Search Results (1,144)

Background: Superior semicircular canal dehiscence (SSCD) is characterized by a bony defect of the superior semicircular canal (SSC), leading to vestibular and auditory symptoms. A process of spontaneous “auto-plugging,” in which the overlying dura mater progressively occludes the SSC, may replicate the effects of surgical canal plugging but remains under-recognized. The present study reports diverse clinical, instrumental, and 3d High Resolution MRI findings in patients with SSCD and subsequently confirmed to present with spontaneous complete or partial auto-plugging. Methods: We retrospectively reviewed 11 patients with SSCD diagnosed on high-resolution CT and suspected auto-plugging based on clinical atypia and large dehiscence (>4 mm). Patients underwent comprehensive neurotological assessment, including pure-tone audiometry, vestibular testing, and HR MRI with 3D labyrinthine reconstructions to identify partial or complete auto-plugging. Auto-plugging was classified as partial (Canalis semicircularis superior depressus) or complete (absence of endolymph fluid signal; Canalis semicircularis superior obturatus). Results: Among 13 ears with auto-plugging, 6 were partial and 7 complete. The mean SSCD size in auto-plugged ears was 5.5 mm. Most ears had normal or near-normal vestibular function on VHIT, with minimal air-bone gaps and preserved VEMP responses. Imaging demonstrated varying degrees of dural contact with the SSC, confirming partial or complete canal occlusion. Conclusions: Spontaneous auto-plugging of the SSC is a plausible, under-recognized phenomenon that may reproduce functional effects of surgical plugging. Dedicated 3D labyrinthine MRI enhances detection and characterization. Prospective multimodal studies are needed to clarify the pathophysiology, progression, and clinical implications, optimizing patient selection for surgical versus conservative management. Full article

Background/Objectives: This study evaluates photon-counting CT (PCCT) for the imaging of mouse femurs and investigates how APOE genotype, sex, and humanized nitric oxide synthase (HN) expression influence bone morphology during aging. Methods: A custom-built micro-CT system with a photon-counting detector (PCD) was used to acquire dual-energy scans of mouse femur samples. PCCT projections were corrected for tile gain differences, iteratively reconstructed with 20 µm isotropic resolution, and decomposed into calcium and water maps. PCD spatial resolution was benchmarked against an energy-integrating detector (EID) using line profiles through trabecular bone. The contrast-to-noise ratio quantified the effects of iterative reconstruction and material decomposition. Femur features such as mean cortical thickness, mean trabecular spacing (TbSp_mean), and trabecular bone volume fraction (BV/TV) were extracted from calcium maps using BoneJ. The statistical analysis used 57 aged mice representing the APOE22, APOE33, and APOE44 genotypes, including 27 expressing HN. We used generalized linear models (GLMs) to evaluate the main interaction effects of age, sex, genotype, and HN status on femur features and Mann–Whitney U tests for stratified analyses. Results: PCCT outperformed EID-CT in spatial resolution and enabled the effective separation of calcium and water. Female HN mice exhibited reduced BV/TV compared to both male HN and female non-HN mice. While genotype effects were modest, a genotype-by-sex stratified analysis found significant effects of HN status in female APOE22 and APOE44 mice only. Linear regression showed that age significantly decreased cortical thickness and increased TbSp_mean in male mice only. Conclusions: These results demonstrate PCCT’s utility for femur analysis and reveal strong effects of sex/HN interaction on trabecular bone health in mice. Full article

The accurate reconstruction of craniofacial defects requires the precise segmentation and mirroring of healthy anatomy. Conventional workflows rely on manual interaction, making them time-consuming and subject to operator variability. This study developed and validated a fully automated digital pipeline that integrates deep learning–based segmentation with algorithmic mirroring for craniofacial reconstruction. A total of 388 cranial CT scans were used to train a three-dimensional nnU-Net model for skull and mandible segmentation. A Principal Component Analysis–Iterative Closest Point (PCA–ICP) algorithm was then applied to compute the sagittal symmetry plane and perform mirroring. Automated results were compared with expert-generated segmentations and manually defined symmetry planes using Dice Similarity Coefficient (DSC), Mean Surface Distance (MSD), Hausdorff Distance (HD), and angular deviation. The nnU-Net achieved high segmentation accuracy for both the mandible (mean DSC 0.956) and the skull (mean DSC 0.965). Mirroring results showed minimal angular deviation from expert reference planes (mandible: 1.32° ± 0.71° in defect cases, 1.58° ± 1.12° in intact cases; skull: 1.75° ± 0.84° in defect cases, 1.15° ± 0.81° in intact cases). The presence of defects did not significantly affect accuracy. This automated workflow demonstrated robust performance and clinical applicability, offering standardized, reproducible, and time-efficient planning for craniofacial reconstruction. Full article

Developing bone substitutes that are mechanically strong, highly biocompatible and capable of controlled degradation is crucial for successful bone regeneration. Magnesium phosphate cements (MPCs) and calcium magnesium phosphate cements (CMPCs) offer higher strength and solubility than established calcium phosphate cements (CPCs). This study aimed to evaluate the in vivo degradation, osteoregeneration and biocompatibility of 3D powder-printed Mg3d (Mg₃(PO₄)₂) and Mg275d (Ca_0.25Mg_2.75(PO₄)₂) scaffolds with alkaline post-treatment, using structurally identical TCP (Ca₃(PO₄)₂) scaffolds as the control. The scaffolds were implanted into the lateral femoral condyle of adult female Zika rabbits and analysed up to 6, 12 and 24 weeks using radiography, microCT, histology, EDX and SEM. All materials demonstrated good biocompatibility. Mg3d and Mg275d scaffolds degraded significantly faster than the TCP scaffolds, with nearly complete degradation after 12 weeks. A cell-rich reconstruction zone formed during degradation, which was subsequently replaced by new bone. The degradation rate of the scaffolds corresponded closely to bone regeneration. Notably, the Mg3d and Mg275d scaffolds supported the faster formation of mature lamellar bone compared to the TCP scaffolds. These results indicate that magnesium phosphate (MgP)-based scaffolds represent a promising alternative to conventional calcium phosphate (CP)-based bone substitutes, given their rapid and almost complete degradation and their effective support of bone regeneration. Full article

Background/Objectives: This study explores the evolution and morphology of the human mandible, focusing on recent changes and adaptations over the last 2000 years. It aims to examine how functional, genetic, and environmental factors influence mandibular size, shape, and sexual dimorphism by analyzing key anatomical landmarks—the horizontal ramus (HR), ascending ramus (AR), and mandibular angle (MA). Methods: A retrospective approach was employed using computed tomography (CT) scans of 39 mandibular samples from various historical periods, ranging from the Roman Imperial Age to the present day. Imaging was conducted using a 64-slice multislice computed tomography (MSCT) scanner, and the resulting data were processed to generate detailed 3D reconstructions for morphological assessment. Results: The analysis reveals that present-day samples exhibit significantly less variation in AR and MA compared to archaeological specimens, suggesting a trend of gracilization over time. Statistically significant differences were found in MA, likely influenced by environmental, dietary, and cultural factors. Correlation analysis showed moderate to weak relationships between AR, HR, and MA across sample groups, with significant sexual dimorphism in AR within the archaeological sample. Principal Component Analysis (PCA) further supported these findings, demonstrating a clear distinction between gracile modern mandibles and more robust ancient ones. Conclusions: These findings provide insights into the evolutionary trajectory of the human mandible, underscoring the influence of dietary and cultural shifts on mandibular structure over the past two millennia. Full article

Posterior instrumentation is used to treat severe adolescent idiopathic scoliosis (AIS) with a Cobb angle greater than 40 degrees. Clinical studies indicate that AIS patients may develop adjacent segment degeneration (ASD) post-surgery. However, there is limited research on the biomechanical effects on adjacent segments after surgery, and straightforward methods for creating finite element (FE) models that reflect vertebral deformation are lacking. Therefore, this study aims to use biplanar X-ray images to establish a case-specific, parameterized FE model reflecting coronal plane vertebral deformation and employ FE analysis to compare pre- and postoperative changes in the range of motion (ROM), endplate stress, and intervertebral disk stress of adjacent segments. We developed an FE model from biplanar X-ray images of a patient with AIS, using ANSYS software to establish pre- and postoperative models. The shape of the preoperative model was validated using computed tomography (CT) reconstruction. A flexion moment was applied to C7 of the spine model to achieve the same forward bending angle in the pre- and postoperative models. This study successfully developed a case-specific parameterized FE model based on X-ray images. The differences between Cobb angle and thoracolumbar kyphosis angle measurements in X-ray images and CT reconstructions were 6.5 and 5.4 mm. This FE model was used to analyze biomechanical effects on motion segments adjacent to the fixation site, revealing a decrease in maximum endplate and disk stress in the cranial segment and an increase in stress in the caudal segment. Full article

The thorax, which serves as the primary center of locomotion for insects, consists of a highly intricate skeletomuscular system. The thoracic morphological transformations during the pupal stage reveal the developmental formation of locomotor systems. Asiophrida xanthospilota is not only capable of flight but is also an exceptional jumper. In this study, we employed micro-CT and 3D reconstruction to document the thoracic internal anatomy of this species on pupal days 1, 2, 4, 6, 8, 10, and 12, with the goal of achieving a more comprehensive understanding of their locomotion mechanisms. In A. xanthospilota, a membrane connecting the occiput and metaphragma is present from pupal days 2 to 8, serving as the attachment site for the notal muscles. Morphological changes in some endoskeletal structures during development result in corresponding shifts in the origins or insertions of associated muscles. On the first day, most muscles are present in the pro- and mesothorax, while the metathorax contains comparatively few, a pattern likely linked to the primary reliance on jumping locomotion of the species. Some muscles that appear only during the early and middle pupal stages might function in structural support. Muscular morphology undergoes diverse changes that are difficult to generalize. On day 4, the muscles show a comparatively small relative volume, which might reflect experimental error or other underlying factors. In addition, the gut and nerve remain largely unchanged. It should be noted that the stroma within the thoracic cavity might have hindered the precise identification of muscles. Full article

Background: Accurate reconstruction of the orbit after trauma or oncological resection requires reliable anatomical references. In unilateral cases, the contralateral orbit can guide repair, but bilateral injuries or pathologies remove this option. To address this problem, we developed a new morphological classification of orbits based on three linear dimensions. Methods: A total of 499 orbits from patients of Caucasian descent (age 8–88 years) were analyzed using three-dimensional models generated from cone-beam and fan-beam CT scans. Orbital depth (D), height (H), and width (W) were measured, and proportional indices were calculated. K-means clustering (k = 3) identified recurring morphotypes, validated by linear discriminant analysis (LDA) and supported by ANOVA, Kruskal–Wallis, and correlation tests (age and sex). Results: Three morphotypes were identified: Tall & Broad (type A, 33.5%), Deep & Broad (type B, 30.2%), and Compact (type C, 36.2%). All dimensions differed significantly between groups (ANOVA, p < 1 × 10⁻¹⁶; η² = 0.40–0.51). Male orbits were significantly deeper and wider than female ones (p < 0.001). LDA demonstrated excellent separation with 97.5% accuracy. A simplified decision algorithm achieved 82.1% classification accuracy. In situations where only orbital depth could be measured, an alternative cut-off-based method reached 61.5% accuracy, with type B and C better distinguished than type A. Conclusions: The proposed classification provides a reproducible framework for describing orbital morphology. It may serve as a reference in cases where local anatomy is disrupted or the contralateral orbit is unavailable. Even millimeter-scale differences in orbital dimensions may correspond to clinically relevant changes in orbital volume and globe position, underlining the potential usefulness of this system in surgical planning. Full article

Background: Multilocular mesothelial inclusion cysts—also known as benign multicystic mesothelioma (BMM)—are rare, typically arising in the peritoneal cavity. Pericardial involvement is extremely uncommon and can pose diagnostic and therapeutic challenges due to their recurrent and infiltrative nature. Accurate diagnosis and surgical strategy are critical for management and recurrence prevention. Methods: We present the case of a 36-year-old woman with a prior history of malignant melanoma who developed recurrent multilocular cystic masses of the pericardium. Initial imaging with echocardiography, cardiac magnetic resonance (CMR), and computed tomography (CT) revealed multilocular pericardial cysts. Surgical resection was performed under cardiopulmonary bypass (CPB), but complete excision was limited due to epicardial infiltration. Histopathology confirmed a benign mesothelial origin. One year later, recurrence prompted a second surgical intervention with total pericardiectomy and Gore-Tex patch reconstruction. Results: Postoperative recovery was uneventful in both instances. Follow-up imaging at 6 and 12 months demonstrated no significant recurrence. Histological analysis confirmed benign cysts lined with mesothelial cells, positive for calretinin and WT-1. This represents one of the first documented living cases of pericardial BMM managed with staged surgery and total pericardiectomy. Conclusions: Pericardial BMM is a rare, benign, but potentially recurrent lesion. In cases of extensive or recurrent disease, total pericardiectomy may offer definitive treatment. Multimodal imaging, histopathological evaluation, and personalized surgical planning are essential for effective management. Full article

Background: Cardiac-respiratory dual gating in SPECT (DG-SPECT) is an emergent technique for alleviating motion blurring artifacts in myocardial perfusion imaging (MPI) due to both cardiac and respiratory motions. Moreover, the attenuation artifact may arise from the spatial mismatch between the sequential SPECT and CT attenuation scans due to the dual gating of SPECT data and non-gating CT images. Objectives: This study adapts a four-dimensional (4D) cardiac SPECT reconstruction with post-reconstruction respiratory motion correction (4D-RMC) for dual-gated SPECT. In theory, a respiratory motion-matched attenuation correction (MAC) method is expected to yield more accurate reconstruction results than the conventional motion-averaged attenuation correction (AAC) method. However, its potential benefit is not clear in the presence of practical imaging artifacts in DG-SPECT. In this study, we aim to quantitatively investigate these two attenuation methods for SPECT MPI: 4D-RMC (MAC) and 4D-RMC (AAC). Methods: DG-SPECT imaging (eight cardiac gates and eight respiratory gates) of the NCAT phantom was simulated using SIMIND Monte Carlo simulation, with a lesion (20% reduction in uptake) introduced at four different locations of the left ventricular wall: anterior, lateral, septal, and inferior. For each respiratory gate, a joint cardiac motion-compensated 4D reconstruction was used. Then, the respiratory motion was estimated for post-reconstruction respiratory motion-compensated smoothing for all respiratory gates. The attenuation map averaged over eight respiratory gates was used for each respiratory gate in 4D-RMC (AAC) and the matched attenuation map was used for each respiratory gate in 4D-RMC (MAC). The relative root mean squared error (RMSE), structural similarity index measurement (SSIM), and a Channelized Hotelling Observer (CHO) study were employed to quantitatively evaluate different reconstruction and attenuation correction strategies. Results: Our results show that the 4D-RMC (MAC) method improves the average relative RMSE by as high as 5.42% and the average SSIM value by as high as 1.28% compared to the 4D-RMC (AAC) method. Compared to traditional 4D reconstruction without RMC (“4D (MAC)”), these metrics were improved by as high as 11.23% and 27.96%, respectively. The 4D-RMC methods outperformed 4D (without RMC) on the CHO study with the largest improvement for the anterior lesion. However, the image intensity profiles, the CHO assessment, and reconstruction images are very similar between 4D-RMC (MAC) and 4D-RMC (AAC). Conclusions: Our results indicate that the improvement of 4D-RMC (MAC) over 4D-RMC (AAC) is marginal in terms of lesion detectability and visual quality, which may be attributed to the simple NCAT phantom simulation, but otherwise suggest that AAC may be sufficient for clinical use. However, further evaluation of the MAC technique using more physiologically realistic digital phantoms that incorporate diverse patient anatomies and irregular respiratory motion is warranted to determine its potential clinical advantages for specific patient populations undergoing dual-gated SPECT myocardial perfusion imaging. Full article

Background/Objectives: Odontoid fractures—prevalently Anderson–D’Alonzo type II—are clinically relevant for their biomechanical instability and risk of non-union. Posterior C1–C2 fusion yields the highest fusion rates but sacrifices atlantoaxial rotation. Anterior odontoid screw fixation (AOSF) enables direct osteosynthesis while preserving motion. This study aimed to evaluate the radiographic outcomes, fusion rate, and technical considerations of AOSF in a consecutive single-center series, highlighting anatomical and procedural factors influencing bone healing. Methods: Retrospective, single-center case series of patients who underwent AOSF for acute type II odontoid fractures (2018–2024). Inclusion criteria included CT-confirmed fractures with reducible alignment. Radiographic parameters (fracture gap and angulation) were measured on standardized sagittal CT reconstructions. Outcomes were evaluated at 6 weeks, 3 months, and 6 months. Mean follow-up was 24 months. Results: The mean fracture gap decreased from 5.3 mm preoperatively to 0.8 mm postoperatively, and angulation from 27.8° to 3.5° (p < 0.0001). Nine of ten patients (90%) achieved solid fusion; one required secondary posterior fixation. No intra- or postoperative infections, neurovascular injuries, or neurological deficits were observed. Conclusions: AOSF is a safe and effective motion-preserving technique in appropriately selected Grauer IIA/IIB fractures. Precise anatomical reduction (<2 mm gap, <5–10° angulation) is a key predictor of successful fusion, even in elderly patients. Future multicenter studies with larger cohorts and standardized clinical outcome measures are needed to validate radiographic thresholds and optimize patient selection. Full article

Background: Hollow posts have been introduced in clinical practice, providing the possibility of injecting luting resin directly into the post. The aim of our study was to compare quartz fiber hollow posts with solid posts. Methods: In total, 20 human teeth with straight single root canals were utilized for this study, divided into two groups with 10 elements each, one restored with radiopaque quartz fiber hollow posts and the other with radiopaque quartz fiber solid posts. In total, two micro-CT (micro-computerized tomography) analyses allowed us to evaluate both the presence of air voids in the luting resin and the different capacities of posts to penetrate until full depth into the post space. Results: The authors observed that hollow quartz fiber posts create a smaller volume of air voids in the luting resin (p < 0.01) and better fit (p < 0.05) the post space compared to the solid posts. Conclusions: Hollow posts can promote retention. Future studies with larger samples are encouraged to confirm these findings and provide possible better long-term results for post-endodontic reconstructions in vivo. Full article

This study presents a finite element analysis (FEA)-based numerical homogenization method for evaluating the effective thermo-mechanical properties of a large-area additively manufactured particulate-filled composite using realistic periodic representative volume elements (RVEs) generated from reconstructed X-ray µ-CT image scans of a 3D-printed bead. The numerical results of the predicted effective properties, including the elastic stiffness, coefficient of thermal expansion (CTE) and thermal conductivity, were benchmarked with the Mori–Tanaka–Benveniste analytical estimates, which were found to be comparable. Initial sensitivity analysis using a single region of interest (ROI) extracted from the bead’s volume was performed to determine a suitable RVE size. The impact of inherent micro-porosities on the resulting composite material’s behavior was also quantified in the current investigation and was shown to reduce the composite’s effective properties. Using a suitable RVE size, the effect of anisotropy due to spatial variation in the microstructure across the bead specimen on the computed composite’s effective properties was also assessed. The results show that the regions closer to the exposed surface of the print bead with highly aligned and densely packed fiber particulates have superior properties as compared to inner regions with a more randomly oriented and less densely packed fibrous microstructure. Full article

Cyclic dynamic loading significantly influences the dynamic mechanical properties of cemented tailings backfill (CTB). This study investigates the dynamic mechanical properties and mesoscopic characteristics of CTB under cyclic dynamic loading. Using a Split Hopkinson Pressure Bar (SHPB) system, impact tests were conducted on CTB specimens subjected to varying numbers of cyclic impacts. The dynamic peak compressive strength (DPCS), elastic modulus, energy evolution, and failure modes were analyzed. Additionally, computed tomography (CT) scanning and 3D reconstruction techniques were employed to examine the internal pore and crack distribution. Results indicate that cyclic impacts lead to a gradual reduction in DPCS and energy absorption capacity, while the elastic modulus shows strain-rate dependency. Mesostructural analysis reveals that cyclic loading promotes the initiation and propagation of microcracks. This study establishes a correlation between mesoscopic damage evolution and macroscopic mechanical degradation, providing insights into the durability and stability of CTB under repeated blasting disturbances in mining environments. Full article

Background/Objectives: Optimization of pediatric head computed tomography (CT) protocols is essential to minimize radiation exposure while maintaining diagnostic image quality. Previous studies mainly relied on phantom-based measurements or visual assessments, and validation using clinical images remains limited. This study aimed to establish quantitative thresholds for noise and contrast-to-noise ratio (CNR) in pediatric head CT by integrating multicenter clinical data with phantom evaluations. Methods: A multicenter retrospective study was conducted using CT systems from eight hospitals, combined with Catphan phantom experiments and pediatric head CT data. Scan parameters, automatic exposure control settings, and reconstruction methods were collected. Image quality was quantified by the standard deviation (SD) of noise and CNR obtained from regions of interest in gray and white matter. Radiation dose was represented by CTDIvol. Relationships among CTDIvol, SD, and CNR were analyzed across scanners from three manufacturers (Canon, FUJI, and GE). Results: Consistent dose–response trends were observed across institutions and manufacturers. Image noise decreased as CTDIvol increased, but reached a plateau at higher doses. CNR improved with dose escalation, then stabilized. Both phantom experiments and clinical analyses identified a target SD of 5 and CNR of 2 as optimal indicators for pediatric head CT. Conclusions: Quantitative thresholds were determined as practical indicators for balancing diagnostic image quality with dose reduction. Further reduction may be achieved through advanced reconstruction methods, such as deep learning-based algorithms. These findings may contribute to standardizing pediatric head CT protocols and supporting safer and more effective diagnostic imaging. Full article