Hiroaki Miyashita

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.

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.

Three-Dimensional Analysis of Facial Expression

Background The Sunnybrook Facial Grading System (FGS) was developed by Ross et al. in 1992 to evaluate facial function after facial nerve injury. This tool is clinically relevant, easy to administer, and requires no specialized equipment. It has clearly demonstrated ability to accurately describe patients’ facial function and monitor their recovery over time. It has strong measurement properties of content and construct validity, interand intra-rater reliability, and responsiveness to change.

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.