OBJECTIVE: To compare the effectiveness of O-arm navigation and C-arm navigation for guiding percutaneous long sacroiliac screws in treatment of Denis type Ⅱ sacral fractures. METHODS: A retrospective study was conducted on clinical data of the 46 patients with Denis type Ⅱ sacral fractures between April 2021 and October 2022. Among them, 19 patients underwent O-arm navigation assisted percutaneous long sacroiliac screw fixation (O-arm navigation group), and 27 patients underwent C-arm navigation assisted percutaneous long sacroiliac screw fixation (C-arm navigation group). There was no significant difference in gender, age, causes of injuries, Tile classification of pelvic fractures, combined injury, the interval from injury to operation between the two groups ( P>0.05). The intraoperative preparation time, the placement time of each screw, the fluoroscopy time of each screw during placement, screw position accuracy, the quality of fracture reduction, and fracture healing time were recorded and compared, postoperative complications were observed. Pelvic function was evaluated by Majeed score at last follow-up. RESULTS: All operations were completed successfully, and all incisions healed by first intention. Compared to the C-arm navigation group, the O-arm navigation group had shorter intraoperative preparation time, placement time of each screw, and fluoroscopy time, with significant differences ( P<0.05). There was no significant difference in screw position accuracy and the quality of fracture reduction ( P>0.05). There was no nerve or vascular injury during screw placed in the two groups. All patients in both groups were followed up, with the follow-up time of 6-21 months (mean, 12.0 months). Imaging re-examination showed that both groups achieved bony healing, and there was no significant difference in fracture healing time between the two groups ( P>0.05). During follow-up, there was no postoperative complications, such as screw loosening and breaking or loss of fracture reduction. At last follow-up, there was no significant difference in pelvic function between the two groups ( P>0.05). CONCLUSION Compared with the C-arm navigation, the O-arm navigation assisted percutaneous long sacroiliac screws for the treatment of Denis typeⅡsacral fractures can significantly shorten the intraoperative preparation time, screw placement time, and fluoroscopy time, improve the accuracy of screw placement, and obtain clearer navigation images.
Humans ; Fracture Fixation, Internal/methods* ; Retrospective Studies ; Imaging, Three-Dimensional ; Bone Screws ; Surgery, Computer-Assisted ; Tomography, X-Ray Computed ; Spinal Fractures/surgery* ; Fractures, Bone/surgery* ; Pelvic Bones/injuries* ; Postoperative Complications ; Neck Injuries

OBJECTIVE: To investigate the clinical application of cone-beam computed tomography (CBCT) among endodontic practitioners, and to analyze the indications and reasonability of CBCT in the diagnosis and treatment of pulpal and periapical diseases. METHODS: The clinical data were collected from patients who visited the Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology and underwent CBCT examination from January to December, 2021. The data with their complete clinical information (including clinical records, radiology request forms/reports, two-dimensional and three-dimensional imaging data) were included. Those who underwent CBCT examination for orthodontic or prosthodontics were excluded. The experience and training background of the endodontic specialists, the number of patients treated in the whole year, the objective and region of interest (ROI) of CBCT examination, technical parameters, such as machine type, field of view (FoV) and radiographic reports were collected and analyzed to evaluate the impact on diagnosis. Wilcoxon and Mann-Whitney tests were used to compare the distribution of CBCT ROI. Chi-squared test and pairwise comparison were used to compare the application of CBCT by endodontic specialists with different clinical experience (senior, middle and junior). RESULTS: In 2021, a total of 3 308 CBCT scans were prescribed by 61 endodontic specialists who treated 34 952 patients throughout the year. 3 218 patients (male ∶female about 1 ∶2) amounting for 10% of the patients treated in the whole year who received CBCT scans with an median age of 35 years (28, 49). Around 98% CBCT examinations were performed after clinical examination and two-dimensional periapical radiographs were taken. The FoV of CBCT scanning less than 10 cm×10 cm accounted for 96% of the total number of the images. Among the 3 308 CBCT scans, 83% of the ROI were in posterior teeth, with a higher number of anterior teeth (Z=-2.278, P < 0.05). Maxillary and mandibular first molars accounted for 35% of the examined teeth. The objectives of CBCT scanning included three aspects: clarifying clinical diagnosis, guiding surgical and non-surgical endodontic treatment (including management of endodontic complications), and outcome assessment, accounting for 1 111 (34%), 1 745 (54%), 311 (10%), respectively. and the others 2%. In the diagnosis process, CBCT was mainly used for the diagnosis of chronic periapical periodontitis, root fracture, root resorption and dental trauma. In the study, 353 CBCT were used in the diagnosis of root fracture, with a positive diagnosis rate of 35% (125/353). 846 CBCT used to reveal the anatomy of the root canal system, of which 297 cases were used to find missed/extra canals after treatment failure, and 58% (171/297) were used to confirm the missed/extra canals. In the management of complications or errors, CBCT was mainly used to assist the diagnosis of perforation and to locate the separated instruments. In the study, 311 CBCT scans were used for outcome assessment, including 240 cases related to non-surgical treatment and 71 cases related to surgical endodontic treatment for follow-up or presence of clinical symptoms, and persistent lesions on 2D films. Among the 61 endodontic specialists who used CBCT, 23 (45%) were with senior experience, 15 (30%) with middle experience, and 23 (25%) with junior experience. The proportion of senior or junior experience prescribing CBCT examination was 10%, higher than that of middle experience (8%, χ₁²=39.4, χ₂²=29.1, P < 0.001). The application rate of chief endodontists was 18%, which was higher than that of associate chief endodontists (9%, χ₁²=139.4, P < 0.001). 31% (1 109/3 308) cases of diagnosis or treatment plans were changed after CBCT was taken. CONCLUSION Use of CBCT in endodontic practice could provide more clinical information, which is helpful for diagnosis, accurate treatment and prognosis evaluation.
Humans ; Male ; Adult ; Prevalence ; Root Canal Therapy/methods* ; Cone-Beam Computed Tomography/methods* ; Tooth ; Imaging, Three-Dimensional

OBJECTIVE: To explore an efficient and automatic method for determining the anatomical landmarks of three-dimensional(3D) mandibular data, and to preliminarily evaluate the performance of the method. METHODS: The CT data of 40 patients with normal craniofacial morphology were collected (among them, 30 cases were used to establish the 3D mandibular average model, and 10 cases were used as test datasets to validate the performance of this method in determining the mandibular landmarks), and the 3D mandibular data were reconstructed in Mimics software. Among the 40 cases of mandibular data after the 3D reconstruction, 30 cases that were more similar to the mean value of Chinese mandibular features were selected, and the size of the mandibular data of 30 cases was normalized based on the Procrustes analysis algorithm in MATLAB software. Then, in the Geomagic Wrap software, the 3D mandibular average shape model of the above 30 mandibular data was constructed. Through symmetry processing, curvature sampling, index marking and other processing procedures, a 3D mandible structured template with 18 996 semi-landmarks and 19 indexed mandibular anatomical landmarks were constructed. The open source non-rigid registration algorithm program Meshmonk was used to match the 3D mandible template constructed above with the tested patient's 3D mandible data through non-rigid deformation, and 19 anatomical landmark positions of the patient's 3D mandible data were obtained. The accuracy of the research method was evaluated by comparing the distance error of the landmarks manually marked by stomatological experts with the landmarks marked by the method of this research. RESULTS: The method of this study was applied to the data of 10 patients with normal mandibular morphology. The average distance error of 19 landmarks was 1.42 mm, of which the minimum errors were the apex of the coracoid process [right: (1.01±0.44) mm; left: (0.56±0.14) mm] and maximum errors were the anterior edge of the lowest point of anterior ramus [right: (2.52±0.95) mm; left: (2.57±1.10) mm], the average distance error of the midline landmarks was (1.15±0.60) mm, and the average distance error of the bilateral landmarks was (1.51±0.67) mm. CONCLUSION The automatic determination method of 3D mandibular anatomical landmarks based on 3D mandibular average shape model and non-rigid registration algorithm established in this study can effectively improve the efficiency of automatic labeling of 3D mandibular data features. The automatic determination of anatomical landmarks can basically meet the needs of oral clinical applications, and the labeling effect of deformed mandible data needs to be further tested.
Humans ; Imaging, Three-Dimensional/methods* ; Mandible/diagnostic imaging* ; Software ; Algorithms ; Anatomic Landmarks/anatomy & histology*

OBJECTIVES: To examine the reliability and accuracy of Walker's model for estimating the sex of Han adults in western China by using cranium three-dimensional (3D) CT reconstruction, and to study the suitable cranial sex estimation model for Han people in western China. METHODS: A total of 576 cranial CT 3D reconstructed images from Hanzhong Hospital in Shaanxi Province from 2017 to 2021 were collected. These images were divided into the experimental group with 486 samples and the validation group with 90 samples. Walker's model was used by observer 1 to estimate the sex of experimental group samples. The logistic function applicable to Han people in western China was corrected by observer 1. The 90 samples in the validation group were scored and substituted into the modified logistic function to complete the back substitution test by observer 1, 2 and 3. RESULTS: The accuracy of sex estimation of Han adults in western China was 63.2%-77.2% by applying Walker's model. The accuracy of modified logistic function was 82.9%. The accuracy of sex estimation through back substitution test by 3 observers was 75.6%-91.1%, with a Kappa value of 0.689 (P<0.05) for inter-observer consistency and 0.874 (P<0.05) for intra-observer consistency. CONCLUSIONS There are great differences in bone characteristics among people from different regions. The modified logistic function can achieve higher accuracy in Han adults in western China.
Humans ; Adult ; Reproducibility of Results ; Sex Determination by Skeleton/methods* ; Forensic Anthropology ; Skull/anatomy & histology* ; Imaging, Three-Dimensional ; China ; Tomography, X-Ray Computed

In light of the increasing digitalization of dentistry, the automatic determination of three-dimensional (3D) craniomaxillofacial features has become a development trend. 3D craniomaxillofacial landmarks and symmetry reference plane determination algorithm based on point clouds has attracted a lot of attention, for point clouds are the basis for virtual surgery design and facial asymmetry analysis, which play a key role in craniomaxillofacial surgery and orthodontic treatment design. Based on the studies of our team and national and international literatures, this article presented the deep geometry learning algorithm to determine landmarks and symmetry reference plane based on 3D craniomaxillofacial point clouds. In order to provide reference for future clinical application, we describe the development and latest research in this field, and analyze and discuss the advantages and limitations of various methods.
Humans ; Imaging, Three-Dimensional/methods* ; Facial Asymmetry ; Algorithms

Objective: To explore an automatic landmarking method for anatomical landmarks in the three-dimensional (3D) data of the maxillary complex and preliminarily evaluate its reproducibility and accuracy. Methods: From June 2021 to December 2022, spiral CT data of 31 patients with relatively normal craniofacial morphology were selected from those who visited the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology. The sample included 15 males and 16 females, with the age of (33.3±8.3) years. The maxillary complex was reconstructed in 3D using Mimics software, and the resulting 3D data of the maxillary complex was mesh-refined using Geomagic software. Two attending physicians and one associate chief physician manually landmarked the 31 maxillary complex datasets, determining 24 anatomical landmarks. The average values of the three expert landmarking results were used as the expert-defined landmarks. One case that conformed to the average 3D morphological characteristics of healthy individuals' craniofacial bones was selected as the template data, while the remaining 30 cases were used as target data. The open-source MeshMonk program (a non-rigid registration algorithm) was used to perform an initial alignment of the template and target data based on 4 landmarks (nasion, left and right zygomatic arch prominence, and anterior nasal spine). The template data was then deformed to the shape of the target data using a non-rigid registration algorithm, resulting in the deformed template data. Based on the unchanged index property of homonymous landmarks before and after deformation of the template data, the coordinates of each landmark in the deformed template data were automatically retrieved as the automatic landmarking coordinates of the homonymous landmarks in the target data, thus completing the automatic landmarking process. The automatic landmarking process for the 30 target data was repeated three times. The root-mean-square distance (RMSD) of the dense corresponding point pairs (approximately 25 000 pairs) between the deformed template data and the target data was calculated as the deformation error of the non-rigid registration algorithm, and the intra-class correlation coefficient (ICC) of the deformation error in the three repetitions was analyzed. The linear distances between the automatic landmarking results and the expert-defined landmarks for the 24 anatomical landmarks were calculated as the automatic landmarking errors, and the ICC values of the 3D coordinates in the three automatic landmarking repetitions were analyzed. Results: The average three-dimensional deviation (RMSD) between the deformed template data and the corresponding target data for the 30 cases was (0.70±0.09) mm, with an ICC value of 1.00 for the deformation error in the three repetitions of the non-rigid registration algorithm. The average automatic landmarking error for the 24 anatomical landmarks was (1.86±0.30) mm, with the smallest error at the anterior nasal spine (0.65±0.24) mm and the largest error at the left oribital (3.27±2.28) mm. The ICC values for the 3D coordinates in the three automatic landmarking repetitions were all 1.00. Conclusions: This study established an automatic landmarking method for three-dimensional data of the maxillary complex based on a non-rigid registration algorithm. The accuracy and repeatability of this method for landmarking normal maxillary complex 3D data were relatively good.
Male ; Female ; Humans ; Adult ; Imaging, Three-Dimensional/methods* ; Reproducibility of Results ; Algorithms ; Software ; Tomography, Spiral Computed ; Anatomic Landmarks/anatomy & histology*

Computer-assisted technology are gradually integrated into dental education and clinical treatment. As a cutting-edge technology in computer-aided medicine, augmented reality can not only be used as an aid to dental education by presenting three-dimensional scenes for teaching demonstration and experimental skills training, but also can superimpose virtual image information of patients onto real lesion areas for real-time feedback and intraoperative navigation. This review explores the current applications and limitations of augmented reality in dentistry to provide a reference for future research.
Humans ; Augmented Reality ; Oral Medicine ; Surgery, Computer-Assisted/methods* ; Imaging, Three-Dimensional

Pelvic floor ultrasound can clearly visualize the position and morphology of pelvic floor organs, observe the pelvic organ prolapse in real-time, and quantify and analyze the degree of the levator ani muscle injury, which is the most common imaging method to assess the morphology and function of the levator ani muscle to date. The different ultrasound imaging techniques provide a variety of indicators, each with its own advantages and limitations.Furthermore, two-dimensional ultrasound is the basis of imaging, but it fails to detect cross-sectional images of the pelvic floor; three-dimensional ultrasound can acquire the axial plane of the levator hiatus; tomographic ultrasound imaging allows real-time observation of the levator ani muscle injury; shear wave elastography can provide a quantitative assessment of the contractility and elastic characteristics of the levator ani muscle in real-time. It is of great significance to summarize the basic principles of various ultrasound imaging techniques, summarize the ultrasound image characteristics of levator ani muscle and its hiatus in different populations and different states, and explore the cut-off values and diagnostic criteria-related ultrasound parameters for improving the diagnostic efficiency of pelvic floor ultrasound for levator ani muscle injury, leading to reducing missed diagnosis and misdiagnosis of lesions.
Humans ; Female ; Pelvic Floor/pathology* ; Pelvic Organ Prolapse/pathology* ; Ultrasonography/methods* ; Imaging, Three-Dimensional

The registration of preoperative magnetic resonance (MR) images and intraoperative ultrasound (US) images is very important in the planning of brain tumor surgery and during surgery. Considering that the two-modality images have different intensity range and resolution, and the US images are degraded by lots of speckle noises, a self-similarity context (SSC) descriptor based on local neighborhood information was adopted to define the similarity measure. The ultrasound images were considered as the reference, the corners were extracted as the key points using three-dimensional differential operators, and the dense displacement sampling discrete optimization algorithm was adopted for registration. The whole registration process was divided into two stages including the affine registration and the elastic registration. In the affine registration stage, the image was decomposed using multi-resolution scheme, and in the elastic registration stage, the displacement vectors of key points were regularized using the minimum convolution and mean field reasoning strategies. The registration experiment was performed on the preoperative MR images and intraoperative US images of 22 patients. The overall error after affine registration was (1.57 ± 0.30) mm, and the average computation time of each pair of images was only 1.36 s; while the overall error after elastic registration was further reduced to (1.40 ± 0.28) mm, and the average registration time was 1.53 s. The experimental results show that the proposed method has prominent registration accuracy and high computational efficiency.
Humans ; Imaging, Three-Dimensional/methods* ; Magnetic Resonance Imaging/methods* ; Ultrasonography/methods* ; Algorithms ; Surgery, Computer-Assisted/methods*

Magnetic resonance (MR) imaging is an important tool for prostate cancer diagnosis, and accurate segmentation of MR prostate regions by computer-aided diagnostic techniques is important for the diagnosis of prostate cancer. In this paper, we propose an improved end-to-end three-dimensional image segmentation network using a deep learning approach to the traditional V-Net network (V-Net) network in order to provide more accurate image segmentation results. Firstly, we fused the soft attention mechanism into the traditional V-Net's jump connection, and combined short jump connection and small convolutional kernel to further improve the network segmentation accuracy. Then the prostate region was segmented using the Prostate MR Image Segmentation 2012 (PROMISE 12) challenge dataset, and the model was evaluated using the dice similarity coefficient (DSC) and Hausdorff distance (HD). The DSC and HD values of the segmented model could reach 0.903 and 3.912 mm, respectively. The experimental results show that the algorithm in this paper can provide more accurate three-dimensional segmentation results, which can accurately and efficiently segment prostate MR images and provide a reliable basis for clinical diagnosis and treatment.
Male ; Humans ; Prostate/diagnostic imaging* ; Image Processing, Computer-Assisted/methods* ; Magnetic Resonance Imaging/methods* ; Imaging, Three-Dimensional/methods* ; Prostatic Neoplasms/diagnostic imaging*