Biomedical subjects

Masami Fujishita

Publications and source records attributed to Masami Fujishita.

4 recordsLinked to original sources

PubMed2005

Image artifact in dental cone-beam CT.

PURPOSE: The purpose of this study was to investigate the appearance and possible cause of an artifact seen in limited-volume cone-beam CT imaging. METHODS: A water-filled plastic cylinder was used as a phantom of the head. A test object was constructed as a bone-equivalent phantom to be imaged. The test object was variously positioned at the center of the phantom and near its margins. CT images of the test object were acquired using a 3DX Accuitomo system. RESULTS: In slice images with the test object positioned near the margin of the phantom, arch-shaped defects or deformities were observed on the side of the object. There was a negative correlation between the artifact and the CT value of the object. The artifact was larger in images scanned with a higher voltage. CONCLUSION: The probability that this artifact is caused by halation from the image intensifier (II) system is suggested.

Artifacts↗

PubMed2005

Condylar head remodeling following mandibular setback osteotomy for prognathism: a comparative study of different imaging modalities.

PURPOSE: Condylar remodeling, which develops after mandibular setback osteotomy, was evaluated and compared in CT, plain film radiographs, and MR images acquired postoperatively. METHODS: Thirty-nine patients treated with sagittal split ramus osteotomy (SSRO) and 46 patients treated with intraoral vertical ramus osteotomy (IVRO) were studied. Remodeling as seen in the images and the diagnostic agreement between imaging modalities was evaluated. RESULTS: A newly formed bone layer in the posterior part of the condylar head was identified as a sign suggestive of remodeling. This sign was seen predominantly at periods over 6 months postoperatively. IVRO subjects had a higher incidence of remodeling than did the SSRO group. The diagnostic agreement between the 3 imaging modalities was substantial. There was a positive correlation between postoperative condylar displacement and the incidence of remodeling. CONCLUSIONS: The incidence of postoperative condylar head remodeling may be predictable. High-dose postoperative imaging studies to assess the TMJ should be restricted to those cases having a clear need for such studies.

Adolescent↗

PubMed2005

3D-CT evaluation of facial asymmetry.

OBJECTIVE: Recently, 3-dimensional-computed tomography (3D-CT) imaging has been used in the diagnosis and surgical treatment planning of patients with craniofacial deformities. The present authors have developed a 3D-CT imaging procedure for a 3-dimensional coordinate point evaluation system to assess and diagnose patients with facial asymmetry. STUDY DESIGN: The CT data of 16 subjects was selected retrospectively as the control group from patients who had undergone CT examinations to diagnose conditions other than maxillofacial deformities. Anatomical landmarks modified from orthodontic craniometric (cephalometric) points were defined on the 3D-CT images and the asymmetry index of each point was calculated in millimeters. A diagrammatic chart with a baseline indicating the mean asymmetry indices plus the standard deviation in the control group was designed. The resulting diagrammatic chart was used to evaluate the degree of deformity in facial asymmetry patients. RESULTS AND CONCLUSIONS: The topography of facial asymmetry was assessed. The 3D-CT imaging technique as described herein is a practical method of evaluating the morphology of facial asymmetry.

Adolescent↗

PubMed2004

3D CT evaluation of masseter muscle morphology after setback osteotomy for mandibular prognathism.

OBJECTIVE: Following mandibular setback osteotomy, changes in the direction, length, and cross-sectional area of the masseter muscle were studied by means of computerized tomography (CT) images generated with a 3-dimensional (3D) reconstructive technique. STUDY DESIGN: Pre- and postoperative CT examinations were performed on 17 prognathic patients treated by sagittal split ramus osteotomy with rigid osteosynthesis and 13 patients treated by intraoral vertical ramus osteotomy without osteosynthesis. The pre- and postoperative masseter muscle direction and length were evaluated using 3D CT images observed from a lateral viewing angle. The cross-sectional area of the masseter muscle was first measured on an axial CT image of a selected slice level, following which the right-angle cross-sectional area of the muscle was revised using the measured area from the axial image. RESULTS: Postoperatively, anterior tilting of the masseter muscle was observed; however, masseter muscle length was unchanged. Three months postoperatively, a significant reduction in the cross-sectional area of the masseter muscle was seen. A tendency to revert back to the normal dimension was seen between 6 months and 1 year postoperatively. No significant difference was noted between the 2 surgical techniques. CONCLUSIONS: Three-dimensional computed tomography is an adequate imaging modality for masseter muscle evaluation. The results of this study suggest the masseter muscle may undergo reversible atrophy after mandibular setback osteotomy.

Adolescent↗