Michio Isono

Observation of the external aperture of the vestibular aqueduct using three-dimensional surface reconstruction imaging

Observation of the external aperture of the vestibular aqueduct was hitherto possible only in cadavers or dry temporal bones; however, by applying three‐dimensional surface reconstruction imaging, it is now possible to observe solid‐looking images of this structure in living humans. When the width of the external aperture of the vestibular aqueduct was measured in 58 people, it was found to be significantly narrower in the affected ears of patients with Menieres disease than in normal ears.

Computerized assessment of the mastoid air cell system.

There have been many arguments on the development of pneumatization of temporal bone. However, a technique for direct volume measurement from high resolution computed tomography has never been reported. The aim of this paper is to develop a technique by using digital image processing to measure the volume of the mastoid air cell system. Forty three ears of 26 healthy subjects (13 males and 13 females) without a history of chronic or exudative otitis media, clear signs of Menieres disease, severe sensorineural hearing impairment or malformation of temporal bone were eligible for enrolment in this study. Using a digital image processing technique, only the black air cells and tympanic cavity on the CT films are easily selected. Then, after image processing, only areas of these extracted black pneumatized parts are calculated. Consequently, the volume of pneumatized parts of temporal bone could be calculated separately as total volume and as partial volume that divided by several CT planes. The average volume of pneumatization in 43 temporal bones was 5.97 ml. However, since the volume of pneumatization in the temporal bone has traditionally been estimated by analyzing areas on X-ray films, the new method described in this study is significant for its ability to directly measure the volume of pneumatization in the temporal bone.

Minute findings of inner ear anomalies by three-dimensional CT scanning

In actual clinical situations, inner ear anomalies must be diagnosed by image diagnosis such as high resolution CT-scanning of the temporal bone before three dimensional (3D) CT-scanning was introduced. In this paper, the usefulness of 3D-CT was investigated in some anomaly cases. It was found that 3D-CT was useful in observing the minute structure of the inner ear in that it could ascertain spatial relationships and minute constrictions and protrusions that could not be detected by 2D analysis. This CT was also capable of assessing the stage of embryological injuries and evaluating anomalies in cochlear turning that are the hidden factors of hearing impairment.

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.

Quantitative analysis of synkinesis following facial nerve palsy

Abstract At present there is no standard objective and quantitative evaluation system of synkinesis following facial nerve palsy. We developed a computer-assisted evaluation system combined with a rating score and investigated the usefulness of video cameras and infrared cameras in this system for evaluating facial mimetic motion. Twenty-four markers were placed on the face and after the extracted images were labeled to leave only marks, using threshold-identified images, the trajectory length of a marker was calculated using the shift in points. Using a camera with a built-in infrared light flasher and higher sampling rates together with reflective markers, the velocity of each point could be evaluated. The trajectory length of the supralabial marker during eye closure and that of an infraorbital palpebrae marker during whistling were significantly longer in patients with postparalytic synkinesis than in normal subjects. The severity of synkinesis was rated using a 3-point scale ranging from 0 to 2 and we found that the velocity of the supralabial marker increased with the score. The results from the computer-assisted evaluation system and grading correlated closely and were useful for the clinical evaluation of synkinesis.

Middle-Ear Paraganglioma Masquerading as Traumatic Facial Nerve Palsy With 1 color plate

We report the case of a 52-year-old female with middle-ear paraganglioma masquerading as a traumatic facial palsy, and describe the diagnostic steps and surgical treatment by the tympanomastoid approach.

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.

Objective Evaluation of Abnormal Associated Movements by Using an Infrared Camera: Eyelid Narrowing During Whistling

Results For the control group, the distance of marker movements of right side was correlated with left side. In the palsy group with the improvement of facial palsy, the right-and-left difference in the distance decreased and disappeared, as did the difference in the maximum velocity. On the other hand, even in palsy group whose facial expression had improved to normal, there was a right-andleft difference in the maximum velocity in the early stage.