Kazuko Nakayama

Three-dimensional Magnetic Resonance Imaging Findings of Inner Ear Anomaly

Using three-dimensional magnetic resonance imaging (3D-MRI), the membranous labyrinth was examined in normal cases and in a case with bilateral Mondini-type inner ear malformations. Both ears were also examined by high-resolution computed tomography (CT) of the temporal bone. 3D-MRI provided more detail than findings obtained by conventional high-resolution CT and it enabled 3D observations to be made. Detailed examination of maximum intensity projection images along the cochlea axis revealed the cochlear turns in three dimensions.Using three-dimensional magnetic resonance imaging (3D-MRI), the membranous labyrinth was examined in normal cases and in a case with bilateral Mondini-type inner ear malformations. Both ears were also examined by high-resolution computed tomography (CT) of the temporal bone. 3D-MRI provided more detail than findings obtained by conventional high-resolution CT and it enabled 3D observations to be made. Detailed examination of maximum intensity projection images along the cochlea axis revealed the cochlear turns in three dimensions.

Computerized assessment of developmental changes in the mastoid air cell system

Abstract Background: We have developed a technique for direct volume measurement based on high-resolution CT. This report will describe our findings on the measurement of the mastoid air cell system of infants, and its developmental changes with age. Methods: The study covered 43 males and 37 females, aged 1–18 years. The temporal bone was imaged by slicing at 2 mm thickness through the high-resolution CT, so that the entire air cell system was included, and the resultant data were analyzed by the image processing technique. Results: It was confirmed that the mastoid air volume increased with age. By 9–10 years old, it had reached about 80% of the volume of an adult, and at 14–15 years old, it had reached the mean adult value. Conclusion: Our technique, based on CT image, proved to be much more useful because of the higher accuracy and capability of three-dimensional assessment. The detailed analysis described here could have been obtained only through the postmortem histological study. Our method is of high significance because it allows assessing the antemortem developmental changes in infants.

Evaluation of reconstructed 3-D images of the middle ear using multi-slice scan CT

Abstract Middle ear structures, especially those around the stapes, which have been difficult to examine, could be visualized by multi-slice scan CT, which allows slicing at 0.5 mm. The CT equipment used was a Toshiba Aquilion multi-slice CT system which can process four slices with a slice thickness of 0.5 mm. The scanning conditions were: Tube current 300 mA, tube potential 120 kV, scanning time 0.5 s/scan, slice thickness 0.5 mm, and helical pitch 3 stac. The reconstitution function, FC81 was used as the algorithm for image reconstruction and an image-processing software (Xtension, Toshiba) was used for preparation of reconstructed 3-D images. Fine structures of the auditory ossicles could be clearly delineated in the images reconstructed by the use of the multi-slice scan CT. Changes around the stapes could be observed in cholesteatoma, and the device is considered to be applicable to preoperative diagnosis of the disease.

Possibility of Three-Dimensional Reconstruction Images in the Temporal Region

With the recent emergence of helical scan CT, which is used widely in the clinical field, it has become easy to create three-dimensional reconstruction images of the living body. With the emergence of multislice helical CT, which enables 0. 5 mm slice-thickness images, it has become possible to create threedimensional images of intricate structures. However, it is known that with three-dimensional reconstruction imaging, the images depicted change according to the image conditions, reconstruction function, and CT value set at the time of image depiction. In particular, the structure of the temporal bone is extremely intricate and anatomically the morphology is complicated, so the effects of such conditions are significant. In the present study we examined how helical scan CT and multi-slice CT three-dimensional reconstruction images in the temporal region change according to changes in the CT threshold, and also assessed the value of diagnosis using the obtained images. We further investigated the three-dimensional image construction conditions most suitable to the temporal region, depicted the structures of the normal middle ear and inner ear under the obtained optimal conditions, and assessed the diagnostic values of the depicted auditory ossicle, vestibulo-cochlea, and semicircular canal. We then applied this to the clinical setting and examined the possibility of applying three-dimensional reconstruction images to the entire temporal region.

Inner Ear Anomaly of Three-dimensional Computed Tomography: Computed Tomographic Attenuation and Image Changes

With regard to image diagnosis of inner ear anomalies, three-dimensional computed tomography (3D-CT) is useful in obtaining very realistic images that are unmatched by 2D-CT. Unlike the step scanning in the existing 2D-CT, in helical 3D-CT, scanning is performed in a spiral motion by continuously rotating the scanner and moving the table along the body axis at a constant speed. As a result, data obtained by this CT are continuous and very smooth curves can be obtained. Among the data, the CT attenuation determines the quality of the final 3D images. In the present paper, the usefulness of 3D-CT was investigated in a case with Mondini-type inner ear malformation.With regard to image diagnosis of inner ear anomalies, three-dimensional computed tomography (3D-CT) is useful in obtaining very realistic images that are unmatched by 2D-CT. Unlike the step scanning in the existing 2D-CT, in helical 3D-CT, scanning is performed in a spiral motion by continuously rotating the scanner and moving the table along the body axis at a constant speed. As a result, data obtained by this CT are continuous and very smooth curves can be obtained. Among the data, the CT attenuation determines the quality of the final 3D images. In the present paper, the usefulness of 3D-CT was investigated in a case with Mondini-type inner ear malformation.