Three-dimensional Shape Model Research Articles

An open-source, three-dimensional growth model of the mandible

The available reference data for the mandible and mandibular growth consists primarily of two-dimensional linear or angular measurements. The aim of this study was to create the first open-source, three-dimensional statistical shape model of the mandible that spans the complete growth period. Computed tomography scans of 678 mandibles from children and young adults between 0 and 22 years old were included in the model. The mandibles were segmented using a semi-automatic or automatic (artificial intelligence-based) segmentation method. Point correspondence among the samples was achieved by rigid registration, followed by non-rigid registration of a symmetrical template onto each sample. The registration process was validated with adequate results. Principal component analysis was used to gain insight in the variation within the dataset and to investigate age-related changes and sexual dimorphism. The presented growth model is accessible globally and free-of-charge for scientists, physicians and forensic investigators for any kind of purpose deemed suitable. The versatility of the model opens up new possibilities in the fields of oral and maxillofacial surgery, forensic sciences or biological anthropology. In clinical settings, the model may aid diagnostic decision-making, treatment planning and treatment evaluation.

Ethnicity Differences in Geometric Remodeling and Myocardial Composition in Hypertension unveiled by Cardiovascular Magnetic Resonance.

Hypertensive patients of African-ancestry (Afr-a) have higher incidences of heart failure and worse clinical outcomes than hypertensive patients of European-ancestry (Eu-a), yet the underlying mechanisms remain misunderstood. This study investigated right (RV) and left (LV) ventricular remodeling alongside myocardial tissue derangements between Afr-a and Eu-a hypertensives. Sixty-three Afr-a and forty-seven Eu-a hypertensives underwent multi-parametric cardiovascular-magnetic-resonance. Biventricular volumes, mass, function, mass/end-diastolic volume (M/V) ratios, T2- and pre/post-contrast T1-relaxation-times, synthetic-extracellular-volume (s-ECV) and myocardial fibrosis (MF) were measured. Three-dimensional shape modeling was implemented to delineate ventricular geometry.LV and RV-mass (indexed to body-surface-area) and M/V ratios were significantly greater in Afr-a than Eu-a hypertensives (67.1±21.7 vs. 58.3±16.7g/m2, 12.6±3.48 vs. 10.7±2.71g/m2, 0.79±0.21 vs. 0.70±0.14g/ml, 0.16±0.04 vs. 0.13±0.03g/ml, respectively; P<0.03) mirroring LV remodeling. Afr-a patients showed greater basal-interventricular-septum thickness than Eu-a patients, which may influence LV hypertrophy and RV cavity changes. This biventricular remodeling was associated with prolonged T2-relaxation-time (47.0±2.2 vs. 45.7±2.2ms, P=0.005) and higher prevalence (23% vs. 4%, P=0.001) and extent of MF (2.3[0.6-14.3] vs. 1.6[0.9-2.5] % of LV-mass, P=0.008) in Afr-a patients. Multivariable linear regression showed modifiable cardiovascular risk-factors and greater end-diastolic volume were independently associated with greater LV or RV-mass. Furthermore, ethnicity was independently associated with greater RV-mass, supporting our hypothesis of ethnic-specific hypertensive remodeling. Afr-a hypertensives had distinctive biventricular remodeling, including increased RV-mass and septal thickening, and subtle myocardial tissue abnormalities compared to Eu-a hypertensives. From this study, modifiable cardiovascular risk-factors, and ventricular geometry, but not ethnicity, were independently associated with higher LV mass.

An advanced three-dimensional analytical model for wind turbine near and far wake predictions

Most existing analytical wake models have been designed to represent the velocity distribution of the far wake region behind a wind turbine, but fail to reproduce the trend of the near wake. In order to meet the demand for both near and far wake velocity predictions, a concise three-dimensional dual-cosine shape (3D-COU) model is proposed. Moreover, by taking into account the wind shear and ground effects in the vertical direction, this model is capable of describing the anisotropic property of the 3-D wake field and is much closer to the reality. The proposed model is then calibrated and validated through a series of test cases, including different scales of turbines that are operating under a wide range of inflow conditions, and meanwhile the reference data resource is diverse. Overall, the results demonstrate that the 3D-COU model can accurately predict the variations of the wake velocity in both the vertical and horizontal directions throughout the whole wake region. Given its good accuracy, simplicity and applicability, this model provides the potential to effectively address practical problems in wind energy projects.

A universal biventricular coordinate system incorporating valve annuli: Validation in congenital heart disease

Universal coordinate systems have been proposed to facilitate anatomic registration between three-dimensional images, data and models of the ventricles of the heart. However, current universal ventricular coordinate systems do not account for the outflow tracts and valve annuli where the anatomy is complex. Here we propose an extension to the ‘Cobiveco’ biventricular coordinate system that also accounts for the intervalvular bridges of the base and provides a tool for anatomically consistent registration between widely varying biventricular shapes. CobivecoX uses a novel algorithm to separate intervalvular bridges and assign new coordinates, including an inflow–outflow coordinate, to describe local positions in these regions uniquely and consistently. Anatomic consistency of registration was validated using curated three-dimensional biventricular shape models derived from cardiac MRI measurements in normal hearts and hearts from patients with congenital heart diseases. This new method allows the advantages of universal cardiac coordinates to be used for three-dimensional ventricular imaging data and models that include the left and right ventricular outflow tracts and valve annuli.

Corrective Osteotomy in a Patient With Congenital Absence of Pronation Based on Three-Dimensional Statistical Shape Modeling

We present a new indication of a three-dimensional statistical shape model (SSM): a patient with bilateral impaired forearm rotation due to a congenital variance in bone shape. A corrective osteotomy was planned and performed to best match the SSM created by computed tomography (CT) scans of 18 peers. Postoperatively, pronation increased by 70°, and the patient was pain-free. A CT scan showed accurate correction of the deformity and union of all osteotomies. This technique offers opportunities for patients with bilateral nontraumatic osseous forearm pathology.

Poster 231: Three-Dimensional Statistical Shape Modeling of Hip Morphology is More Predictive of Femoroacetabular Impingement Syndrome Compared to Traditional Two-Dimensional Radiographic Metrics

Objectives: Femoroacetabular impingement syndrome (FAIS) is classically described as cam, pincer, or mixed morphology, leading to pathologic osseous contact between the femur and acetabulum (Beck JBJS). Many studies have analyzed femur shape variability and/or acetabulum shape variability in isolation, rather than utilizing meaningful articulation of a loaded joint. At present, there is limited evidence characterizing how morphologic variations of an articulated hip joint contribute to FAIS. The primary objective of this study was to assess morphologic variations of the articulated hip joint amongst patients with FAIS compared to an asymptomatic cohort using statistical shape modeling (SSM). The secondary objective was to determine which two-dimensional (2D) measures have the strongest correlation with three-dimensional (3D) parameters associated with FAIS. Methods: This retrospective case-control study recruited 14 patients with unilateral or bilateral symptomatic FAIS and 24 asymptomatic controls with no known history of hip surgery, chronic hip- related pathology, or severe musculoskeletal injury to the lumbar spine, hip, or lower extremity. Participants underwent computed tomography (CT) scans of their bilateral pelvis and proximal femurs (0.5 x 0.5 x 1.25 mm) that were used to create preoperative subject-specific bone models of the proximal femur and hip joint. Participants also underwent static standing biplane radiographs that were used to characterize articulation of their loaded hip joint. These 3D hip positions were determined with sub-millimeter accuracy using a previously validated volumetric model-based tracking process that matched the subject-specific bone models to the biplane radiographs. Once co-registered, left-sided hip joints were mirrored for each patient, to allow for comparison between left and right hip joints, and uploaded to Shapeworks 6.3 for SSM analysis. Using principal component analysis (PCA), complex morphologic variations within the study population were distilled into more digestible categories known as modes, which represented simplified independent morphologic variations. Scores for each mode for each hip are derived from the PCA and represent the morphology of patient-specific hip joints as compared to the overall study cohort. Multivariate regression was performed to identify subject-specific mode scores and demographics that predicted FAI using Stata 16E software. Lastly, Pearson correlations were utilized to correlate 2D measurements of alpha angle, femoral version, and acetabular version to mode scores. Results: Of the 14 symptomatic cases with known cam-type FAIS, 11 met inclusion/exclusion criteria, yielding 11 cases (22 hip joints). Of the 24 controls recruited, no patients were excluded, resulting in 48 additional hip joints. Therefore, the final cohort consisted of 35 patients, roughly one-third of which showed FAIS pathology and eventually underwent femoroplasty, and two-thirds had no history of pathology prior to recruitment. Table 1 details mode descriptions from a surgeon with specialized fellowship training in hip preservation and the amount of explained morphologic variation captured by each mode. Figure 1 illustrates a montage of images that represent variations across Mode 1. Only Mode 1 (p = 0.0006), Mode 6 (p = 0.031), and patient age (p = 0.002) were able to distinguish between cases and controls. However, when further specifying the laterality of surgical intervention for FAIS correction, an interaction was observed between Mode 1 and patient age. More specifically, hip joints with lower Mode 1 values were more likely to require surgery at a younger age; whereas higher Mode 1 values demonstrated no association between age and probability of undergoing surgical intervention ( Figure 2). Mode 6 was not predictive of surgical intervention. When considering 2D measurements, femoral version was the only parameter associated with Mode 1 values (r = -.41, p = 0.004), while alpha angle was the only predictor of Mode 6 values (r = -.41, p = 0.001). Acetabular version was not associated with either. Conclusions: Diagnostic criteria for FAIS are heterogeneous and imprecise. Femoral neck rotation within the acetabulum in combination with anteroposterior placement of the greater trochanter relative to the femoral neck axis is the strongest predictor of symptomatic FAIS. These results highlight the limitations of using 2D static imaging to represent highly complex 3D articulating structures, especially femoral variations. Although less precise than 3D methods, 2D measurements of femoral version, rather than alpha angle, may serve as a more accurate risk assessment for FAIS. SSM more accurately predicts symptomatic FAIS requiring surgery compared to traditional 2D radiographic metrics. This technique may help to identify patients who may benefit from early intervention and facilitate joint preservation. Furthermore, SSM may help identify patients who have a morphology that may be better treated with open rotational osteotomy rather than hip arthroscopy surgery. [Table: see text]

Three-dimensional assessment of interfractional cervical and uterine motions using daily magnetic resonance images to determine margins and timing of replanning.

This study was conducted to determine the margins and timing of replanning by assessing the daily interfractional cervical and uterine motions using magnetic resonance (MR) images. Eleven patients with cervical cancer, who underwent intensity-modulated radiotherapy (IMRT) in 23-25 fractions, were considered in this study. The daily and reference MR images were converted into three-dimensional (3D) shape models. Patient-specific anisotropic margins were calculated from the proximal 95% of vertices located outside the surface of the reference model. Population-based margins were defined as the 90th percentile values of the patient-specific margins. The expanded volume of interest (expVOI) for the cervix and uterus was generated by expanding the reference model based on the population-based margin to calculate the coverage for daily deformable mesh models. For comparison, expVOIconv was generated using conventional margins: right (R), left (L), anterior (A), posterior (P), superior (S), and inferior (I) were (5, 5, 15, 15, 10, 10) and (10, 10, 20, 20, 15, 15) mm for the cervix and uterus, respectively. Subsequently, a replanning scenario was developed based on the cervical volume change. ExpVOIini and expVOIreplan were generated before and after replanning, respectively. Population-based margins were (R, L, A, P, S, I) of (7, 7, 11, 6, 11, 8) and (14, 13, 27, 19, 15, 21) mm for the cervix and uterus, respectively. The timing of replanning was found to be the 16th fraction, and the volume of expVOIreplan decreased by >30% compared to that of expVOIini . However, margins cannot be reduced to ensure equivalent coverage after replanning. We determined the margins and timing of replanning through detailed daily analysis. The margins of the cervix were smaller than conventional margins in some directions, while the margins of the uterus were larger in almost all directions. A margin equivalent to that at the initial planning was required for replanning.

Fully Automatic initialization and segmentation of left and right ventricles for large-scale cardiac MRI using a deeply supervised network and 3D-ASM

Background and objectiveThe sheer volume of data generated by population imaging studies is unparalleled by current capabilities to extract objective and quantitative cardiac phenotypes; subjective and time-consuming manual image analysis remains the gold standard. Automated image analytics to compute quantitative imaging biomarkers of cardiac function are desperately needed. Data volumes and their variability pose a challenge to most state-of-the-art methods for endo- and epicardial contours, which lack robustness when applied to very large datasets. Our aim is to develop an analysis pipeline for the automatic quantification of cardiac function from cine magnetic resonance imaging data. MethodThis work adopt 4,638 cardiac MRI cases coming from UK Biobank with ground truth available for left and RV contours. A hybrid and robust algorithm is proposed to improve the accuracy of automatic left and right ventricle segmentation by harnessing the localization accuracy of deep learning and the morphological accuracy of 3D-ASM (three-dimensional active shape models). The contributions of this paper are three-fold. First, a fully automatic method is proposed for left and right ventricle initialization and cardiac MRI segmentation by taking full advantage of spatiotemporal constraint. Second, a deeply supervised network is introduced to train and segment the heart. Third, the 3D-ASM image search procedure is improved by combining image intensity models with convolutional neural network (CNN) derived distance maps improving endo- and epicardial edge localization. ResultsThe proposed architecture outperformed the state of the art for cardiac MRI segmentation from UK Biobank. The statistics of RV landmarks detection errors for Triscuspid valve and RV apex are 4.17 mm and 5.58 mm separately. The overlap metric, mean contour distance, Hausdorff distance and cardiac functional parameters are calculated for the LV (Left Ventricle) and RV (Right Ventricle) contour segmentation. Bland–Altman analysis for clinical parameters shows that the results from our automated image analysis pipelines are in good agreement with results from expert manual analysis. ConclusionsOur hybrid scheme combines deep learning and statistical shape modeling for automatic segmentation of the LV/RV from cardiac MRI datasets is effective and robust and can compute cardiac functional indexes from population imaging.

Accuracy of ZedView, the Software for Three-Dimensional Measurement and Preoperative Planning: A Basic Study.

Background and Objectives: In the field of orthopedic surgery, novel techniques of three-dimensional shape modeling using two-dimensional tomographic images are used for bone-shape measurements, preoperative planning in joint-replacement surgery, and postoperative evaluation. ZedView® (three-dimensional measurement instrument and preoperative-planning software) had previously been developed. Our group is also using ZedView® for preoperative planning and postoperative evaluation for more accurate implant placement and osteotomy. This study aimed to evaluate the measurement error in this software in comparison to a three-dimensional measuring instrument (3DMI) using human bones. Materials and Methods: The study was conducted using three bones from cadavers: the pelvic bone, femur, and tibia. Three markers were attached to each bone. Study 1: The bones with markers were fixed on the 3DMI. For each bone, the coordinates of the center point of the markers were measured, and the distances and angles between these three points were calculated and defined as "true values." Study 2: The posterior surface of the femur was placed face down on the 3DMI, and the distances from the table to the center of each marker were measured and defined as "true values." In each study, the same bone was imaged using computed tomography, measured with this software, and the measurement error from the corresponding "true values" was calculated. Results: Study 1: The mean diameter of the same marker using the 3DMI was 23.951 ± 0.055 mm. Comparisons between measurements using the 3DMI and this software revealed that the mean error in length was <0.3 mm, and the error in angle was <0.25°. Study 2: In the bones adjusted to the retrocondylar plane with the 3DMI and this software, the average error in the distance from the planes to each marker was 0.43 (0.32-0.58) mm. Conclusion: This surgical planning software could measure the distance and angle between the centers of the markers with high accuracy; therefore, this is very useful for pre- and postoperative evaluation.

Understanding and Improving Risk Assessment of Abdominal Aortic Aneurysm Growth Using Statistical Shape Modeling of the Infrarenal Aorta

Maximum diameter of the aneurysmal sac remains the primary method for defining surveillance intervals and the timing for surgical intervention. Recent studies have attempted to expand on this one-dimensional metric by incorporating additional descriptors of the aneurysmal sac such as undulation, curvature and tortuosity. However, these metrics are often biased and may overlook certain anatomical abnormalities, limiting predictive potential. This study aimed to identify novel three-dimensional shape features of the aneurysmal flow lumen and outer wall structure (OWS, with or without intraluminal thrombus) to predict aneurysmal growth. A cohort of 192 patients (median age, 72 [range, 62-79]; 99% male) with infrarenal abdominal aortic aneurysms (AAAs) (initial max diameter, 50.3 ± 4.2 mm) and serial computed tomography images obtained during AAA surveillance (median follow-up, 2.0 years [range, 1.0-5.3 years]) were retrospectively considered for this study. Estimated annual AAA growth was the clinical end point and was used to classify patients into slow (first quintile, <2.5 mm/year) and fast (fifth quintile, >5.0 mm/year) cohorts. A previously validated pipeline was implemented to automatically segment computed tomography images. Three-dimensional statistical shape models of the aneurysmal flow lumen and OWS were used to identify three-dimensional patterns involved in AAA growth. Undulation index and radius of curvature of the AAA, previously suggested to be predictive of AAA growth, were also calculated. Model training with derived shape features was performed using iterated 10-fold optimization with shuffling (100 iterations). C-statistics for each feature combination was used to evaluate performance. Integrating the lumen and OWS as unique components within the three-dimensional statistical shape model captured the lumen-thrombus interface. These features proved to be superior to max diameter, undulation index, and radius of curvature in prediction of AAA growth phenotype (P < .001). Corresponding median C-statistics for predicting slow and fast growth are highlighted in the Figure. Integrated models outperformed individual components in prediction of both slow and fast AAA growth (P < .001). Standardized feature extraction from both the aneurysmal flow lumen and the OWS, enabled by a fully automated pipeline, can characterize the evolving lumen-thrombus interface, and improves AAA growth prediction. Future work is focused on validating this statistical shape-based model on larger cohorts that also include smaller AAAs.

Effect Analysis of Nursing Intervention on Lower Extremity Deep Venous Thrombosis in Patients

In the modern era, nursing intervention is an increased commitment to patient quality and protection that allows nurses to make evidence-based healthcare decisions. The challenging characteristic of patients such as high deep venous thrombosis (DVT) and respiratory embolisms (RE) are significant health conditions that lead to post-operative severe injury and death. In this article, hybrid machine learning (HML) is used for senile patients with lower extremity fractures during the perioperative time and the clinical effectiveness of early stages nursing protocol for deep venous thrombosis of patients and nurses. A three-dimensional shape model of the user interface is shown the examined vessels, which have compression measurements mapped to the surface as colors and virtual image plane representation of DVT. The measures of comprehension have been validated using HML model segmentation experts and contrasted with paired f-tests to reduce the incidence of lower extremity deep venous thrombosis in patients and nurses.

Concurrent left ventricular myocardial diffuse fibrosis and left atrial dysfunction strongly predicts incident heart failure and all-cause mortality

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Academy of Medical Sciences Background LV myocardial interstitial fibrosis has been reported to influence LA morphology and function via LV remodelling and diastolic dysfunction. However, this association, as well as their combined influence on clinical outcomes remains poorly characterised. Aim To evaluate the relationship between left ventricular (LV) fibrosis quantified by native T1 times and left atrial (LA) global and phasic function and their impact on clinical outcomes. Methods A total of 40,818 UK Biobank participants with cardiovascular magnetic resonance data were included. Native T1 mapping was performed using Shortened Modified Look-Locker Inversion recovery sequence with global myocardial T1 estimated by an automatic segmentation framework. Ten parameters of LA phasic function were calculated from normalised LA volume-time curves derived by a three-dimensional sparse active shape model. LV parameters (mass, end-diastolic volume, and ejection fraction) were extracted by a fully convolutional neural network. Multivariable regression models were used to assess the associations between T1 and LA parameters. Lastly, survival analysis was performed to assess the interplay between T1, LA function and incident heart failure, atrial fibrillation, major adverse cardiovascular event (MACE) and all-cause mortality. Results The mean age of study population was 64.0 ± 7.7 years; 47.8% were men. Higher T1 values were associated with larger LA minimum size (Beta= 0.89ml per 100ms; 95% confidence interval (CI) = 0.62, 1.17), and lower LA global emptying fraction (Beta= -0.012 per 100ms; CI= -0.015, -0.010), LA reservoir function (Beta= -0.060 per 100ms; CI= -0.083, -0.037) and LA booster function (Beta= -0.014 per 100ms; CI= -0.017, -0.011). Among LA phasic functional parameters, LA booster function is most strongly associated with T1. Survival analysis revealed concurrent high T1 and low LA function had a significant influence on incident heart failure (Hazard Ratio [HR] = 2.99; CI=1.91,2.01), atrial fibrillation (HR = 4.86; CI=3.51-6.54), MACE (HR = 1.86; CI = 1.36-2.54) and all-cause mortality (HR = 1.86; CI=1.22-2.82) compared to either parameter alone, even after accounting for LV parameters (Figure 1). Conclusion This is the first study to robustly demonstrate the associations between myocardial diffuse fibrosis and reduced LA global and phasic functional measurements. We reveal the independent prognostic role of high T1 values accompanied by low LA function in predicting adverse clinical outcomes in a general population. These findings advance our understanding of the relationships between myocardial fibrosis and LA biomechanics at an early, subclinical stage, and highlight the additive value of incorporating these biomarkers into clinical decision making.

Developing a three-dimensional statistical shape model of normal dentition using an automated algorithm and normal samples

The statistical shape model (SSM) is a model of geometric properties of a set of shapes based on statistical shape analysis. The SSM develops an average model of several objects using an automated algorithm that excludes the operator's subjectivity. The aim of this study was to develop a three-dimensional (3D) SSM of normal dentition to provide virtual templates for efficient treatment. Dental casts were obtained from participants with normal dentition. After acquiring the 3D models, the SSMs of the individual teeth and whole dental arch were generated by an iterative closest point (ICP)-based rigid registration and point correspondences, respectively. Then, the individual tooth SSM was aligned to the whole dental arch SSM using ICP-based registration to generate an average model of normal dentition. The generated 3D SSM showed specific morphological features of normal dentition similar to those previously reported. Moreover, on measuring the arch dimensions, all values in this study were similar to those previously reported using normal dentition. The 3D SSM of normal dentition may increase the diagnostic efficiency of orthodontic treatments by providing a visual objective. It can be alsoused as a 3D template in various fields of dentistry. Our SSM of normal dentition provides both quantitative and qualitative information on the 3D morphology of teeth and dental arches, which may provide valuable information on 3D virtual-setup, bracket fabrication, and aligner treatment.

All Roads Lead to Rome: Diverse Etiologies of Tricuspid Regurgitation Create a Predictable Constellation of Right Ventricular Shape Changes.

Introduction: Myriad disorders cause right ventricular (RV) dilation and lead to tricuspid regurgitation (TR). Because the thin-walled, flexible RV is mechanically coupled to the pulmonary circulation and the left ventricular septum, it distorts with any disturbance in the cardiopulmonary system. TR, therefore, can result from pulmonary hypertension, left heart failure, or intrinsic RV dysfunction; but once it occurs, TR initiates a cycle of worsening RV volume overload, potentially progressing to right heart failure. Characteristic three-dimensional RV shape-changes from this process, and changes particular to individual TR causes, have not been defined in detail. Methods: Cardiac MRI was obtained in 6 healthy volunteers, 41 patients with ≥ moderate TR, and 31 control patients with cardiac disease without TR. The mean shape of each group was constructed using a three-dimensional statistical shape model via the particle-based shape modeling approach. Changes in shape were examined across pulmonary hypertension and congestive heart failure subgroups using principal component analysis (PCA). A logistic regression approach based on these PCA modes identified patients with TR using RV shape alone. Results: Mean RV shape in patients with TR exhibited free wall bulging, narrowing of the base, and blunting of the RV apex compared to controls (p 0.05). Using four primary PCA modes, a logistic regression algorithm identified patients with TR correctly with 82% recall and 87% precision. In patients with pulmonary hypertension without TR, RV shape was narrower and more streamlined than in healthy volunteers. However, in RVs with TR and pulmonary hypertension, overall RV shape continued to demonstrate the free wall bulging characteristic of TR. In the subgroup of patients with congestive heart failure without TR, this intermediate state of RV muscular hypertrophy was not present. Conclusion: The multiple causes of TR examined in this study changed RV shape in similar ways. Logistic regression classification based on these shape changes reliably identified patients with TR regardless of etiology. Furthermore, pulmonary hypertension without TR had unique shape features, described here as the “well compensated” RV. These results suggest shape modeling as a promising tool for defining severity of RV disease and risk of decompensation, particularly in patients with pulmonary hypertension.

A new three-dimensional analytical model for wind turbine wake turbulence intensity predictions

In wind farm design, accurately predicting the wake turbulence level is crucial for turbine power and load evaluation. However, a knowledge gap still exists on the characteristics of wake turbulence, meanwhile there has been little work on the development of related engineering models. In view of this, firstly, one-dimensional analytical models that can estimate the wake width and maximum wake turbulence level at any streamwise positions are proposed and validated. Based on these, a highly simple three-dimensional cosine shape (3D-COTI) model is proposed for estimating the wake turbulence intensity in an effective way. Moreover, by taking into account the wind shear and ground effects, this proposed model is capable of describing the anisotropic property of the 3-D wake field. Afterwards, model evaluations are performed through several test cases consisting various types of turbines operating under a wide range of inflow conditions. Overall, the proposed model shows a good agreement with the measurements about the spatial distribution of turbulence enhancement within the wake flow. Because of its good accuracy, simplicity and universality, the present model has potential for large-scale wind farm applications.

Flow vorticity relationships with right ventricular geometry in adult tetralogy of Fallot

Abstract Background Repaired tetralogy of Fallot adults (rToF) undergo right ventricular (RV) remodeling, in part due to volume overload of residual pulmonary regurgitation volume (PRV). Time-resolved phase-contrast cardiac magnetic resonance imaging (4D Flow MRI) enables the qualitative and quantitative measurement of altered blood flow patterns, including vorticity. Cardiac atlases allow for complex three-dimensional heart shapes to be expressed as morphometric scores. Those scores show the extent of geometrical shift and can help explore uncharted relationships between vorticity and architecture. Purpose We aimed to quantify vorticity, incorporating deep learning to enhance 4D Flow data, and correlate this with global cardiac parameters and morphometric scores. Methods 12 Adult rToF patients and 10 age-matched controls underwent 4D flow MRI and cine imaging. RV interventricular vorticity was calculated for outflow and inflow tracts. EDV, ESV and SV were computed from cines which were also used to build three-dimensional shape models. The biventricular models were projected onto an atlas generated from 95 rToF patients, and twenty-one principal component analysis shape modes were correlated with cardiac metrics and vorticity to identify global shape variations. Association between biventricular shape and vorticity was further analysed using multivariate multiple regression models. Results Strong correlation was found between PRV and the right ventricular outflow tract (RVOT) vorticity. PRV and RVOT vorticity both correlated with the same 3 shape modes (r=−0.55, −0.50 and 0.6 (p&amp;lt;0.05) respectively for PR and r=0.63, −0.82 and 0.60 (p&amp;lt;0.05) respectively for vorticity) i.e., the RV dilates with an increase in basal bulging, apical bulging and tricuspid annulus tilting with more severe regurgitation, as well as a smaller LV, and a paradoxical movement of the septum (Figure 1). However, RV vorticity correlated with 2 modes that did not correlate with PRV, (r=−0.62, −0.69, p&amp;lt;0.05). With higher vorticity the RV was longer, increased tilting of the tricuspid annulus and an increased basal bulge around the tricuspid area. The multivariate analysis model demonstrated that higher vorticity was associated with displacement of the pulmonary valve and change in the RVOT length and direction. A septal displacement towards the left ventricle was observed and increased apical flatness of the RV (Figure 1). Qualitatively, vorticity in rToF group was more heterogeneous than controls (Figure 2). Conclusions Vorticity is a novel marker based on the influence of blood motion providing new insight into early diagnosis and prognosis of cardiac disease. This is the first study to examine the relationships between vorticity and regional RV shape changes in rToF. Mode associations with vorticity were different to associations with PRV. More longitudinal studies are required for standardization of change in vorticity with the disease process. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): The New Zealand heart foundation Mode variations and morphometric modelVorticity visualization and analysis

A three-dimensional statistical shape model of the growing mandible

Mandibular growth and morphology are important topics in the field of oral and maxillofacial surgery. For diagnostic and planning purposes, a normative database or statistical shape model of the growing mandible can be of great benefit. A collection of 874 cadaveric children’s mandibles with dental age between 1 and 12 years old were digitized using computed tomography scanning and reconstructed to three-dimensional models. Point correspondence was achieved using iterative closest point and coherent point drift algorithms. Principal component analysis (PCA) was applied to find the main modes of variation in the data set. The average mandible was presented, along with the first ten PCA modes. The first mode explained 78% of the total variance; combining the first ten modes accumulated to 95% of the total variance. The first mode was strongly correlated with age and hence, with natural growth. This is the largest study on three-dimensional mandibular shape and development conducted thus far. The main limitation is that the samples lack information such as gender and cause of death. Clinical application of the model first requires validation with contemporary samples.

Mapping a duck: geological features and region definitions on comet 67P/Churyumov-Gerasimenko

The data from the Rosetta mission have permitted a reconstruction of the shape of comet 67P/Churyumov-Gerasimenko and an identification of the terrains and features forming the surface. The peculiar shape of the comet has made it challenging to project these geological features onto an unambiguous frame. As a result, the geological maps published to date are created on top of comet images, making them dependent on the viewing angle and image resolution. To overcome this limitation, we present an integrated set of geological maps of the northern hemisphere of the comet, displayed in an unambiguous projection. The new maps combine the geological landmarks published in previous studies in a single framework and are completed with newly identified features. We have located the landmarks on OSIRIS images projected onto the surface of a three-dimensional shape model of the comet. For each region, the geological maps are displayed in the Quincuncial adaptive closed Kohonen (QuACK) map projection. The QuACK map solves the spatial ambiguity issues and reduces the shape and area distortions of classical global projections, which particularly affect the polar regions. The outcome of this research is a set of individual geological maps that are displayed both on top of OSIRIS images and in the QuACK map projection. These maps are analysed and grouped by similarities in terrain and morphology to find common characteristics that allow expanding our knowledge of the formation processes of comets. Based on this analysis, the north-south dichotomy is confirmed, and a redefinition of the regional boundaries is proposed for the Anubis-Atum and Aker-Babi frontiers. This research fills the gap in the field of mapping comet 67P/Churyumov-Gerasimenko and provides an innovative method for treating the surface of highly irregular bodies.

Stochastic PCA-Based Bone Models from Inverse Transform Sampling: Proof of Concept for Mandibles and Proximal Femurs

Principal components analysis is a powerful technique which can be used to reduce data dimensionality. With reference to three-dimensional bone shape models, it can be used to generate an unlimited number of models, defined by thousands of nodes, from a limited (less than twenty) number of scalars. The full procedure has been here described in detail and tested. Two databases were used as input data: the first database comprised 40 mandibles, while the second one comprised 98 proximal femurs. The “average shape” and principal components that were required to cover at least 90% of the whole variance were identified for both bones, as well as the statistical distributions of the respective principal components weights. Fifteen principal components sufficed to describe the mandibular shape, while nine components sufficed to describe the proximal femur morphology. A routine has been set up to generate any number of mandible or proximal femur geometries, according to the actual statistical shape distributions. The set-up procedure can be generalized to any bone shape given a sufficiently large database of the respective 3D shapes.

Computer-Aided Assessment of Displacement and Reduction of Distal Radius Fractures.

This study aims to investigate displacements and reductions of distal radius fractures using measurement indices based on the computer-aided three-dimensional (3D) radius shape model. Fifty-two distal radius fracture patients who underwent osteosynthesis were evaluated with pre- and post-operative distal radius 3D images. In the 3D images, three reference points, i.e., the radial styloid process (1), sigmoid notch volar, and dorsal edge (2) (3) were marked. The three-dimensional coordinates of each reference point and the barycentric coordinates of the plane connecting the three reference points were evaluated. The distance and direction moved, due to the reductions for each reference point, were (1) 12.1 ± 8.1 mm in the ulnar-palmar-distal direction, (2) 7.5 ± 4.1 mm in the ulnar-palmar-proximal direction, and (3) 8.2 ± 4.7 mm in the ulnar-palmar-distal direction relative to the preoperative position. The barycentric coordinate moved 8.4 ± 5.3 mm in the ulnar-palmar-distal direction compared to the preoperative position. This analyzing method will be helpful to understand the three-dimensional direction and the extent of displacements in distal radius fractures.