Article
Comparison of radiographic imaging of temporal bone specimen with High-Resolution Computer Tomography and Digital Volume Tomography
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Published: | September 7, 2006 |
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Background: High-Resolution Computer Tomography (HRCT) has meanwhile replaced conventional radiographic imaging. Even modern CT´s present limitations concerning the visualization of smaller bony pathologies compared to Digital Volume Tomography (DVT). DVT with its high resolution of 0,125 mm (>2 line pairs/mm) demonstrates even smallest bony lesions. Both radiographic methods were used to evaluate their potentials by examination of temporal bone specimen.
Materials and Methods: Thirty-eight temporal bone specimens were used in this trial. The specimens were examined by DVT (3D Accu-I-tomo, Morita, Japan) and HRCT (Hi-speed, General Electrics, USA). Through a 360° rotation of the emitter-detection unit a trimensional volume of 6 x 6 cm is captured in DVT. The gained data is then analyzed with a PC. The angle of the axial, coronal and sagital sections could be changed freely in order to represent single structures with a high-resolution slice thickness of 0,125 mm. With HRCT the axial section was chosen parallel to the orbitomeatal line, the coronal section in orthogonal orientation with a slice thickness of 1 mm.
Results: With both procedures middle-ear and inner ear structures as well as the mastoid and the labyrinth could be represented radiologically. Also missing ossicles could be diagnosed for example after experimental removal. However, the visualization of smallest pathologies like an erosion of the incus and semicircular canals was feasible by DVT, even if this could not be represented in HRCT. Furthermore through freely eligible section angulations specific anatomical structures as for example the chorda tympani or ductus endolymphaticus could be visualized in DVT subsequently even if these were not recognizable during the initial slicing, this was not possible in HRCT.
Conclusion: The digital Volume Tomography extends the diagnostic potential of radiographic imaging of bony lesions of the lateral skull base. Compared to HRCT the DVT offers lower radiation dosage combined with higher resolution that contributes the precise diagnosis of smallest bony pathologies of for example the ossicles.