Download Purpose Materials and Methods Conclusion

MRI 3-D Reconstruction of the Internal Auditory Canal and Inner Ear.
Can we eliminate CT?
D Salgado, R Glikstein, M Ojiaku, M dos Santos, M Kingstone, T Almansoori, R Thornhill
The Ottawa Hospital, Department of Medical Imaging, Ottawa, Ontario
University of Ottawa, Ottawa, Ontario
Purpose
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The purpose of this retrospective analysis was to determine
if 3-Dimensional (3-D) T2-weighted Magnetic Resonance
Imagine (MRI) reconstructions of the inner ear were more
useful than Computerized Tomography (CT) at identifying
the anatomy and pathologies of the inner ear and internal
auditory canal (IAC).
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A
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Materials and Methods
For this study we used 3T MRI (Siemens). MRI's from 161
hearing impaired patients were chosen from the year
2014-2015 from our database at The Ottawa Hospital. A
3-D T2-weighted MRI reconstruction of the inner ear was
created for each patient. Three neuroradiologists, a
neuroradiology fellow, a radiology resident and a third
year medical student analyzed these reconstructions
using a scoring system for the semi-circular canals (SCC),
the cochlea and the internal auditory canal (IAC).
Structures could also be described as abnormal including
a description of that abnormality. Inter-rater agreement
was assessed via intraclass correlation coefficients (ICC).
B
E
Figure 3: T2-weighted MRI showing an axial view at the level
of the inner ear with an IAC mass. Red arrow showing IAC mass.
C
Conclusion
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D
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Figure 1: 3-D T2-weighted MRI reconstruction of a normal inner ear. Models labelled
A-G representing rotation of the structure. In model A, the IAC is visible from the red
arrow, cochlea from the blue and semi-circular canals from the yellow.
Results
Of the 161 cases studied, 1% of them could not be
reconstructed due to movement artifact. 79.8% of patients
IAC's were normal and well visualized. 17.7% of patients
had a mass present in their IAC and 1% had a fistula.
0.12% of IAC's were not visble and 2.36% were only
partially seen. Masses ranged in size from 2mm in size to
23mm. 97.2% of cochleas were normal and well visualized.
0.31% had a mass present in their cochlea. 0.12% of
cochlea's weren't visible and 2.36% were only partially
seen. 81.49% of SCC's were normal and well visualized.
1.24% had a mass present in their SCC. 1.42% of SCC's
were not visible and 15.83% were partially seen. Vascular
loops and hypoplastic SCC were also identified.
There was substantial agreement among readers for
the right and left IAC as well as the cochlea and SCC.
Our reconstructions allow detailed visualization of the
inner ear structures and could be an excellent
complimentary test for surgical planning. Other findings
such as fistula's, vascular loops and hypoplastic SCC
can be easily viewed. These reconstructions may also
be used for pre-cochlear implant evaluation.
References
Cerini, R., Faccioli, N., Cicconi, D., Schenal, G., Cugini, C., Giarbini, N., Colletti, V.
& Mucelli, R. P. (2006) ‘Role of CT and MRI in the preoperative evaluation of
auditory brainstem implantation in patients with congenital inner ear pathology’,
Radiology Medicine, 111, pp. 978-988.
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A
Ellul, S., Shelton, C., Davidson, C. & Harnsberger, H. R. (2000) ‘Preoperative
Cochlear Implant Imaging: Is Magnetic Resonance Imaging Enough?’, The
American Journal of Otology, 21, pp. 528-533.
B
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C
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Figure 2: 3-D T2 weighted MRI reconstruction of a pathological inner ear. Models
labelled A-C representating different views of the structure. The red arrow points to the
IAC with a mass.
Seidmen, D.A., Chute, P. M. & Parisier, S. (1994) ‘Temporal Bone Imaging for
Cochelar Implantation’, Larnygoscope, 104, pp. 562-565.
Sennaroglu, L., Aralasmak, A., Gursel, B. & Turan, E. (2002) ‘Magnetic resonance
imaging versus computed tomography in pre-operative evaluation of cochlear
implant candidates with congenital hearing loss’, The Journal of Larnygology &
Otology, 116, pp. 804-810.