3D Torso Research Articles

Activation time at left ventricular pacing site (QLV) in relation to actual site of latest activation; effect on response to cardiac resynchronization therapy

Abstract Background Among techniques to improve CRT efficacy, longer QLV (activation time at the left ventricular (LV) pacing site (LVPS)) has been proposed to correlate to response to cardiac resynchronization therapy (CRT), supporting that pacing close to the latest LV electrically activated site (LEAS) improves CRT efficacy. A QLV cut-off of > 95 ms has been proposed, however, predictive value was modest. This may be because LEAS was not identified, and empirically delivered leads may have missed it (described by a longer interval QLEAS (activation time at LEAS) to QLV. Purpose We compared QLEAS to QLV, and assessed effect of the interval QLEAS-QLV, on response to CRT. Methods We studied patients who had received CRT for Class I or Class IIa indications, regardless of CRT response, at 5 European sites. LV lead placement, device programming and follow up (FU) followed physician preference and site protocol. All patients had clinical FU 6-12 months post-implant, including echocardiographic study. CRT non-response was defined as LV end-systolic volume (LVESV) reduction of <15%. Patients underwent noninvasive 3D electrical activation mapping and torso CT 6-24 months post-implant. QLV and QLEAS were assessed from the noninvasive activation map in a blinded core lab. Logistic regression modelling was conducted for QLV and the interval QLEAS-QLV against CRT response, and the optimal cut-off points were calculated. Results Of 111 patients (age 64±11 years (mean±SD), 74% male, 98% LBBB, QRS duration 172±21 ms, baseline LVEF 28±6%, LVESV 183±87 mL, implant duration 12±5 months, 31%/69% NYHA Class II/III, 38% ischemic heart disease), 67% responded at 10±3 months post-implant. QLV overall was 97±23 ms (range 42-148 ms), 103±21 ms for responders and 83±22 for non- responders (p<0.001), QLEAS was 109±19 ms (range 66-150 ms), 109±20 ms for responders and 110±19 ms for non- responders (p=0.74). QLEAS-QLV overall was 13±18 ms (range 0-120 ms), 6±10 ms for responders and 27±22 ms for non-responders (p<0.001) (Figure 1). Optimal cut-off point for QLV was 85 ms with sensitivity 0.89, specificity 0.57 and an AUC of 0.742 (95% CI: 0.637- 0.846). Optimal cut-off point for QLEAS-QLV was 6 ms (sensitivity 0.77, specificity 0.95, AUC 0.901 (95% CI: 0.844-0.957) (Figure 1). The AUC of QLV cut-off and QLEAS-QLV cut-off differed significantly (p<0.001). 18/111 patients (16%) were non-responders despite a QLV≥85 ms, whereas 2 patients (2%) were non-responders despite a QLEAS-QLV≤6 ms. Conclusion QLEAS has greater discriminatory power than a QLV cut-off of 85 ms to separate CRT responders from non-responders in patients with LBBB and long QRS duration. QLV guided LV lead placement without prior knowledge of the latest LV activation in individual patients will miss the ideal LV pacing site in 16% of cases. Using noninvasive 3D global mapping to identify LEAS pre-CRT implant and directing LV lead placement to within 6 ms of this may improve CRT efficacy.Figure 1

Severity and Cobb angle of scoliosis patients quantified with markerless trunk surface topography using k-NN search and multivariate regression analysis

ABSTRACT Adolescent Idiopathic Scoliosis (AIS) is a complex 3D condition that affects the shape of the torso by increasing bilateral asymmetries. To analyse the 3D torso shape and consequently the severity of scoliosis, markerless surface topography (ST) has been successfully applied in combination with asymmetry contour maps. The main benefits are a reduction of X-ray radiation to patients and an impression of the 3D torso asymmetric shape pattern. The purpose of this work is to improve the classification accuracy for severity based on k-NN search and to provide a prediction tool for the Cobb angle based on multivariate linear regression.

CI-452767-4 NON-INVASIVE 3D ELECTRICAL ACTIVATION MAPPING TO PREDICT CRT RESPONSE: SITE OF LATEST LV ACTIVATION RELATIVE TO PACING SITE

Left ventricular (LV) pacing remote to the latest LV electrically activated site (LEAS) may diminish efficacy of cardiac resynchronization therapy (CRT). However, this has not been evaluated rigorously using global LV mapping. Test whether the distance “dp” between LV pacing site (LVPS) and LEAS influences the rate of CRT response. Consecutive CRT patients in 5 centers underwent noninvasive 3D electrical activation mapping and torso CT 6-24 months post-implant. LVPS, LEAS and dp were assessed. LV end-systolic volume (LVESV) reduction of ≥15% at clinical follow-up defined response. Logistic regression probabilistically modeled Non-Response; variables included demographics, heart failure classification, left bundle branch block (LBBB), ischemic heart disease, atrial fibrillation (AF), baseline QRS duration, baseline ejection fraction (EF), baseline LVESV, comorbidities, use of CRT optimization algorithm, ACE inhibitor/ARB, beta-blocker, diuretics, and dp. Of 111 patients (age 64 ± 11 years, baseline LVEF 28 ± 6%, baseline QRS duration 172 ± 21 ms, baseline LVESV 183 ± 87 mL, implant duration 12 ± 5 months (mean ± SD); 93%/7% had class I/IIa CRT indication, 31%/69% had NYHA Class II/III, 74% were males, 98% had LBBB, 38% had ischemic heart disease and 18% had a history of AF), 67% responded at 10 ±3 months post-implant (55% and 75% for ischemic and non-ischemic patients, respectively). LEAS were outside the mid and basal lateral segments in 35% of the patients. dp was 42 ± 23 mm (range 2-137): 31 ± 14 mm in Responders vs 63 ± 24 mm in Non-Responders. The distance dp, and the use of CRT optimization algorithms, remained the only independent predictors of non-response (area under the curve (AUC) 0.906). dp = 47 mm delineated Responders from Non-Responders (AUC 0.931). The distance between LV pacing site and site of latest electrical activation is a strong independent predictor for CRT response. Non-invasive electrical evaluation to characterize intrinsic activation and guide LV lead deployment may improve CRT efficacy.

PO-02-226 NON-INVASIVE ELECTROCARDIOGRAPHIC IMAGING FOR THE CHARACTERIZATION OF COMPLEX ATRIAL TACHYARRHYTHMIAS

Non-invasive characterization of complex atrial tachyarrhythmias, regarding atrial flutter (AFL) and focal atrial tachycardia (AT) is challenging. Conventional electrocardiogram (ECG) faces several limitations. Planning a preprocedural strategy before AFL-AT catheter ablation (CA) is needed. To evaluate the diagnostic capacity of a novel non-invasive electrocardiographic imaging (ECGI) system that does not require previous CT or MRI cardiac imaging. 42 patients (27 males, CHA2DS2-VASc score 2±1, LVEF 54.5 ± 11.0 %, and LA area 31.3 ± 7.0 cm2) undergoing CA for AT-AFL were prospectively included in the study. Before the procedure, the ECGI system estimated the patient atria geometry using a 3D torso reconstruction and an artificial intelligence-based algorithm. Multiple electrocardiograms were recorded using a 64-electrodes vest during the CA procedure. The different diagnostic capacities of the periprocedural ECG and ECGI were assessed compared with endocavitary electroanatomical mapping (EAM) regarding three endpoints: (1) the involved atrial cavity, (2) the mechanism (focal or macro-reentry), and (3) the ablation target site defined as the area where the earliest activation was located for focal arrhythmias, and the precise anatomical pathway for macro re-entrant tachyarrhythmias. Regarding the ECG, endpoints were assessed based on validated algorithms by 2 different observers blinded from the diagnosis. 48 atrial tachyarrhythmias were evaluated and its characterization using this novel ECGI system was possible in 94% of the cases: directly for 36 arrhythmias and after decreasing ventricular response using vagal maneuvers for 9. ECGI obtained global accuracy to identify the involved atrial cavity of 92%, the mechanism of 90%, and the ablation target of 83% (Table). In challenging cases, such as in patients with a history of CA for atrial fibrillation and in patients without a final diagnosis of typical counterclockwise AFL, the accuracy of ECGI was consistent compared to the whole study population (Table). The ECGI diagnostic capacity significantly outclassed the ECG regarding the identification of the involved cavity (p<0.001), the mechanism (p<0.05), and the ablation target (p<0.001). ECGI could have prevented all unnecessary transseptal punctures (n=7), representing 28% of the overall punctures. This novel non-invasive ECGI system accurately characterizes complex atrial tachyarrhythmias (Figure) without needing previous CT or MRI cardiac imaging.

Dual-Band Self-Complementary 5G Antenna for Wireless Body Area Network

A design of a self-complementary dual-band fifth-generation (5G) antenna for a wireless body area network (WBAN) has been presented in this paper. Like many other advantages, dual-band antennas have the benefit of being able to establish a reliable wireless connection in places that are frequently out of reach. The antenna operates at two popular 5G NR, FR-2 frequency bands: n257, or 28 GHz, and n260, or 39 GHz. FR-2 bands are prominent for high-speed data transactions within a limited range, which is perfect for WBAN applications. The proposed self-complementary single element design has a physical size of 6 mm × 8 mm × 1.59 mm and is designed with a Rogers RT6002 substrate with a dielectric constant of 2.94. In free space simulations, the antenna performed satisfactorily, achieving around 90% efficiency and having return losses of 16.32 dB and 20.47 dB at the lower and upper frequency bands sequentially. The antenna generated almost omnidirectional patterns at both frequencies with a peak gain of 4.74 dB. By placing the antenna next to a 3D human torso phantom that had been digitally created with accurate human body features, the design’s onbody performance was assessed. Onbody simulations produced favorable performance with a small dispersion from their peak values in some parameters, i.e., efficiency and reflection coefficients but produced more gains: 4.34 dBi at 28 GHz and 6.19 dBi at 39 GHz. For further distance-based investigation, the antenna was placed in five different positions relative to the torso. The test yields 67% efficiency with the minimum gap and 71% at the highest distance from the human body for the lowest band. Though the lower-frequency band produces better results with more gaps, the higher-frequency band performs consistently better in even the closest placement to the human body model by reaching more than 6 dB of gain with above 81% efficiency and wider than 10 GHz of bandwidth. The overall performance indicates this design can be a good solution to complex WBAN scenarios.

A non-invasive method for scoliosis assessment-A new mathematical concept using polar angle.

Scoliosis is one of the most common pediatric spinal diseases that leads to a three-dimensional deformity of the spine and has a high risk of progression during growth. Regular clinical monitoring and follow-up X-rays are needed to providing proper treatment at that time. Repetitive X-rays can results in an increased risk of radiation related health problems. We present a non-invasive, ionizing radiation-free method for assessing scoliosis and its progression from the 3D images of the body torso, captured by a body scanner. A new concept is introduced based on a mathematical method in polar coordinate system to quantify and characterize the deformities in the torso from 2D transverse cross-sections of the 3D torso images at example cases for a healthy individual and for two patients with scoliosis. To capture quantitatively the characteristics of scoliosis, and to verify them at the example cases two asymmetry parameters and a linear fitting parameter are calculated: a) back side area asymmetry, b) left right area asymmetry, and c) coefficient of determination (R2). Within the analyzed patients, both the area asymmetries are maximum at the apex of scoliosis, and increase with the severity of scoliosis. R2 values are smaller in the case of patients compared with the healthy. Furthermore, the parameters show a trend when compared with the Cobb angle from the X-ray and the findings match with clinical examination. Therefore, the quantities are able to capture, certain characteristics associated with scoliosis. These quantities can be compared as a measure of deformities of torso, during the follow-up examinations in the future, without ionizing radiations.

A shape classification scheme for female torso

This paper presents a shape classification scheme for the female torso, based on anthropometric measurements and 3D body scans from a large scale anthropometric survey. The ability to classify the female body shape is highly desired by the clothing industry and apparel researchers for improving pattern design and fit. In order to objectively classify female torso shapes, we employed principal component analysis on torso related anthropometric measurements and three-dimensional (3D) torso surface data to identify the most dominant measurements. The principal component analysis of the anthropometric measurements show that Waist Circumference is the most dominant variable to define overall female torso size, and that Chest-Waist Drop and Waist-Buttock Drop jointly define the local shape of the torso. Using these findings, a torso shape classification scheme was developed, where nine shape categories were defined from Chest-Waist Drop and Waist-Buttock Drop while torso sizes were divided by Waist Circumference. The distribution of nine shape categories is dependent on the value of Waist Circumference. Mean shape of each shape category was then generated from 3D scans.

A Novel Design and Study of a Self-Complimentary Miniaturized Millimeter Wave Antenna for Body-Centric Networks

A new self-complimentary compact antenna operating at 60 GHz within the millimeter wave frequency range has been presented in this paper. The design is intended for the wireless body-centric network (WBCN). The proposed compact design has a dimension of 4.5 × 6.03 × 1.59 mm3. The antenna was designed with multiple geometrical structures held upon a narrow feed line with a rectangular slot and parasitic elements to increase bandwidth. Free space simulations of the antenna produced optimistic results in terms of gain, radiation efficiency, and bandwidth; a maximum gain of 6.7 dB was achieved with an efficiency of 84.5%. Parametric studies were carried out to better understand its nature by modifying the key design aspects and comparing the outcomes. A 3D human torso phantom was virtually created with natural human body properties, and the on-body performance of the design was tested by placing the antenna in its near field. With some slight deviation from their peak performance, on-body simulations displayed better results in most of the cases. The antenna was positioned five different gaps from the torso for future investigations. The result of the distance-based study was amazingly good as the antenna performance was consistent throughout all distances. 10.77 GHz of bandwidth is found for the closest distance to the human torso, while the on-body radiation efficiency is also outstanding; the minimum radiation efficiency recorded is 73.78 when the antenna is just a couple of millimeters away. Overall, the comparison shows that the antenna worked best when it was placed only 2 mm apart from the body. Investigation indicates the antenna is a promising candidate for BCN applications because of its wider bandwidth and better on-body efficiency.

Automated Torso Contour Extraction from Clinical Cardiac MR Slices for 3D Torso Reconstruction.

Whilst the electrocardiogram (ECG) is an essential tool for diagnosing cardiac electrical abnormalities, its characteristics are dependent on anatomical variability. Specifically variation in torso geometry affects relative positions of the leads with respect to the heart. We propose a novel pipeline that uses standard cardiac magnetic resonance images to reconstruct the torso and heart, and recreate the ECG considering torso and cardiac anatomy. This requires automated extraction of the torso contours. Our method combines an initial u-net segmenter with a second network that refines contours and removes spurious segments. The networks were evaluated on a cross validation study dataset and an independent test set. The use of two-channel input, including both original image and initial segmentation, in the refinement network significantly improved performance on the independent test set, reducing the Hausdorff distance from 9.1 pixels to 4.3 pixels and increasing Dice coefficient from 0.75 to 0.93. Clinical Relevance- This method can be utilized to allow ECG simulations with personalized torso geometry which has previously been demonstrated to significantly effect QRS parameters. A clinical tool can be developed using this method that accounts for torso geometry in ECG interpretation.

Full torso and limited-domain computer models for epicardial pulsed electric field ablation

Background and objectivesPulsed Electric Field (PEF) ablation has been proposed as a non-thermal energy to treat atrial fibrillation (AF) by ablation of ganglionated plexi using the epicardial approach. The electric field distribution at the target site (heart) and its surroundings has not yet been assessed previously, using epicardial ablation technique. Our objective was to develop computational models, incorporating the real anatomy of the heart and the patient's torso, to assess the electric field distribution when applying epicardial monopolar PEF. MethodsA novel 3D realistic full torso model was built with the multi-electrode ablation device placed on the epicardium and a dispersive pad on the patient's back to evaluate the electric field distribution. The 400 V/cm isoline was used to estimate the ‘PEF-zone’. A 3D limited-domain model was also built including only the region of interest around the ablation device to assess its validity in comparison with the full torso model. ResultsThe electrical field is mainly limited to the target site (PEF-zone with lengths of 25.79 to 29.00 mm, depths of 5.98−7.02 mm and maximum widths of 8.75−10.57 mm) and is practically negligible in adjacent organs (<30 V/cm and <36 V/cm in oesophagus and lungs, respectively). The electrical currents ranged from 3.67 A to 7.44 A. The 3D limited-domain model provided a similar electric field distribution to those obtained from the 3D full torso models (differences < 0.5 mm in PEF-zone depth). ConclusionsComputational results suggest that PEF-zone is very focused around the ablation catheter. Limited-domain models offer similar results in terms of PEF-zone size, reducing the complexity of the modelling.

Model-Based Radiation-Free Assessment of Scoliosis: A Principle Validation Study

PurposeAdolescent scoliosis is one of the common pediatric spinal diseases which has a high risk of progression due to the rapid growth of the skeleton during the growing stage therefore needs regular clinical monitoring including X-rays. Because X-rays could lead to ionizing radiation-related health problems, an ionizing radiation-free, non-invasive method is presented here to estimate the degree of scoliosis and to potentially support the medical assessment.MethodsThe radiation-free body scanner provides a 3D surface scan of the torso. A basic 3D structure of the human ribcage and vertebral column was modeled and simulated with computer-aided design software and finite element method calculation. For comparison with X-rays, courses of vertebral columns derived from 3D torso images and 3D models were analyzed with respect to their apex positions and angles.ResultsThe methods show good results in the estimation of the apex positions of scoliosis. Strong correlations (R = 0.8924) were found between the apex and Cobb angle from X-rays. Similar correlations (R = 0.8087) was obtained between the apex angles extracted from X-rays and the combination of torso scan images with 3D model simulations. Promising agreement was obtained between the spinal trajectories extracted from X-ray and 3D torso images.ConclusionsVery strong correlations suggest that the apex angle could potentially be used for scoliosis assessment in follow-up examinations in complement to the Cobb angle. However, further improvements of the methods and tests on a larger number of data set are necessary before their introduction into the clinical application.

Automated Localization of Focal Ventricular Tachycardia From Simulated Implanted Device Electrograms: A Combined Physics-AI Approach.

Background: Focal ventricular tachycardia (VT) is a life-threating arrhythmia, responsible for high morbidity rates and sudden cardiac death (SCD). Radiofrequency ablation is the only curative therapy against incessant VT; however, its success is dependent on accurate localization of its source, which is highly invasive and time-consuming.Objective: The goal of our study is, as a proof of concept, to demonstrate the possibility of utilizing electrogram (EGM) recordings from cardiac implantable electronic devices (CIEDs). To achieve this, we utilize fast and accurate whole torso electrophysiological (EP) simulations in conjunction with convolutional neural networks (CNNs) to automate the localization of focal VTs using simulated EGMs.Materials and Methods: A highly detailed 3D torso model was used to simulate ∼4000 focal VTs, evenly distributed across the left ventricle (LV), utilizing a rapid reaction-eikonal environment. Solutions were subsequently combined with lead field computations on the torso to derive accurate electrocardiograms (ECGs) and EGM traces, which were used as inputs to CNNs to localize focal sources. We compared the localization performance of a previously developed CNN architecture (Cartesian probability-based) with our novel CNN algorithm utilizing universal ventricular coordinates (UVCs).Results: Implanted device EGMs successfully localized VT sources with localization error (8.74 mm) comparable to ECG-based localization (6.69 mm). Our novel UVC CNN architecture outperformed the existing Cartesian probability-based algorithm (errors = 4.06 mm and 8.07 mm for ECGs and EGMs, respectively). Overall, localization was relatively insensitive to noise and changes in body compositions; however, displacements in ECG electrodes and CIED leads caused performance to decrease (errors 16–25 mm).Conclusion: EGM recordings from implanted devices may be used to successfully, and robustly, localize focal VT sources, and aid ablation planning.

Automatic analysis method of 3D images in patients with scoliosis by quantifying asymmetry in transverse contours

Scoliosis is characterized by a lateral curvature of spine in the coronal plane of at least 10°, showing three-dimensional deformities of the torso. Recently, a 3D body scanner was proposed as an ionizing radiation-free method, supplementary to clinical examinations and X-rays, for assessing scoliosis and its progression. Here we present an automatic method of analysis of the 3D images of the body torso delivered by the scanner, with the objective of capturing and characterizing deformities in the torso due to scoliosis. The method quantifies asymmetries in each of the torso contours, extracted from 2D cross sections of the 3D torso images, transverse to the vertical axis of the body. Three parameters were calculated: (1) circularity, (2) difference between the areas to left and right of the spinous process (LRAsm), and (3) difference between the ratios width/depth to the left and right of the centroid of the contour (ASR). The method was verified by analyzing twenty-six computed tomography images of patients with different types of scoliosis. In patients with thoracic scoliosis both LRAsm and ASR were larger, that is the asymmetry was stronger, in the thoracic than in the lumbar region, whilst in patients with lumbar scoliosis the inverse was obtained. Furthermore, larger values of LRAsm coincided with the apex position of scoliosis. The circularity factor did not capture scoliosis-related asymmetries. It may, however, be useful in localizing the vertebral level during analysis of 3D scanner data. The method can have the potential to use it for follow-up examinations of scoliosis, in addition to clinical examinations. Further validation of the method requires its application to 3D body scanner data, particularly for more cases of severe scoliosis, which have more irregular transverse contours and thus potential for improvement.

In-silico pace-mapping using a detailed whole torso model and implanted electronic device electrograms for more efficient ablation planning

BackgroundPace-mapping is a commonly used electrophysiological (EP) procedure which aims to identify exit sites of ventricular tachycardia (VT) by matching ventricular activation patterns (assessed by QRS morphology) at specific pacing locations with activation during VT. However, long procedure durations and the need for VT induction render this technique non-optimal.To demonstrate the potential of in-silico pace-mapping, using stored electrogram (EGM) recordings of clinical VT from implanted devices to guide pre-procedural ablation planning. MethodSix scar-related VT episodes were simulated in a 3D torso model reconstructed from computed tomography (CT) imaging data, including three different infarct anatomies mapped from infarcted porcine imaging data. In-silico pace-mapping was performed to localise VT exit sites and isthmuses by using 12-lead electrocardiogram (ECG) signals and different combinations of EGM sensing vectors from implanted devices, through the creation of conventional correlation maps and reference-less maps. ResultsOur in-silico platform was successful in identifying VT exit sites for a variety of different VT morphologies from both ECG correlation maps and corresponding EGM maps, with the latter dependent upon the number of sensing vectors used. We also showed the added utility of both ECG and EGM reference-less pace-mapping for the identification of slow-conducting isthmuses, uncovering the optimal algorithm parameters. Finally, EGM-based pace-mapping was shown to be more dependent upon the mapped surface (epicardial/endocardial), relative to the VT origin. ConclusionsIn-silico pace-mapping can be used along with EGMs from implanted devices to localise VT ablation targets in pre-procedural planning.

128Non-invasive 3D mapping of earliest activation of premature ventricular complexes originating from intracardiac structures to guide catheter ablation

Abstract Funding Acknowledgements Research funding from Catheter Precision, Inc. Introduction Catheter ablation for ventricular arrhythmias such as premature ventricular complexes and ventricular tachycardia is an established management approach. Non-invasive mapping to localise the earliest activation (site of origin) on the myocardium may help guide ablation. Established ECGi methods using the inverse solution to reconstruct epicardial electrograms are unable to accurately locate arrhythmias from the endocardium or from intracardiac structures. VIVO™ (Catheter Precision) is a novel vectorcardiography based 3D mapping system that may be able to localise arrhythmias from any part of the ventricle. Methods We reviewed our initial experience utilising this mapping system to guide catheter ablation of ventricular ectopics from the inter-ventricular septum, coronary cusp or papillary muscle. A patient-specific 3D heart and torso model was created using semi-automated segmentation of MRI or CT scan images. A 3D topographic image of the patient’s torso was taken to accurately position surface ECG electrode locations onto the 3D heart-torso model. An ECG of the PVC was imported from LabSystemPro (Bard) into VIVO™ for analysis prior to ablation. The result was then compared with the site of earliest activation identified using invasive electro-anatomical (EA) mapping. Results VIVO™ was used in 12 cases where the PVC was localised to an intracardiac structure – six papillary muscle, four to the septum and two from the coronary cusp. VIVO™ was able to accurately localise the earliest activation site when compared to the invasive map in 5/6 papillary muscle cases, 3/4 septal cases and 2/2 coronary cusp cases. Ablation was acutely successful in all cases. One additional patient had a PVC localised non-invasively to the postero-medial papillary muscle, however an invasive 3D electro-anatomical map or ablation was not performed. In three cases we were able to merge the 3D geometry of the non-invasive map from VIVO™ into the Carto™ system to guide mapping and ablation in real time (see figure). Conclusion Our experience shows promising results for accurate non-invasive localisation of ventricular arrhythmias originating from intracardiac structures. Non-invasive localisation is of particular value in cases where the arrhythmia is infrequent, difficult to induce or poorly tolerated haemodynamically. The two cases where PVC localisation was inaccurate were performed using an older version of the software. With recent refinements, localisation is anticipated to be improved further. We also present the first experience of combining the VIVO™ geometry with the real-time invasive EA map. This has potential to significantly speed up mapping time and reduce the need for expensive multi-polar catheters by allowing the operator to see their target in real time 3D. Further work is ongoing to validate the accuracy of VIVO™ prospectively and quantitatively. Abstract Figure. VIVO map merged with Carto LV geometry

Estimation of WorldSID thorax kinematics using multiple 3-axis accelerometers

It is essential to analyze the kinematics of anthropometry dummy in vehicle’s crash test. In general, it is required to measure the linear and angular components in the three orthogonal directions, respectively, in order to calculate the 3D kinematics of a rigid body. The WorldSID is originally designed to measure the tri-axis linear accelerations at the first (T1), fourth (T4), and twelfth (T12) thoracic vertebrae segments and the angular accelerations in the x and z directions. However, only three tri-axis linear accelerations are often measured for the sake of convenience. The lack of the required information results in the inaccurate calculation of the 3D torso kinematics. In this study, we propose an algorithm to accurately estimate the 3D torso kinematics when only three tri-axis linear accelerations at T1, T4, and T12 are available. Given the fact that the three tri-axis accelerometers are fixed in the torso segment, the mathematical algorithm is developed to estimate the linear acceleration at the location of the center of mass for the torso and the angular acceleration of the torso. The accuracy of the proposed algorithm is validated against the results from a rigid-body model that models the WorldSID’s spine block and tri-axis accelerometers attached to T1, T4, and T12. According to the comparison against the rigid-body model, the estimated values are calculated to be within 1.7 % of the target values. After the validation is achieved, the 3D kinematics of WorldSID’s torso is estimated using a set of actual side impact test data. In conclusion, the proposed algorithm accurately estimates the 3D WorldSID kinematics when at least three sets of tri-axis linear accelerations are available without any measurements of angular components.

Body shape: Implications in the study of obesity and related traits.

The diagnosis and treatment of obesity are usually based on traditional anthropometric variables including weight, height, and several body perimeters. Here we present a three-dimensional (3D) image-based computational approach aimed to capture the distribution of abdominal adipose tissue as an aspect of shape rather than a relationship among classical anthropometric measures. A morphometric approach based on landmarks and semilandmarks placed upon the 3D torso surface was performed in order to quantify abdominal adiposity shape variation and its relation to classical indices. Specifically, we analyzed sets of body cross-sectional circumferences, collectively defining each, along with anthropometric data taken on 112 volunteers. Principal Component Analysis (PCA) was performed on 250 circumferences located along the abdominal region of each volunteer. An analysis of covariance model was used to compare shape variables (PCs) against anthropometric data (weight, height, and waist and hip circumferences). The observed shape patterns were mainly related to nutritional status, followed by sexual dimorphism. PC1 (12.5%) and PC2 (7.5%) represented 20% of the total variation. In PCAs calculated independently by sex, linear regression analyses provide statistically significant associations between PC1 and the three classical indexes: body mass index, waist-to-height ratio, and waist-hip ratio. Shape indicators predict well the behavior of classical markers, but also evaluate 3D and geometric features with more accuracy as related to the body shape under study. This approach also facilitates diagnosis and follow-up of therapies by using accessible 3D technology.

Personalized Cardiac Computational Models: From Clinical Data to Simulation of Infarct-Related Ventricular Tachycardia.

In the chronic stage of myocardial infarction, a significant number of patients develop life-threatening ventricular tachycardias (VT) due to the arrhythmogenic nature of the remodeled myocardium. Radiofrequency ablation (RFA) is a common procedure to isolate reentry pathways across the infarct scar that are responsible for VT. Unfortunately, this strategy show relatively low success rates; up to 50% of patients experience recurrent VT after the procedure. In the last decade, intensive research in the field of computational cardiac electrophysiology (EP) has demonstrated the ability of three-dimensional (3D) cardiac computational models to perform in-silico EP studies. However, the personalization and modeling of certain key components remain challenging, particularly in the case of the infarct border zone (BZ). In this study, we used a clinical dataset from a patient with a history of infarct-related VT to build an image-based 3D ventricular model aimed at computational simulation of cardiac EP, including detailed patient-specific cardiac anatomy and infarct scar geometry. We modeled the BZ in eight different ways by combining the presence or absence of electrical remodeling with four different levels of image-based patchy fibrosis (0, 10, 20, and 30%). A 3D torso model was also constructed to compute the ECG. Patient-specific sinus activation patterns were simulated and validated against the patient's ECG. Subsequently, the pacing protocol used to induce reentrant VTs in the EP laboratory was reproduced in-silico. The clinical VT was induced with different versions of the model and from different pacing points, thus identifying the slow conducting channel responsible for such VT. Finally, the real patient's ECG recorded during VT episodes was used to validate our simulation results and to assess different strategies to model the BZ. Our study showed that reduced conduction velocities and heterogeneity in action potential duration in the BZ are the main factors in promoting reentrant activity. Either electrical remodeling or fibrosis in a degree of at least 30% in the BZ were required to initiate VT. Moreover, this proof-of-concept study confirms the feasibility of developing 3D computational models for cardiac EP able to reproduce cardiac activation in sinus rhythm and during VT, using exclusively non-invasive clinical data.

Nonrigid reconstruction of 3D breast surfaces with a low-cost RGBD camera for surgical planning and aesthetic evaluation.

Accounting for 26% of all new cancer cases worldwide, breast cancer remains the most common form of cancer in women. Although early breast cancer has a favourable long-term prognosis, roughly a third of patients suffer from a suboptimal aesthetic outcome despite breast conserving cancer treatment. Clinical-quality 3D modelling of the breast surface therefore assumes an increasingly important role in advancing treatment planning, prediction and evaluation of breast cosmesis. Yet, existing 3D torso scanners are expensive and either infrastructure-heavy or subject to motion artefacts. In this paper we employ a single consumer-grade RGBD camera with an ICP-based registration approach to jointly align all points from a sequence of depth images non-rigidly. Subtle body deformation due to postural sway and respiration is successfully mitigated leading to a higher geometric accuracy through regularised locally affine transformations. We present results from 6 clinical cases where our method compares well with the gold standard and outperforms a previous approach. We show that our method produces better reconstructions qualitatively by visual assessment and quantitatively by consistently obtaining lower landmark error scores and yielding more accurate breast volume estimates.

Magnetocardiogram forward problem based on personalized three-dimensional heart-torso model

In order to simulate the distribution of magnetic field generated by cardiac electrophysiological activities, a three-dimensional (3D) computing framework of magnetocardiogram forward problem based on a finite element method (FEM) is proposed. First, the 3D heart-torso geometry model is established from the 3D reconstruction of magnetic resonance images. Then the modified FitzHugh-Nagumo (FHN) equation combined with 3D cardiac geometry is used to investigate the propagation of transmembrane potential (TMP). In the end, quasi-static Maxwell equations and 3D torso model are used to explore the propagation of the bioelectromagnetic field produced by TMP. In our calculation, the Galerkin finite element method is used. The results show that the FEM-model can simulate extracorporeal magnetic field. Further, numerical solutions of simplified models with the one-dimensional FHN equation and the straight wire are respectively consistent with the analytical solutions, which verifies the feasibility of the computing framework. In summary, this framework successfully simulates the cardiac TMP and extracorporeal magnetic field, which may conduce to the study of magnetocardiogram inverse problem.