3D CT Images Research Articles

Evaluation of the geometric and dosimetric accuracies of deformable image registration of targets and critical organs in prostate CBCT-guided adaptive radiotherapy.

Kilovoltage cone beam computed tomography (kVCBCT)-guided adaptive radiation therapy (ART) uses daily deformed CT (dCT), which is generated automatically through deformable registration methods. These registration methods may perform poorly in reproducing volumes of the target organ, rectum, and bladder during treatment. We analyzed the registration errors between the daily kVCBCTs and corresponding dCTs for these organs using the default optical flow algorithm and two registration procedures. We validated the effectiveness of these registration methods in replicating the geometry for dose calculation on kVCBCT for ART. We evaluated three deformable image registration (DIR) methods to assess their registration accuracy and dose calculation effeciency in mapping target and critical organs. The DIR methods include (1) default intensity-based deformable registration, (2) hybrid deformable registration, and (3) a two-step deformable registration process. Each technique was applied to a computerized imaging reference system (CIRS) phantom (Model 062M) and to five patients who received volumetric modulated arc therapy to the prostate. Registration accuracy was assessed using the 95% Hausdorff distance (HD95) and Dice similarity coefficient (DSC), and each method was compared with the intensity-based registration method. The improvement in the dCT image quality of the CIRS phantom and five patients was assessed by comparing dCT with kVCBCT. Image quality quantitative metrics for the phantom included the signal-to-noise ratio (SNR), uniformity, and contrast-to-noise ratio (CNR), whereas those for the patients included the mean absolute error (MAE), mean error, peak signal-to-noise ratio (PSNR), and structural similarity index measure (SSIM). To determine dose metric differences, we used a dose-volume histogram (DVH) and 3.0%/0.3mm gamma analysis to compare planning computed tomography (pCT) and kVCBCT recalculations with restimulated CT images used as a reference. The dCT images generated by the hybrid (dCTH) and two-step (dCTC) registration methods resulted in significant improvements compared to kVCBCT in the phantom model. Specifically, the SNR improved by 107% and 107.2%, the uniformity improved by 90% and 75%, and the CNR improved by 212.2% and 225.6 for dCTH and dCTC methods, respectively. For the patient images, the MAEs improved by 98% and 94%, the PSNRs improved by 16.3% and 22.9%, and the SSIMs improved by 1% and 1% in the dCTH and dCTC methods, respectively. For the geometric evaluation, only the two-step registration method improved registration accuracy. The dCTH method yielded an average HD95 of 12mm and average DSC of 0.73, whereas dCTC yielded an average HD95 of 2.9mm and average DSC of 0.902. The DVH showed that the dCTC-based dose calculations differed by <2% from the expected results for treatment targets and volumes of organs at risk. Additionally, gamma indices for dCTC-based treatment plans were >95% at all points, whereas they were <95% for kVCBCT-based treatment plans. The two-step registration method outperforms the intensity-based and hybrid registration methods. While the hybrid and two-step-based methods improved the image quality of kVCBCT in a linear accelerator, only the two-step method improved the registration accuracy of the corresponding structures among the pCT and kVCBCT datasets. A two-step registration process is recommended for applying kVCBCT to ART, which achieves better registration accuracy for local and global image structures. This method appears to be beneficial for radiotherapy dose calculation in patients with pelvic cancer.

Impact of interplay effects on spot scanning proton therapy with motion mitigation techniques for lung cancer: SFUD versus robustly optimized IMPT plans utilizing a four-dimensional dynamic dose simulation tool

BackgroundThe interaction between breathing motion and scanning beams causes interplay effects in spot-scanning proton therapy for lung cancer, resulting in compromised treatment quality. This study investigated the effects and clinical robustness of two types of spot-scanning proton therapy with motion-mitigation techniques for locally advanced non-small cell lung cancer (NSCLC) using a new simulation tool (4DCT-based dose reconstruction).MethodsThree-field single-field uniform dose (SFUD) and robustly optimized intensity-modulated proton therapy (IMPT) plans combined with gating and re-scanning techniques were created using a VQA treatment planning system for 15 patients with locally advanced NSCLC (70 GyRBE/35 fractions). In addition, gating windows of three or five phases around the end-of-expiration phase and two internal gross tumor volumes (iGTVs) were created, and a re-scanning number of four was used. First, the static dose (SD) was calculated using the end-of-expiration computed tomography (CT) images. The four-dimensional dynamic dose (4DDD) was then calculated using the SD plans, 4D-CT images, and the deformable image registration technique on end-of-expiration CT. The target coverage (V98%, V100%), homogeneity index (HI), and conformation number (CN) for the iGTVs and organ-at-risk (OAR) doses were calculated for the SD and 4DDD groups and statistically compared between the SD, 4DDD, SFUD, and IMPT treatment plans using paired t-test.ResultsIn the 3- and 5-phase SFUD, statistically significant differences between the SD and 4DDD groups were observed for V100%, HI, and CN. In addition, statistically significant differences were observed for V98%, V100%, and HI in phases 3 and 5 of IMPT. The mean V98% and V100% in both 3-phase plans were within clinical limits (> 95%) when interplay effects were considered; however, V100% decreased to 89.3% and 94.0% for the 5-phase SFUD and IMPT, respectively. Regarding the significant differences in the deterioration rates of the dose volume histogram (DVH) indices, the 3-phase SFUD plans had lower V98% and CN values and higher V100% values than the IMPT plans. In the 5-phase plans, SFUD had higher deterioration rates for V100% and HI than IMPT.ConclusionsInterplay effects minimally impacted target coverage and OAR doses in SFUD and robustly optimized IMPT with 3-phase gating and re-scanning for locally advanced NSCLC. However, target coverage significantly declined with an increased gating window. Robustly optimized IMPT showed superior resilience to interplay effects, ensuring better target coverage, prescription dose adherence, and homogeneity than SFUD.Trial registration: None.

A 3D U-NET BASED ON EARLY FUSION MODEL: IMPROVEMENT, COMPARATIVE ANALYSIS WITH STATE-OF-THE-ART MODELS AND FINE-TUNING

Multi-organ segmentation is the process of identifying and separating multiple organs in medical images. This segmentation allows for the detection of structural abnormalities by examining the morphological structure of organs. Carrying out the process quickly and precisely has become an important issue in today's conditions. In recent years, researchers have used various technologies for the automatic segmentation of multiple organs. In this study, improvements were made to increase the multi-organ segmentation performance of the 3D U-Net based fusion model combining HSV and grayscale color spaces and compared with state-of-the-art models. Training and testing were performed on the MICCAI 2015 dataset published at Vanderbilt University, which contains 3D abdominal CT images in NIfTI format. The model's performance was evaluated using the Dice similarity coefficient. In the tests, the liver organ showed the highest Dice score. Considering the average Dice score of all organs, and comparing it with other models, it has been observed that the fusion approach model yields promising results.

Importance of gap evaluation in the ossification of posterior longitudinal ligament lesions using 3-dimensional computed tomography

BACKGROUND CONTEXTEvaluating the gaps within the ossification of the posterior longitudinal ligament (OPLL) lesions, which may contribute to neurological symptoms, using conventional imaging techniques is challenging. OBJECTIVEThis study aimed to investigate the importance of evaluating gaps using 3-dimensional computed tomography (3D-CT) and their association with the occurrence of magnetic resonance imaging (MRI) T2 high intensity in the spinal cord. STUDY DESIGN/SETTINGRetrospective cohort study. PATIENT SAMPLERetrospective analysis of 116 patients diagnosed with cervical OPLL. OUTCOME MEASURESPresence of gaps in OPLL, presence of T2 high intensity in the cervical spinal cord, and OPLL thickness were evaluated. METHODSLateral X-ray, CT, and reconstructed 3D-CT images were reviewed to assess lesion characteristics and the presence of gaps. MRI was used to evaluate the change in spinal cord signal intensity. The relationship among gap presence, lesion morphology, and MRI T2 high intensity in the spinal cord was examined. RESULTSA significant difference in gap detection accuracy was observed between CT and 3D-CT (p=.0054). CT demonstrated false-positive results in the detection of gaps as compared with 3D-CT. The presence of gaps was significantly associated with an increased likelihood of MRI T2 high intensity in the spinal cord (p=.037). Patients with thicker lesions and smaller space available for the spinal cord (SAC) were more likely to exhibit T2 high intensity. Meanwhile, patients with gaps co-occurring with T2 high intensity exhibited significantly thinner lesions (p=.011) and larger SACs (p=.0002). Patients with gaps had a significantly lower JOA scores (p=.0035), which indicates that patient with gaps are likely to exhibit more severe clinical neurological symptoms. CONCLUSION3D-CT showed superiority in accurately identifying gaps within OPLL lesions, while CT demonstrated false-positive results in the detection of gaps. Furthermore, the gap presence was a risk factor for MRI T2 high intensity in the spinal cord, independent of lesion thickness. In addition, gaps are related to more severe clinical symptoms. This study highlighted the importance of evaluating gaps within OPLL lesions using 3D-CT to clarify neurological pathogenesis.

Sparse-view neutron CT 3D image reconstruction algorithm based on split Bregman method

Sparse-view neutron CT 3D image reconstruction algorithm based on split Bregman method

861: Personalized contrast-enhanced 4D-CT imaging for target definition in pancreatic and liver SBRT

861: Personalized contrast-enhanced 4D-CT imaging for target definition in pancreatic and liver SBRT

Very fast, high-resolution aggregation 3D detection CAM to quickly and accurately find facial fracture areas

Background and objective:The incidence of facial fractures is on the rise globally, yet limited studies are addressing the diverse forms of facial fractures present in 3D images. In particular, due to the nature of the facial fracture, the direction in which the bone fractures vary, and there is no clear outline, it is difficult to determine the exact location of the fracture in 2D images. Thus, 3D image analysis is required to find the exact fracture area, but it needs heavy computational complexity and expensive pixel-wise labeling for supervised learning. In this study, we tackle the problem of reducing the computational burden and increasing the accuracy of fracture localization by using a weakly-supervised object localization without pixel-wise labeling in a 3D image space. Methods:We propose a Very Fast, High-Resolution Aggregation 3D Detection CAM (VFHA-CAM) model, which can detect various facial fractures. To better detect tiny fractures, our model uses high-resolution feature maps and employs Ablation CAM to find an exact fracture location without pixel-wise labeling, where we use a rough fracture image detected with 3D box-wise labeling. To this end, we extract important features and use only essential features to reduce the computational complexity in 3D image space. Results:Experimental findings demonstrate that VFHA-CAM surpasses state-of-the-art 2D detection methods by up to 20% in sensitivity/person and specificity/person, achieving sensitivity/person and specificity/person scores of 87% and 85%, respectively. In addition, Our VFHA-CAM reduces location analysis time to 76 s without performance degradation compared to a simple Ablation CAM method that takes more than 20 min. Conclusion:This study introduces a novel weakly-supervised object localization approach for bone fracture detection in 3D facial images. The proposed method employs a 3D detection model, which helps detect various forms of facial bone fractures accurately. The CAM algorithm adopted for fracture area segmentation within a 3D fracture detection box is key in quickly informing medical staff of the exact location of a facial bone fracture in a weakly-supervised object localization. In addition, we provide 3D visualization so that even non-experts unfamiliar with 3D CT images can identify the fracture status and location.

Brain tumor detection in combined 3D MRI and CT images using Dictionary learning based Segmentation and Spearman Regression

Brain tumor detection in combined 3D MRI and CT images using Dictionary learning based Segmentation and Spearman Regression

PRSCS-Net: Progressive 3D/2D rigid Registration network with the guidance of Single-view Cycle Synthesis

The 3D/2D registration for 3D pre-operative images (computed tomography, CT) and 2D intra-operative images (X-ray) plays an important role in image-guided spine surgeries. Conventional iterative-based approaches suffer from time-consuming processes. Existing learning-based approaches require high computational costs and face poor performance on large misalignment because of projection-induced losses or ill-posed reconstruction. In this paper, we propose a Progressive 3D/2D rigid Registration network with the guidance of Single-view Cycle Synthesis, named PRSCS-Net. Specifically, we first introduce the differentiable backward/forward projection operator into the single-view cycle synthesis network, which reconstructs corresponding 3D geometry features from two 2D intra-operative view images (one from the input, and the other from the synthesis). In this way, the problem of limited views during reconstruction can be solved. Subsequently, we employ a self-reconstruction path to extract latent representation from pre-operative 3D CT images. The following pose estimation process will be performed in the 3D geometry feature space, which can solve the dimensional gap, greatly reduce the computational complexity, and ensure that the features extracted from pre-operative and intra-operative images are as relevant as possible to pose estimation. Furthermore, to enhance the ability of our model for handling large misalignment, we develop a progressive registration path, including two sub-registration networks, aiming to estimate the pose parameters via two-step warping volume features. Finally, our proposed method has been evaluated on a public dataset CTSpine1k and an in-house dataset C-ArmLSpine for 3D/2D registration. Results demonstrate that PRSCS-Net achieves state-of-the-art registration performance in terms of registration accuracy, robustness, and generalizability compared with existing methods. Thus, PRSCS-Net has potential for clinical spinal disease surgical planning and surgical navigation systems.

A position-enhanced sequential feature encoding model for lung infections and lymphoma classification on CT images.

Differentiating pulmonary lymphoma from lung infections using CT images is challenging. Existing deep neural network-based lung CT classification models rely on 2D slices, lacking comprehensive information and requiring manual selection. 3D models that involve chunking compromise image information and struggle with parameter reduction, limiting performance. These limitations must be addressed to improve accuracy and practicality. We propose a transformer sequential feature encoding structure to integrate multi-level information from complete CT images, inspired by the clinical practice of using a sequence of cross-sectional slices for diagnosis. We incorporate position encoding and cross-level long-range information fusion modules into the feature extraction CNN network for cross-sectional slices, ensuring high-precision feature extraction. We conducted comprehensive experiments on a dataset of 124 patients, with respective sizes of 64, 20 and 40 for training, validation and testing. The results of ablation experiments and comparative experiments demonstrated the effectiveness of our approach. Our method outperforms existing state-of-the-art methods in the 3D CT image classification problem of distinguishing between lung infections and pulmonary lymphoma, achieving an accuracy of 0.875, AUC of 0.953 and F1 score of 0.889. The experiments verified that our proposed position-enhanced transformer-based sequential feature encoding model is capable of effectively performing high-precision feature extraction and contextual feature fusion in the lungs. It enhances the ability of a standalone CNN network or transformer to extract features, thereby improving the classification performance. The source code is accessible at https://github.com/imchuyu/PTSFE .

Effect of the Sauvé–Kapandji method on the wrist contact surface for distal radial ulnar joint disorders

BackgroundThe Sauvé–Kapandji (S-K) method is a surgical procedure performed for chronic deformities of the distal radial ulnar joint (DRUJ). Changes to the joint contact surface from pre- to postoperatively under physiological in vivo conditions have not yet been determined for this useful treatment. The aim of the present study was therefore to compare the articular contact area of the wrist joint between before and after the S-K method for DRUJ disorders.MethodsThe SK method was performed for 15 patients with DRUJ osteoarthritis and ulnar impaction syndrome. We calculated the Mayo Wrist Score as the patient’s clinical findings and created 3-dimensional bone models of cases in which the S-K method was performed and calculated the contact area and shift in the center of the contact area using customized software.ResultsThe Mean modified Mayo Wrist Score improved significantly from 60.3 preoperatively to 80.3 postoperatively (P < 0.01). Scaphoid contact area to the radius increased significantly from 112.6 ± 37.0 mm2 preoperatively to 127.5 ± 27.8 mm2 postoperatively (P = 0.03). Lunate contact area to radius-ulna was 121.3 ± 43.3 mm2 preoperatively and 112.5 ± 37.6 mm2 postoperatively, but this decrease was not significant (P = 0.38). Contact area ratio of scaphoid to lunate increased significantly from 1.01 ± 0.4 preoperatively to 1.20 ± 0.3 postoperatively (P = 0.02). Postoperative translations of the center of the scaphoid and lunate contact areas were decomposed into ulnar and proximal directions. Ulnar and proximal translation distances of the scaphoid contact area were 0.8 ± 1.7 mm and 0.4 ± 0.6 mm, respectively, and those of the lunate contact area were 1.1 ± 1.7 mm and 0.4 ± 1.1 mm, respectively. This study revealed changes in wrist contact area and center of the contact area before and after the S-K method.ConclusionThese results may accurately indicate changes in wrist joint contact area from pre- to postoperatively using the S-K method for patients with DRUJ disorder. Evaluation of changes in contact area due to bone surface modeling of the wrist joint using 3DCT images may be useful in considering surgical methods.

The contribution of E3D imaging integrated with robotic navigation: analysis of the first 80 consecutive posterior spinal fusion cases

Eighty consecutive complex spinal robotic cases utilizing intraoperative 3D CT imaging (E3D, Group 2) were compared to 80 age-matched controls using the Excelsius robot alone with C-arm Fluoroscopic registration (Robot Only, Group 1). The demographics between the two groups were similar—severity of deformity, ASA Score for general anesthesia, patient age, gender, number of spinal levels instrumented, number of patients with prior spinal surgery, and amount of neurologic compression. The intraoperative CT scanning added several objective factors improving patient safety. There were significantly fewer complications in the E3D group with only 3 of 80 (4%) patients requiring a return to the operating room compared to 11 of 80 (14%) patients in the Robot Only Group requiring repeat surgery for implant related problems (Chi squared analysis = 5.00, p = 0.025). There was a significant reduction the amount of fluoroscopy time in the E3D Group (36 s, range 4–102 s) compared to Robot only group (51 s, range 15–160 s) (p = 0.0001). There was also shorter mean operative time in the E3D group (257 ± 59.5 min) compared to the robot only group (306 ± 73.8 min) due to much faster registration time (45 s). A longer registration time was required in the Robot only group to register each vertebral level with AP and Lateral fluoroscopy shots. The estimated blood loss was also significantly lower in Group 2 (mean 345 ± 225 ml) vs Group 1 (474 ± 397 ml) (p = 0.012). The mean hospital length of stay was also significantly shorter for Group 2 (3.77 ± 1.86 days) compared to Group 1 (5.16 ± 3.40) (p = 0.022). There was no significant difference in the number of interbody implants nor corrective osteotomies in both groups—Robot only 52 cases vs. 42 cases in E3D group.Level of evidence: IV, Retrospective review.

Quantitative 3D-CT imaging of sarcopenia mitigation in the elderly: evidence from a case report.

This case study examines the effectiveness of using combined CT imaging and 3D imaging in monitoring the prevention of sarcopenia through continuous daily exercises in an elderly patient. Using a 256-slice CT scanner with dose reduction technology and advanced muscle segmentation with the open-source software DAFNE, we compared changes in muscle mass and density in a 70-year-old patient in 2014 and in 2023. The obtained images allowed the creation of detailed 3D models for a more accurate and intuitive assessment of the leg musculature. Despite aging, the results of the scans performed at the beginning and end of the study period did not show significant changes in the patient's musculature, suggesting that a persistent Full-Body in-Bed Gym protocol ("Gym Bed" exercise routine) can effectively contribute to maintaining muscle mass and density in the elderly. These preliminary results highlight the potential of advanced imaging techniques not only to diagnose but also to quantify the effectiveness of non-pharmacological interventions against sarcopenia.

Optimizing Choice of Skin Surrogates for Surface-Guided Stereotactic Body Radiotherapy of Lung Lesions Using Four-Dimensional Computed Tomography.

Image-guided radiotherapy supported by surface guidance can help to track lower lung lesions' respiratory motion while reducing a patient's exposure to ionizing radiation. However, it is not always clear how the skin's respiratory motion magnitude and its correlation with the lung lesion's respiratory motion vary between different skin regions of interest (ROI). Four-dimensional computed tomography (4DCT) images provide information on both the skin and lung respiratory motion and are routinely acquired for the purpose of treatment planning in our institution. An analysis of 4DCT images for 57 patients treated in our institution has been conducted to provide information on the respiratory motion magnitudes of nine skin ROIs of the torso, a tracking structure (TS) representing a lower lung lobe lesion, as well as the respiratory motion correlations between the nine ROIs and the TS. The effects of gender and the adipose tissue volume and distribution on these correlations and magnitudes have been analyzed. Significant differences between the ROIs in both the respiratory motion magnitudes and their correlations with the TS have been detected. An overall negative correlation between the ROI respiratory magnitudes and the adipose tissue has been detected for ROIs with rib cage support. A weak to moderate negative correlation between the adipose tissue volume and ROI-to-TS respiratory correlations has been detected for upper thorax ROIs. The respiratory magnitudes in regions without rib support tend to be larger for men than for women, but no differences in the ROI-to-TS correlation between sexes have been detected. The described findings should be considered when choosing skin surrogates for lower lung lesion motion management.

Evaluation of ventral branches of segment VI portal vein relative to the right hepatic vein in laparoscopic right anterior sectionectomy.

The right intersectional plane and the right hepatic hilum were noted too often exhibit anatomical variations, making difficult the laparoscopic right anterior sectionectomy (LRAS). We analyzed the anatomical features employing 3D-CT images of 55 patients, and evaluated these features according to the course of ventral branches of segment VI of the portal vein (PV, P6a) relative to the right hepatic vein (RHV). P6a run on the dorsal side of RHV in 32 patients (58%, Dorsal-P6a) and the ventral side of RHV in 23 (42%, Ventral-P6a). Ventral-P6a had more patients with S6 partially drained by middle hepatic vein (MHV, 39% vs. 0%, P < 0001), the narrower angle between the anterior and posterior branches of PV (73.1° vs. 93.8°, P = 0.006), the wider angle between the RHV and inferior vena cava (54.3° vs. 44.3°, P < 0.001), and more steeply pitched angle between S6 and S7 along the RHV (140.6° vs. 162.0°, P < 0.001) compared to Dorsal-P6a. In LRAS for Dorsal-P6a patients, the transection surface was relatively flat. In LRAS for Ventral-P6a patients, the narrow space between anterior and posterior glissons makes difficult the glissonean approach. The transection plane was steeply pitched, and RHV was partially exposed. S6 was often partially drained to MHV in 39% of the Ventral-P6a patients, which triggers congestion during liver transection of a right intersectional plane after first splitting the confluence of this branch.

3D CT based age estimation from the pubic symphyseal surface in an Indian population using the Chen et al. method.

The pubic symphyseal surface is one of the reliable parameters used to estimate age, as it consistently shows degenerative observational variations throughout the lifespan, particularly from the 3rd decade onwards. These changes have been extensively studied to generate population-specific models for forensic age estimation. In the past, there have been many studies used to estimate age at death from the pubis symphysis using skeletal remains. However, due to dearth of contemporary skeletal repositories, and the resource intensive maceration process required for obtaining examination quality bones, studies on cadaver are difficult to conduct. Moreover, due to recent advancements in the science of medical imaging, newer radiological modalities like computed tomography (CT) can be used to visualize previously inaccessible areas such as the pubic symphysis in cadavers and the living alike, and subsequent age estimation is feasible. Recently, Chen et al. (2008, 2011) conducted a study on the cadaveric Chinese Han population in both males and females separately by using nine morphological changes and scoring them according to the changes that occurred. The present study aimed to estimate an individual's age using CT images of the pubic symphysis, by applying the scoring method for its morphological changes given by Chen et al. The present study was conducted on 263 randomly selected participants (Males = 154, Females = 109), who came for diagnostic purposes to the hospital. The CT images of these individuals were collected after obtaining ethical approval and proper consent from the study participants. Each of the morphological indicators was assessed, and appropriate scores were given according to criteria given by Chen et al. In the present study, both linear and multiple regression models to estimate age using the pubic symphyseal morphological changes were developed. From the results of the present study, it was concluded that the Chen et al. scoring method can be used to accurately estimate age from 3DCT images of the living, and the models derived in the present study could be applicable to individuals from the Indian subcontinent.

HCA-DAN: hierarchical class-aware domain adaptive network for gastric tumor segmentation in 3D CT images

BackgroundAccurate segmentation of gastric tumors from CT scans provides useful image information for guiding the diagnosis and treatment of gastric cancer. However, automated gastric tumor segmentation from 3D CT images faces several challenges. The large variation of anisotropic spatial resolution limits the ability of 3D convolutional neural networks (CNNs) to learn features from different views. The background texture of gastric tumor is complex, and its size, shape and intensity distribution are highly variable, which makes it more difficult for deep learning methods to capture the boundary. In particular, while multi-center datasets increase sample size and representation ability, they suffer from inter-center heterogeneity.MethodsIn this study, we propose a new cross-center 3D tumor segmentation method named Hierarchical Class-Aware Domain Adaptive Network (HCA-DAN), which includes a new 3D neural network that efficiently bridges an Anisotropic neural network and a Transformer (AsTr) for extracting multi-scale context features from the CT images with anisotropic resolution, and a hierarchical class-aware domain alignment (HCADA) module for adaptively aligning multi-scale context features across two domains by integrating a class attention map with class-specific information. We evaluate the proposed method on an in-house CT image dataset collected from four medical centers and validate its segmentation performance in both in-center and cross-center test scenarios.ResultsOur baseline segmentation network (i.e., AsTr) achieves best results compared to other 3D segmentation models, with a mean dice similarity coefficient (DSC) of 59.26%, 55.97%, 48.83% and 67.28% in four in-center test tasks, and with a DSC of 56.42%, 55.94%, 46.54% and 60.62% in four cross-center test tasks. In addition, the proposed cross-center segmentation network (i.e., HCA-DAN) obtains excellent results compared to other unsupervised domain adaptation methods, with a DSC of 58.36%, 56.72%, 49.25%, and 62.20% in four cross-center test tasks.ConclusionsComprehensive experimental results demonstrate that the proposed method outperforms compared methods on this multi-center database and is promising for routine clinical workflows.

Modified double-pulley fixation provides better reduction of bone fragments and union compared to single-point fixation in bony Bankart lesions.

The purpose of this study was to compare clinical scores and imaging outcomes of bony Bankart lesions that underwent single-point and modified double-pulley fixation after at least 2 years of follow-up. Patients who underwent surgery to treat bony Bankart injuries were included and divided into groups A and B. A total of 69 patients were included (32 in group A and 37 in group B). Patients in group A underwent arthroscopic modified double-pulley fixation and patients in group B underwent arthroscopic single-point fixation. Three-dimensional computed tomography (3D-CT) was used to assess glenoid reduction one day after surgery. Postoperative bony union was assessed using 3D-CT and multiplanar reconstruction images 6 months after surgery. Constant-Murley, Rowe rating system, visual analogue scale and University of California at Los Angeles and American Shoulder and Elbow Surgeons scores were recorded before and after surgery. In terms of imaging measurements, there was no significant group difference in the preoperative size of the glenoid defect, the size of the bony fragment or the expected postoperative size of the glenoid defect. The sizes of the actual postoperative glenoid defects differed significantly between the groups (p = 0.027), as did the absolute difference between the expected and actual glenoid defect sizes (p < 0.001). At 6 months postoperatively, 50.0% of group A patients and 24.3% of group B patients exhibited complete bony union (p = 0.027); the rates of partial union were 37.5% and 56.8%, respectively. At the final follow-up, all clinical scores were significantly better than the preoperative scores (all p < 0.05), with no significant group differences (not significant). The use of the modified double-pulley technique with two anchors to treat bony Bankart injuries provides a better reduction of bone fragments than single-point fixation with two anchors and was associated with a higher rate of early bone union. Level III.

ANATOMY OF THE INSERTION OF THE POSTERIOR INFERIOR TIBIOFIBULAR LIGAMENT AND ITS RELEVANCE TO POSTERIOR MALLEOLAR ROTATIONAL PILON FRACTURES

IntroductionThe treatment of posterior malleolar fractures is developing. Mason and Molloy (Foot Ankle Int. 2017 Nov;38(11):1229-1235) identified only 49% of posterior malleolar rotational pilon type fractures had syndesmotic instabilities. This was against general thinking that fixation of such a fragment would stabilize the syndesmosis.MethodsWe examined 10 cadaveric lower limbs that had been preserved for dissection at the Human Anatomy and Resource Centre at Liverpool University in a solution of formaldehyde. The lower limbs were carefully dissected to identify the ligamentous structures on the posterior aspect of the ankle. To compare the size to the rotational pilon posterior malleolar fracture (Mason and Molloy 2A and B) we gathered information from our posterior malleolar fracture database. 3D CT imaging was analysed using our department PACS system.ResultsThe PITFL insertion on the posterior aspect of the tibia is very large. The average size of insertion was 54.9×47.1mm across the posterior aspect of the tibia. Medially the PITFL blends into the sheath of tibialis posterior and laterally into the peroneal tendon sheath.78 posterior lateral and 35 posterior medial fragments were measured. On average, the lateral to medial size of the posteromalleolar fragment was 24.5mm in the posterolateral fragment, and 43mm if there is a posteromedial fragment present also. The average distal to proximal size of the posterolateral fragment was 24.5mm and 18.5mm for the posteromedial fragment.ConclusionThe PITFL insertion on the tibia is broad. In comparison to the average size of the posterior malleolar fragments, the PITFL insertion is significantly bigger. Therefore, for a posterior malleolar fracture to cause posterior syndesmotic instability, a ligamentous injury will also have to occur. This explains the finding by Mason and Molloy that only 49% of type 2 injuries had a syndesmotic injury on testing.

Quantitative Analysis and 3D Visualization of Crack Behavior in 3D-Printed Rock-Like Specimens with Single Flaw Using In-Situ Micro-CT Imaging

3D printing technology allows for precise control of preparing complex geometries and internal defects in printed rock analogs, while in-situ Micro-CT imaging enables real-time observation of crack behavior. The combination of these technologies offers a new research approach for studying rock crack behavior. In this study, 3D-printed rock-like specimens containing a pre-existing flaw were prepared using a gypsum powder-based 3D printer. An advanced in-situ Micro-CT system equipped with a loading device was used to quantitatively and visually investigate the crack behavior in 3D-printed specimens under uniaxial compression testing. 2D CT images obtained from in-situ compression testing at different deformations could be used to reconstruct a 3D model and visually identify the crack patterns of the extracted cracks in 3D-printed specimens. The initiation angle of cracks, volume of the pre-existing flaw, volume of newly formed cracks, and damage value with respect to strains were analyzed to quantitatively investigate crack behavior. The results indicated that within the 3D-printed specimens, tensile cracks were first initiated near the internal flaw, followed by the occurrence of shear cracks or tensile-shear mixed cracks at the flaw tips. Additionally, there was a negative linear correlation between the initiation angle of newly formed cracks and the initial flaw angle. For flaw angles in the range of 0° ≤ α ≤ 45°, a higher number of newly formed cracks were observed in the 3D-printed specimens, and the rates of increase in crack volume and damage values with strain were faster. However, for flaw angles in the range of 45° < α ≤ 90°, the results showed the opposite trend. Furthermore, through comparison with the crack behavior of natural rocks containing a single flaw, it was found that the failure modes and crack behavior of the 3D-printed specimens exhibit certain similarities with natural rocks.