In-house fabrication of three-dimensional (3D) models for medical use has become easier in recent years. Cone beam computed tomography (CBCT) images are increasingly used as source data for fabricating osseous 3D models. The creation of a 3D CAD model begins with the segmentation of hard and soft tissues of the DICOM images and the creation of an STL model; however, it can be difficult to determine the binarization threshold in CBCT images. In this study, how the different CBCT scanning and imaging conditions of two different CBCT scanners affect the determination of the binarization threshold was evaluated. The key to efficient STL creation through voxel intensity distribution analysis was then explored. It was found that determination of the binarization threshold is easy for image datasets with a large number of voxels, sharp peak shapes, and narrow intensity distributions. Although the intensity distribution of voxels varied greatly among the image datasets, it was difficult to find correlations between different X-ray tube currents or image reconstruction filters that explained the differences. The objective observation of voxel intensity distribution may contribute to the determination of the binarization threshold for 3D model creation.
Abstract. Users require navigation for many location-based applications using moving sensors, such as autonomous robot control, mapping route navigation and mobile infrastructure inspection. In indoor environments, indoor positioning systems using GNSSs can provide seamless indoor-outdoor positioning and navigation services. However, instabilities in sensor position data acquisition remain, because the indoor environment is more complex than the outdoor environment. On the other hand, simultaneous localization and mapping processing is better than indoor positioning for measurement accuracy and sensor cost. However, it is not easy to estimate position data from a single viewpoint directly. Based on these technical issues, we focus on geofencing techniques to improve position data acquisition. In this research, we propose a methodology to estimate more stable position or location data using unstable position data based on geofencing in indoor environments. We verify our methodology through experiments in indoor environments.
In recent years, an increased emphasis on enhancing the care and health management of captive marine mammals has been observed. Belugas (White Whale, Delphinapterus leucas), belonging to the family Monodontidae, are of considerable importance and often the centerpiece of aquarium collections worldwide. This study aimed to investigate the effects of the administration of prebiotics on the gut microbiota and overall health of the beluga. Prebiotic 1-kestose, a fructooligosaccharide comprising sucrose and fructose, was administered to three belugas, alongside their regular vitamin supplements for a duration of 8 weeks. 16S rRNA gene amplicon sequencing of intestinal DNA revealed that the relative abundance of the genus Turicibacter, a potentially pathogenic bacteria, significantly reduced after 1-kestose administration when compared to that at baseline (P=0.050). In addition, a quantitative PCR analysis revealed that the levels of collagenase gene, a putative virulence factor gene of Turicibacter, significantly reduced after 1-kestose administration (P=0.050). Blood creatinine levels that were initially above the normal value also reduced after 1-kestose administration (P=0.023). Therefore, this study demonstrated the potential of 1-kestose to improve the health and welfare of aquarium belugas.
Abstract Background: Extracting and three-dimensional (3D) printing an organ in a region of interest in DICOM images typically calls for segmentation in support of 3D printing as a first step. The DICOM images are not exported to STL data immediately, segmentation masks are exported to STL models. After primary and secondary processing, including noise removal and hole correction, the STL data can be 3D printed. The quality of the 3D model is directly related to the quality of the STL data. This study focuses and reports on DICOM to STL segmentation performance for nine software packages.Methods: Multi-detector row CT scanning was performed on a dry human mandible with two 10-mm-diameter bearing balls as a phantom. The DICOM images file was then segmented and exported to a STL file using nine different commercial/open-source software packages. Once the STL models were created, the data (file) properties and the size and volume of each were measured and differences across the software packages were noted. Additionally, to evaluate differences between the shapes of the STL models by software package, each pair of STL models was superimposed, with observed differences between their shapes characterized as shape error. Results: The data (file) size of the STL file and the number of triangles that constitute each STL model were different across all software packages, there was no statistically significant difference were found across software packages. The created ball STL model expanded in the X-, Y-, and Z-axis directions, with the length in the Z-axis direction (body axis direction) being slightly longer than other directions. There were no significant differences in shape error across software packages for the mandible STL model. Conclusions: The different characteristics of each software package were noticeable, such as different effects in the thin cortical bone area, likely due to the partial volume effect, which may reflect differences in image binarization algorithms. Although the shape of the STL model differs slightly depending on the software, our results indicate that shape error in 3D printing for clinical use in the operation of osseous structures.
Change in soft tissue in relation to that in hard tissue following orthognathic surgery was evaluated. Twenty-five patients were enrolled in the study. The diagnosis in all was jaw deformity (maxillary retrusion and mandibular protrusion) and all underwent a Le Fort I osteotomy and bilateral sagittal splitting ramus osteotomy. Three-dimensional (3D) computer-aided design (CAD) models (polygon models) of the hard and soft tissue of the maxilla and mandible were constructed and superimposed. Reference points were established on the pre- and postoperative hard and soft tissues. Specific elements of each reference point were divided into X, Y, and Z components, respectively, and the distances in each direction and 3D distance (normal distance) measured. The Wilcoxon signed-rank test was used to determine differences in the mean values for the distance moved of each element as the error between pre- and postoperatively. The results revealed statistically significant differences in the Y-direction in the maxilla and the X- and Z-directions in the mandible. A significant difference was also observed in the 3D distances of the maxilla and mandible. Little evidence was found of linearity between the amount of hard and soft tissue movement in the X- and Z-directions in the maxilla. This means that 3D movement in the maxilla was masked more by changes in the morphology of the soft tissue than in the mandible, making it less evident. The results of this study suggest that the 3D analysis method used enables changes in hard and soft tissues to be understood qualitatively, and that it can be used in diagnosis and treatment in orthognathic surgery. It may also be useful in simulation of morphological change in soft tissue.
Safe sedation doses for performing minor procedures such as bronchoscopy, endoscopy, and tooth extraction for beluga whales (Delphinapterus leucas) require elucidation. This study aimed to provide suggestions for determining appropriate midazolam and butorphanol doses to adequately sedate beluga whales to complete procedures and minimize the risk of side effects. We administered midazolam and butorphanol to six captive beluga whales (9-44 years old). Topical lidocaine anesthesia was administered during bronchoscopy. The sedation doses for the beluga whales varied from 0.020 to 0.122 mg/kg for midazolam and from 0.020 to 0.061 mg/kg for butorphanol. In beluga whales, optimal midazolam and butorphanol doses were lowest in old whales. These findings contribute to knowledge regarding appropriate sedation and prevention of overdose accidents during minor procedures in beluga whales.
Le Fort I osteotomy is one of the surgical procedures now routinely and safely performed. It is possible to move the maxilla in three dimensions, but it is necessary to separate the bones around the maxillary sinus. Therefore, with surgery, maxillary sinus mucosal thickening occurs. By knowing the changes in the sinus mucosa after surgery and the factors affecting it, it is possible to better predict the outcomes of surgery and contribute to safer surgery. In this study, thickening of maxillary sinus mucosa before and after surgery in Le Fort I osteotomy was evaluated using multidetector-row computed tomography (MDCT) images, and the changes in mucosal thickening and the related factors were examined.Using MDCT images, the maxillary sinus mucosa of 125 patients who had undergone Le Fort I osteotomy was retrospectively evaluated before surgery, 1 month after surgery, and 1 year after surgery. On the MDCT images, the maxillary sinus was judged as mucosal thickening and classified into three grades according to the proportion occupying the maxillary sinus. In the evaluation of factors related to mucosal thickening, the following eight factors were examined: sex, age, diagnosis, operating time, amount of postoperative bleeding, with/without bone graft, with/without multisegmental osteotomy, and with/without macrolide therapy after surgery.The mean age at the time of surgery was 25.6 ± 8 years. Of all 125 patients, 66 had bilateral thickening, 19 had unilateral thickening, and 40 had no thickening. Factors that were significantly related to mucosal thickening were the operative time for the maxilla, bone grafts, and macrolide therapy after surgery.Operative time for the maxilla, bone grafts, and macrolide therapy after surgery were found to be related to mucosal thickening. In addition, MDCT scanning 1 month after surgery was considered to be appropriate for evaluation of maxillary sinus mucosal thickening.
