (lateral view) shows the aberrant right ICA (*). There is no attachment of the malleus (M) to the artery. In = incus. (f) Three-dimensional VR CT image (lateral view) clearly demonstrates attachment of the abnormally long manubrium of the left malleus (M) to the aberrant left ICA (*) by a band of soft tissue (arrow). In = incus.

 

Figure 18
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  		Figure 18f.  Aberrant ICAs in a 26-year-old woman with bilateral tinnitus, which was more pronounced in the left ear. (a, b) CT scans of the right (a) and left (b) temporal bones show bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in b) was identified only retrospectively, after evaluation of the 3D VR CT images (cf c, d), as being in proximity to the aberrant left ICA. (c, d) Corresponding 3D VR CT images also demonstrate the bilateral aberrant ICAs (*). The manubrium of the left malleus (arrow in d) appears to be attached to the aberrant left ICA. On the contralateral side, the right malleus (arrowhead in c) is not as close to the aberrant right ICA. (e) Three-dimensional VR CT image (lateral view) shows the aberrant right ICA (*). There is no attachment of the malleus (M) to the artery. In = incus. (f) Three-dimensional VR CT image (lateral view) clearly demonstrates attachment of the abnormally long manubrium of the left malleus (M) to the aberrant left ICA (*) by a band of soft tissue (arrow). In = incus.

 

Figure 19
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  		Figure 19a.  Cholesteatoma in a 26-year-old woman with right-sided hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show erosion of the right malleus and incus (arrow). The stapes (St) is intact and is better appreciated on the 3D image. The left malleus and incus (arrowhead) are normal. (c) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows pressure erosion of the head of the right malleus (Me) and the body of the incus (BIe), along with nearly complete erosion of the short process of the incus (SPe). Extension of the erosion into the incudomalleolar articulation (IMe) is also noted. (d) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows the normal left side for comparison. IM = incudomalleolar articulation, In = incus, M = malleus, SP = short process of the incus.

 

Figure 19
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  		Figure 19b.  Cholesteatoma in a 26-year-old woman with right-sided hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show erosion of the right malleus and incus (arrow). The stapes (St) is intact and is better appreciated on the 3D image. The left malleus and incus (arrowhead) are normal. (c) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows pressure erosion of the head of the right malleus (Me) and the body of the incus (BIe), along with nearly complete erosion of the short process of the incus (SPe). Extension of the erosion into the incudomalleolar articulation (IMe) is also noted. (d) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows the normal left side for comparison. IM = incudomalleolar articulation, In = incus, M = malleus, SP = short process of the incus.

 

Figure 19
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  		Figure 19c.  Cholesteatoma in a 26-year-old woman with right-sided hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show erosion of the right malleus and incus (arrow). The stapes (St) is intact and is better appreciated on the 3D image. The left malleus and incus (arrowhead) are normal. (c) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows pressure erosion of the head of the right malleus (Me) and the body of the incus (BIe), along with nearly complete erosion of the short process of the incus (SPe). Extension of the erosion into the incudomalleolar articulation (IMe) is also noted. (d) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows the normal left side for comparison. IM = incudomalleolar articulation, In = incus, M = malleus, SP = short process of the incus.

 

Figure 19
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  		Figure 19d.  Cholesteatoma in a 26-year-old woman with right-sided hearing loss. (a, b) CT scan (a) and corresponding 3D CT reformatted image (b) show erosion of the right malleus and incus (arrow). The stapes (St) is intact and is better appreciated on the 3D image. The left malleus and incus (arrowhead) are normal. (c) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows pressure erosion of the head of the right malleus (Me) and the body of the incus (BIe), along with nearly complete erosion of the short process of the incus (SPe). Extension of the erosion into the incudomalleolar articulation (IMe) is also noted. (d) Three-dimensional VR CT image (lateral view after dissection of the anteroinferior portion of the EAC) shows the normal left side for comparison. IM = incudomalleolar articulation, In = incus, M = malleus, SP = short process of the incus.

 

Figure 20
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  		Figure 20a.  Temporal bone fracture caused by trauma in a 51-year-old man. (a) CT scan shows a fracture (arrowhead) through the posterior semicircular canal (PSCC) extending to involve the ossicles (arrows). (b) Corresponding 3D CT reformatted image also demonstrates the fracture (arrowheads) through the base of the posterior semicircular canal (PSCC) extending to the ossicles. The ossicles appear to have an abnormal configuration, suggesting possible dislocation of one of the ossicles (arrow) into the external auditory canal (EAC). (c) Three-dimensional VR CT image (posteroinferior view) shows the fractured bony labyrinth, with the fracture line (Fx) extending through the base of the posterior semicircular canal (PSCC) into the round window (RW) and oval window (OW). (d) Three-dimensional VR CT image (anterior view after dissection of the anterior wall of the EAC) shows incudomalleolar disarticulation, with the incus (In) located lateral to the malleus (M) and partly within the external auditory canal (EAC).

 

Figure 20
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  		Figure 20b.  Temporal bone fracture caused by trauma in a 51-year-old man. (a) CT scan shows a fracture (arrowhead) through the posterior semicircular canal (PSCC) extending to involve the ossicles (arrows). (b) Corresponding 3D CT reformatted image also demonstrates the fracture (arrowheads) through the base of the posterior semicircular canal (PSCC) extending to the ossicles. The ossicles appear to have an abnormal configuration, suggesting possible dislocation of one of the ossicles (arrow) into the external auditory canal (EAC). (c) Three-dimensional VR CT image (posteroinferior view) shows the fractured bony labyrinth, with the fracture line (Fx) extending through the base of the posterior semicircular canal (PSCC) into the round window (RW) and oval window (OW). (d) Three-dimensional VR CT image (anterior view after dissection of the anterior wall of the EAC) shows incudomalleolar disarticulation, with the incus (In) located lateral to the malleus (M) and partly within the external auditory canal (EAC).

 

Figure 20
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  		Figure 20c.  Temporal bone fracture caused by trauma in a 51-year-old man. (a) CT scan shows a fracture (arrowhead) through the posterior semicircular canal (PSCC) extending to involve the ossicles (arrows). (b) Corresponding 3D CT reformatted image also demonstrates the fracture (arrowheads) through the base of the posterior semicircular canal (PSCC) extending to the ossicles. The ossicles appear to have an abnormal configuration, suggesting possible dislocation of one of the ossicles (arrow) into the external auditory canal (EAC). (c) Three-dimensional VR CT image (posteroinferior view) shows the fractured bony labyrinth, with the fracture line (Fx) extending through the base of the posterior semicircular canal (PSCC) into the round window (RW) and oval window (OW). (d) Three-dimensional VR CT image (anterior view after dissection of the anterior wall of the EAC) shows incudomalleolar disarticulation, with the incus (In) located lateral to the malleus (M) and partly within the external auditory canal (EAC).

 

Figure 20
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  		Figure 20d.  Temporal bone fracture caused by trauma in a 51-year-old man. (a) CT scan shows a fracture (arrowhead) through the posterior semicircular canal (PSCC) extending to involve the ossicles (arrows). (b) Corresponding 3D CT reformatted image also demonstrates the fracture (arrowheads) through the base of the posterior semicircular canal (PSCC) extending to the ossicles. The ossicles appear to have an abnormal configuration, suggesting possible dislocation of one of the ossicles (arrow) into the external auditory canal (EAC). (c) Three-dimensional VR CT image (posteroinferior view) shows the fractured bony labyrinth, with the fracture line (Fx) extending through the base of the posterior semicircular canal (PSCC) into the round window (RW) and oval window (OW). (d) Three-dimensional VR CT image (anterior view after dissection of the anterior wall of the EAC) shows incudomalleolar disarticulation, with the incus (In) located lateral to the malleus (M) and partly within the external auditory canal (EAC).

 




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