Measured Body Surface Research Articles

On the reconstruction of cardiac transmembrane potential pattern from body surface measurement

Electrocardiographic imaging (ECGI) is a diagnostic tool designed for the noninvasive detection of electrical activity in the heart. Mathematically, this imaging process can be modelled by an inverse problem for the coupled elliptic system with Cauchy data. For the bidomain model describing the electrical activity in the myocardium, we reconstruct the transmembrane potential on the heart surface from ECG recordings. The reconstruction process is split into two steps: firstly computing the electrical potential and current on heart surface from torso surface recordings and then recovering the transmembrane potential on the heart surface. The first step is essentially a Cauchy problem for elliptic equation which is well-known to be severely ill-posed. We realize this step in terms of boundary integral system by a quasi-regularization scheme to deal with the ill-posedness. The second step is implemented by an integral equation of the second kind with nontrivial null space. We remove the non-uniqueness and then provide a numerical scheme by the boundary element method to obtain the transmembrane potential on the heart surface. The regularized solution obtained from noisy measurement data is proven rigorously to be convergent to the exact solution as the measurement error in the torso surface tends to zero. For solving the regularizing system numerically, we establish quadrature formulas for boundary potentials for 3-dimensional bio-tissue in terms of the concept of solid angles. The numerical realizations for different configurations are finally presented to show the validity of the proposed scheme.

Utility of noninvasive electrocardiographic imaging in the localization of nonpulmonary vein triggers of atrial fibrillation determined by pacing common trigger sites.

Identifying the origin of nonpulmonary vein atrial fibrillation (AF) triggers (NPVTs) after pulmonary vein isolation (PVI) can be challenging. We aimed to determine if noninvasive electrocardiographic imaging (ECGi) could localize pacing from common NPVT sites. ECGi combines measured body surface potentials with heart-torso geometry acquired from computed tomography (CT) to generate an activation map. In 12 patients with AF undergoing first time ablation, the ECGi vest was fitted for preprocedural CT scan and worn during the procedure. After PVI, we performed steady-state pacing from 15 typical anatomic NPVT sites at a cycle length of 700-800 ms. We co-registered the invasive anatomic map with the CT-based ECGi epicardial activation map to compare ECGi predicted to true pacing origin. In the study cohort (67% male, 58% persistent AF, and 67% with left atrial dilation), 148 (82%) pacing sites had both capture and adequate anatomy acquired from the three-dimensional mapping system to co-register with ECGi activation map. Median distance between true pacing sites and point of earliest epicardial activation derived from the ECGi maps for all sites was 17 mm (interquartile range, 10-22 mm). Assuming paced sites treated as regions with a radius of 2.5 cm, the earliest activation site on ECGi map falls within the region with 94% accuracy. ECGi can approximate the origin of paced beats from common NPVT sites to within a median distance of 17 mm. A rapidly identified region may then be the focus of more detailed catheter-based mapping techniques to facilitate successful localization and ablation of NPVTs.

Clinical Implementation and Initial Validation of Respiratory-Gated Stereotactic Body Radiotherapy for Thoracoabdominal Tumors Under Abdominal Compression Using an Anzai Laser-Based Gating Device With Visual Guidance on an Elekta Linear Accelerator.

We have clinically implemented gated stereotactic body radiotherapy under abdominal compression using an Anzai laser-based gating device with visual guidance in combination with an Elekta linear accelerator. To ensure accuracy, we configured the gating window for each patient by correlating the respiratory curve from the laser sensor and the tumor positions from the 4D computed tomography (CT) images reconstructed with the aid of the respiratory curve. This allowed us to define a patient-specific gating window to keep the tumor displacement below 5 mm from the end-expiration, assuming the reproducibility of the tumor trajectories and the laser-based body surface measurements. Results are summarized as follows: 1) A patient-specific gating window internal target volume (ITV) with a prespecified maximum tumor displacement relative to the end-expiration was obtained by acquiring a 4D CT consisting of 20 phase CT sets and a respiratory curve from the Anzai system. 2) Respiratory hysteresis was managed by setting two different thresholds on the respiratory curve based on the predetermined maximum tumor displacement relative to end-expiration. 3) Abdominal compression increased gating window width, thereby presumably leading to faster gated-beam delivery. 4) Gamma index pass rates in sliding-window gated intensity-modulated radiotherapy (IMRT) were superior to those in gated volumetric modulated arc therapy (VMAT). 5) Intrafraction gated cone-beam computed tomography (CBCT) demonstrated that the tumor appeared to remain within the gating window ITV during the stereotactic gated sliding-window IMRT. In conclusion, we have successfully implemented gated stereotactic body radiotherapy at our clinic and achieved a favorable clinical validation result. More cases need to be evaluated to increase the validity.

Initial validation of a diaphragm tracking system for multiple breath-hold volumetric modulated arc therapy of abdominal tumors: A phantom study.

The breath-hold radiotherapy has been increasingly used to mitigate interfractional and intrafractional breathing impact on treatment planning and beam delivery. Previous techniques include body surface measurements or radiopaque metal markers, each having known disadvantages. We recently proposed a new markerless technique without the disadvantages, where diaphragm was registered between DRR and fluoroscopic x-ray projection images every 180ms during VMAT delivery. An initial validation of the proposed diaphragm tracking system (DiaTrak) was performed using a chest phantom to evaluate its characteristics. Diaphragm registration was performed between DRR and projection streaming kV x-ray images of a chest phantom during VMAT delivery. Streaming data including the projection images and the beam angles were transferred from a linac system to an external PC, where the diaphragm registration accuracy and beam-off latency were measured based on image cross correlation between the DRR and the projection images every 180ms. It was shown that the average of the beam-off latency was 249.5ms and the average of the diaphragm registration error was 0.84mm CONCLUSIONS: Initial validation of the proposed DiaTrak system for multiple breath-hold VMAT of abdominal tumors has been successfully completed with a chest phantom. The resulting beam-off latency and the diaphragm registration error were regarded clinically acceptable.

Oleogel-S10 in Dystrophic Epidermolysis Bullosa: A Case Series Evaluating the Impact on Wound Burden Over Two Years.

Epidermolysis bullosa (EB) is a group of rare, difficult-to-treat, inherited multisystem diseases affecting epithelial integrity. Impaired wound healing is central and can lead to serious clinical complications, deformities, and symptoms with a devastating impact on quality of life (QoL). Dressing changes and wound care are central to the management of EB. Recently Oleogel-S10 (also known as birch bark extract or birch triterpenes) was approved in Europe and the UK for treating EB wounds. This approval was based on data from the EASE phase3 study, which demonstrated Oleogel-S10 accelerated wound healing, reduced total wound burden, and decreased the frequency of dressing changes in patients with EB. A retrospective analysis of medical records was conducted for up to 24months in 13 patients with EB treated with Oleogel-S10 through an early access programme in Colombia. Effectiveness was assessed by measuring body surface area percentage (BSAP) and total body wound burden (EBDASI). Tolerability and safety were monitored throughout. This is the first report to evaluate the effectiveness of Oleogel-S10 in clinical practice. The results showed a reduction in percentage of BSA affected, from a mean of 27.3% at baseline to 10.4% at 24-month follow-up, despite treatment interruptions. A reduction in EBDASI skin activity score of - 16.2 (24months) together with a reduced skin damage index score of - 15.4 (18months) was also observed. Physicians, patients, and caregivers perceived faster wound closure. Adherence with therapy by patients was good, and patients expressed satisfaction with treatment and reported improvements in self-esteem, productivity, and social interaction. Oleogel-S10 was well tolerated; however, two patients reported worsening wounds related to gauze adherence. Two deaths during treatment interruption were reported and was not considered related to Oleogel-S10. This study supports the effectiveness of Oleogel-S10 in a real-world scenario in a country with scarce resources for the treatment of EB.

Calculation of body surface area of corn snakes (Pantherophis guttatus) utilizing computed tomography.

To determine the K-constant for body surface area calculation from body weight in corn snakes (Pantherophis guttatus) through the use of computed tomography (CT) measurements. 12 adult corn snakes held by North Carolina State University for research purposes underwent CT between November 2022 and January 2023. Each snake had a CT scan, physical examination, and body weight measurement. CT images were uploaded into software able to perform 3-D reconstruction and measure body surface area. The species-specific K-constant was determined using nonlinear regression analysis between body surface area and (body weight in grams)2/3. The mean body weight of the 12 adult corn snakes was 228 g, with a mean body surface area of 505.1 cm2. The calculated K-constant was 13.6 (P < .001). The resulting formula for body surface area in corn snakes is BSA in cm2 = 13.6 X (body weight in grams)2/3. The body surface area formula developed for corn snakes will allow for improved dosing accuracy for medications with low therapeutic safety margins. Additional pharmacokinetic and pharmacodynamic studies are necessary to determine the safety and efficacy of individual medications.

Uncertainty quantification of the effect of cardiac position variability in the inverse problem of electrocardiographic imaging

Objective. Electrocardiographic imaging (ECGI) is a functional imaging modality that consists of two related problems, the forward problem of reconstructing body surface electrical signals given cardiac bioelectric activity, and the inverse problem of reconstructing cardiac bioelectric activity given measured body surface signals. ECGI relies on a model for how the heart generates bioelectric signals which is subject to variability in inputs. The study of how uncertainty in model inputs affects the model output is known as uncertainty quantification (UQ). This study establishes develops, and characterizes the application of UQ to ECGI. Approach. We establish two formulations for applying UQ to ECGI: a polynomial chaos expansion (PCE) based parametric UQ formulation (PCE-UQ formulation), and a novel UQ-aware inverse formulation which leverages our previously established ‘joint-inverse’ formulation (UQ joint-inverse formulation). We apply these to evaluate the effect of uncertainty in the heart position on the ECGI solutions across a range of ECGI datasets. Main results. We demonstrated the ability of our UQ-ECGI formulations to characterize the effect of parameter uncertainty on the ECGI inverse problem. We found that while the PCE-UQ inverse solution provided more complex outputs such as sensitivities and standard deviation, the UQ joint-inverse solution provided a more interpretable output in the form of a single ECGI solution. We find that between these two methods we are able to assess a wide range of effects that heart position variability has on the ECGI solution. Significance. This study, for the first time, characterizes in detail the application of UQ to the ECGI inverse problem. We demonstrated how UQ can provide insight into the behavior of ECGI using variability in cardiac position as a test case. This study lays the groundwork for future development of UQ-ECGI studies, as well as future development of ECGI formulations which are robust to input parameter variability.

Novel Muscle Sensing by Radiomyography (RMG) and Its Application to Hand Gesture Recognition.

Conventional electromyography (EMG) measures the continuous neural activity during muscle contraction, but lacks explicit quantification of the actual contraction. Mechanomyography (MMG) and accelerometers only measure body surface motion, while ultrasound, CT-scan and MRI are restricted to in-clinic snapshots. Here we propose a novel radiomyography (RMG) for continuous muscle actuation sensing that can be wearable or touchless, capturing both superficial and deep muscle groups. We verified RMG experimentally by a wearable forearm sensor for hand gesture recognition (HGR). We first converted the sensor outputs to the time-frequency spectrogram, and then employed the vision transformer (ViT) deep learning network as the classification model, which can recognize 23 gestures with an average accuracy up to 99% on 8 subjects. By transfer learning, high adaptivity to user difference and sensor variation were achieved at an average accuracy up to 97%. We further extended RMG to monitor eye and leg muscles and achieved high accuracy for eye movement and body posture tracking. RMG can be used with synchronous EMG to derive stimulation-actuation waveforms for many potential applications in kinesiology, physiotherapy, rehabilitation, and human-machine interface.

Tip orientation under real-time point-of-care neck ultrasonic monitoring is advantageous in peripherally inserted central catheter procedures: a retrospective cohort study

Abstract Background We analyzed the success and catheter tip malposition rates of peripherally inserted central catheter (PICC) placement using ultrasonic monitoring. Methods A total of 564 patients were recruited and assigned to either the intervention or control group. In the intervention group, 282 patients underwent ultrasound-guided PICC insertion, which helped to identify the position and depth of the catheter tip. From a total of 9000 patients, 282 were selectively chosen to receive the traditional method using body surface measurements (control group). The primary endpoint was the success rate; the secondary endpoint was the catheter tip malposition rate as detected by postprocedure chest radiography. Results In the intervention group, a total of 94 catheters were in a suboptimal position; 26 were too deep, 68 were too shallow, and 1 was inserted into the subclavian vein, with success and malposition rates of 66.3% and 0.4%, respectively. In the control group, 139 catheters were in a suboptimal position; 88 were too deep, 51 were too shallow, 9 were inserted into the jugular vein, and 2 were inserted into the subclavian vein, with success and malposition rates of 46.8% (P &lt; 0.001) and 3.9% (P = 0.004), respectively. Significant differences were observed in success and malposition rates between the 2 groups. Conclusion Ultrasound-guided PICC procedures achieved higher success rates and lower malposition rates.

The Value of Non-Contact Infrared Thermometer in Measuring Temperatures of Different Body Surfaces: A Clinical Diagnostic Study

Objectives: This study aimed to determine the optimal cutoff value for fever based on temperature measurements of different body surfaces using a non-contact infrared thermometer. Methods: A total of 229 participants were conveniently sampled for this clinical diagnostic study. Oral temperature was measured using a mercury thermometer, while the temperatures of the forehead, neck, and wrists were measured using a non-contact infrared thermometer. The differences and linear relationships between the temperature measurements of different body surfaces and oral temperature were analyzed using statistical methods. Receiver operating characteristic (ROC) curves were constructed to determine the optimal cutoff values for fever on the forehead, neck, and wrists. Results: The optimal cutoff values for fever on the neck, forehead, and wrists were 37.1°C, 36.9°C, and 36.8°C, respectively, as measured by the non-contact infrared thermometer. Conclusion: The non-contact infrared thermometer is a reliable tool for measuring body surface temperatures. The optimal cutoff values for fever using a non-contact infrared thermometer are 37.1°C for the neck, 36.9°C for the forehead, and 36.8°C for the wrists.

Associations of Three-Dimensional Anthropometric Body Surface Scanning Measurements and Coronary Artery Disease.

Background and Objectives: The relationship between three-dimensional (3D) scanning-derived body surface measurements and biomarkers in patients with coronary artery disease (CAD) were assessed. Methods and Methods: The recruitment of 98 patients with CAD confirmed by cardiac catheterization and 98 non-CAD patients were performed between March 2016 and December 2017. A health questionnaire on basic information, life style variables, and past medical and family history was completed. 3D body surface measurements and biomarkers were obtained. Differences between the two groups were assessed and multivariable analysis performed. Results: It was found that chest width (odds ratio [OR] 0.761, 95% confidence interval [CI] = 0.586-0.987, p = 0.0399), right arm length (OR 0.743, 95% CI = 0.632-0.875, p = 0.0004), waist circumference (OR 1.119, 95% CI = 1.035-1.21, p = 0.0048), leptin (OR 1.443, 95% CI = 1.184-1.76, p = 0.0003), adiponectin (OR 0.978, 95% CI = 0.963-0.994, p = 0.006), and interleukin 6 (OR 1.181, 95% CI = 1.021-1.366, p = 0.0254) were significantly associated with CAD. The combination of biomarker scores and body measurement scores had the greatest area under the curve and best association with CAD (area under the curve of 0.8049 and 95% CI = 0.7440-0.8657). Conclusions: Our study suggests that 3D derived body surface measurements in combination with leptin, adiponectin, and interleukin 6 levels may direct us to those at risk of CAD, allowing a non-invasive approach to identifying high-risk patients.

Optimal diagnostic fever thresholds using non-contact infrared thermometers under COVID-19.

Fever screening is an effective method to detect infectors associated with different variants of coronavirus disease 2019 (COVID-19) based on the fact that most infectors with COVID-19 have fever symptoms. Non-contact infrared thermometers (NCITs) are widely used in fever screening. Nevertheless, authoritative data is lacking in defining "fever" at different body surface sites when using NCITs. The purpose of this study was to determine the optimal diagnostic threshold for fever screening using NICTs at different body surface sites, to improve the accuracy of fever screening and provide theoretical reference for healthcare policy. Participants (n = 1860) who were outpatients or emergency patients at Chengdu Women's and Children's Central Hospital were recruited for this prospective investigation from March 1 to June 30, 2021. NCITs and mercury axillary thermometers were used to measure neck, temple, forehead and wrist temperatures of all participants. Receiver operating characteristic curves were used to reflect the accuracy of NCITs. Linear correlation analysis was used to show the effect of age on body temperature. Multilinear regression analysis was used to explore the association between non-febrile participant's covariates and neck temperature. The mean age of participants was 3.45 ± 2.85 years for children and 28.56 ± 7.25 years for adults. In addition 1,304 (70.1%) participants were children (≤12), and 683 (36.7%) were male. The neck temperature exhibited the highest accuracy among the four sites. Further the optimal fever diagnostic thresholds of NCITs at the four body surface measurement sites were neck (36.75 °C, sensitivity: 0.993, specificity: 0.858); temple (36.55 °C, sensitivity: 0.974, specificity: 0.874); forehead (36.45 °C, sensitivity: 0.961, specificity: 0.813); and wrist (36.15 °C, sensitivity: 0.951, specificity: 0.434). Based on the findings of our study, we recommend 36.15, 36.45, 36.55, and 36.75 °C as the diagnostic thresholds of fever at the wrist, forehead, temple and neck, respectively. Among the four surface sites, neck temperature exhibited the highest accuracy.

Revised spectral metrics for body surface measurements of gastric electrophysiology.

Electrogastrography (EGG) non-invasively evaluates gastric function but has not achieved common clinical adoption due to several technical limitations. Body Surface Gastric Mapping (BSGM) has been introduced to overcome these limitations, but pitfalls in traditional metrics used to analyze spectral data remain unaddressed. This study critically evaluates five traditional EGG metrics and introduces improved BSGM spectral metrics, with validation in a large cohort. Pitfalls in five EGG metrics were assessed (dominant frequency, percentage time normogastria, amplitude, power ratio, and instability coefficient), leading to four revised BSGM spectral metrics. Traditional and revised metrics were compared to validate performance using a standardized 100-subject database of BSGM tests (30 min baseline; 4-h postprandial) recorded using Gastric Alimetry® (Alimetry). BMI and amplitude were highly correlated (r= -0.57, p< 0.001). We applied a conservative BMI correction to obtain a BMI-adjusted amplitude metric (r= -0.21, p= 0.037). Instability coefficient was highly correlated with both dominant frequency (r= -0.44, p< 0.001), and percent bradygastria (r= 0.85, p< 0.001), in part due to misclassification of low frequency transients as gastric activity. This was corrected by introducing distinct gastric frequency and stability metrics (Principal Gastric Frequency and Gastric Alimetry Rhythm Index (GA-RI)TM ) that were uncorrelated (r= 0.14, p= 0.314). Only 28% of subjects showed a maximal averaged amplitude within the first postprandial hour. Calculating Fed:Fasted Amplitude Ratio over a 4-h postprandial window yielded a median increase of 0.31 (IQR 0-0.64) above the traditional ratio. The revised metrics resolve critical pitfalls impairing the performance of traditional EGG, and should be applied in future BSGM spectral analyses.

Abstract 14320: Regionalization of Non-Pulmonary Vein Triggers for Atrial Fibrillation Using Non-Invasive Electrocardiographic Imaging

Introduction Ablation of non-pulmonary vein triggers (NPVTs) after pulmonary vein isolation (PVI) reduces atrial fibrillation (AF) recurrence, but localizing NPVTs can be challenging. We evaluated the potential for noninvasive electrocardiographic imaging (ECGi) to regionalize NPVTs and expedite more focused catheter-based mapping. ECGi combines measured body surface potentials with heart-torso geometry acquired from computed tomography (CT), to generate an activation map from a single recorded beat. Methods In 12 patients with AF undergoing first time AF ablation, the ECGi vest was fitted for preprocedural CT scan and then worn during procedure. Following completion of PVI, we paced from 15 atrial sites where NPVTs commonly arise (Figure 1), and evaluated the epicardial activation map generated by ECGi during steady state pacing at cycle length of 700-800 ms allowing an unobscured P wave. Merging of invasive anatomic map with CT-based ECGi map allowed comparison of ECGi activation map with true pacing location (Figure 2). Results From 180 pacing sites in our patient cohort (67% male, 58% persistent AF, 67% left atrial dilation), median distance between earliest activation site on ECGi map and pacing location was 16 mm (interquartile range, 11-22 mm), with 95% of sites within 30 mm (Figure 2). Septal pacing sites were measured to the epicardial aspect of the interatrial septum. Conclusions ECGi is able to consistently approximate the origin of paced beats from common NPVT sites and suggests the potential for rapid regionalization of NPVTs. The identified region can then be the focus of more detailed catheter-based mapping techniques to facilitate successful ablation of NPVTs.

Use of caliper-based external measurement of body surface in assessing the severity of pectus excavatum.

IntroductionObjective assessment of the severity of pectus excavatum (PE) mainly depends on internal imaging examination, which poses radiation exposure risks and high financial costs. Our study explores the feasibility of caliper-based external measurements of the body surface to assess PE severity.Materials and methodsPatients with PE aged 4–18 years who underwent both internal imaging examinations and external measurements were chosen for the study. Overall, 176 patients underwent surgery and 21 underwent regular observation. The Haller index (HI) and correction index (CI) were used to derive the external measurement indices, HI-caliper and CI-caliper. Receiver-operator characteristic analysis provided the optimal cut-off values and compared the diagnostic values of HI-caliper and CI-caliper. Spearman's correlation coefficient and Cohen's kappa coefficient were used to analyze the correlation and consistency between HI-caliper or CI-caliper and HI-CT or CI-CT, respectively. Also, a paired samples t-test was used to compare the differences of HI-caliper or CI-caliper before and after surgery.ResultsHI-caliper and CI-caliper measurements had strong correlations with HI-CT and CI-CT results (rs = 0.70, p < 0.001; rs = 0.69, p < 0.001), respectively. The optimal cut-off values of HI-caliper and CI-caliper were 1.83 (sensitivity = 0.841, specificity = 0.905) and 12% (sensitivity = 0.881, specificity = 0.857), exhibiting comparable diagnostic values with HI-CT and CI-CT. HI-caliper > 1.83 or CI-caliper > 12% had medium intensity consistency with HI-CT ≥ 3.25 or CI-CT ≥ 28% (k = 0.545, 95% confidence interval: 0.374–0.716, p < 0.001). The HI-caliper and CI-caliper values were significantly different before and after surgery.ConclusionCaliper-based external measurement is a feasible method to screen patients who require surgical intervention and for monitoring the progression of PE severity.

Intracavitary electrocardiography for femorally inserted central catheter tip location in adult patients.

BackgroundIn this study, the intracavitary electrocardiogram (ECG) P‐wave and QRS‐wave changes during femorally inserted central catheter (FICC) placement in adults were observed with the aim of reducing malposition occurrence. The observed method provides venous access in patients who have limited upper limb venous catheterization potential and require medium‐term and long‐term infusions.MethodsA retrospective analysis of 34 adult patients who underwent FICC placement was conducted. After body surface measurements were taken, all patients were connected to an ECG during catheter placement, and the P‐wave and QRS‐wave changes were observed. Next, the catheter tip position was confirmed with an abdominal X‐ray, and an analysis of the changes occurring during the procedure was conducted.ResultsIn the 34 patients included in the present study, the catheter tips were located below the diaphragm level in the inferior vena cava. Of the patients, 18 showed negative P waves, biphasic P waves, and positive high‐amplitude P waves with increasing the insertion depth. In 16 patients, no P‐wave characteristic changes were observed during catheterization, and an abdominal X‐ray confirmed that the catheter tip was positioned below the level of the first lumbar vertebra.ConclusionNegative P waves, biphasic P waves, and positive high‐amplitude P waves appeared during FICC placement in adults. Catheter withdrawal until the P wave reverted to normal indicated that a tip position close to the inferior vena cava above the diaphragm level was ideal.

The Influence of High Temperature Weather on Human Body Temperature Measurement by Infrared Thermal Imaging Thermometer

Infrared thermography thermometer is a non-contact temperature measuring equipment, which is widely used in the stage of large-scale epidemic of the covid-19 pandemic. It is used for rapid screening of human body temperature in crowded places at the entrance and exit of airports, docks, shopping malls, stations and schools. But when the outdoor temperature approaches or exceeds the body temperature in summer, can this method of measuring body surface temperature by infrared thermal imager be used as a standard for screening fever? Under the condition of high temperature in summer, the field experiment of measuring body temperature by infrared thermal imager is carried out, the experimental results are analyzed. We recommend the use of relative temperature difference for screening patients with fever.

Cardiac Activation Maps Reconstruction: A Comparative Study Between Data-Driven and Physics-Based Methods.

One of the essential diagnostic tools of cardiac arrhythmia is activation mapping. Noninvasive current mapping procedures include electrocardiographic imaging. It allows reconstructing heart surface potentials from measured body surface potentials. Then, activation maps are generated using the heart surface potentials. Recently, a study suggests to deploy artificial neural networks to estimate activation maps directly from body surface potential measurements. Here we carry out a comparative study between the data-driven approach DirectMap and noninvasive classic technique based on reconstructed heart surface potentials using both Finite element method combined with L1-norm regularization (FEM-L1) and the spatial adaptation of Time-delay neural networks (SATDNN-AT). In this work, we assess the performance of the three approaches using a synthetic single paced-rhythm dataset generated on the atria surface. The results show that data-driven approach DirectMap quantitatively outperforms the two other methods. In fact, we observe an absolute activation time error and a correlation coefficient, respectively, equal to 7.20 ms, 93.2% using DirectMap, 14.60 ms, 76.2% using FEM-L1 and 13.58 ms, 79.6% using SATDNN-AT. In addition, results show that data-driven approaches (DirectMap and SATDNN-AT) are strongly robust against additive gaussian noise compared to FEM-L1.

Adverse body measurements are superior to sarcopenia-associated measurements in predicting chronic diseases

Few studies have demonstrated an association of sarcopenia-associated body measurements with chronic diseases through a comprehensive methodology. This study aims to examine the relationship between sarcopenia-associated body measurements and chronic diseases. This is a cohort study. We recruited 316 community dwellers, including 76 patients with sarcopenia and 240 controls, and obtained their body measurements associated with sarcopenia. We collected three-dimensional anthropometric body-surface measurements from 11,158 participants during 2000–2008 and followed up this cohort for 15 years to examine the association of these measurements with the risk of chronic diseases such as hypertension, type 2 diabetes mellitus (T2DM), heart disease, and nephrotic syndrome. Univariate analysis, canonical correlation, and Cox regression analysis were performed to explore the associations. Decreased waist width, upper left arm circumference, and left thigh circumference were significantly associated with sarcopenia. The adverse body measure score (ABMS) was derived by combining significant measurements, namely left upper arm circumference, waist width, and left thigh circumference, and used to predict the risk of hypertension, T2DM, heart diseases, and nephrotic syndrome. A positive association was observed between the ABMS and chronic diseases. Considering the first quartile of the ABMS as a reference, we determined hazard ratios of 2.259, 2.495, 1.332, and 1.595 for hypertension, T2DM, heart disease, and nephrotic syndrome, respectively, in the fourth quartile. Chronic diseases were more strongly associated with the ABMS than with sarcopenia-related body measurements alone. A high ABMS, which includes higher upper arm circumference, higher waist width, and lower thigh circumference, can significantly predict chronic diseases.

Electrocardiographic Imaging: A Comparison of Iterative Solvers.

Cardiac disease is a leading cause of morbidity and mortality in developed countries. Currently, non-invasive techniques that can identify patients at risk and provide accurate diagnosis and ablation guidance therapy are under development. One of these is electrocardiographic imaging (ECGI). In ECGI, the first step is to formulate a forward problem that relates the unknown potential sources on the cardiac surface to the measured body surface potentials. Then, the unknown potential sources on the cardiac surface are reconstructed through the solution of an inverse problem. Unfortunately, ECGI still lacks accuracy due to the underlying inverse problem being ill-posed, and this consequently imposes limitations on the understanding and treatment of many cardiac diseases. Therefore, it is necessary to improve the solution of the inverse problem. In this work, we transfer and adapt four inverse problem methods to the ECGI setting: algebraic reconstruction technique (ART), random ART, ART Split Bregman (ART-SB) and range restricted generalized minimal residual (RRGMRES) method. We test all these methods with data from the Experimental Data and Geometric Analysis Repository (EDGAR) and compare their solution with the recorded epicardial potentials provided by EDGAR and a generalized minimal residual (GMRES) iterative method computed solution. Activation maps are also computed and compared. The results show that ART achieved the most stable solutions and, for some datasets, returned the best reconstruction. Differences between the solutions derived from ART and random ART are almost negligible, and the accuracy of their solutions is followed by RRGMRES, ART-SB and finally the GMRES (which returned the worst reconstructions). The RRGMRES method provided the best reconstruction for some datasets but appeared to be less stable than ART when comparing different datasets. In conclusion, we show that the proposed methods (ART, random ART, and RRGMRES) improve the GMRES solution, which has been suggested as inverse problem solution for ECGI.