Alignment Of Segments Research Articles

Alignment Goals in Adult Spinal Deformity Surgery.

Study DesignNarrative review.ObjectivesAdult spinal deformity (ASD) surgery has progressively transitioned from mean regional alignment targets to individualized segmental alignment goals, and from health-related quality of life (HRQL) alignment goals to the prevention of mechanical complications.MethodsNarrative review discussing sagittal alignment concepts and goals in ASD surgery.ResultsTraditional metrics for measuring sagittal spinal alignment such as pelvic incidence - lumbar lordosis (PI-LL), thoracic kyphosis, and sagittal vertical axis (SVA) may lack the specificity necessary for individualized alignment planning. Compensatory pelvic retroversion and knee flexion are critical determinants of maintaining the upright position. Research has been conflicting as to whether postoperative sagittal alignment is associated with improvements in HRQOL's. However, this may reflect a lack of sensitivity in the traditional alignment targets and PROM's measures, rather than a true lack of relationship between sagittal alignment and functional outcomes. Recent studies show that sagittal parameters have a limited impact on HRQL scores in non-operated patients, but significantly impact post-operative HRQOL measures and mechanical complications in patients treated with spinal fusion. Latest evidence suggests that compensatory mechanisms need to be eliminated and the ideal shape needs to be restored with surgery, to reduce postoperative mechanical complications. Multiple alignment strategies are proposed for that purpose.ConclusionsWhile best evidence shows an improvement in ASD alignment strategies over the last decade, mechanical failures and reoperations are still a cause for concern. This narrative review analyzes the strengths and weaknesses of the different alignment strategies and identifies the main areas of debate.

Revealing teaching quality through lesson semantics: A GPT-assisted analysis of transcripts.

Existing conceptions of teaching quality assume that classroom interactions serve as the foundation for effective teaching. The resulting data necessitates analytical approaches capable of extracting the semantics of these interactions. This study investigates whether and to what extent lesson semantics provide insights into teaching quality (i.e., cognitive engagement, encouragement and warmth, multiple approaches, and the nature of discourse). To achieve this, GPT-4 was applied as a tool for analysing lesson transcripts. The study is based on data from the TALIS Video study, which included N = 50 teachers delivering two consecutive mathematics lessons in 9th grade. Teaching quality was annotated by trained observers across multiple dimensions. The analysis involved embedding segmented lesson transcripts to examine their semantic characteristics and associations with human annotations of teaching quality. Additionally, we applied content-informed prompting to evaluate the interpretability of semantic characteristics for the considered dimensions. GPT-4 identified five distinct semantic representations of transcripts, varying at both the teacher and lesson levels. These representations were related to teaching quality, accounting for up to 20% of variance in teaching quality annotations. Content-informed prompting aligned lesson segments more closely with semantic representations, supporting their interpretability. The findings suggest that lesson semantics serve as indicators of teaching quality, offering a promising approach to understanding effective classroom learning.

Dorsalgia and Resting Horizontal Positions

When addressing the etiopathogenesis of dorsalgia, we often neglect the potential impact of resting horizontal positions. Yet, their possible adverse effects may be a contributing factor to the onset of various types of back pain, its chronic persistence, recurrences, and therapeutic failures. Pain and rest/sleep are mutually influential factors. Resting horizontal positions can be categorised functionally as either sleeping positions or relief positions (antalgic-corrective). Relief positions are used in an effort to alleviate painful conditions. Their correct setting can be facilitated by the use of positioning aids such as cushions or rolls. To ensure optimal horizontal resting positions, we promote the following basic therapeutic-preventive principles: 1. Maximisation of body symmetry – including the alignment of body segments – since any prolonged asymmetric posture is inappropriate (special attention is given to keeping the head aligned with the trunk), 2. Minimisation of axial system rotation, 3. Minimisation of anteflexion and retroflexion, including of the head, 4. Minimisation of capsular, myofascial, and neural tension. Sleeping and relief positions may be supine (on the back), semi-supine, prone (on the stomach), semi-prone, or side-lying. During position changes, the supportive function of the peripheral parts of the body (limbs, head) should be utilised in order to avoid overloading the axial structure – the spine. The therapeutic-preventive efficacy of appropriate sleeping and relief positions can be enhanced by facilitating a more physiological breathing pattern. Through targeted tactile stimuli (such as hands placed in the inguinal or thoracic region, or the use of expanders around the chest), it is possible to activate under-engaged areas of the diaphragm – most commonly its posterior and lateral attachments – thereby supporting its respiratory, postural, and stabilising functions. Dysfunction in these areas represents a key etiopathogenetic factor in dorsalgia. By facilitating breathing, we also influence the function of internal organs, thus addressing the visceral component of dorsalgia. As part of a comprehensive therapeutic and preventive approach to dorsalgia, patients should be educated about the general principles of quality rest – including bed firmness, choice of pillow, and environmental factors such as temperature and lighting.

Boundary feature alignment for semi-supervised medical image segmentation

Boundary feature alignment for semi-supervised medical image segmentation

Clinical Outcomes of N‐HA/pa66 and Titanium Mesh in the Treatment of Lower Cervical Spine Fractures and Dislocations During an 8‐Year Follow‐Up Period

ABSTRACTObjectiveStudies evaluating the long‐term outcomes of the nano‐hydroxyapatite/polyamide 66 cages (n‐HA/PA66) in treating lower cervical spine fractures have not been reported. The objective is to compare the long‐term clinical and radiographic outcomes of titanium mesh cage (TMC) and‐HA/PA66 for anterior cervical corpectomy and fusion (ACCF) in the treatment of lower cervical spine fractures and dislocations.MethodThis retrospective analysis included 223 patients treated at our hospital between January 2010 and January 2016 who had undergone single‐level anterior corpectomy for lower cervical spine fractures and dislocations (with a minimum follow‐up of 8 years) using either a TMC (n = 130) or an n‐HA/PA66 cage (n = 93). The radiographic parameters, including segmental alignment (SA), cage subsidence, plate‐to‐disc distance, cervical lordosis (CL), intervertebral height, and fusion status, along with clinical metrics such as Japanese Orthopedic Association (JOA) scores and visual analog scale (VAS) assessments, were systematically analyzed at preoperative, postoperative, and final follow‐up intervals for the patients involved in the study. The Chi‐Square (χ2) test for categorical variables and the Student's t‐test for numerical data were used to assess differences between the two groups.ResultThe mean follow‐up durations for the TMC group and n‐HA/PA66 group were9.81 ± 2.21 and 9.43 ± 0.92 years, respectively. Moreover, final fusion rates were not significantly different between the n‐HA/PA66 group and the TMC group (97.8% and 96.9%, respectively). The final cage subsidence was significantly lower in the n‐HA/PA66 group (1.56 ± 0.88 mm, with 17.6% subsidence of > 3 mm) than in the TMC group (2.70 ± 2.02 mm, with 36.9% subsidence) (p < 0.01). Furthermore, CL, SA, plate‐to‐disc distance, JOA scores, and VAS scores were not significantly different between the two groups (all p > 0.05).ConclusionWithin 8 years following single level ACCF surgery, the n‐HA/PA66 cage may be better than TMC in anterior cervical construction for treating lower cervical fractures and dislocations.

Targeted anterior expansion of the cervical facet joints achieves indirect foraminal decompression and reduces spondylolisthesis via a posterior approach: a cadaveric study

BackgroundIn this cadaveric study, we aimed to assess the effects of distraction at the anterior end of the cervical facet joints (CFJ), achieved via a posterior cervical approach (PCA), on intervertebral neural foraminal height (IVFH) and segmental alignment. A novel cervical expandable facet implant (CeLFI) was used to facilitate anterior expansion within the CFJ.MethodsThis study was conducted in three time periods (2018, 2019, and 2024). The CeLFI was primarily placed at the CSPL levels or at the non-fused C3–7 levels if no CSPL was present. Pre- and post-implantation outcomes were assessed using cervical spine radiography and computed tomography (CT) scan. Changes in facet joint space (FJS) height, IVFH, interspinous distance (ISD), intervertebral disc height (IVDH), and cervical alignment were assessed.ResultsCeLFI insertion (n = 12) resulted in an increase in the mean IVFH (+ 1.5 mm left; + 2 mm right, both p < 0.001), FJS height (+ 2.41 mm left; 2.53 mm right, both p < 0.001), ISD (+ 2.83 mm, p = 0.003), and posterior IVDH (+ 1.16 mm p = 0.001). In the cadavers with CSPL (n = 9), a segmental reduction was observed, which remained stable in flexion–extension radiographs. Two cadavers also showed unbuckling of the posterior interspinous ligaments on post-insertion CT. No significant changes in overall cervical alignment were observed after CeLFI insertion.ConclusionsIndirect cervical intervertebral foraminal decompression and reduction of cervical segmental spondylolisthesis were achieved via a PCA with targeted distraction at the anterior end of the CFJ. This novel concept is promising but requires further clinical studies to evaluate its benefit for patients with degenerative cervical spine disease.

Improving text collations by local text resegmentation

Abstract In almost all current approaches, the collation of large texts is applied to a fixed given segmentation of the two texts witnesses to be compared and consists of two consecutive steps. First, the segments of the two texts are aligned, and then the aligned segments are compared in detail. For larger manuscripts or books consisting of many pages, the segments are usually the paragraphs of the texts. When comparing two texts, where the second text is a revised version of the first, poor local alignments can arise. This occurs in places where paragraphs have been split into two smaller paragraphs to insert a new paragraph in between, or where several consecutive sentences have been moved from one paragraph to the previous or next paragraph. Most paragraph collation tools cannot handle these scenarios properly because they align each paragraph with at most one paragraph of the other text. In this paper, we discuss this problem in detail and present a heuristic for resegmenting the two texts to be compared in order to achieve a better collation.

Redefining physiological whole-body alignment according to pelvic incidence: normative values and prediction models.

Spinopelvic alignment assessment needs to account for pelvic incidence (PI). This study aimed at providing normative values for commonly used parameters in whole-body alignment analysis based on PI. Multicentric prospective study. This study included healthy volunteers with full-body biplanar radiograph in free-standing position. All radiographic data were collected from 3D reconstructions: Sagittal vertical axis (SVA), T1 pelvic angle (TPA), spino-sacral angle (SSA), sagittal odontoid-hip axis angle (ODHA), pelvic parameters, sacro-femoral angle (SFA), knee flexion angle (KFA), ankle flexion angle (AA), Pelvic shift (PSh), lumbar lordosis (LL), thoracic kyphosis (TK) and cervical lordosis (CL). Population was divided into five groups according to PI. Normative values were described for each group. Linear regressions including age and PI provided prediction formulas for PT, TPA, SSA and SFA. 642 subjects were included. Mean age was 37.7 ± 16.3 years (range: 18-90). Mean PI in the cohort was 49.3 ± 9.5°. LL, PT, SFA, SSA and TPA correlated with PI and age. ODHA, TK, CL and the other lower limb parameters were not associated with PI. All normative values across PI groups are provided for segmental, regional and global alignment parameters. Prediction formulas were: PT=-12.7 + 0.38*PI + 0.14*Age, TPA=-16.9 + 0.34*PI + 0.15*Age, SSA = 109.8 + 0.58*PI-0.19*Age, and SFA = 173 + 0.39*PI + 0.11*Age. SSA, PT, TPA and SFA must be assessed according to patient's PI. This study provides normative values for each PI group, and predictive formulas taking age and PI into account. PI cannot be used to define thoracic and cervical curvatures. II.

Construction Methods and Applications of Spatial Measurement Fields in Shipyards

_ To enhance the digitalization level of shipbuilding, this study focuses on the construction methods and applications of digital shipyards. The design of different quantities and layouts of reference points is based on the dock’s spatial dimensions, the principles of reference point arrangement, and the required measurement accuracy. An assembly coordinate system is established using the horizontal reference plane determined by the electronic level and the longitudinal movement direction of the assembly system equipment. A digital measurement process specification is developed based on the constructed spatial measurement field. Finally, using a specific ship structure model as an example, three typical application scenarios are introduced: segment assembly positioning measurement, total segment alignment positioning measurement, and structural internal equipment base positioning measurement. The construction of the spatial measurement field in the shipyard lays an important foundation for the subsequent creation of a digital shipyard. Keywords fabrication; robotics; shipyards

Concurrent Validity of Three Photogrammetric Methods for Assessing Knee Alignment in Sagittal Plane.

Background: Evidence supporting the validity of photogrammetry for assessing body segment alignment remains limited, with most studies focusing on spinal evaluation. Thus, there is a lack of robust research examining its use for other body segments such as the lower limbs. Objective: This study aimed to evaluate the concurrent validity of three photogrammetric methods for measuring knee alignment in the sagittal plane with and without corrections for potential rotational deviations in the participant's thigh and leg. Methods: A total of 21 adults underwent sequential evaluations involving panoramic radiography of the lower limbs and photogrammetry at a private radiology clinic. Photogrammetric analysis involved identifying the following anatomical landmarks: the greater trochanter of the femur (GTF), the lateral condyle of the femur (LCF), the head of the fibula (HF), and lateral malleolus (LM). Three photogrammetric methods were employed: (1) the condylar angle (CA) defined by the GTF, LCF, and LM points; (2) the fibula head angle (FHA) defined by the GTF, HF, and LM points; and (3) the four-point angle (4PA) incorporating the GTF, LCF, HF, and LM. Concurrent validity was assessed using correlation analysis, agreement with radiographic measurements, and the root mean square error (RMSE). Each photogrammetric method was tested using raw (CA, FHA, and 4PA) and corrected (CAcorr, FHAcorr, and 4PAcorr) values, accounting for thigh and/or leg rotational deviations. Results: Correcting for thigh and leg rotations significantly improved the validity metrics for all methods. The best performance was observed with the corrected condylar angle (CAcorr: r = 0.746; adjusted r2 = 0.533; RMSE = 2.9°) and the corrected four-point angle (4PAcorr: r = 0.733; adjusted r2 = 0.513; RMSE = 3.0°); however, the measurements presented proportional errors, possible due the method of assessment of rotations. Conclusions: The findings validate the evaluated photogrammetric methods for assessing sagittal knee alignment. Accounting for thigh and leg rotational deviations is critical for achieving accurate measurements, raising the need of accurate tools for measuring rotational changes in the lower limbs to avoid errors.

Beyond Pixel and Object: Part Feature as Reference for Few-Shot Video Object Segmentation

Few-Shot Video Object Segmentation (FSVOS) aims to achieve accurate segmentation of video sequences supported by limited annotated images. In this work, we analyze the deficiencies inherent in the use of object prototypes and pixel features as references in previous methods. Then we shed light on that part features, with the ability to adapt to appearance variations and resist noise, are advantageous as representative reference features for aligning support images and query videos. Therefore, we propose a Part Agent Learning Network (PALN) to leverage part features from two aspects. First, we elaborately employ Optimal Transport algorithm with equal partition constraint to make part agents capable of dividing support objects into diverse parts in an adaptive manner. Second, we design a dedicated cache mechanism to learn temporal part agents as lightweight historic target representation to exploit temporal consistency. With the aid of these learned part agents, our PALN can effectively achieve support-query alignment and temporal alignment for accurate segmentation of query videos. Extensive experimental results on two challenging benchmarks demonstrate that our method performs favorably against state-of-the-art FSVOS methods.

Design and Verification of a Human Energy Metabolism Detection System Based on Breath-by-Breath Method

To accurately measure human energy metabolism with high temporal resolution, a respiratory gas analysis system was designed using a breath-by-breath approach. Firstly, indirect calorimetry was employed in respiratory gas analysis to measure the respiratory flow and concentration signals in real-time. Secondly, oxygen consumption and carbon dioxide production were calculated through respiratory characteristic alignment and respiratory signal segmentation. Finally, metabolic indexes were calculated according to the Weir formula. Furthermore, a controlled trial was formulated for validation comparisons with the MGC ULTIMA SYSTEM PFX CARDIO2. The results indicate that the data points of metabolic indexes measured by this system all fall within the confidence interval when compared with those of the MGC. The system has high consistency with the MGC measurement results. Thus, the system can accurately measure metabolism in real-time and provide data support for clinical nutrition assessment and therapy.

Statistical Learning of Robotic Demonstration Trajectories Based on Multicriteria Segmentation and Multi-Demonstration Alignment (HSMM)

Statistical Learning of Robotic Demo Trajectories Based on Multicriteria Segmentation and Multi-Demonstration Alignment (HSMM) addresses complex tasks in human-robot interaction and intelligent manufacturing. The research goal of this study is to automatically extract generalized key segments from multiple robotic demonstration trajectories in the absence of prior annotations and establish statistical and parametric models for universal trajectory reproduction across diverse tasks and conditions. To achieve this, the research tasks include multicriteria segmentation (speed, curvature, acceleration, direction change), trajectory alignment using Hidden Semi-Markov Models (HSMM), and subsequent implementation of statistical representations (ProMP, GMM/GMR, DMP). The proposed methodology begins with the smoothing of raw data and the identification of key points via topological simplification and non-maximum suppression, then, using HSMM, it ensures consistent segmentation of multiple demonstrations into characteristic segments. The conducted experiments confirm the results of the approach, demonstrating low reconstruction error while simultaneously improving data compression and preserving key actions, indicating the high efficiency of the method. Finally, the novelty and practical significance of this study can be highlighted by the potential industrial applications (such as welding, painting, etc.), as well as the future prospective expansions of the method to more dynamic and non-stationary scenarios, requiring adaptive and statistically grounded trajectory planning.

Rationale and recommendations for occupational therapy and physiotherapy in positioning adults with acute respiratory failure connected to extracorporeal membrane oxygenation. A narrative review.

Extracorporeal membrane oxygenation (ECMO) is a life support system that facilitates gas exchange in patients experiencing catastrophic respiratory failure. ECMO connection can last from a few days to several weeks, resulting in muscle atrophy, pathological changes in the lengths of both active and passive joint stabilising structures, and alterations in the alignment of body segments. These dysfunctions may be exacerbated if patients do not maintain proper positioning, which can delay rehabilitation. Therapeutic positioning (TP) is a fundamental tool in caring for patients hospitalised in the intensive care unit. Adequate TP application helps prevent immobility complications, promotes body alignment, and enhances the patient's functionality during recovery. From a biomechanical perspective, TP supports preserving essential musculoskeletal functions such as strength, joint mobility, and endurance, facilitating patient participation in meaningful activities. Its implementation should be based on biomechanical principles, personalised adaptations, and continuous monitoring to ensure effectiveness in rehabilitation. This review examines the rationale for TP in adults with acute respiratory failure on ECMO from occupational and physical therapy perspectives. Additionally, recommendations are provided to improve the application of this intervention, particularly in the increasingly common context of prone positioning in patients with ECMO.

Management of Zygomaticomaxillary Complex Fractures in Children.

Zygomaticomaxillary complex (ZMC) fractures in children can lead to severe aesthetic and functional complications, including pronounced facial asymmetry, visual impairment, associated ophthalmic injuries. The management of ZMC fractures in pediatric patients presents unique challenges. This article verified the feasibility of using absorbable plate through intraoral approach in the reduction and fixation of ZMC fractures in children. The operation was performed through the intraoral maxillary sulcus incisions. The 3D printed prototype and repaired models were used intraoperatively. The tooth germs in the maxilla were revealed by fenestration on the models. Collapsed fracture segments were reduced and fixed with absorbable plates at the infraorbital margin and upper end of the zygomatic alveolar ridge. The patient's facial appearance was restored after the surgery. The postoperative CT showed good alignment of the fracture segments. The drilling holes at the zygomatic alveolar ridge were located outside the tooth germs region. The intraoral maxillary sulcus incision is suitable for treating ZMC fractures in children with Knight and North Group Ⅲ zygomatic fractures. Stable reduction can be achieved by using absorbable plates at the inferior orbital margin and the upper end of the zygomatic alveolar ridge. The 3D printed model with tooth germs revealed can provide practical reference value.

TIME TO ALIGNMENT OF ANTERIOR SEGMENT CROWDING TREATED WITH NiTi AND COPPER NiTi ARCH WIRES

Abstract Introduction Treatment duration and cost are integral aspects of orthodontic treatment planning and are required to predict outcomes. Shorter treatment regimens prevent the adverse effects of orthodontic treatment. Contemporary arch wires have properties that potentially shorten orthodontic treatment time. This study aimed to determine the time to alignment of anterior segment crowding with NiTi and CuNiTi arch wires. Methods: A randomized controlled trial carried out at the Orthodontic unit of a tertiary hospital. Thirty-two arches with Little’s Irregularity Index (LII) of ≥ 4mm on anterior permanent teeth were involved in the study. The LII was measured on study models at pre-treatment and after commencement of orthodontic treatment, at each review visit until it reduced to 3.0mm or less. The results were analyzed on the Statistical Package for Social Sciences Chicago Inc. V. with Mann-Whitney U test, Kaplan-Meier methods, the Log rank test and Cox regression at p&lt;0.05. RESULTS: The arches had moderate 22 (34.3%), severe 25 (39.1%) and very severe 17 (26.6%) crowding. The mean time to alignment was 55.69 ± 20.18 days (CuNiti) and 67.19±33.91 days (Niti). The time to resolution of crowding for 50% of the arches was similar for the wires (p =0.07). The resolution of crowding was 0.77 times higher with CuNiTi wires. Arches with initial severe crowding had a 4.56 increase in the time to alignment with every 1 mm increase in their LII (p value ˂0.05). Conclusion The time to alignment of anterior segment crowding with NiTi and CuNiTi arch wires was similar.

Anterior cervical trapezoid corpectomy and fusion (ACTCF): a novel technique for cervical spondylotic myelopathy.

To describe a novel technique, namely, anterior cervical trapezoid corpectomy and fusion (ACTCF), and to research its initial clinical efficacy in the treatment of cervical spondylotic myelopathy (CSM). A total of 30 patients with CSM who were admitted to the hospital and treated with the ACTCF between May and December 2021 were retrospectively reviewed. The main surgical procedures include discectomy, trapezoidal osteotomy, pruning and replanting of autogenous bone, and implantation of cage. Relevant data, including patient sex, age, follow-up time, operative duration, postoperative complications, operative level, and osteotomy segment, were collected. Visual analog scale (VAS), Japanese Orthopaedic Association (JOA) scores and Neck Disability Index (NDI) before surgery, immediately, 1 month, 3 months, 6 months and 12 months after surgery were collected. The decompression and fusion outcomes were evaluated by X-ray and CT. Disc height of involved segment, C2-C7 cervical lordosis (C2-C7 CL) and sagittal segmental alignment (SSA) before surgery, immediately, 1 month, 3 months, 6 months and 12 months after surgery were measured. All patients in this study had favorable outcomes and experienced no postoperative complications. The limbs and neurological symptoms of 30 patients improved significantly after the operation. The mean follow-up was 13.4 months. The VAS, JOA scores and NDI significantly improved at immediately, 1 month, 3 months, 6 months and 12 months after surgery (p < 0.05). Disc height of involved segment, C2-C7 CL and SSA improved at immediately, 1 month, 3 months, 6 months and 12 months after surgery (p < 0.05). Radiographic review revealed no significant back plant settlement, and good fusion was observed at an early stage. For the treatment of CSM with cervical spinal stenosis, ACTCF may be a good alternative to traditional ACCF which can reduce complications, maintain intervertebral height, and accelerate fusion time.

MetaboLabPy-An Open-Source Software Package for Metabolomics NMR Data Processing and Metabolic Tracer Data Analysis.

Introduction: NMR spectroscopy is a powerful technique for studying metabolism, either in metabolomics settings or through tracing with stable isotope-enriched metabolic precursors. MetaboLabPy (version 0.9.66) is a free and open-source software package used to process 1D- and 2D-NMR spectra. The software implements a complete workflow for NMR data pre-processing to prepare a series of 1D-NMR spectra for multi-variate statistical data analysis. This includes a choice of algorithms for automated phase correction, segmental alignment, spectral scaling, variance stabilisation, export to various software platforms, and analysis of metabolic tracing data. The software has an integrated help system with tutorials that demonstrate standard workflows and explain the capabilities of MetaboLabPy. Materials and Methods: The software is implemented in Python and uses numerous Python toolboxes, such as numpy, scipy, pandas, etc. The software is implemented in three different packages: metabolabpy, qtmetabolabpy, and metabolabpytools. The metabolabpy package contains classes to handle NMR data and all the numerical routines necessary to process and pre-process 1D NMR data and perform multiplet analysis on 2D-1H, 13C HSQC NMR data. The qtmetabolabpy package contains routines related to the graphical user interface. Results: PySide6 is used to produce a modern and user-friendly graphical user interface. The metabolabpytools package contains routines which are not specific to just handling NMR data, for example, routines to derive isotopomer distributions from the combination of NMR multiplet and GC-MS data. A deep-learning approach for the latter is currently under development. MetaboLabPy is available via the Python Package Index or via GitHub.

The effect of degenerative scolioisis on segmental thoracolumbar sagittal alignment compared to age- and pelvic incidence-matched reference values.

In asymptomatic subjects, variations of sagittal alignment parameters according to age and pelvic incidence (PI) has been reported. The aim of this observational study was to describe thoraco-lumbar sagittal alignment in patients with degenerative scoliosis and to compare them to asymptomatic individuals, seeking for the specific effect of deformity in similar age and PI groups. Full spine radiographs of 235 asymptomatic subjects and 243 scoliosis patients were analyzed: cervico-thoracic inflexion point (CTIP), thoraco-lumbar inflexion point (TLIP), lumbar lordosis (LL) L1-S1, LL (TLIP-S1), LL superior arch (TLIP-lumbar apex), LL inferior arch (lumbar apex-S1), PI, thoracic kyphosis (TK) T5-T12, TK T1-T12, number of vertebrae CTIP-TLIPandTLIP-S1. The distribution of parameters was analyzed using a Bayesian inference (significant when Pr > 0.975 or Pr < 0.025). Comparisons between reference (R) and pathologic (P) groups were matched according to age (40-60 years; >60 years) and PI (< 45°; 45-60°; >60°). LL L1-S1 was significantly lower in the P-group (Pr = 1.0), decreased with age (Pr > 0.99) and increased with PI (Pr < 0.001). In contrast, there was no significant decrease with age for LL (TLIP-S1) or LL (superior arch) (respectively Pr < 0.92 and Pr > 0.19). LL in the inferior arch was significantly lower in the P-group (Pr = 1.0) and decreased with age (Pr = 0.99). The number of vertebrae TLIP-S1 was significantly lower in the P-group compared to the reference group (Pr < 0.001).Thoracic kyphosis T1-T12 was significantly lower in the P-group (Pr < 0.001), without significant influence of age or PI. The number of vertebrae CTIP-TLIP increased significantly in the P-group (Pr < 0.001) and with PI (Pr < 0.004). This observational study highlights specific thoraco-lumbar sagittal alignment adaptations in degenerative scoliosis, matched on age and PI. Beyond the decrease in LL due to aging, degenerative scoliosis leads to a distal migration of the TLIP, an increase in the number of vertebrae in TK and a decrease in LL. This phenomenon was linked to kyphosis at the thoraco-lumbar junction due to scoliosis and was more important in high PI.

CADS: A Self-Supervised Learner via Cross-Modal Alignment and Deep Self-Distillation for CT Volume Segmentation.

Self-supervised learning (SSL) has long had great success in advancing the field of annotation-efficient learning. However, when applied to CT volume segmentation, most SSL methods suffer from two limitations, including rarely using the information acquired by different imaging modalities and providing supervision only to the bottleneck encoder layer. To address both limitations, we design a pretext task to align the information in each 3D CT volume and the corresponding 2D generated X-ray image and extend self-distillation to deep self-distillation. Thus, we propose a self-supervised learner based on Cross-modal Alignment and Deep Self-distillation (CADS) to improve the encoder's ability to characterize CT volumes. The cross-modal alignment is a more challenging pretext task that forces the encoder to learn better image representation ability. Deep self-distillation provides supervision to not only the bottleneck layer but also shallow layers, thus boosting the abilities of both. Comparative experiments show that, during pre-training, our CADS has lower computational complexity and GPU memory cost than competing SSL methods. Based on the pre-trained encoder, we construct PVT-UNet for 3D CT volume segmentation. Our results on seven downstream tasks indicate that PVT-UNet outperforms state-of-the-art SSL methods like MOCOv3 and DiRA, as well as prevalent medical image segmentation methods like nnUNet and CoTr. Code and pre-trained weight will be available at https://github.com/yeerwen/CADS.