Torso Model Research Articles

A torso model comparison of temperature preservation devices for use in the prehospital environment

BackgroundHypothermia is an independent predictor of increased morbidity and mortality in patients with trauma. Several strategies and products have been developed to minimise patients’ heat loss in the prehospital arena,...

A Novel Method of Deep Tissue Biomedical Imaging Using a Wearable Sensor

We present a novel monitoring method for continuous real-time imaging of deep human tissues using a body-worn sensor. The sensor operates at 40 MHz, and consists of a set of transmitting and receiving probes placed around the human body. For the first time, this portable and body-worn sensor provides for deep tissue pixel-by-pixel imaging. A demonstration of the concept is carried out by retrieving a 16-pixel image of the underlying cross section with accuracy better than 6%. This paper also provides a theoretical analysis for assessing the sensor’s accuracy. The analysis is based on line-source scattering by a two-layer cylindrical model of the human torso. Full-wave simulations are then carried out to demonstrate the sensor’s imaging capabilities pixel-by-pixel. Overall, the proposed sensor can be the basis for a portable and low-cost alternative to the conventional imaging techniques suitable for a wide range of applications (among them, the prevention of cardiovascular diseases and tumor growth monitoring).

A novel distractive and mobility-enabling lumbar spinal orthosis.

PurposeLumbar spinal orthoses are often used as non-surgical treatment and serve to support the spine and alleviate low back pain. More recently, dynamic orthoses claiming to decompress the spine have been introduced. A previously developed prototype of dynamic mobility orthosis (DMO1) was designed that provided a distractive load across the lumbar spine but required higher sagittal bending moments and was unable to maintain spinal off-loading throughout extended ranges of movement. The objective was to design a new orthosis (DMO2) that reduced bending moment buildup and sustained spinal off-loading throughout daily living ranges of flexion and extension movement.MethodsA mechanical analog upper torso model and programmable robotic testing platform were used to design features of DMO2: a mobility-enabling component and a distractive force component. Test conditions for DMO2 were 300 N of applied vertical torso load over a range of 25° flexion to 10° extension. Loads carried by the brace were determined throughout flexion and extension ranges. Applied moments to the upper torso model and transferred moments to the spine were measured. The difference in applied and transferred moments represented brace moment effects.ResultsThe DMO2 prototype improved spinal off-loading capacity from 172 N to 290 N at end-range flexion and from 247 N to 293 N at end range extension compared to the original DMO1 prototype. End-range applied moments (flexion-DMO1: 32.4 Nm/DMO2: 21.7 Nm; extension-DMO1: 15.0 Nm/DMO2: 10.9 Nm) and brace moments (flexion-DMO1: 18.6 Nm/DMO2: 6.6 Nm; extension-DMO1: 15.0 Nm/DMO2: 4.4 Nm) were also reduced.ConclusionsA novel dynamic spinal orthosis was designed that maintained spinal off-loading throughout extended ranges of flexion and extension movement without buildup of adverse bending moments.

Abstract 17832: A New Rapid Vector Technique to Localize the PVC Origin From the 12-lead Ecg Compared to Cips

Introduction: Prior accurate PVC localization improves the time and outcome of ablative procedures. We developed a new manual Vector Technique (VcT) to localize the PVC origin to cardiac anatomy regions. In contrast, our Cardiac Isochrone Positioning System (CIPS) is a computer based system that localizes the PVC to patient specific cardiac anatomy from the MRI and electrode positions from the 3D Camera. Hypothesis: We hypothesize that this new VcT can rapidly quantitate the location of PVC to anatomical regions whereas CIPS localizes the PVCs to more specific cardiac anatomical segments. Method: The VcT assumes the frontal plane leads are formatted on the chest as an equilateral triangle and the horizontal leads as a partial sphere. Using the concept that a lead recording perpendicular to a dipole vector is zero, the QRS axis vectors of the PVC were calculated manually within 3.8 to 7.5 degrees in the frontal and horizontal planes. CIPS computed the electrode positions by registration of the MRI derived torso model with the 3D image of the patient. The ECG signals were used by both methods to localize the PVC origin to the cardiac anatomy. Result: In 12 patients (below), this manual VcT separated without overlap in the horizontal plane the PVC into Left Ventricle (LV 30-45°), Right Ventricular (RV 308-348°), and Papillary Muscle (PM 128-150°) regions, but not in the frontal plane. CIPS localized 10 PVCs to the same and 2 to adjacent anatomical segments while the vector technique cannot because of the need for a database to create a PVC anatomic segment model. Conclusion: This new VcT can be used by anyone to localize rapidly the PVC by a QRS vector plot to regions like the left & posterior for the RV, left & anterior for the LV, and right & anterior for the papillary muscles while CIPS can localize PVCs more specifically to anatomical segments. Using the 12 lead ECG, this VcT creates a quantitative cardiac anatomical segment model of PVC locations integrated into CIPS that can improve the accuracy of VcT.

Detailed Anatomical and Electrophysiological Models of Human Atria and Torso for the Simulation of Atrial Activation.

Atrial arrhythmias, and specifically atrial fibrillation (AF), induce rapid and irregular activation patterns that appear on the torso surface as abnormal P-waves in electrocardiograms and body surface potential maps (BSPM). In recent years both P-waves and the BSPM have been used to identify the mechanisms underlying AF, such as localizing ectopic foci or high-frequency rotors. However, the relationship between the activation of the different areas of the atria and the characteristics of the BSPM and P-wave signals are still far from being completely understood. In this work we developed a multi-scale framework, which combines a highly-detailed 3D atrial model and a torso model to study the relationship between atrial activation and surface signals in sinus rhythm. Using this multi scale model, it was revealed that the best places for recording P-waves are the frontal upper right and the frontal and rear left quadrants of the torso. Our results also suggest that only nine regions (of the twenty-one structures in which the atrial surface was divided) make a significant contribution to the BSPM and determine the main P-wave characteristics.

Strain Gauge Sensors Implemented in a New Female Torso Model Have Increased Student's Motivation and Confidence in Gynecologic Bimanual Examination on Clinical Skill Training

A good mannequin is needed to improve the quality of clinical skill learning. A strain sensors gauge can be applied into gynecologic bimanual examination mannequin. This study compared a new strain gauge sensors mannequin and non-sensor mannequin for gynecologic bimanual examination training in undergraduate medical student. We made a new female torso model implemented with strain gauge sensors in the definitive landmark, then used this new mannequin for gynecologic bimanual examination training in undergraduate medical student, and evaluated using questioner. We observed 4 parameters: mannequin appearance, student’s self confidence to palpate uterus and ovary, and student’s learning motivation. The new model improved student’s confident to palpate ovary (p<0.05) and student’s motivation (p<0.001) compared to non-sensor mannequin. In contrast, the gross appearance of the new mannequin was inferior (p<0.05). However, there was no difference in defining the uterus position during examination (p>0.05) in both mannequins. A new female torso model with strain gauge sensors can be applied for gynecologic examination training.

Quantitative Analysis of Torso FDG-PET Scans by Using Anatomical Standardization of Normal Cases from Thorough Physical Examinations.

Understanding of standardized uptake value (SUV) of 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography (FDG-PET) depends on the background accumulations of glucose because the SUV often varies the status of patients. The purpose of this study was to develop a new method for quantitative analysis of SUV of FDG-PET scan images. The method included an anatomical standardization and a statistical comparison with normal cases by using Z-score that are often used in SPM or 3D-SSP approach for brain function analysis. Our scheme consisted of two approaches, which included the construction of a normal model and the determination of the SUV scores as Z-score index for measuring the abnormality of an FDG-PET scan image. To construct the normal torso model, all of the normal images were registered into one shape, which indicated the normal range of SUV at all voxels. The image deformation process consisted of a whole body rigid registration of shoulder to bladder region and liver registration and a non-linear registration of body surface by using the thin-plate spline technique. In order to validate usefulness of our method, we segment suspicious regions on FDG-PET images manually, and obtained the Z-scores of the regions based on the corresponding voxels that stores the mean and the standard deviations from the normal model. We collected 243 (143 males and 100 females) normal cases to construct the normal model. We also extracted 432 abnormal spots from 63 abnormal cases (73 cancer lesions) to validate the Z-scores. The Z-scores of 417 out of 432 abnormal spots were higher than 2.0, which statistically indicated the severity of the spots. In conclusions, the Z-scores obtained by our computerized scheme with anatomical standardization of torso region would be useful for visualization and detection of subtle lesions on FDG-PET scan images even when the SUV may not clearly show an abnormality.

A New Algorithm to Diagnose Atrial Ectopic Origin from Multi Lead ECG Systems - Insights from 3D Virtual Human Atria and Torso

Rapid atrial arrhythmias such as atrial fibrillation (AF) predispose to ventricular arrhythmias, sudden cardiac death and stroke. Identifying the origin of atrial ectopic activity from the electrocardiogram (ECG) can help to diagnose the early onset of AF in a cost-effective manner. The complex and rapid atrial electrical activity during AF makes it difficult to obtain detailed information on atrial activation using the standard 12-lead ECG alone. Compared to conventional 12-lead ECG, more detailed ECG lead configurations may provide further information about spatio-temporal dynamics of the body surface potential (BSP) during atrial excitation. We apply a recently developed 3D human atrial model to simulate electrical activity during normal sinus rhythm and ectopic pacing. The atrial model is placed into a newly developed torso model which considers the presence of the lungs, liver and spinal cord. A boundary element method is used to compute the BSP resulting from atrial excitation. Elements of the torso mesh corresponding to the locations of the placement of the electrodes in the standard 12-lead and a more detailed 64-lead ECG configuration were selected. The ectopic focal activity was simulated at various origins across all the different regions of the atria. Simulated BSP maps during normal atrial excitation (i.e. sinoatrial node excitation) were compared to those observed experimentally (obtained from the 64-lead ECG system), showing a strong agreement between the evolution in time of the simulated and experimental data in the P-wave morphology of the ECG and dipole evolution. An algorithm to obtain the location of the stimulus from a 64-lead ECG system was developed. The algorithm presented had a success rate of 93%, meaning that it correctly identified the origin of atrial focus in 75/80 simulations, and involved a general approach relevant to any multi-lead ECG system. This represents a significant improvement over previously developed algorithms.

Effects of L-type calcium channel and human ether-a-go-go related gene blockers on the electrical activity of the human heart: a simulation study.

AimsClass III and IV drugs affect cardiac human ether-a-go-go related gene (IKr) and L-type calcium (ICaL) channels, resulting in complex alterations in repolarization with both anti- and pro-arrhythmic consequences. Interpretation of their effects on cellular and electrocardiogram (ECG)-based biomarkers for risk stratification is challenging. As pharmaceutical compounds often exhibit multiple ion channel effects, our goal is to investigate the simultaneous effect of ICaL and IKr block on human ventricular electrophysiology from ionic to ECG level.Methods and resultsSimulations are conducted using a human body torso bidomain model, which includes realistic representation of human membrane kinetics, anatomy, and fibre orientation. A simple block pore model is incorporated to simulate drug-induced ICaL and IKr blocks, for drug dose = 0, IC50, 2× IC50, 10× IC50, and 30× IC50. Drug effects on human ventricular activity are quantified for different degrees and combinations of ICaL and IKr blocks from the ionic to the body surface ECG level. Electrocardiogram simulations show that ICaL block results in shortening of the QT interval, ST elevation, and reduced T-wave amplitude, caused by reduction in action potential duration and action potential amplitude during the plateau phase, and in repolarization times. In contrast, IKr block results in QT prolongation and reduced T-wave amplitude. When ICaL and IKr blocks are combined, the degree of ICaL block strongly determines QT interval whereas the effect of IKr block is more pronounced on the T-wave amplitude.ConclusionOur simulation study provides new insights into the combined effect of ICaL and IKr blocks on human ventricular activity using a multiscale computational human torso model.

Sensitivity of CIPS-computed PVC location to measurement errors in ECG electrode position: the need for the 3D Camera

BackgroundThe Cardiac Isochrone Positioning System (CIPS) is a non-invasive method able to localize the origins of PVCs, VT and WPW from the 12 lead ECG. The CIPS model integrates a standard 12-lead ECG with an MRI derived model of the heart, lungs, and torso in order to compute the precise electrical origin of a PVC from within the myocardium. To make these calculations, CIPS uses virtually represented ECG electrode positions. These virtual electrode positions, however, are currently assumed to represent the standard 12 lead positions in the model without taking into account the actual, anatomical locations on a patient. The degree of error introduced into the CIPS model by movement of the virtual electrodes is unknown. Therefore, we conducted a model-based study to determine the sensitivity of CIPS to changes in its virtually represented ECG electrode positions. MethodsPreviously, CIPS was tested on 9 patients undergoing PVC ablation, producing a precise myocardial PVC location for each patient. These initial results were used as controls in two different simulation experiments. The first moved all virtual precordial leads in CIPS simultaneously up and down to recalculate a PVC origin. The second moved each virtual precordial lead individually, using 8 points on multiple concentric circles of increasing radius to recalculate a PVC origin. The distance of the newly calculated PVC origin from the control origin was used as a metric. ResultsMoving either all electrodes simultaneously or each V1-6 precordial electrode independently resulted in non-linear and unpredictable shifts of the CIPS-computed PVC origin. Simultaneously moving all V1-6 precordial electrodes by 10mm increments produced a shift in CIPS-computed PVC origin between 0 and 62mm. Independently moving an electrode, a shift of more than 10mm resulted in an unpredictable CIPS-computed PVC origin relocation between 0 and 40mm. The effect of moving the virtual electrodes on CIPS modeling more pronounced the closer the virtual electrode was positioned to the actual PVC origin. ConclusionsSlight changes in the virtual positions of the V1-6 precordial electrodes produce marked, non-linear and unpredictable shifts in the CIPS-computed PVC origin. Thus, any variation in the physical ECG electrode placement on a patient can result in significant error within the CIPS model. These large errors would make CIPS useless and underscore the need for accurate, patient specific measurement of electrode position relative to the patient specific torso geometries. A potential solution to this problem could be the introduction of a 3D camera to incorporate accurate measurement of physical electrode placement into the CIPS model.Since the 3D camera software integrates the 3D imaged position of the electrode with the MRI derived torso model, it is conveniently incorporated in the next generation CIPS software to decrease the errors in modeled location of the electrodes. Thus, the 3D camera will be the IIIrd component of the CIPS to increase its accuracy in PVC, VT, and WPW localization.

A theoretical analysis of the electrogastrogram (EGG).

In this study, a boundary element model was developed to investigate the relationship between the gastric electrical activity, also known as slow waves, and the electrogastrogram (EGG). A dipole was calculated to represent the equivalent net activity of gastric slow waves. The dipole was then placed in an anatomically-realistic torso model to simulate EGG. The torso model was constructed from a laser-scanned geometry of an adult male torso phantom with 190 electrode sites equally distributed around the torso so that simulated EGG could be directly compared between the physical model and the mathematical model. The results were analyzed using the Fast Fourier Transforms (FFT), spatial distribution of EGG potential and a resultant EGG based on a 3-lead configuration. The FFT results showed both the dipole and EGG contained identical dominant frequency component of 3 cycles per minute (cpm), with this result matching known physiological phenomenon. The -3 dB point of the EGG was 110 mm from the region directly above the dipole source. Finally, the results indicated that electrode coupling could theoretically be used in a similar fashion to ECG coupling to gain greater understanding of how EGG correlate to gastric slow waves.

Dyadic Green's Function of a Nonspherical Model of the Human Torso

The proposed model of the human torso is principally a host sphere, filled with muscle tissue, wherein three eccentric spherical inclusions are accommodated. Two of them are twins and represent the lungs, whereas the third, referred to as the abdomen, represents all human organs beneath the diaphragm. The host sphere is surrounded by two concentric layers, which represent skin and fat. The dyadic Green's function (dGf) of this nonspherical body is determined by application of the principle of superposition and by enforcement of the boundary conditions on all interfaces. The outcome is a set of linear equations for the vector wave amplitudes of the dGF, and that set is solved by truncation and matrix-inversion. Once this is done, the dGf is available as a sum of dyads, and the electric-field intensity can be determined by integration of the dGf, dot multiplied by the current density of the source. The numerical results correspond to an electric Hertz dipole placed near the waist, i.e., the equator of this torso model, and radiating at a WiFi frequency. Plots of the electric-field intensity along the waist and field maps across the equator plane manifest how protected the internal organs are from the external point source, which is practically attached to the surface, and how sensitive to internal organs is the field on the waist.

청진 훈련 모형용 청음판 검출 알고리즘 개발

The control system of human torso model and driving system of stethoscope for physical assessment trainer are developed. The detecting characteristics of circular pickup coil which is driven by square wave voltage signal with resonance frequency of LC circuits are investigated and it is confirmed that the pickup coil can detect the existence of chestpiece near the coil region. The control system of human torso model is composed of 8 channel pickup coils, Mp3 and Bluetooth module. The driving system of stethoscope is composed of chestpiece with contact switch and Bluetooth headset. The chestpiece detecting algorithm check the contact of chestpiece with human body model first and excite the pickup coil sequentially to find the location. The proposed system can be applied the physical assessment trainer.

Design of a digital phantom population for myocardial perfusion SPECT imaging research

Digital phantoms and Monte Carlo (MC) simulations have become important tools for optimizing and evaluating instrumentation, acquisition and processing methods for myocardial perfusion SPECT (MPS). In this work, we designed a new adult digital phantom population and generated corresponding Tc-99m and Tl-201 projections for use in MPS research. The population is based on the three-dimensional XCAT phantom with organ parameters sampled from the Emory PET Torso Model Database. Phantoms included three variations each in body size, heart size, and subcutaneous adipose tissue level, for a total of 27 phantoms of each gender. The SimSET MC code and angular response functions were used to model interactions in the body and the collimator-detector system, respectively. We divided each phantom into seven organs, each simulated separately, allowing use of post-simulation summing to efficiently model uptake variations. Also, we adapted and used a criterion based on the relative Poisson effective count level to determine the required number of simulated photons for each simulated organ. This technique provided a quantitative estimate of the true noise in the simulated projection data, including residual MC simulation noise. Projections were generated in 1 keV wide energy windows from 48–184 keV assuming perfect energy resolution to permit study of the effects of window width, energy resolution, and crosstalk in the context of dual isotope MPS. We have developed a comprehensive method for efficiently simulating realistic projections for a realistic population of phantoms in the context of MPS imaging. The new phantom population and realistic database of simulated projections will be useful in performing mathematical and human observer studies to evaluate various acquisition and processing methods such as optimizing the energy window width, investigating the effect of energy resolution on image quality and evaluating compensation methods for degrading factors such as crosstalk in the context of single and dual isotope MPS.

Impact of the Patient Torso Model on the Solution of the Inverse Problem of Electrocardiography

Cardiac diagnostics based on a solution of the inverse problem of electrocardiography offers new tools for visual assessment of cardiac ischemia. The accuracy of the inverse solution is influenced by fidelity of the patient torso model. As optimum, an individual torso model with real heart shape and position obtained from CT or MRI is desirable. However, imaging is not always available in clinical practice, hence we investigated, if a generic torso shape individually adjusted according to patient‘s chest dimensions, with a simplified heart model placed to a vertical position obtained from inverse localization of the early ventricular activation can result in an inverse solution close to the result obtained with an accurate torso model. Simulated inverse localization of 18 ischemic lesions for 9 subjects showed that the use of individually adjusted generic torso instead of real torso shape led to an acceptable increase of the lesion localization error from 0.7±0.7 cm to 1.1±0.7 cm when accurate heart model was used. However, if simplified heart model was used and placed in a vertical position according to the V2 lead level, the lesion localization error increased to 3.5±0.9 cm. Moving the simplified heart model to a position estimated by the inverse solution decreased the vertical heart positioning error from 1.6±2.3 cm to 0.2±1.2 cm but without adjusting the heart shape and rotation the lesion localization error did not improve and reached 3.7±1.0 cm.

Anthropomorphic robotic arm with integrated elastic joints for TCM remedial massage

SUMMARYFor reproducing the manipulation of Traditional Chinese Medicine (TCM) remedial massage and meanwhile guaranteeing safety, a 4-degree-of-freedom anthropomorphic robotic arm with integrated elastic joints is developed, and a passivity-based impedance control is used. Due to the series elasticity, integrated joints may minimize large forces that occur during accidental impacts, and, further, may offer more accurate and stable force control and a capacity for energy storage. Human expert's fingertip force curve in the process of massage therapy is acquired in vivo by a dedicated measurement device. Then three massage techniques, pressing, kneading, and plucking, are implemented by the soft arm, respectively, on torso model in vitro and on human body in vivo. Experimental results show that the developed robotic arm can effectively replicate the TCM remedial massage techniques.

Air Permeability of Sports Fabrics at Running Speeds

To measure fabric permeability over the body at air velocities encountered in running, a series of air pressure measurements were conducted on a mannequin torso in a wind tunnel. Pressure measurements were made at wind speeds of 3.3 m/sec, 5.3 m/sec and 10.0 m/sec from 15 pressure taps that ringed the circumference of the mannequin torso. The pressure measurements were then repeated at the two higher velocities when the pressure taps were covered in one of five fabrics commonly used for sports apparel. Each of the fabrics are considered highly permeable, based on an air permeability rating provided by the fabric manufacturer. The goals of the pressure measurements were: (1) to quantify the ability for air to be transmitted through a garment to an athlete's skin when the athlete is running; and (2) to compare the pressure tap measurements with the manufacturers’ air permeability ratings. The pressure measurements indicated that the only areas of the torso that encounter measurable airflow at wind velocities up to 10 m/sec are the flanks, a phenomenon also observed during dye-injection flow visualization studies conducted on a torso model in a water flume. Covering portions of the torso that receive very little airflow with any fabric further subdued the incoming airflow and the reduction in airflow was not consistently correlated with the fabric air permeability rating. The results of this study suggest that fabric air permeability ratings are of limited utility in the selection of permeable materials for running apparel because of the low air pressures encountered by the torso at running velocities.

Virtual 3D Heart Models to Aid Pacemaker Implantation in Children

Virtual 3D Heart Models to Aid Pacemaker Implantation in Children

Influence of Torso Model Accuracy on the Noninvasive Localization of Heart Pathologies

The influence of the fidelity of an inhomogeneous torso model on the noninvasive inverse localization of selected heart pathologies was studied. It was supposed that the pathology is small enough to be represented by a single dipole. In the simulation study the accuracy of localization of an ischemic lesion was investigated. 18 ischemic lesions in the ventricles were modeled and corresponding ECGs were simulated in 7 CT-based realistic torso models. Position of each lesion represented by a single dipole was then searched by an inverse solution using different approximations of the torso and heart. If the realistic CT-based torso and heart model was used the mean error of the lesion localization was 0.7 cm. When a common torso model adjusted to patient-specific shape using 10 anthropometric parameters with a common heart model was used, the localization error reached 3.4 cm and decreased to 1.0 cm if properly formed and rotated heart model was used. In the experimental study the site of ectopic activation was noninvasively localized in a patient with premature ventricular activity. The assessed site position was in agreement with the site determined by intracardiac mapping if realistic or adjusted common torso model with lungs and properly formed and located heart model were used. From the results of both studies it can be concluded that the use of a common torso model adjusted in concordance with patient torso dimensions and with realistic heart model can lead to acceptable accuracy of the inverse localization of the searched heart pathology.

New Computer Program for Detecting 12-Lead ECG Misplacement in the EP Lab Using a 3D Kinect Camera

The accurate electrode positions are required by our cardiac isochrones positioning system. Therefore we developed a KINECT camera based system to localize the electrodes. The KINECT camera was used to take 3D images of the torso of five male subjects with ECG electrodes attached. Our software transformed the 3D quantitative image into a subject specific electrode torso model. These torso models were scaled to obtain an objective standard for electrode misplacement. New KINECT camera computer software automatically and rapidly detected misplacement of 12-lead ECGs electrodes. An increased database is needed to calculate the sensitivity and specificity of distances and angles to determine accurately misplaced leads.