Medical Engineering & Physics最新文献

{"title":"Biomechanical evaluation of a poly(vinyl alcohol) hydrogel testicular prosthesis for tissue-mimicking soft-tissue replacement.","authors":"Ruby Dhaliwal, Jaymes Schmidt, Ryan Flannigan, Hadi Mohammadi","doi":"10.1088/1873-4030/ae9bc3","DOIUrl":"10.1088/1873-4030/ae9bc3","url":null,"abstract":"<p><p>Current testicular prostheses are predominantly manufactured from silicone elastomers and often fail to reproduce the biomechanical and viscoelastic characteristics of native testicular tissue. This study aimed to develop and mechanically characterize a poly(vinyl alcohol) (PVA) hydrogel-based testicular prosthesis with tissue-mimicking properties. PVA hydrogels with concentrations of 5%, 10%, and 15% (w/v) were fabricated using a freeze-thaw crosslinking process and evaluated through comprehensive mechanical testing, including uniaxial compression, tensile testing, stress relaxation, creep, dynamic mechanical analysis, and cyclic compression fatigue testing. A prototype hydrogel testicular prosthesis was subsequently fabricated and its mechanical performance compared with native testicular tissue and a commercially available silicone implant. Mechanical behavior was strongly dependent on polymer concentration. Increasing PVA concentration resulted in significant increases in compressive modulus, tensile strength, toughness, storage modulus, and fatigue resistance. The 10% PVA hydrogel demonstrated the closest overall agreement with native tissue, exhibiting a compressive modulus of 78 ± 10 kPa compared with 64 ± 12 kPa for native tissue, while maintaining comparable tensile strength, recovery ratio, and energy dissipation characteristics. Viscoelastic characterization revealed tissue-like stress relaxation and creep responses, whereas cyclic compression testing demonstrated stable mechanical performance over 1000 loading cycles. In contrast, the silicone implant exhibited lower compliance, reduced energy dissipation capacity, and inferior overall biomechanical similarity to native tissue. These findings demonstrate that freeze-thaw PVA hydrogels provide a promising platform for biomimetic testicular prostheses. By tailoring polymer concentration, hydrogel implants can achieve mechanical and viscoelastic properties that more closely replicate native tissue than conventional silicone devices. The proposed hydrogel-based approach may improve implant realism and patient outcomes, providing a foundation for future long-term durability studies and<i>in vivo</i>evaluation.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148800827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Portable RGB-D stabilometry for unsupervised postural assessment in Antarctic field conditions.","authors":"Petr Volf, Marek Sokol, Lýdie Leová, Jan Hejda, Patrik Kutílek","doi":"10.1088/1873-4030/aea621","DOIUrl":"10.1088/1873-4030/aea621","url":null,"abstract":"<p><p>Portable quantification of postural sway remains challenging in remote and resource-limited environments where laboratory force platforms and motion-capture systems are impractical. We evaluated an autonomous RGB-D stabilometry workflow during an Antarctic expedition by comparing camera-derived center-of-mass (CoM) sway with a portable center-of-pressure (CoP) reference and testing leave-one-subject-out calibration. Thirteen participants performed modified Romberg trials while an Intel RealSense D455 camera and a Wii Balance Board (WBB) recorded postural data. Full-body CoM trajectories were reconstructed from three-dimensional landmarks; facial-landmark head tracking was evaluated as a secondary fallback modality. In total, 192 quality-controlled WBB-camera pairs were analyzed. Temporal-alignment diagnostics showed strong anteroposterior signal overlap with the CoP reference (median post-lag Pearson= 0.847-0.929 for full-body tracking;= 0.825-0.905 for head tracking). Raw full-body metrics underestimated root-mean-square anteroposterior sway (bias =5.62 mm) and overestimated mean velocity (bias = 8.67 mm s). Passing-Bablok calibration reduced RMS AP bias relative to the WBB reference to 0.01 mm and narrowed the width of the limits of agreement from 12.15 to 7.15 mm. After empirical mapping, the inter-method reliability of Rambling RMS AP sway relative to the WBB reference was excellent (ICC(2,1) = 0.956), whereas mediolateral outcomes were less reliable and should be interpreted as exploratory in this camera configuration, likely reflecting lower ML amplitude and three-quarter camera geometry. Clock-based fixed windows yielded lower correlations, whereas a single global acquisition-latency correction applied identically to all trials, without per-trial window optimization, recovered correlations close to those of the optimized analysis. All estimates are relative to the portable WBB field reference rather than a laboratory-grade standard, and the calibration is a task- and setup-specific empirical mapping, not a universal biomechanical transformation.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148945259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fig-based phantom materials for benchtop evaluation of endovascular devices in chronic post-thrombotic venous obstruction.","authors":"Zhaokun Zhang, Minhaj S Khaja, Ben Houle, Andrea T Obi, Albert J Shih","doi":"10.1088/1873-4030/ae9ff9","DOIUrl":"10.1088/1873-4030/ae9ff9","url":null,"abstract":"<p><p>This study investigates a fig-based phantom material for benchtop evaluation of endovascular devices intended for treatment of chronic post-thrombotic venous obstruction, a common sequela of deep vein thrombosis. The proposed phantom is designed to reproduce selected functional mechanical characteristics relevant to device interaction with fibrotic, organized post-thrombotic lesions, is fabricated using controlled aging durations and temperatures to tune its mechanical properties. Phantom formulations were evaluated by combining clinician haptic feedback (device-mediated resistance and force transmission) assessment with uniaxial compression testing. Haptic feedback evaluation was performed by experienced interventional clinicians using a 1-10 similarity scale to assess correspondence with clinical recanalization procedures. Compression testing demonstrated formulation-dependent differences in mechanical behavior, while clinician evaluations indicated comparable levels of perceived procedural realism across the tested formulations. Exploratory correlation analyses revealed positive associations between compressive resistance and clinician similarity scores, although these relationships did not reach statistical significance. The fig-based phantoms exhibited a reproducible nonlinear compression response with strain-dependent stiffening, resembling the mechanical behavior of organized post-thrombotic tissue. Together, these results support the feasibility of using fig-based materials as controlled and reproducible surrogate lesions for functional benchtop testing. Such a platform could complement higher-fidelity biological models by enabling accessible and standardized early-stage evaluation of endovascular devices for chronic venous recanalization.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148851581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility and accuracy of low-angle, non-orthogonal biplane fluoroscopic 2D-3D registration for dynamic analysis of the thumb carpometacarpal joint.","authors":"Ryoya Shiode, Satoshi Miyamura, Tasuku Miyake, Hiroki Kondo, Toru Iwahashi, Hiroyuki Tanaka, Yoshito Otake, Yoshinobu Sato, Tsuyoshi Murase, Seiji Okada, Kunihiro Oka","doi":"10.1088/1873-4030/aea4b6","DOIUrl":"10.1088/1873-4030/aea4b6","url":null,"abstract":"<p><p><i>Background.</i>Accurate three-dimensional dynamic assessment of the thumb carpometacarpal (CMC) joint is important for understanding the pathomechanics of CMC osteoarthritis and evaluating treatment outcomes. Intensity-based biplane 2D-3D registration is a promising approach for dynamic bone motion analysis; however, conventional orthogonal biplane configurations are often difficult to implement for small-joint imaging in clinical settings.<i>Methods.</i>We validated the accuracy of intensity-based biplane 2D-3D registration for thumb CMC joint kinematic analysis using a phantom model under a low-angle, non-orthogonal biplane fluoroscopic configuration (53°). Registration-derived bone poses were compared with radiostereometric analysis-derived ground truth across 252 biplane fluoroscopic image pairs during palmar and radial abduction tasks. Translational and rotational errors were calculated for the thumb proximal phalanx, first metacarpal, trapezium, and second metacarpal.<i>Results.</i>The method achieved submillimeter mean overall component-wise translational errors for all evaluated bones (range: 0.11-0.31 mm). Mean overall component-wise rotational errors were below 3° for all bones (range: 0.44-2.64°). Larger axis-specific rotational root mean square errors were observed for the trapezium and thumb proximal phalanx, reflecting bone- and axis-dependent error patterns.<i>Conclusion.</i>Intensity-based biplane 2D-3D registration can provide sufficient accuracy for dynamic analysis of the thumb CMC joint using a low-angle, non-orthogonal biplane configuration. This approach may serve as a clinically feasible platform for assessing small-joint kinematics in settings where conventional orthogonal biplane systems are difficult to implement, supporting future<i>in vivo</i>studies of dynamic thumb CMC joint motion.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148921720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress or arousal? Exercise confounding in wearable stress detection.","authors":"Yiğit Aydoğan, Federico Villagra Povina","doi":"10.1088/1873-4030/aea41e","DOIUrl":"10.1088/1873-4030/aea41e","url":null,"abstract":"<p><p>Wearable stress-detection models are commonly validated by separating rest from stress, but this does not establish that their outputs are specific to stress rather than broader physiological activation. We re-analysed two public wearable datasets and made a matched within-dataset stress-specificity experiment the primary test. PhysioNet event tags were used to reconstruct protocol-defined rest and stress-induction blocks; 29 participants with matched aerobic and anaerobic recordings contributed 522 rest, 192 stress, and 3431 exercise-session windows. Four feature-based classifiers were trained to distinguish rest from stress under nested leave-one-participant-out evaluation. Preprocessing, hyperparameter selection, and probability-threshold calibration used training participants only, and exercise-session data were excluded from all model development. The best calibrated model, XGBoost, achieved balanced accuracy of 0.703, stress detection of 0.604, and rest specificity of 0.801, yet labelled 82.6% of held-out exercise-session windows as stress. At participant level, its exercise-session false-stress rate was 0.840 [0.775, 0.897], compared with a rest false-stress rate of 0.221 [0.151, 0.301], giving a paired difference of 0.619 [0.537, 0.699]. Protocol-defined stress blocks also had higher self-reported stress than rest blocks (mean difference 1.22 [0.89, 1.53] on the supplied 1-10 scale; 27/29 participants; one-sided Wilcoxon). Adding time-domain heart-rate-variability features did not materially change the result. A wearable stress and affect detection-to-PhysioNet transfer analysis remained poor but was treated as secondary evidence because it also contains dataset and protocol shift. These findings show that exercise-associated activation can produce substantial false-stress responses even when stress recognition and an exercise-session challenge are evaluated within the same dataset and the challenge data are excluded from model development.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148914011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finite element mechanical analysis of rigid internal fixation selection for distal femur fractures.","authors":"Meng Li, Zicheng Zhang, Ming Chen, Jiantao Li, Wei Zhang","doi":"10.1088/1873-4030/ae9c40","DOIUrl":"10.1088/1873-4030/ae9c40","url":null,"abstract":"<p><p><i>Background and Objective.</i>Compared with lateral locking plate (LLP) fixation, dual-plate (DP) fixation has not demonstrated superior clinical outcomes in the treatment of distal femur fractures. We propose that this discrepancy arises from unclear indications. This study examining the influence of varying metaphyseal defect sizes on the mechanical behavior of the two fixation constructs, provides insight into defining their appropriate clinical indications.<i>Methods.</i>Finite element analysis was conducted to compare the biomechanical performance of LLP-only versus DP fixation in AO/ASIF type C2 fractures with varying metaphyseal defect sizes (0, 5, 10, 15, 20, 25, and 30 mm). Fourteen models were established and subjected to axial (700 N) and torsional (14 Nm) loading. We extracted six parameters, including the axial stiffness, the maximum displacement of the femur, the torsional stiffness and the torsion micromotion of the fracture, and the peak VMS stress on both the medial and lateral plates under both axial and torsional loadings.<i>Results.</i>As the metaphyseal defect size increased (0-30 mm), all measured parameters under axial compression and torsional loading exhibited consistent trends. Overall, changes were more pronounced in the LLP-only group. Under axial loading, increasing defect size led to a 95.2% reduction in axial stiffness, a 58.2-fold increase in axial displacement, and 7.7 times rise in the maximum equivalent stress of the LLP-only fixation. In contrast, DP fixation showed only a 9.4% decrease in axial stiffness, a 5.4-fold increase in displacement, and a 2.7% increase in lateral plate stress. Under torsional loading, LLP-only models exhibited an 87.4% decrease in torsional stiffness, a 26.9% increase in torsional displacement, and a 6.9% rise in lateral plate stress. Corresponding changes for DP models were a 64.7% decrease in torsional stiffness, a 13.5% increase in displacement, and a 57.4% increase in stress.<i>Conclusions.</i>This study demonstrates that larger metaphyseal defects result in decreased fixation stiffness, increased fracture-site displacement, and elevated plate stress, including in the medial plate of DP constructs. These changes are consistently less pronounced with DP fixation compared to LLP-only constructs. Biomechanically, a transitional range exists between the two methods, with a mechanical suitability threshold near a metaphyseal defect size of 15 mm.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148800757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disentangling history and propagation dependencies in cross-subject knee contact stress prediction using a shared MeshGraphNet backbone.","authors":"Zhengye Pan, Jianwei Zuo, Jiajia Luo","doi":"10.1088/1873-4030/ae9b0d","DOIUrl":"10.1088/1873-4030/ae9b0d","url":null,"abstract":"<p><p><i>Background.</i>Subject-specific finite element analysis accurately characterizes knee joint mechanics but is computationally expensive. Deep surrogate models provide a near-real-time alternative, yet their generalization across subjects under limited pose and load inputs remains unclear. It remains unclear whether prediction uncertainty under limited pose/load inputs is more strongly associated with temporal history dependence or with spatial propagation dependence.<i>Methods.</i>To disentangle these factors, we employed a shared MeshGraphNet (MGN) backbone under a shared reference anatomy and mesh topology. A dataset of running trials from nine subjects was constructed using an OpenSim-FEBio workflow. We developed four model variants to isolate specific dependencies: (1) a baseline MGN; (2) CT-MGN, incorporating a control Transformer (CT) to encode short-horizon history; (3) MsgModMGN, applying state-conditioned modulation to message passing for adaptive propagation; and (4) CT-MsgModMGN, combining both mechanisms. Models were evaluated using a rigorous grouped 3-fold cross-validation on unseen subjects.<i>Results.</i>The models incorporating history encoding (CT-MGN and CT-MsgModMGN) significantly outperformed the baseline MGN and MsgModMGN in global accuracy (lower root-mean-square error) and spatial consistency (higher Dice). Crucially, the CT-based models mitigated the peak-shaving tendency commonly observed in deep surrogates and reduced peak-stress reconstruction error (<i>RE</i>_max). In contrast, the spatial propagation modulation message modulation (MsgMod) alone yielded no significant improvement over the baseline, and combining it with CT provided no additional benefit.<i>Conclusion.</i>Temporal-history-related limitations contributed more strongly to prediction uncertainty than spatial propagation modulation in the present setting. Explicitly encoding short-horizon driver sequences enables the surrogate model to capture useful temporal context related to phase/state transitions, thereby achieving superior fidelity in peak-stress capture and high-risk-region localization compared to purely state-based approaches.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148800771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolving base of support associated multicontact stability analysis reveals distinct sit-to-stand motor control pattern in stroke survivors.","authors":"Daoyuan Wang, Shuijing Zhang, Yang Tang, Yichong Wang, Wenbing Liu, Gangmin Ning","doi":"10.1088/1873-4030/ae9e2c","DOIUrl":"10.1088/1873-4030/ae9e2c","url":null,"abstract":"<p><p>Sit-to-stand (STS) transition is a prerequisite for independent mobility and a primary benchmark for post-stroke functional recovery. However, conventional event-based measures fail to continuously resolve weight transfer, and the classical Extrapolated center of mass (XcoM) and margin of stability (MoS) framework cannot represent evolving multicontact support, vertical acceleration dynamics, or whole-body angular momentum, thereby obscuring phase-specific motor control strategies. To address this problem, we proposed a continuous biomechanical framework for analyzing multicontact STS dynamics by integrating a time-evolving effective base of support (BoS) with a Vertical-Dynamics-Informed XcoM (VDI-XcoM) that incorporates vertical dynamics and an angular-momentum-related correction. Combining these formulations yields the Multicontact MoS (MMoS). The framework was evaluated in a method agreement study (MAS) and a clinical comparison study (CCS). The MAS showed agreement between the rapidly deployable Kinect-based method and the laboratory reference for VDI-XcoM and effective-BoS trajectories, while MMoS metrics exhibited high within-session repeatability in the CCS. Critically, whereas conventional discrete descriptors and the pre-seat-off minimum MoS failed to differentiate stroke survivors from healthy controls, MMoS successfully isolated a low-stability-margin phase before seat-off in stroke survivors, showing a shallower primary valley and smaller negative area than controls. Effective-BoS analysis demonstrated that the increase in plantar anteroposterior support in stroke survivors was insufficient to offset seat support reduction, while VDI-XcoM decomposition identified smaller velocity- and angular-momentum-related changes in the margin between the extrapolated body state and effective BoS before seat-off. Together, these findings characterize incomplete seat-to-foot transfer and reduced pre-seat-off forward-momentum generation and transfer after stroke. By unifying evolving support boundary with body-state dynamics, the framework provides phase-specific biomechanical information for objective post-stroke STS analysis and may support the motor control assessment in rehabilitation treatment.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148820180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finite element evaluation of the biomechanical feasibility of a multi-shield socket shield technique for a vertically fractured maxillary central incisor.","authors":"Haidong Teng, Yuanli Zhang, Bingmei Shao, Zhan Liu","doi":"10.1088/1873-4030/aea29a","DOIUrl":"10.1088/1873-4030/aea29a","url":null,"abstract":"<p><p>The socket shield technique (SST) preserves peri-implant tissues during immediate implant placement in teeth with intact roots, yet its biomechanical behavior in the presence of vertical root fractures (VRFs) remains unquantified. This study evaluated the mechanical feasibility of a modified multi-shield SST (MS-SST) designed for single-fracture-line scenarios in maxillary central incisors. Three-dimensional finite element models representing conventional immediate implantation (CII), classic SST (C-SST), and MS-SST were subjected to 45° oblique occlusal loading from 10 to 100 N in 10 N increments. Bone and tooth structures were modeled as heterogeneous isotropic materials based on computed tomography gray values, whereas the periodontal ligament (PDL) was simulated using a nonlinear first-order Ogden hyperelastic constitutive law. Biomechanical metrics included von Mises stresses on the implant and abutment, displacements of the shield and PDL, hydrostatic pressure in the PDL and peri-implant bone, and strain energy density (SED) of the peri-implant bone. Comparative response patterns remained consistent across all loading magnitudes. At the representative peak load of 100 N, CII produced the most unfavorable peri-implant bone response, with the highest hydrostatic pressure (compressive: 26.94 MPa; tensile: 37.67 MPa) and SED (0.0447 MPa). C-SST yielded the lowest peri-implant SED (0.0302 MPa) and implant-abutment stresses. MS-SST exhibited intermediate SED (0.0347 MPa) and stress magnitudes, while reducing adverse peri-implant bone mechanical indicators relative to CII. Although MS-SST generated higher tensile hydrostatic pressure within the PDL than C-SST (0.0304 vs 0.0166 MPa), shield displacement remained comparably low (0.0101 vs 0.0104 mm). Within the assumptions of this finite element model, MS-SST appears mechanically feasible as a compromise design for vertically fractured maxillary central incisors when preservation of an intact buccal shield is not possible. Buccal shield segmentation did not markedly compromise shield stability and reduced adverse peri-implant biomechanical environment relative to CII. Further experimental and clinical validation remains necessary.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148892081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Appearance-aware robustness probes for strict external breast ultrasound segmentation under multi-source joint training.","authors":"Lin Ma","doi":"10.1088/1873-4030/ae9ff7","DOIUrl":"10.1088/1873-4030/ae9ff7","url":null,"abstract":"<p><p>Breast ultrasound segmentation is sensitive to external-domain shift caused by scanner, acquisition, annotation and appearance variation. Shadowing, gain and contrast variation are particularly relevant given that ultrasound is not an optical imaging modality, yet many segmentation reports still rely mainly on randomly split or source-overlapping validation. We reformulated the study as a strict external validation analysis. Six model configurations-U-Net, CMU-Net, RTCMUNet, PMix, CGate and PMix+CGate-were evaluated under three source-composition protocols: all-source joint training, leave-BUS-UCLM-out training and leave-BUS-BRA-out training. BUS () and BUSI-WHU () were held out from training and validation under all protocols and used as fixed strict external out-of-distribution cohorts. The primary endpoint was image-level intersection over union (IoU), with paired image-level bootstrap (10 000 resamples) used to estimate 95% confidence intervals. A targeted source-inclusion sensitivity analysis additionally compared two training-pool compositions for RTCMUNet and PMix+CGate that differed only in whether a small set of previously excluded malignant-red lesion images from one source was added. PMix+CGate under all-source joint training achieved the highest average strict external out-of-distribution IoU across the two held-out cohorts (equal-domain mean 72.19). Against RTCMUNet trained without BUS-UCLM, the cross-protocol delta was +1.32 percentage points; the 95% CI [0.33, 2.98] crossed zero and did not support a cross-protocol advantage. In the source-inclusion sensitivity analysis, RTCMUNet and PMix+CGate responded in opposite directions to the same compositional change, producing a model-by-composition interaction in IoU (4.31 percentage points, 95% CI [6.66,2.15]) whose image-sampling interval excluded zero. PMix+CGate achieved the highest average strict external out-of-distribution IoU under all-source joint training, but its cross-protocol advantage over RTCMUNet was not supported by an interval that crossed zero. The source-inclusion analysis further indicates model- and cohort-dependent sensitivity to training-pool composition, rather than a universal benefit from adding data or a universally preferred configuration.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148851439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}