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This study proposes a novel hybrid simulation technique for analyzing structural deformation and stress using light detection and ranging (LiDAR)-scanned point cloud data (PCD) and polynomial regression processing. The method estimates the edge and corner points of the deformed structure from the PCD. It transforms into a Dirichlet boundary condition for the numerical simulation using the particle difference method (PDM), which utilizes nodes only based on the strong formulation, and it is advantageous for handling essential boundaries and nodal rearrangement, including node generation and deletion between analysis steps. Unlike previous studies, which relied on digital images with attached targets, this research uses PCD acquired through LiDAR scanning during the loading process without any target. Essential boundary condition implementation naturally builds a boundary value problem for the PDM simulation. The developed hybrid simulation technique was validated through an elastic beam problem and a three-point bending test on a rubber beam. The results were compared with those of ANSYS analysis, showing that the technique accurately approximates the deformed edge shape leading to accurate stress calculations. The accuracy improved when using a linear strain model and increasing the number of PDM model nodes. Additionally, the error that occurred during PCD processing and edge point extraction was affected by the order of polynomial regression equation. The simulation technique offers advantages in cases where linking numerical analysis with digital images is challenging and when direct mechanical gauge measurement is difficult. In addition, it has potential applications in structural health monitoring and smart construction involving machine leading techniques. [ABSTRACT FROM AUTHOR]

Introduction/Aims: Intraneural ganglion cysts (INGCs) are non‐neoplastic mucinous cysts within the epineurium of peripheral nerves. Characteristics of INGCs around the hip joint have not been adequately described. We aimed to describe clinical features, imaging findings, and treatment outcomes in patients with INGCs originating from the hip joint. Methods: We retrospectively included cystic lesions around the hip joint satisfying the following inclusion criteria over 6 years: (1) multilocular elongated hyperintense cystic mass on T2‐weighted imaging; and (2) distribution along the course of the peripheral nerve and its branches on magnetic resonance imaging (MRI). Results: Six patients with an INGC around the hip joint were identified. Parent peripheral nerves were the sciatic nerve (four patients), the superior gluteal nerve (one patient), and the nerve to quadratus femoris (one patient). Buttock, groin, or lower extremity pain/paresthesias were the initial symptoms in all patients. INGCs within the articular branches of the hip joint were identified on MRI. Four patients underwent arthroscopic debridement and capsulotomy. All patients showed generally favorable outcome regardless of treatment. Discussion: Physicians should consider the possibility of INGCs originating from the hip joint as a cause of nontraumatic hip, buttock, or lower extremity pain. This can occur in any nerve innervating the hip joint, and usually it originates in the posterior capsule of the hip joint. Arthroscopic surgery shows promising results; however, more information about the surgical technique and long‐term follow‐up results are needed. See Editorial on pages 236‐239 in this issue [ABSTRACT FROM AUTHOR]

Objectives: To assess the diagnostic accuracy of conventional MRI for detecting and grading subscapularis (SSC) tears by applying the Yoo and Rhee classification. Materials and methods: A total of 179 patients who underwent MRI followed by arthroscopic rotator cuff surgery were enrolled. Two musculoskeletal radiologists evaluated the SSC using axial, oblique sagittal, and oblique coronal MRI according to the Yoo and Rhee classification. Using arthroscopic findings as the reference standard, the sensitivity, specificity, accuracy, and interobserver agreement of SSC tears were analyzed. Results: Arthroscopy confirmed that the numbers of type I, IIA, IIB, III, IV, and V tears were 35, 70, 35, 9, 9, and 0, respectively. The sensitivity, specificity, and accuracy of readers 1 and 2 for the detection of tears (type IIA or higher) were 85%, 75%, and 82%, and 89%, 70%, and 83%, respectively, while those for the detection of surgical candidates (type IIB or higher) were 77%, 75%, and 75%, and 77%, 83%, and 82%, respectively. The interobserver agreement for detecting SSC tear presence was substantial (κ = 0.70) for reader 1 vs. reader 2, and those for detecting the surgical candidate group was substantial (κ = 0.68) for reader 1 vs. reader 2. The interobserver agreement for grading SSC tears was excellent (κ = 0.86) for reader 1 vs. reader 2. Conclusion: Conventional MRI showed 82.5% and 78.5% average accuracy in detecting IIA and IIB or higher tears by applying the Yoo and Rhee classification for the diagnosis of SSC tears with an excellent interobserver agreement in tear grading. [ABSTRACT FROM AUTHOR]

• The quantity and attenuation of skeletal muscle were linked to bone quality in men. • This connection appears stronger with trabecular attenuation than with bone BMD. • Visceral adiposity negatively correlates with trabecular attenuation in both sexes. To investigate the relationship of body composition metrics with bone mineral density (BMD) and trabecular attenuation in a cohort of healthy individuals. We retrospectively analyzed data of consecutively evaluated individuals who underwent dual-energy X-ray absorptiometry (DXA) and abdominopelvic computed tomography (CT) on the same day during routine medical check-ups between January 2021 and December 2021. Trabecular attenuation was measured at L1 level, while body composition metrics, including skeletal muscle index (SMI), skeletal muscle attenuation (SMA), visceral fat index (VFI), and subcutaneous fat index (SFI), were measured at L3 level. The association of body composition metrics with BMD and trabecular attenuation was analyzed using partial correlation analysis. A total of 634 patients (median age, 56 years; range 50–62 years; 392 men) were included. In men, the SMI and SMA were positively correlated with BMD and trabecular attenuation, both before (r, 0.157–0.344; p < 0.05) and after (r, 0.103–0.246; p < 0.05) adjusting for age and body mass index. The VFI showed negative correlations with trabecular attenuation in both men (r, −0.170; p = 0.001) and women (r, −0.394; p < 0.001), which remained significant after adjusting for age and body mass index (r, −0.181 to −0.122; p < 0.05). Low skeletal muscle mass and attenuation were significantly correlated with low BMD and trabecular attenuation in men. Visceral adiposity was associated with reduced BMD and trabecular attenuation in both men and women, demonstrating a stronger correlation with trabecular attenuation. [ABSTRACT FROM AUTHOR]

This study aimed to investigate whether in vivo MR-electrical properties tomography (MR-EPT) is feasible in musculoskeletal tissues by evaluating the conductivity of muscle, cartilage, and peripheral nerve around the knee joint, and to explore whether these measurements change after exercise. This prospective study was approved by the institutional review board. On February 2020, ten healthy volunteers provided written informed consent and underwent MRI of the right knee using a three-dimensional balanced steady-state free precession (bSSFP) sequence. To test the effect of loading, the subjects performed 60 squatting exercises after baseline MRI, immediately followed by post-exercise MRI with the same sequences. After reconstruction of conductivity map based on the bSSFP sequence, conductivity of muscles, cartilages, and nerves were measured. Measurements between the baseline and post-exercise MRI were compared using the paired t-test. Test–retest reliability for baseline conductivity was evaluated using the intraclass correlation coefficient. The baseline and post-exercise conductivity values (mean ± standard deviation) [S/m] of muscles, cartilages, and nerves were 1.73 ± 0.40 and 1.82 ± 0.50 (p = 0.048), 2.29 ± 0.47 and 2.51 ± 0.37 (p = 0.006), and 2.35 ± 0.57 and 2.36 ± 0.57 (p = 0.927), respectively. Intraclass correlation coefficient for the baseline conductivity of muscles, cartilages, and nerves were 0.89, 0.67, and 0.89, respectively. In conclusion, in vivo conductivity measurement of musculoskeletal tissues is feasible using MR-EPT. Conductivity of muscles and cartilages significantly changed with an overall increase after exercise. [ABSTRACT FROM AUTHOR]

Objectives: To explore whether texture features using T1-weighted images correlate with fat fraction, and whether they differ between Charcot-Marie-Tooth (CMT) disease patients and volunteers.Methods: The institutional review board approved this retrospective study, and the requirement for informed consent was waived; data of eighteen CMT patients and eighteen healthy volunteers from a previous study was used. Texture features of the muscles including mean, standard deviation (SD), skewness, kurtosis, and entropy of the signal intensity were derived from T1-weighted images. Spearman's correlation analysis was used to assess the relationship between texture features and fat fraction measured by 3D multiple gradient echo Dixon-based sequence. Mann-Whitney U test was used to compare the texture features between CMT patients and volunteers. Intraobserver and interobserver agreements for the texture features were assessed using the intraclass correlation coefficient.Results: The SD (ρ = 0.256, p < 0.001) and entropy (ρ = 0.263, p < 0.001) were significantly and positively correlated with fat fraction; skewness (ρ = - 0.110, p = 0.027) and kurtosis (ρ = - 0.149, p = 0.003) were significantly and inversely correlated with fat fraction. The CMT patients showed a significantly higher SD (63.45 vs. 49.26; p < 0.001), skewness (1.06 vs. 0.56; p < 0.001), kurtosis (4.00 vs. 1.81; p < 0.001), and entropy (3.20 vs. 3.02; p < 0.001) than did the volunteers. Intraobserver and interobserver agreements were almost perfect for mean, SD, and entropy.Conclusions: Texture features using T1-weighted images correlated with fat fraction and differed between CMT patients and volunteers.Key Points: • Standard deviation and entropy of muscles derived from T1-weighted images were significantly and positively correlated with the muscle fat fraction. • Mean, standard deviation, and entropy were considered highly reliable in muscle analyses. • Texture features may have the potential to diagnose early stage of intramuscular fatty infiltration. [ABSTRACT FROM AUTHOR]

Objectives: To examine the correlation of diffusion-weighted and dynamic contrast-enhanced magnetic resonance imaging (MRI) parameters with Ki-67 labeling index (LI) in soft tissue sarcoma (STS).Methods: The institutional review board approved this retrospective study, and the requirement for informed consent was waived. Thirty-six patients with STS who underwent 3.0-T MRI, including diffusion-weighted and dynamic contrast-enhanced MRI, between July 2011 and February 2018, were included in this study. The mean and minimum apparent diffusion coefficients (ADCs) (ADCmean and ADCmin, respectively), volume transfer constant, reflux rate, and volume fraction of the extravascular extracellular matrix of each lesion were independently analyzed by two readers. Their relationship with the Ki-67 LI was examined using Spearman's correlation analyses. Differences between low- and high-proliferation groups based on Ki-67 LI were evaluated statistically. Optimal cut-off points were determined using the area under the curve analysis for significant parameters. Interobserver agreement was assessed with the intraclass correlation coefficient.Results: ADCmean (ρ = - 0.333, p = 0.047) was significantly and inversely correlated with Ki-67 LI. The high-proliferation group showed a significantly lower ADCmean than did the low-proliferation group (median, 1.08 vs. 1.20; p = 0.048). When a cut-off ADCmean value of 1.16 × 10-3 mm2/s was used, the sensitivity, specificity, and area under the curve for differentiating low- and high-proliferation groups were 75.0%, 60.0%, and 0.712, respectively. Interobserver agreements between the two readers were almost perfect for all parameters.Conclusions: ADCmean was correlated with Ki-67 LI and could help differentiate between STS with low and high proliferation potential.Key Points: • ADC meanwas significantly and inversely correlated with Ki-67 labeling index in soft tissue sarcoma. • In the high-proliferation group, ADC meanvalues were significantly lower than those of the low-proliferation group. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to evaluate whether diffusion tensor imaging (DTI) parameters and cross-sectional area (CSA) can differentiate between the sciatic nerve of Charcot-Marie-Tooth (CMT) disease type I (demyelinating form) patients and that of controls.Methods: This prospective comparison study included 18 CMT type I patients and 18 age/sex-matched volunteers. Magnetic resonance imaging including DTI and axial T2-weighted Dixon sequence was performed for each subject. Region of interest analysis was independently performed by two radiologists on each side of the sciatic nerve at four levels: hamstring tendon origin (level 1), lesser trochanter of the femur (level 2), gluteus maximus tendon insertion (level 3), and mid-femur (level 4). Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated. The CSA of the sciatic nerve bundle was measured using axial water-only image at each level. Comparisons of DTI parameters between the two groups were performed using the two-sample t test and Mann-Whitney U test. Interobserver agreement analysis was also conducted.Results: Interobserver agreement was excellent for all DTI parameter analyses. FA was significantly lower at all four levels in CMT patients than controls. RD, MD, and CSA were significantly higher at all four levels in CMT patients. AD was significantly higher at level 2 in CMT patients.Conclusion: DTI assessment of the sciatic nerve is reproducible and can discriminate the demyelinating nerve pathology of CMT type I patients from normal nerves. The CSA of the sciatic nerve is also a potential parameter for diagnosing nerve abnormality in CMT type I patients.Key Points: • Diffusion tensor imaging parameters of the sciatic nerve at proximal to mid-femur level revealed significant differences between the Charcot-Marie-Tooth disease patients and controls. • The cross-sectional area of the sciatic nerve was significantly larger in the Charcot-Marie-Tooth disease patients. • Interobserver agreement was excellent (intraclass coefficient > 0.8) for all diffusion tensor imaging parameter analyses. [ABSTRACT FROM AUTHOR]

A modified extended finite element method (XFEM) for dynamic fracture is presented with a new methodology to construct the XFEM basis for discontinuities. In this method, the enrichment bases are defined to capture the characteristic discontinuities across the interface. The enrichments are vanished outside the element domain so that no blending of the local partition unity is required. The enrichment parameters effectively represent the physics of the discontinuity and are assigned to non-nodal points, which helps to impose Dirichlet boundary conditions on the interface. This feature successfully dissociates the finite element nodes from the extended finite element approximation; it facilitates the treatment of arbitrary crack propagation in explicit methods. The approach is applied to linear three-node triangular elements for element-by-element crack propagation modeling. The proposed method combined with explicit time integration and a cohesive law can successfully predict the dynamic fracture of ductile and brittle materials. Dynamic simulation results in terms of crack path and speed were effectively computed and match the experimental results. Through these numerical examples, the robustness and performance of the method were successfully demonstrated. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the difference between T2 relaxation values of the subtalar cartilage in lateral ankle instability patients and healthy volunteers.Materials and Methods: This institutional review board-approved study included 27 preoperative magnetic resonance imaging (MRI) examinations of 26 patients who underwent Broström operations. Data of previously enrolled healthy volunteers (12 volunteers, 13 MRIs) were used as controls. Two radiologists independently measured T2 values in eight posterior subtalar joint cartilage compartments: central calcaneus anterior (CCA) and posterior (CCP), central talus anterior (CTA) and posterior (CTP), lateral calcaneus anterior (LCA) and posterior (LCP), and lateral talus anterior (LTA) and posterior (LTP). Patient and control values were compared using linear regression analysis. Inter- and intraobserver agreement was calculated.Results: Mean T2 values were significantly higher in the patient group in all measurements of subtalar joint cartilage compartments (p < 0.05) except that in LTP (p = 0.085) measured by reviewer 1. Both inter- and intraobserver agreements were excellent.Conclusions: The T2 relaxation values of the subtalar cartilage were significantly higher in lateral ankle instability patients compared with those of controls.Key Points: • Subtalar cartilage T2 values are increased in patients with lateral ankle instability. • This trend was demonstrated regardless of the presence of talar dome cartilage lesions. • Inter-and intraobserver agreements were excellent (intraclass coefficient range, 0.765-0.951) in subtalar cartilage T2 mapping. [ABSTRACT FROM AUTHOR]

This study presents a sustainable design method that optimizes the embodied energy and carbon dioxide (CO 2 ) emissions of a reinforced concrete (RC) column. Conventionally, the design of RC structures has been focused on the minimization of construction costs while satisfying the structural design code. Recently, however, sustainability aspect in structural design has drawn big attention to structural engineers, especially for structure life cycle assessment. Therefore, it is crucial to understand the relationship between construction costs and consumption of energy including CO 2 emissions, in the design process of RC structures. In the sustainable design process, the objective functions for the cost, embodied energy, and CO 2 emissions were set and numerous optimization analyses for various loading conditions were conducted as the failure mode of RC columns varies according to the eccentricity involving the axial forces and moment. A thorough investigation of the optimization analysis results shows that, when a 10% cost increase is assumed, the embodied energy and CO 2 emissions might undergo an overall reduction of up to 22% and 63%, respectively. As a result, the proposed design method enables the embodied energy and CO 2 emissions to be effectively optimized in the conventional design process of RC columns. [ABSTRACT FROM AUTHOR]

Background Although we observed that subcortical cysts near the attachment of the meniscus or cruciate ligaments are frequently seen with a tear or degeneration of the adjacent meniscus and/or cruciate ligament, there is no large study describing the prevalence, distribution, and associated findings of these cysts. Purpose To evaluate the prevalence and distribution of subcortical cysts near the attachments of the meniscus or cruciate ligaments and evaluate pathologies of the meniscus or cruciate ligaments using magnetic resonance imaging (MRI). Material and Methods We reviewed 1009 knee MRIs for the presence of subcortical cysts near the meniscus or cruciate ligament attachments and evaluated their size, location, edema of the adjacent bone marrow, and integrities of the medial and lateral meniscus and anterior and posterior cruciate ligaments. Results The 110 cysts were found in either the middle (n = 56), posterior (n = 52), or anterior (n = 2) subspinous regions. Sixty-two were at meniscal root insertion, including seven at the lateral meniscus anterior horn, five at the lateral meniscus posterior horn, 48 at the medial meniscus posterior horn, and two at the medial meniscus anterior horn. All were associated with an adjacent meniscal pathology. Of the 34 cysts at the anterior cruciate ligament (ACL) insertion, 28 had ACL pathology. Nine cysts had surrounding edema in the adjacent bone marrow. Conclusion Subcortical cysts at the subspinous region of the knee were seen in 9.6% of knee MRI examinations. Most were in close proximity to the meniscal or cruciate ligaments with associated pathologies, suggesting that abnormal stress on the bone induces cyst formation. [ABSTRACT FROM AUTHOR]

A new dynamic particle difference method (PDM) for the simulation of a proportionally damped system subjected to dynamic load and the fracture simulation of cracked concrete beam is presented. The dynamic PDM utilizes only node model without involving any mesh or grid structure to take advantage of the merits of strong formulation; it remarkably accelerates computational speed owing to the avoidance of numerical integration and also sophisticatedly handles awkward topological change due to the crack growth in node model. The proportional damping is successfully implemented in the dynamic PDM by adding both mass and stiffness proportional terms to the equation of motion and the constitutive equation, respectively. It provides extra stability in the dynamic fracture simulation by eliminating erroneous oscillations. Governing partial differential equation is straightforwardly discretized in time by using the central difference method. However, a novel modification is devised in the Newmark method implementation where the transient equations and update formulae for kinematic variables are newly formulated; this modification appropriately corrects the period and amplitude of kinematic variable responses. The stability and accuracy of the developed methods are verified by solving various dynamic problems involving transient loading. Furthermore, the fracture process of the cracked concrete beam under the impact loading is successfully simulated and the dynamic energy release rates are effectively evaluated during the simulation. [ABSTRACT FROM AUTHOR]

We present a strong-form meshfree collocation method for frictional contact of two deformable bodies within the context of frictional crack problems. The method inherently achieves desirable features of meshfree methods by completely avoiding the construction of meshes or grids, such that the only required numerical approximation units are nodes (used as collocation points). For the recognition of a contact or crack surface, a line segment is used without any connection with the node structure. A contact constraint due to two body frictional contact is implemented in the strong-form meshfree discretization. Since the contact boundary is a Neumann boundary, it contributes to the system of equations as a traction boundary condition, but it does not yield extra unknowns. Although the material is linear elastic, the presence of the constraint formulation leads to an iterative nonlinear solution procedure. The assembled discrete system generates a consistent and stable solution despite the presence of contact constraints and the crack discontinuity, because the constraint formulation and crack modeling are well combined with the strong-form meshfree collocation method. Numerical experiments demonstrate the robustness and consistency of the method through comparison with analytical and finite element solutions. • Strong form meshfree collocation method for modeling stationary frictional crack. • Approximation of derivatives via generalized moving least-square approximation. • Representing contact constraints with penalty method and return mapping algorithm. • Applications to benchmark frictional two-body and crack contact problems. [ABSTRACT FROM AUTHOR]

Background and Purpose: Slice-Encoding Metal Artifact Correction (SEMAC) sequence is one of the metal artifact reduction techniques of anatomical structure, but there has been no report about evaluation of post-operative complications. The purpose of this article is to compare the anatomical visibility between fast spin echo (FSE) and FSE-SEMAC and to evaluate the additional value of FSE-SEMAC in diagnostic confidence of the complications. Materials and Methods: We conducted a retrospective study with 54 patients who received lumbar spinal surgery and MR images including FSE-SEMAC. For the semi-quantitative evaluation, the visibility of anatomical structures (neural foramen, bone-inter-body cage interface, central canal, nerve root in epidural space, back muscle, and bone-pedicle screw interface) was evaluated. For qualitative evaluation, we evaluated FSE and FSE with FSE-SEMAC independently, and recorded the diagnostic confidence level of post-operative complications. Generalized estimating equation regression analysis was used for statistical analysis, and a weighted kappa was used for inter-observer agreement. Results: Scores of 6 imaging findings with FSE-SEMAC were significantly higher than that of FSE (P-value < .0001). Inter-observer agreements show good reliability (weighted kappa = 0.45–0.75). Both reviewers deemed 37 (reviewer 1) or 19 more (reviewer 2) post-operative complications with FSE plus FSE-SEMAC, compared to FSE only. Except for central canal stenosis (P-value = .2408), diagnostic confidence level for other post-operative complications were significantly higher with FSE plus FSE-SEMAC (P-value = .0000) than FSE. Conclusions: FSE-SEMAC significantly reduces image distortion, compared to FSE sequence in 3.0-T MR. Also, diagnostic confidence for post-operative complications was higher when FSE with additional FSE-SEMAC compared to FSE only. [ABSTRACT FROM AUTHOR]

Background: Indirect magnetic resonance (MR) arthrography is a non-invasive method for shoulder imaging. However, there are no studies that have examined the diagnostic performance of indirect MR arthrography for the diagnosis of rotator cuff tears in a large patient population. Purpose: To assess the diagnostic performance of indirect fast spin-echo (FSE) MR arthrography for the diagnosis of rotator cuff tears at 3.0 T. Material and Methods: A total of 149 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery were enrolled in this retrospective study. Two musculoskeletal radiologists evaluated images from each patient for the presence of supraspinatus-infraspinatus (SSP-ISP) or subscapularis (SSC) tendon tears. Using the arthroscopic findings as the reference standard, the overall diagnostic performance and detection rates for SSP-ISP and SSC tendon tears were calculated. Results: The sensitivity, specificity, and accuracy of readers I and II for the diagnosis of SSP-ISP tendon tears were 94% and 95%, 89% and 85%, and 93% and 93%, respectively. The sensitivity of imaging for detection of SSP-ISP tendon tears by readers I and II were 100% and 100% for full-thickness tears and 84% and 86% for partial-thickness tears, respectively. The sensitivity, specificity, and accuracy of readers I and II for the diagnosis of SSC tendon tears were 80% and 76%, 89% and 93%, and 85% and 85%, respectively. Conclusion: Indirect MR arthrography is useful for the detection of SSP-ISP and SSC tendon tears. [ABSTRACT FROM AUTHOR]

In this paper, we present an extended particle difference method for moving boundary (or interface) problems. The particle derivative approximation is further developed to approximate the Taylor polynomial with the moving least squares method through completely node-wise computations. The discontinuity (or singularity) in the derivative field and the kinetic relation of the interfacial physics are effectively immersed into the particle derivative approximation. The segmented points that discretize the moving interface are consecutively updated in an explicit manner to track the evolution of the moving interface topology. Discretized difference equations for the governing equations are directly constructed at the nodes and the segmented points of the computational domain and the moving interface, respectively. Assemblage of the discretized difference equations yields a linear algebraic system of equations that provides efficient and stable solution procedure for a strong formulation. Numerical examples demonstrate that this method achieves excellent accuracy and efficiency for moving boundary problems. [ABSTRACT FROM AUTHOR]

A multiscale aggregating discontinuities method for treating unit cells which undergo material failure is further described; the method can also be used when the material response predicted by the unit cell loses rank-one stability. Its notable features are the decomposition of the unit cell response into a continuous and a discontinuous response, and the extraction of the equivalent discontinuities by coarse-graining procedures. In this study, the method is further combined with the extended finite element method for macro model and the cracking nodes method for micro model so that arbitrary discontinuities in the macro and the micro models can be treated free from the initial mesh topologies. The examples that are studied include a composite with circular inclusions and a micro cracking solid with an emerging macro failure. [ABSTRACT FROM AUTHOR]

The Extended Particle Difference Method is developed for interfacial singularity problems based on the Extended Particle Derivative Approximation scheme. Node-wise strong formulations are adopted for transient heat transfer problems, potential problems, and elasticity problems with various interfacial boundaries. The governing partial differential equations are directly discretized at interior and boundary nodes and the interface condition is immersed in the derivative approximation or is enforced at interfacial points. Assemblage of the discretized equations generates a linear algebraic system of equations, which accelerates computation speed due to the avoidance of numerical integration. Solving the system gives the nodal solution together with the jump solutions. We also demonstrate the robustness and effectiveness of the developed method with various numerical examples. Despite the existence of the singularity in the solution fields, the method overcomes the geometrical complexity inherent in interface modeling and thus achieves the second-order accuracy. [ABSTRACT FROM AUTHOR]

In this paper, the extended particle derivative approximation (EPDA) scheme is developed to solve weak and strong discontinuity problems. In this approximation scheme, the Taylor polynomial is extended with enrichment functions, i.e. the step function, the wedge function, and the scissors function, based on the moving least squares procedure in terms of nodal discretization. Throughout numerical examples, we demonstrate that the EPDA scheme reproduces weak and strong discontinuities in a singular solution quite well, and effectively copes with the difficulties in computing the derivatives of the singular solution. The governing partial differential equations, including the interface conditions, are directly discretized in terms of the EPDA scheme, and the total system of equations is derived from the formulation of difference equations which is constructed at the nodes and points representing the problem domain and the interfacial boundary, respectively. [ABSTRACT FROM AUTHOR]

Although radiation therapy (RT) plays an important role in the palliation of localized bone metastases, there is no consensus on a reliable method for evaluating treatment response. Therefore, we retrospectively evaluated the potential of magnetic resonance imaging (MRI) using apparent diffusion coefficient (ADC) maps and conventional images in whole-tumor volumetric analysis of texture features for assessing treatment response after RT. For this purpose, 28 patients who received RT for osteolytic bone metastasis and underwent both pre- and post-RT MRI were enrolled. Volumetric ADC histograms and conventional parameters were compared. Cox regression analyses were used to determine whether the change ratio in these parameters was associated with local disease progression-free survival (LDPFS). The ADCmaximum, ADCmean, ADCmedian, ADCSD, maximum diameter, and volume of the target lesions after RT significantly increased. Change ratios of ADCmean < 1.41, tumor diameter ≥ 1.17, and tumor volume ≥ 1.55 were significant predictors of poor LDPFS. Whole-tumor volumetric ADC analysis might be utilized for monitoring patient response to RT and potentially useful in predicting clinical outcomes. [ABSTRACT FROM AUTHOR]

Objective: To compare the diagnostic value of indirect magnetic resonance arthrography (I-MRA) with that of direct MR arthrography (D-MRA) for labral tears, rotator cuff tears, and long head of biceps tendon (LHBT) tears using a 3-T MR unit.Materials and Methods: Institutional review board approval was given; written informed consent was obtained from all patients. From November 2005 to June 2006, 19 patients (eight men and 11 women; mean age, 51 years) who had undergone both I-MRA and D-MRA underwent arthroscopic surgery. Both methods were performed in fat-saturated axial, coronal oblique, and sagittal oblique T1-weighted sequences, as well as axial and coronal oblique T2-weighted sequences. Two radiologists independently and retrospectively evaluated two sets of MRA for the diagnosis of superior and anterior labral tears, subscapularis tendon (SSC), and supraspinatus-infraspinatus tendon (SSP-ISP) tears, and LHBT tears. With the arthroscopic finding as a gold standard, we analyzed statistical differences of sensitivities and specificities between two sets of MRA and inter-observer agreement was evaluated using the kappa value.Results: The sensitivity and specificity of I-MRA and D-MRA for reader 1 were 79/80% and 71/80%, respectively, for superior labral tears; 100/100% and 100/100%, respectively, for anterior labral tears; 64/75% and 64/100%, respectively, for SSC tears; 100/86% and 100/100%, respectively, for SSP-ISP tears; and 67/100% and 78/100%, respectively, for LHBT tears. Those of I-MRA and D-MRA for reader 2 were 86/80% and 71/100%, respectively, for superior labral tears; 100/83% and 100/100%, respectively, for anterior labral tears; 64/88% and 82/100%, respectively, for SSC tears; 92/86% and 100/100%, respectively, for SSP-ISP tears; and 78/90% and 89/100%, respectively, for LHBT tears. No significant differences were found between the methods. Inter-observer agreements were higher than moderate (kappa > 0.41) with both methods.Conclusions: Based on a relatively small number of patients, no significant difference was detected between I-MRI and D-MRI with regard rotator cuff, labral, and LHBT tears. [ABSTRACT FROM AUTHOR]

Abstract: A sharp meshfree approximation for derivative discontinuities across arbitrary interfaces is proposed. The interface can be arbitrarily located in a domain in which nodes are distributed uniformly or irregularly. The proposed meshfree approximations consist of two parts, singular and regular. The moving least square meshfree approximation is used together with the local wedge function as basis functions. The approximations for discontinuities are applied in a meshfree point collocation method to obtain solutions of the Poisson problem with a layer delta source on the interface and second order elliptic problems with discontinuous coefficients and/or the singular layer sources along the interface. The numerical calculations show that this method has good performance even on irregular node models. [Copyright &y& Elsevier]

Abstract: A meshfree collocation method with intrinsic enrichment for solving elastic crack problems is presented. A diffuse derivative approximation is applied in conjunction with an intrinsic enrichment of the near-tip asymptotic fields and a polynomial basis. These consistent diffuse derivatives of the approximation do not require computing the derivative of the weight function or that of the moment matrix. The local behavior of the near-tip stresses is successfully captured so that the stress intensity factors can be accurately computed. Numerical experiments demonstrate the accuracy and robustness of the method for solving elastic fracture problems. [Copyright &y& Elsevier]

An enhanced element-free Galerkin (EFG) method with enhancement functions is proposed to improve the solution accuracy for linear elastic fracture problem. The enhancement functions are added to the conventional EFG approximation for the implicit description of near-tip field. The discontinuity of crack surface is efficiently modeled by introducing a discontinuity function. Essential boundary conditions are enforced with the penalty method and a coupling with finite element. The proposed method models the crack growth implicitly without node operation so that the initial node arrangement is not modified until the end of analysis. Numerical examples for various crack problems show the robustness of the proposed method by examining the stress intensity factor, near-tip stress field and errors. [Copyright &y& Elsevier]

• Numerical analysis for rate dependency of concrete using Particle Difference Method based on the strong formulation • Simulation of viscosity and softening in concrete by proportional damping algorithm and damage model. • Modeling of crack propagation shape by visibility criterion and extension of traction boundary. • Examining the relationship between the mass and stiffness professional damping effects and the rate dependency of concrete. • Checking the impact of rate dependency of concrete on crack propagation. This study presents the use of the dynamic particle difference method (PDM) to analyze tensile failure in concrete subjected to high loading rates. In general, strong form-based meshfree methods suffer from limitations pertaining to the material modeling of concrete because concrete exhibits both softening and damage behaviors that initiate crack growth under an impact load. These methods are generally based on the direct discretization of the governing equations, such as Navier's equation, which involves second-order differentiation. However, conventional material models are based on the first-order derivatives of displacement. The newly developed dynamic PDM can effectively address the limitations of material modeling using a combination of first-order derivative approximations. This circumvents the requirement for high-order derivative approximations, which are essential in strong formulations, such as the finite difference method and point collocation method. The strain rate effect caused by an extremely high loading speed was successfully modeled by accurately reflecting the energy dissipations that result from the cohesive property of the concrete and brittle cracking. Although the developed method incorporates the elastic constitutive relation, it enables the effective modeling of these nonlinear effects. In addition, it can reduce the computational effort. The proportional damping algorithm simulates the effect of velocity in the equation of motion and the cohesion effect in the concrete material. The damage model and the visibility criterion adequately handle crack initiation and propagation in the concrete member. Furthermore, it is noteworthy that the final discrete forms of the dynamic PDM are similar to the integrands of the weak form in the conventional finite element formulation. We ascertained that the stiffness and mass proportional damping effects are related to the inertia and strain of the material, respectively. It was confirmed that the location and direction of crack propagation in concrete varied with the strain rate. Hence, the accuracy and robustness of the proposed method were successfully verified by simulation, and the strain-rate dependency of concrete fracture was efficiently simulated using the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the Interface Immersed Particle Difference Method (IIPDM) for weak discontinuity in elliptic problems is presented. Heat conduction and potential flow problems with smooth and non-smooth interfaces are considered. The previously developed Particle Difference Method (PDM) accurately solves this class of interfacial singularity problems, however, it requires additional difference equations on the interfacial points. In contrast, the IIPDM no longer requires the additional interfacial equations since the interface condition is already immersed in the particle derivative approximation through the moving least squares procedure. The method successfully captures both singularities and discontinuities in the derivative field due to the interface geometry regardless of its smoothness. In fact, enforcement of the interface condition is conducted both in an implicit manner and in an explicit manner enriching the polynomial basis as well as the local approximation. Under the constrained derivative approximation, discretization of the elliptic PDE in its strong form leads to a difference scheme or a point collocation scheme involving only the particles. Consequently, the strong formulation can avoid the increase in total system size and improves the computational efficiency. Numerical experiments show that the IIPDM can sharply capture discontinuities and singularities within a solution field. Furthermore, convergence studies of various elliptic interface problems demonstrate efficiencies captured from the IIPDM when comparing convergence rates against the PDM. • Strong form meshfree collocation method for weak discontinuity. • Particle derivative approximation with the immersed interface condition. • Enforcing interface condition through the enriched local approximation. • Improving computational efficiency by avoiding increasing the total system size. • Heat conduction and potential flow problems with smooth and non-smooth interfaces. [ABSTRACT FROM AUTHOR]

In this study, an influence of the front steel plate of the steel-plate concrete (SC) composite walls on the impact resistance performance is analytically derived, and verified by comparison with numerical analyses and experiment results. SC composite wall is remarkably superior in resistance against impacts compared to normal concrete because steel plates control and prevent fragmentation caused by the fracture of concrete material. An analytical criterion for estimating resistance capacity against impact loads is proposed by adding the effect of a front steel plate into the existing impact resistance equation of SC composite walls, and the criterion more accurately predicts the failure modes of SC composite walls in the impact tests. Finite element (FE) models are constructed to predict the impact response of SC composite walls numerically and verified with experiment results. The critical velocity is numerically derived using FE models by performing a large number of iterative simulations, and the proposed criterion including the effect of front steel plate is more accurate for estimating critical velocity than the formula that ignores the front steel plate. The proposed analytical and numerical procedures will be useful for assessing the critical velocities and failure modes of SC composite walls with better accuracy. • We derive an analytical criterion including the effect of the front steel plate. • Numerical models are verified in terms of the residual velocity of the projectile. • The criterion is verified by comparing with experimental and numerical results. • The effect of the front plate should be considered for accurate estimation. [ABSTRACT FROM AUTHOR]

The objectives of this study were to assess the fat fraction (FF) and cross-sectional area (CSA) of the sciatic nerve in Charcot-Marie-Tooth disease type 1A (CMT1A) patients using Dixon-based proton density fat quantification MRI and to elucidate its potential association with clinical parameters. Thigh MRIs of 18 CMT1A patients and 18 age- and sex-matched volunteers enrolled for a previous study were reviewed. Analyses for FF and CSA of the sciatic nerve were performed at three levels (proximal to distal). CSA and FF were compared between the two groups and among the different levels within each group. The relationship between the MRI parameters and clinical data were assessed in the CMT1A patients. The CMT1A patients showed significantly higher FF at level 3 (p = 0.0217) and significantly larger CSA at all three levels compared with the control participants (p < 0.0001). Comparisons among levels showed significantly higher FF for levels 2 and 3 than for level 1 and significantly larger CSA for level 2 compared with level 1 in CMT1A patients. CSA at level 3 correlated positively with the CMT neuropathy score version 2 (CMTNSv2). In conclusion, the sciatic nerve FF of CMT1A patients was significantly higher on level 3 compared with both the controls and the measurements taken on more proximal levels, suggesting the possibility of increased intraepineurial fat within the sciatic nerves of CMT1A patients, with a possible distal tendency. Sciatic nerve CSA at level 3 correlated significantly and positively with CMTNSv2, suggesting its potential value as an imaging marker for clinical severity. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop, validate, and compare nomograms for malignancy prediction in soft tissue tumors (STTs) using conventional and diffusion-weighted magnetic resonance imaging (MRI) measurements. Between May 2011 and December 2016, 239 MRI examinations from 236 patients with pathologically proven STTs were included retrospectively and assigned randomly to training (n = 100) and validation (n = 139) cohorts. MRI of each lesion was reviewed to assess conventional and diffusion-weighted imaging (DWI) measurements. Multivariate nomograms based on logistic regression analyses were built using conventional measurements with and without DWI measurements. Predictive accuracy was measured using the concordance index (C-index) and calibration plots. Statistical differences between the C-indexes of the two models were analyzed. Models were validated by leave-one-out cross-validation and by using a validation cohort. The mean lesion size, presence of infiltration, edema, and the absence of the split fat sign were significant and independent predictors of malignancy and included in the conventional model. In addition to these measurements, the mean and minimum apparent diffusion coefficient values were included in the DWI model. The DWI model exhibited significantly higher diagnostic performance only in the validation cohort (training cohort, 0.899 vs. 0.886, P = 0.284; validation cohort, 0.791 vs. 0.757, P = 0.020). Calibration plots showed fair agreements between the nomogram predictions and actual observations in both cohorts. In conclusion, nomograms using MRI features as variables can be utilized to predict the malignancy probability in patients with STTs. There was no definite gain in diagnostic accuracy when additional DWI features were used. [ABSTRACT FROM AUTHOR]

Objectives: To retrospectively determine the diagnostic ability of MRI in differentiating between intradural extramedullary spinal schwannomas and meningiomas. Methods: A total of 199 patients with spinal intradural extramedullary tumors who underwent preoperative contrast-enhanced MRI between January 2012 and December 2018 were included in this study. Two radiologists independently analyzed the presence of cystic change, dural tail sign, and neural foraminal extension. Clinical and MRI features between the two groups were compared by univariable and multivariable analyses using logistic regression. Interobserver agreements were calculated using kappa statistics. Results: Patients with schwannoma showed significantly higher frequency of cystic change (96% vs 24%, P < 0.001), neural foraminal extension (29% vs 3%, P = 0.001), and lumbar location (41% vs 5%, P = 0.008). Patients with meningioma showed significantly higher frequency of dural tail sign (64% vs 1%, P < 0.001), thoracic location (75% vs 31%, P = 0.007), older age (59.7 years vs 47.6 years, P < 0.001), higher female predominance (83% vs 50%, P < 0.001), and smaller size (19.8 cm vs 28.8 cm, P < 0.001). Multivariable analysis showed that cystic change (P < 0.001; odds ratio [OR], 0.02), dural tail sign (P < 0.001; OR, 36.23), age (P = 0.032; OR, 1.06), and lumbar location (P = 0.006; OR, 0.02) were independent factors. Interobserver agreements were almost perfect for all analyses. Conclusions: MRI features were useful in differentiating between intradural extramedullary schwannomas from meningiomas. The presence of cystic change and dural tail sign were independently significant discriminators. [ABSTRACT FROM AUTHOR]

Objectives: To compare magnetic resonance imaging (MRI) parameters of small, deeply located non-malignant and malignant soft-tissue tumors (STTs). Methods: Between May 2011 and December 2017, 95 MRIs in 95 patients with pathologically proven STTs of small size (<5 cm) and deep location (66 non-malignant and 29 malignant) were identified. For qualitative parameters, consensus reading was performed by three radiologists for presence of necrosis, infiltration, lobulation, and the tail sign. Apparent diffusion coefficient (ADC) was analyzed by two other radiologists independently. Univariable and multivariable analyses were performed to determine the diagnostic performances of MRI parameters in differentiating non-malignancy and malignancy, and for non-myxoid, non-hemosiderin STTs and myxoid STTs as subgroups. Interobserver agreement for ADC measurement was calculated with the intraclass correlation coefficient. Results: Interobserver agreement on ADC measurement was almost perfect. On univariable analysis, the malignant group showed a significantly larger size, lower ADC, and higher incidence of all qualitative MRI parameters for all STTs. Size (p = 0.012, odds ratio [OR] 2.57), ADC (p = 0.041, OR 3.85), and the tail sign (p = 0.009, OR 6.47) were independently significant on multivariable analysis. For non-myxoid, non-hemosiderin STTs, age, size, ADC, frequency of infiltration, lobulation, and the tail sign showed significant differences between non-malignancy and malignancy on univariable analysis. Only ADC (p = 0.032, OR 142.86) retained its independence on multivariable analysis. For myxoid STTs, only size and tail sign were significant on univariable analysis without independent significance. Conclusions: Size, ADC, and incidence of qualitative MRI parameters were significantly different between small, deeply located non-malignant and malignant STTs. Only ADC was independently significant for both overall analysis and the non-myxoid, non-hemosiderin subgroup. [ABSTRACT FROM AUTHOR]

I Purpose or Learning Objective: i Spinal myxopapillary ependymoma is a rare but clinically distinct intradural extramedullary tumor that can share imaging features with a schwannoma. Patients with myxopapillary ependymoma showed a significantly higher frequency of lower extremity weakness (33.33% versus 3.77%; I P i = 0.001), bladder/bowel dysfunction (25% versus 0%; I P i < 0.001), and local recurrence/leptomeningeal seeding progression on follow-up MRI (13.33% versus 0%; I P i = 0.049). Patients with myxopapillary ependymoma showed a higher frequency of lower extremity weakness and bladder/bowel dysfunction at presentation. [Extracted from the article]

The objective of this study was to examine the tumor spatial heterogeneity in myxoid-containing soft-tissue tumors (STTs) using texture analysis of diffusion-weighted imaging (DWI). A total of 40 patients with myxoid-containing STTs (23 benign and 17 malignant) were included in this study. The region of interest (ROI) was manually drawn on the apparent diffusion coefficient (ADC) map. For texture analysis, the global (mean, standard deviation, skewness, and kurtosis), regional (intensity variability and size-zone variability), and local features (energy, entropy, correlation, contrast, homogeneity, variance, and maximum probability) were extracted from the ADC map. Student’s t-test was used to test the difference between group means. Analysis of covariance (ANCOVA) was performed with adjustments for age, sex, and tumor volume. The receiver operating characteristic (ROC) analysis was performed to compare diagnostic performances. Malignant myxoid-containing STTs had significantly higher kurtosis (P = 0.040), energy (P = 0.034), correlation (P<0.001), and homogeneity (P = 0.003), but significantly lower contrast (P<0.001) and variance (P = 0.001) compared with benign myxoid-containing STTs. Contrast showed the highest area under the curve (AUC = 0.923, P<0.001), sensitivity (94.12%), and specificity (86.96%). Our results reveal the potential utility of texture analysis of ADC maps for differentiating benign and malignant myxoid-containing STTs. [ABSTRACT FROM AUTHOR]

We aimed to derive comprehensive MRI parameters that reflect intramuscular fat infiltration severity for designated lower extremity levels, based on semiquantitative analyses in Charcot-Marie-Tooth disease type 1A (CMT1A) patients. We reviewed lower extremity MRIs of 116 CMT1A patients. Intramuscular fat infiltration grading using the Mercuri scale was performed for the non-dominant lower extremity at three levels (proximal, mid, and distal) for the thigh and at two levels (proximal and distal) for the lower leg. Based on MRI results, the following parameters were calculated for each level and for entire muscles: fat infiltration proportion (FIP), significant fat infiltration proportion (SigFIP), and severe fat infiltration proportion (SevFIP). The relationships between the MRI parameters and clinical data were evaluated using Spearman's correlation analysis. FIP, SigFIP, and SevFIP measured for entire muscles significantly correlated with Charcot-Marie-Tooth Neuropathy Score (p < 0.001), functional disability scale (p < 0.001), 10-m walk test time (p = 0.0003, 0.0010, and 0.0011), and disease duration (p < 0.001). Similar correlations were demonstrated for FIP, SigFIP, and SevFIP acquired from the lower leg. Our MRI parameters obtained through semiquantitative analyses of muscles significantly correlated with clinical parameters in CMT1A patients, suggesting their potential applicability as imaging markers for clinical severity. [ABSTRACT FROM AUTHOR]

Introduction: We aimed to identify imaging‐based findings that can differentiate between spinal subchondral bone metastasis with focal pathologic endplate fracture and oedematous Schmorl's nodes that have been histopathologically confirmed. Methods: Between March 2010 and April 2016, 11 patients who had undergone spinal magnetic resonance (MR) imaging or computed tomography (CT) with final radiologic reports that included 'subchondral bone metastasis with focal pathologic endplate fracture' or 'edematous Schmorl's node' and had also undergone percutaneous imaging‐guided spinal biopsies were included. Two radiologists retrospectively evaluated the following imaging features in consensus: size, location, presence of sclerotic margin, presence of intralesional or perilesional enhancement and opposite endplate enhancement of the involved disc, presence of disc height loss and presence of metabolic uptake at a corresponding lesion on nuclear medicine imaging. Results: A total of 11 patients, including six patients with spinal subchondral bone metastasis with focal pathologic endplate fracture and five patients with oedematous Schmorl's nodes, were included in this study (median age, 58 years; range, 50–63 years; six men). Sclerotic margin (P = 0.002) and enhancement on the opposite endplate of the involved disc (P = 0.047) were significantly different between oedematous Schmorl's node and subchondral bone metastasis with focal pathologic endplate fracture. Conclusion: Sclerotic margin and enhancement on the opposite endplate of the involved disc suggest oedematous Schmorl's node rather than subchondral bone metastasis with focal pathologic endplate fracture. Decreased disc height is likely to be an oedematous Schmorl's node rather than subchondral bone metastasis with focal pathologic endplate fracture. [ABSTRACT FROM AUTHOR]

This paper presents a novel particle difference method (PDM) for solving dynamic crack propagation problems. The PDM is based on the strong formulation that directly discretizes the governing partial differential equations for space and takes advantage of fast computation speed owing to the exemption of numerical integration and the full differentiation of the approximation by using the Taylor polynomial expanded by the moving least squares method. It also differentiates the discrete equations for time through both explicit and implicit algorithms; specifically, the Newmark method (NM) is effectively modified for complete explicit and implicit time integrations. Nodal topology change due to the crack propagation modeling is easily conducted by simple addition and deletion of nodes. Dynamic fracture simulation is successfully performed by the help of the visibility criterion and dynamic energy release rate evaluation. Robustness and effectiveness of the PDM are thoroughly verified through various numerical experiments. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed metastases involving the subcutaneous fat layer of the trunk and pelvis.We included 30 patients with subcutaneous metastases in the trunk and pelvis, verified by ultrasound-guided biopsy. We comprehensively reviewed ultrasound findings of all 30 patients and contrast-enhanced CT findings of 25 patients obtained before biopsy. Medical records were reviewed, including primary malignancy type, presence of coexisting distant metastasis, and detection method leading to biopsy referral.Most subcutaneous metastases were heterogeneously hypoechoic (86.7%) with well-defined margins (80.0%), lobulated (46.7%) or round-to-oval (40.0%) shape, and vascularity (96.7%). Metastases frequently exhibited no contact (53.3%) or focal contact with deep peripheral fascia, resulting in acute contact angle formation (30.0%). Common CT manifestations included central low attenuation with peripheral rim-like enhancement (60.0%) or well-circumscribed lesion with heterogeneous enhancement (32.0%). Lung cancer (46.7%) was the prevalent primary malignancy. CT was the predominant detection method (56.7%). Coexisting subcutaneous metastases were present in 50.0% of cases, and distant metastases (less subcutaneous metastases) were observed in 90.0% of patients.This study describes typical imaging findings of subcutaneous metastases involving the trunk and pelvis. CT may play a crucial role in their early detection, and our results may assist radiologists in their diagnosis.Materials and methods: This study aimed to describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed metastases involving the subcutaneous fat layer of the trunk and pelvis.We included 30 patients with subcutaneous metastases in the trunk and pelvis, verified by ultrasound-guided biopsy. We comprehensively reviewed ultrasound findings of all 30 patients and contrast-enhanced CT findings of 25 patients obtained before biopsy. Medical records were reviewed, including primary malignancy type, presence of coexisting distant metastasis, and detection method leading to biopsy referral.Most subcutaneous metastases were heterogeneously hypoechoic (86.7%) with well-defined margins (80.0%), lobulated (46.7%) or round-to-oval (40.0%) shape, and vascularity (96.7%). Metastases frequently exhibited no contact (53.3%) or focal contact with deep peripheral fascia, resulting in acute contact angle formation (30.0%). Common CT manifestations included central low attenuation with peripheral rim-like enhancement (60.0%) or well-circumscribed lesion with heterogeneous enhancement (32.0%). Lung cancer (46.7%) was the prevalent primary malignancy. CT was the predominant detection method (56.7%). Coexisting subcutaneous metastases were present in 50.0% of cases, and distant metastases (less subcutaneous metastases) were observed in 90.0% of patients.This study describes typical imaging findings of subcutaneous metastases involving the trunk and pelvis. CT may play a crucial role in their early detection, and our results may assist radiologists in their diagnosis.Results: This study aimed to describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed metastases involving the subcutaneous fat layer of the trunk and pelvis.We included 30 patients with subcutaneous metastases in the trunk and pelvis, verified by ultrasound-guided biopsy. We comprehensively reviewed ultrasound findings of all 30 patients and contrast-enhanced CT findings of 25 patients obtained before biopsy. Medical records were reviewed, including primary malignancy type, presence of coexisting distant metastasis, and detection method leading to biopsy referral.Most subcutaneous metastases were heterogeneously hypoechoic (86.7%) with well-defined margins (80.0%), lobulated (46.7%) or round-to-oval (40.0%) shape, and vascularity (96.7%). Metastases frequently exhibited no contact (53.3%) or focal contact with deep peripheral fascia, resulting in acute contact angle formation (30.0%). Common CT manifestations included central low attenuation with peripheral rim-like enhancement (60.0%) or well-circumscribed lesion with heterogeneous enhancement (32.0%). Lung cancer (46.7%) was the prevalent primary malignancy. CT was the predominant detection method (56.7%). Coexisting subcutaneous metastases were present in 50.0% of cases, and distant metastases (less subcutaneous metastases) were observed in 90.0% of patients.This study describes typical imaging findings of subcutaneous metastases involving the trunk and pelvis. CT may play a crucial role in their early detection, and our results may assist radiologists in their diagnosis.Conclusion: This study aimed to describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed metastases involving the subcutaneous fat layer of the trunk and pelvis.We included 30 patients with subcutaneous metastases in the trunk and pelvis, verified by ultrasound-guided biopsy. We comprehensively reviewed ultrasound findings of all 30 patients and contrast-enhanced CT findings of 25 patients obtained before biopsy. Medical records were reviewed, including primary malignancy type, presence of coexisting distant metastasis, and detection method leading to biopsy referral.Most subcutaneous metastases were heterogeneously hypoechoic (86.7%) with well-defined margins (80.0%), lobulated (46.7%) or round-to-oval (40.0%) shape, and vascularity (96.7%). Metastases frequently exhibited no contact (53.3%) or focal contact with deep peripheral fascia, resulting in acute contact angle formation (30.0%). Common CT manifestations included central low attenuation with peripheral rim-like enhancement (60.0%) or well-circumscribed lesion with heterogeneous enhancement (32.0%). Lung cancer (46.7%) was the prevalent primary malignancy. CT was the predominant detection method (56.7%). Coexisting subcutaneous metastases were present in 50.0% of cases, and distant metastases (less subcutaneous metastases) were observed in 90.0% of patients.This study describes typical imaging findings of subcutaneous metastases involving the trunk and pelvis. CT may play a crucial role in their early detection, and our results may assist radiologists in their diagnosis. [ABSTRACT FROM AUTHOR]

Background: Perineural spread (PNS) of tumors from pelvic malignancies is a rare phenomenon but constitutes an important differential diagnosis of lumbosacral plexopathy (LSP). Herein, we describe the clinical and imaging features of patients with LSP due to PNS of pelvic malignancies along with a literature review. Methods: We retrospectively reviewed 9 cases of LSP caused by PNS of pelvic malignancy between January 2006 and August 2021, and all clinical and imaging parameters were recorded in detail. Clinical symptoms and signs of patients were described and listed in the order in which they occurred. The results of imaging test were analyzed to describe specific findings in LSP caused by PNS. Results: This study enrolled nine adult patients (mean age, 50.1 years). Two cases initially presented as LSP and were later diagnosed with pelvic malignancy. Pain in the perianal or inguinal area preceded pain at the extremities in six patients. Neurogenic bladder or bowel symptoms developed in five patients. On the magnetic resonance imaging (MRI), the S1-S2 spinal nerve was most commonly involved, and S1 myotome weakness was more prominent in six patients than the other myotomes. One patient had an intradural extension. 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) showed abnormal signal intensity in six patients. No abnormality in 18F-FDG PET/CT was detected in the nervous structures in one patient. Only four patients survived until the last follow-up visit. Conclusions: Though rare, physicians should always keep in mind the possibility of LSP due to the PNS in patients with pelvic malignancy. Thorough physical examination and history taking could provide clues for diagnosis. Pelvic MRI and 18F-FDG-PET/CT should be considered for patients with LSP to rule out neoplastic LSP. [ABSTRACT FROM AUTHOR]

A meshfree collocation method with an intrinsic wedge enrichment is presented for solving interface problems. To approximate the class of functions with discontinuous derivatives on the interface, the wedge is asymptotically added to the basis functions. A general class of wedge basis functions with specified orders of asymptotic behavior at the interface is developed for moving least square approximations. These are implemented in diffuse derivative methods where the shape functions are approximately differentiated. The reproducing properties of these approximations for the polynomial part and for the wedge function along straight boundaries of the basis are demonstrated. For curved boundaries, the reproducing properties of the wedge functions are more restricted. Numerical results show the ease of constructing the intrinsic enrichment and the robustness of the numerical scheme in solving interface problems. [ABSTRACT FROM AUTHOR]

Objectives Muscle involvement in Behçet's disease (BD) is rare, and several cases have been reported in the literature. Therefore, this study aimed to describe the clinical, laboratory and imaging findings in adult patients presenting with BD-associated myositis before the diagnosis of BD. Methods We retrospectively screened patients who visited a locomotive medicine clinic presenting with myalgia, local swelling, or tenderness of extremities without an established diagnosis of BD. We enrolled patients whose pain in the extremities was proven to be suggestive of focal vasculitic myositis and who were eventually diagnosed as having BD at the initial visit or during follow-up. We thoroughly reviewed the clinical, histological and imaging findings and treatment outcomes in patients who presented with focal vasculitic myositis as the primary manifestation of BD. Results Ten adult patients with focal vasculitic myositis as the primary manifestation of BD were enrolled. The lower and upper extremities were affected in eight and two patients, respectively. The affected lower extremities were the calf (n  = 6) and thigh muscles (n  = 2). The common findings of MRI included high signal intensity of the affected muscles and intermuscular fascia on fat-suppressed images, suggestive of myofascitis and oedematous changes in the subcutaneous layer. The results of skin or muscle biopsy were suggestive of vasculitis. All the patients were pain-free at the short-term follow-up (1–3 weeks) after oral steroid therapy. Conclusion Focal vasculitic myositis can be a primary manifestation of BD warranting medical attention. BD-associated myositis responds well to oral steroid therapy. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the yield of concurrent systemic biopsy (SB) during MRI-targeted biopsy (MRTB) as Prostate Imaging Reporting and Data System (PI-RADS) version 2 (v2) interpretations in patients with suspected prostate cancer (PCa). Methods: A total of 285 patients with suspected PCa underwent prebiopsy 3-T MRI, followed by MRI-transrectal ultrasound fusion targeted biopsy and concurrent standard SB for lesions with PI-RADS v2 scores 3–5. Detection rates and positive core rates of PCa and clinically significant cancer (CSC) were evaluated. Results: In concurrent MRTB and SB, PCa and CSC detection rates were 18.9% and 9.4% for PI-RADS score 3, 45.9% and 32.4% for PI-RADS score 4, and 82.1% and 72.6% for PI-RADS score 5, respectively. Overall detection rate of CSCs (40.0%) for concurrent MRTB and SB was significantly higher than that of MRTB (34.4%, p = 0.004) or SB alone (27.7%, p < 0.001): an increase of 5.6% (16 patients) compared with MRTB alone. For patients with PI-RADS score 4 or 5, the CSC detection rate of concurrent MRTB and SB was 47.0%, an increase of 6.1% when compared with MRTB (40.9%) only (p < 0.001). Of the 110 patients with both MRTB- and SB-positive findings, 22 (20.0%) had the highest Gleason score in SB compared with that in MRTB. In 9.5% (27/285) patients including 12 patients with CSCs, only SB was positive, with negative MRTB. Conclusion: Concurrent SB with MRTB based on PI-RADS v2 can yield a higher CSC detection rate compared with MRTB alone in patients with suspected PCa. Key Points: • Concurrent SB with MRTB yields an increase of 5.6% CSC detection compared with MRTB alone. • Of both MRTB- and SB-positive findings, 20.0% patients have upgraded Gleason score in SB. • In 18.4% patients, only SB was positive, with negative MRTB. Adding MRTB to SB is helpful for adequate risk stratification, reducing diagnostic uncertainty of PCa. [ABSTRACT FROM AUTHOR]

Purpose: To assess graft vascularity via dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) at 1-year and 2-year postoperatively and to evaluate the relationship between the vascularity using DCE-MRI and the synovialization using second-look arthroscopy.Materials and Methods: Fifty-four patients from prospective data included who underwent anterior cruciate ligament reconstruction (ACLR) and DCE-MRI. The graft was divided into proximal, middle, and distal zones; average of three zones was calculated. Signal/noise quotient (SNQ) was measured on proton-density image and normalized area under the curve (nAUC) was calculated from DCE-MRI. The results at 1-year (SNQ-1 and nAUC-1) and 2-year (SNQ-2 and nAUC-2) postoperatively were compared between two time points. Forty-one patients underwent second-look arthroscopy were classified into three groups according to the synovialization: Excellent (n = 17), Fair (n = 16), and Poor (n = 8). The SNQs and nAUCs were compared between three groups.Results: Fifty-four and 23 patients underwent DCE-MRI at 1-year and 2-year, respectively. A significant decrease was observed from nAUCaverage-1 to nAUCaverage-2 (95 % confidential interval, 0.4-2.3; P = .007). Both SNQaverage-1 and SNQaverage-2 were significantly lower in the excellent than in the poor (SNQaverage-1, P < .001; SNQaverage-2, P = .003). Both SNQaverage-1 and SNQaverage-2 were significantly lower in the fair than in the poor (SNQaverage-1, P=.032; SNQaverage-2, P = .012). Both nAUCaverage-1 and nAUCaverage-2 were significantly higher in the excellent than in the poor (nAUCaverage-1, P < .001; nAUCaverage-2, P = .010). The nAUCaverage-1 was significantly higher in the excellent than the fair (nAUCaverage-1, P < .001).Conclusion: Well-synovialized grafts showed significantly lower SNQs and significantly higher nAUCs than did poor-synovialized grafts based on the second-look arthroscopic findings. We can indirectly infer from this result that well-synovialized grafts may have better biomechanical properties. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the prognostic value of diffusion-weighted imaging (DWI) in predicting clinical outcome in patients with cervical cancer after concurrent chemoradiotherapy (CCRT).Methods: We enrolled 124 cervical cancer patients who received definitive CCRT and underwent 3 T-MRI before and 1 month after initiating treatment. The mean apparent diffusion coefficient (ADC) value was measured on the tumor and the changes in ADC percentage (ΔADCmean) between the two time points were calculated. The Cox proportion hazard model was used to evaluate the associations between imaging or clinical variables and progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS).Results: In multivariate analysis, ΔADCmean was the only independent predictor of PFS (hazard ratio [HR] = 0.2379, p = 0.005), CSS (HR = 0.310, p = 0.024), and OS (HR = 0.217, p = 0.002). Squamous cell carcinoma antigen, histology, and pretreatment tumor size were significantly independent predictors of PFS. Tumor size response was significantly independent predictor of CSS and OS. Using the cutoff values of ΔADCmean, the PFS was significantly lower for ΔADCmean < 27.8% (p = 0.001). The CSS and OS were significantly lower for ΔADCmean < 16.1% (p = 0.002 and p < 0.001, respectively).Conclusion: The percentage change in tumor ADC may be a useful predictor of disease progression and survival in patients with cervical cancer treated with CCRT.Key Points: • DWI is widely used as a potential marker of tumor viability. • Percentage change in tumor ADC (ΔADC mean ) was an independent marker of PFS, CSS, and OS. • Survival was better in patients with ≥ ΔADC mean cutoff value than with < the cutoff value. [ABSTRACT FROM AUTHOR]

True neurogenic thoracic outlet syndrome (TN-TOS) is an extremely rare neuromuscular disease. We report clinical, electrodiagnostic and radiologic features of patients with TN-TOS. Retrospective chart review of patients satisfying criteria was done. Nerve conduction study (NCS) and needle electromyography (EMG) of upper extremity were reviewed. Brachial plexus MRI and computed tomography angiography (CTA) were also reviewed. Thirteen TN-TOS patients were identified. The most common neurologic signs were hypesthesia in the medial forearm or ulnar digits and weakness of the abductor pollicis brevis (APB) muscle. In NCS, medial antebrachial cutaneous (MABC) sensory nerve action potential amplitude was decreased in all tested patients. The APB muscle was most commonly involved in EMG. Among radiologic criteria, focal stenosis of subclavian artery in CTA was the most common finding. We confirmed that TN-TOS is T1 predominant lower roots/trunk brachial plexopathy with clinical and electrodiagnostic features. Radiologic studies may be used to detect structural abnormalities. As MABC NCS showed abnormal results in all tested patients, it should be added to electrodiagnostic study as screening method. If present, structural abnormalities might be confirmed with radiologic studies. • Contrary to the traditional view, TN-TOS patients often present with sensory symptoms. • The decrease of SNAP amplitude of MABC nerve in NCS seems the most sensitive marker. • MRI and CTA findings could be used as an ancillary data for the diagnosis of TN-TOS. [ABSTRACT FROM AUTHOR]

The adverse effects of silver nanoparticles (AgNPs) have been studied in various models. However, there has been discordance between molecular responses across the literature, attributed to methodological biases and the physicochemical variability of AgNPs. In this study, a gene pathway meta-analysis was conducted to identify convergent and divergent key events (KEs) associated with AgNPs and explore common patterns of these KEs across species. We performed a cross-species analysis of transcriptomic data from multiple studies involving various AgNPs exposure. Pathway enrichment analysis revealed a set of pathways linked to oxidative stress, apoptosis, and metabolite and lipid metabolism, which are considered potentially conserved KEs across species. Subsequently, experiments confirmed that oxidative stress responses could be early KEs in both Caenorhabditis elegans and HepG2 cells. Moreover, AgNPs preferentially impaired the mitochondria, as evidenced by mitochondrial fragmentation and dysfunction. Furthermore, disruption of amino acids, nucleotides, sulfur compounds, glycerolipids, and glycerophospholipids metabolism were in good agreement with gene pathway shreds of evidence. Our findings imply that, although there may be organism-specific responses, potentially conserved events could exist regardless of species and physicochemical factors. These results provide valuable insights into the development of adverse outcome pathways of AgNPs across species and the regulatory toxicity of AgNPs. [Display omitted] • Meta-analysis of pathway enrichment on toxicogenomics data of AgNPs was performed. • Conserved toxic responses potentially exist among multiple species exposed to AgNPs. • Cross-species reserved Key Events were further validated using HepG2 and C. elegans. • Oxidative stress and altered mitochondrial functions are Key Events among organisms. • Amino acids, sulfur compounds, and various lipid metabolism are highly perturbed. [ABSTRACT FROM AUTHOR]

Background: Although numerous studies have examined the anatomic characteristics of the anterior cruciate ligament (ACL), its actual shape remains unclear. Purpose: To determine the average shape of the ACL by analyzing its cross section through the use of high-resolution magnetic resonance imaging (MRI) data. Study Design: Descriptive laboratory study. Methods: The study included 96 MRIs, conducted using a 3.0-T magnet, to analyze the shape of the ACL. Three-dimensional, curved multiplanar reconstruction was used to obtain cross sections at 7 points (femoral insertion; midsubstance 1, 2, 3, 4, and 5 from the femoral side to the tibial side; and tibial insertion). The width and thickness of cross sections were measured by 2 independent observers, and the ratio of width to thickness was calculated to determine the proportions of each cross section. The 7 cross sections were accumulated and standardized to generate an average model through the use of image analysis software developed by the authors. Results: The mean ± SD width (femoral insertion, 17.02 ± 2.17 mm; tibial insertion, 17.33 ± 2.03 mm) and thickness (femoral insertion, 11.03 ± 1.75 mm; tibial insertion, 10.09 ± 1.70 mm) of both insertions were significantly larger than those of midsubstance 4 (width, 9.99 ± 1.87 mm; thickness, 6.53 ± 1.25 mm) (P < .001). The mean ratios of width to thickness of the 7 cross sections from femoral insertion to tibial insertion were 1.57 ± 0.23, 3.36 ± 0.57, 3.07 ± 0.81, 2.18 ± 0.54, 1.56 ± 0.32, 2.16 ± 0.48, and 1.75 ± 0.28, respectively. The shape of the cross section at midsubstance 4 was an oval isthmus, which was the most narrow and well-balanced shape. It was transformed into a wide band at midsubstance 1 and 5. The shape of the femoral insertion was semicircular, with its anterior side slightly straight and its posterior side convex. The tibial insertion was kidney bean–shaped. Conclusion: On 3.0-T MRI, the ACL has a “bow tie” shape, including an oval isthmus, with a semicircular femoral insertion and kidney bean–shaped tibial insertion. Clinical Relevance: The measurement method will allow surgeons to quantitatively diagnose partial injuries of the ACL using a noninvasive system in actual patients. [ABSTRACT FROM AUTHOR]

Objective: To describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed skeletal muscle metastases involving trunk and pelvis. Methods: 71 patients with 71 skeletal muscle metastases of the trunk and pelvis, pathologically proven by ultrasound‐guided biopsy, were included in the study, and ultrasound findings were reviewed. CT findings were reviewed for 60 patients who underwent post‐contrast CT obtained prior to biopsy, which included skeletal muscle metastases. Medical records, including the type of primary malignancy, presence of coexisting distant metastasis, and method of detection that led to referral for biopsy, were reviewed. Results: Most skeletal muscle metastases were hypoechoic (98.6%) with well‐defined margins (85.9%), round‐to‐oval (47.9%), or lobulated (42.2%) with intralesional vascularity (64.8%). Typical CT findings included abscess‐like lesions with rim enhancement (53.3%) or round‐to‐oval lesions with homogeneous enhancement (40.0%). The most common primary malignancy was lung cancer (49.3%), followed by gastrointestinal cancer (7.0%). Distant metastases other than muscle metastases were found in 84.5% of patients, and coexisting skeletal muscle metastases were found in 47.9%. CT was the most common detection method for metastases (57.8%), being more common than positron emission tomography‐CT (22.5%). Conclusion: The current study describes the typical imaging findings of skeletal muscle metastases of the trunk and pelvis in patients with advanced cancer. CT may play an important role in the early detection of skeletal muscle metastases, and our results may aid radiologists in their diagnosis. Advances in knowledge: 1. Skeletal muscle metastases of the trunk and pelvis demonstrate typical imaging findings on ultrasound and CT. 2. CT may aid in the early detection of skeletal muscle metastases, which are among the rarest, and our results may aid radiologists in their diagnosis. [ABSTRACT FROM AUTHOR]

Objective: To describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed skeletal muscle metastases involving trunk and pelvis. Methods: 71 patients with 71 skeletal muscle metastases of the trunk and pelvis, pathologically proven by ultrasound‐guided biopsy, were included in the study, and ultrasound findings were reviewed. CT findings were reviewed for 60 patients who underwent post‐contrast CT obtained prior to biopsy, which included skeletal muscle metastases. Medical records, including the type of primary malignancy, presence of coexisting distant metastasis, and method of detection that led to referral for biopsy, were reviewed. Results: Most skeletal muscle metastases were hypoechoic (98.6%) with well‐defined margins (85.9%), round‐to‐oval (47.9%), or lobulated (42.2%) with intralesional vascularity (64.8%). Typical CT findings included abscess‐like lesions with rim enhancement (53.3%) or round‐to‐oval lesions with homogeneous enhancement (40.0%). The most common primary malignancy was lung cancer (49.3%), followed by gastrointestinal cancer (7.0%). Distant metastases other than muscle metastases were found in 84.5% of patients, and coexisting skeletal muscle metastases were found in 47.9%. CT was the most common detection method for metastases (57.8%), being more common than positron emission tomography‐CT (22.5%). Conclusion: The current study describes the typical imaging findings of skeletal muscle metastases of the trunk and pelvis in patients with advanced cancer. CT may play an important role in the early detection of skeletal muscle metastases, and our results may aid radiologists in their diagnosis. Advances in knowledge: 1. Skeletal muscle metastases of the trunk and pelvis demonstrate typical imaging findings on ultrasound and CT. 2. CT may aid in the early detection of skeletal muscle metastases, which are among the rarest, and our results may aid radiologists in their diagnosis. [ABSTRACT FROM AUTHOR]