Torso Shape Research Articles

Anthropomorphic breast measurement: protocol and results in 50 women with aesthetically perfect breasts and clinical application.

This paper presents a simple protocol for the measurement and evaluation of the difficult physiognomy of the female breast and the application of the protocol in clinical practice. The protocol includes measurement of the breast and its landmarks and their relevant position from fixed skeletal points. Volume was measured with the Grossman-Roudner device. The protocol provides a useful tool in the accurate evaluation of patients preoperatively and in the assessment of surgical results. The protocol is compared with the two previously reported protocols. The paper presents the anthropomorphic measurements of 50 women with aesthetically perfect breasts utilizing this protocol. Aesthetically perfect was defined as a nonptotic breast in which no common aesthetic procedure would be considered appropriate (excluding augmentation) to enhance the breast's form. Results were compared with those reported in the two previous studies. The paper presents the clinical correlation obtained by statistical analysis of the results of the measurements of the 50 women. Although the results of the measurements indicate the range and variance in the aesthetically perfect breast, there still was a statistically significant correlation of some of the parameters of the breast and torso shape to breast volume. This correlation can be used preoperatively to predict desired breast shape and volume in breast augmentation, reduction, and reconstruction. Clinical application of the concepts proposed will lead to better surgical goal orientation and improve evaluation of surgical results. A formula for calculating appropriate breast size based on torso parameters is presented.

Gender discrimination in biological motion displays based on dynamic cues

Studies of human locomotion have found that male and female walkers differ in terms of lateral body sway, with males tending to swing their shoulders from side to side more than their hips, and females tending to swing their hips more than their shoulders. Experiments reported here demonstrate that naive viewers can identify the gender of the figure in a biological motion display very reliably when the display contains gender-specific lateral body sway. Sensitivity to gender is high even for displays containing only a fraction of a step cycle. This dynamic cue dominates structural cues based on torso shape (`centre-of-moment9) when the cues are set in opposition. It is mediated by gender-specific differences in the velocity of shoulder and hip dots, not by positional differences in shoulder and hip dots during the step cycle.

Analysis of PTCA-induced ischemia using an ECG inverse solution or the wavelet transform

In patients without significant collaterals, percutaneous transluminal coronary angioplasty (PTCA) produces acute transient ischemia that is detectable in both standard electrocardiograms (ECG) and body surface potential maps (BSPMs). Control recordings made before or between inflations provide personalized baselines, which isolate the effects of ischemia from interpatient differences, such as torso shape and electrode location. In this study, two methods of evaluating PTCA-induced ischemia from BSPM recordings are presented. In the first method, an ECG inverse solution that estimates epicardial potentials from body surface signals using a realistic model of torso geometry is applied. The strength of this method lies in its potential ability to localize areas of cardiac ischemia on the epicardial surface. In the second approach, wavelet transforms were used to perform a multiresolution decomposition of the BSPM data into different frequency bands. The basis functions of the wavelet transform are time-limited and narrow band and hence can be expected to be sensitive to features of the BSPM that originate in discrete electrophysiologic events, such as intrusion of the activation front onto regions of ischemia or arrhythmias due to local conduction abnormalities. The method also offers a means of temporal and frequency localization of cardiac events related to the initiation of injury currents and abnormal conduction due to PTCA-induced ischemia. The inverse solution and the wavelet transform each offer new views of the spatial and temporal courses of acute ischemia potentially leading to new diagnostic insights in ECG patient examination.

Electrical impedance tomography. Solving anisotropic mixed boundary value problems by means of the boundary element method.

In a previous study we have shown that an anisotropic volume conduction problem involving the Neumann condition at the outer surface of a volume conductor can be solved by means of the boundary element method by applying an appropriate coordinate transformation (Zhou and van Oosterom 1991). In this paper we will show that this approach can also be applied to solve the anisotropic mixed boundary value condition problems studied in electrical impedance tomography (EIT). Results are presented of numerical computations, which were carried out for a volume conductor of irregular (torso) shape.

The effect of measurement conditions on MCG inverse solutions.

A magnetic inverse solution that uses a single current dipole in a homogeneous volume conductor with realistic torso shape was tested numerically to establish the effect of magnetic noise, number of measurement points, and torso size on the localization accuracy. Seven different sites of cardiological interest were selected as locations for the source dipole. The three components of the magnetic field were calculated as if measured by second order gradiometers, Gaussian noise was added, and Monte Carlo tests performed for inverse solutions using a single field component, or all three combined. It was found that for any of the single component solutions, and a signal-to-noise ratio of 100, 25 measuring points are sufficient for good accuracy; just 12 points are needed if all three components are used together. If, however, the torso size of the inverse solution is different from that of the field data by 10 or 20%, a larger error occurs, even for 56 measurement points and no noise. In this case, the field component orthogonal to the measurement grid, Bz, yields better results than the other two components, or even all three combined. We conclude that a multichannel system measuring the z component of the magnetic field in about 30 locations would be the best choice to locate a dipolar source, provided the torso of the field data is closely matched by the model used in the inverse solution. To this effect, scaling of the torso model can easily be included in the computation. Imaging techniques could be used to accommodate different torso shapes.

Esophageal atrial pacing: Computerized two-dimensional echocardiography in evaluation of left ventricle dynamic asynergies in coronary patients

We studied the implementation of a patient-specific torso model created without the use of magnetic resonance imaging in the inverse problem of electrocardiology.Three types of inhomogeneous numerical torso models were created, with different degrees of adjustment of the outer surface to patients, whereas the heart and lung models remained unchanged. The torso models were used in the inverse localization of small areas with repolarization changes from simulated difference integral QRST maps. The localization error (LE) was evaluated as the distance between the centers of the modeled and the inversely found area with repolarization changes.The mean LE was 1.88 cm with the standard torso model. After adapting the torso shape, the mean LE was 1.83 cm, whereas after adapting both, the shape and electrode positions, the mean LE was 1.02 cm.If torso imaging is not available, a torso model with adapted shape and electrode positions gives only slightly less accurate results.

Developmental differences in visceral morphology of megophryine pelobatid tadpoles in relation to their body form and mode of life

Tadpoles face severe packing constraints on viscera within the pleuro-peritoneal cavity because of their extremely short torsos—a feature they share with adult anurans—and the concomitant need for relatively slender torsos for efficient locomotion. We examined the effects of differences in body form and habits on the size, shape and development of viscera in three kinds of sympatric, stream-associated pelobatid tadpoles. Leptobrachium montanumlarvae are generalized, wide, deep-bodied tadpoles. Larval Leptolalax gracilis are very slender and live in the crevices between rocks on the bottom of riffles. Larval Megophrys nasuta are intermediate between the other two in body form, and live with L. montanum in a variety of microhabitats but feed at the surface film. In all three species, liver, gall bladder, arid kidneys begin development early and grow isometrically throughout larval life. The gut and pancreas have a growth spurt shortly after hatching, then grow at a constant rate until near metamorphosis when both shrink drastically. The spleen grows at a slower rate than the body throughout the larval period. Lungs do not appear in L. gracilis until the tadpole approaches metamorphosis, which accords with its benthic habits, whereas they grow throughout the larval period in L. montanum and M. nasuta. In M. nasuta, however, the lungs are unusually wide anteriorly; this shifts buoyancy forward and facilitates the head-up feeding posture characteristic of that species. Gonads appear early in L. montanum and L. gracilis, but not until near metamorphosis in M. nasuta. We suggest that accelerated gonadal development in tadpoles characterizes species that metamorphose close to their size at first reproduction. Leptobrachium montanum, with the bulkiest body and most generalized habits, has relatively and absolutely the largest gut, liver (x of combined gut and liver volume = 24%, of total volume), and kidneys. Leptolalax gracilis, the most slender tadpole, has relatively the smallest combined gut and liver volume (x = 10% of total volume). Other premetamorphic differences among the species were observed in gut coiling, liver, pancreas and kidney shape and left/right asymmetry of urogenital organs. The major interspecific differences we observed in the size, shape, and developmental patterns of viscera in tadpoles are clearly related to interspecific differences in torso shape, microhabitat distribution and mode of feeding.

A noninvasive method for locating a cardiac dipolar source in humans

A noninvasive method for locating isolated areas of cardiac electrical activity, such as an ectopic focus, is introduced and evaluated. Surface electric potentials due to the source are recorded at 20-25 points on the chest. Each chest is measured and its configuration is approximated by a grid of 126 points. A computer program utilizes these data to calculate the x, y, z coordinates of the cardiac source, and this calculated location is displayed on the bi-plane chest x-rays of the patient. Errors that may occur in other methods that utilize average torso shape and average heart position are eliminated in the proposed method. The method was evaluated by using it for locating the electrodes of implanted pacemakers from their "spikes" in the ECG's, and also from the potentials at the onset of the induced QRS complexes. The results were compared with bi-plane x-rays of the same patients. It was found that the average errors in locating the electrodes from their "spikes" in the ECG's were 1.3 cm in the frontal view and 1.4 cm in the lateral view. The errors in locating the paced myocardial area at the beginning of the QRS complex were similar. The errors in the lateral view are systematic and may be attributed to the effects of the intracavity blood volume (Brody's effect), which are neglected in this method.

Computational assessment of electrocardiographic measurement sensitivity.

A detailed description is provided of a computational model that has been developed for assessing the sensitivity of electrocardiographic measurements to changes in electrode placement, torso shape, conductivities of internal organs and driving currents from the heart. By invoking asurface admittance and theextended boundary condition (concepts which have been exploited successfully in recent years by radio scientists) the model has been simplified. Representative numerical results are presented, illustrating the practical utility of the model.

Apparatus for the rapid measurement of electrocardiographic body surface potentials

A method for the rapid and reproducible recording of 24 chest electrode potentials is described. Rigid electrodes are equally spaced around the thorax in three rows of eight. The electrodes move radially and are spring loaded so as to maintain contact with the skin regardless of the shape of the subject's torso. The inclusion of an impedance convertor in the electrode assembly removes the necessity for using electrode cream. Although equal spacing of the electrodes around the thorax is inefficient in terms of information content per electrode the attention to detail required for electrode placement using the described system is minimised as compared with other multiple lead systems. Furthermore, the principles adopted in the design and construction of the apparatus do not limit the number of chest electrodes to 24.

Effects of torso shape and change of dipole location on ECG and VCG lead vectors in a homogeneous torso model

To evaluate the effect of torso shape on ECG and VCG, the lead vectors of various ECG and VCG leads and the image loops of torsos at the level of the 5th intercostal space were obtained experimentally from three torso models molded after an adult male, an adult female, and a child. In corrected orthogonal lead systems, the most remarkable effect on the lead vectors was in their magnitudes, ratios being 1.0 (adult male) to 1.2 (adult female) to 2.4 (child) regardless of the lead. The direction of these lead vectors, however, was not affected seriously. Lead vectors of leads V3 and V4 obtained on the male torso model were 10 to 20% greater than those obtained on the female one, which is compatible with clinical observations in which the QRS amplitude in these leads was found to be statistically greater in the male than in the female. The magnitude of the lead vectors of the corrected orthogonal lead systems was greater in the female torso model than in the male, in disagreement with reports that VCG loops are on the average greater in the male than in the female. The discrepancy was supposed to be caused by thicker subcutaneous fat tissue in female.

Simulation studies of the electrocardiogram. I. The normal heart.

A digital computer model is presented for the simulation of the body surface electrocardiogram (ECG) during ventricular activation and recovery. The ventricles of the heart are represented in detail by a three-dimensional array of approximately 4000 points which is subdivided into 23 regions. Excitation sequence and cellular action potential data taken from the literature are used to determine the spatial distribution of intracellular potentials at each instant of time during a simulated cardiac cycle. The moment of the single dipole representing each region is determined by summing the spatial gradient of the intracellular potential distribution throughout the region. The resulting set of 23 dipoles is then used to calculate the potentials on the surface of a bounded homogeneous volume conductor with the shape of an adult torso. Simulated isopotential surface maps during both activation and recovery are in good agreement with data for humans reported in the literature.

A rapid assay of dipolar and extradipolar content in the human electrocardiogram

Summary o 1. A rapid iterative method has been developed for the calculation of the surface potentials on a bounded homogeneous torso shape resulting from a dipole of known size, orientation and site in the heart region. In essence, the approach is a convergent search for a potential distribution which will reduce to the desired dipole upon Gabor-Nelson surface integration. 2. This means of obtaining the surface effect of a dipolar generator has been applied to the specific problem of finding a series of surface voltages resulting from 18 instantaneous equivalent dipoles during the QRS complex in 25 normal young men. 3. In these normal subjects, the dipolar components of surface electrocardiographic potential had an average relative magnitude of .90 compared with whole real surface potential distribution, whereas the residual extradipolar component had an average relative magnitude about one-half this or .44. 4. There is a continuous extradipolar component throughout the QRS complex which is proportional in magnitude to the surface potential. It is not synomymous with multiple peaks and valleys seen in body surface maps; the latter is an easily visible special instance of “multipolar effect. While extradipolar component includes such peaks and valleys, it is a quantifiably comprehensive statement of total multipolar effect.

The path of the electrical center of the human heart determined from surface electrocardiograms

The path of the moving electrical center of the heart during P, QRS, and T has been derived from measurements of torso shape and surface electrocardiographic potentials alone. The locus of the path is within the heart border throughout the cardiac cycle, in the atria during P and in the ventricles during QRS and T. The general features of the path during P and QRS agree well with the known events of the activation sequence.

Comparison of Limb and Precordial Vectorcardiographic Systems

Two advanced types of vectorcardiographic systems have been applied to 104 miscellaneous patients for the purpose of comparing practical features and electric results. The 2 systems showed satisfactory average agreement, as expected, but there were marked individual differences in many cases. Despite corrections for torso shape and typical eccentric ventricle location, the limb electrode system yielded results significantly outside attainable limits, and hence is considered unsatisfactory for quantitative work despite its practical advantages.

An accurate, clinically practical system for spatial vectorcardiography.

This paper describes a news improved system of spatial vectorcardiography that is practical for clinical use. It represents an optimum compromise among such factors as soundness of theoretic basis, accuracy, reproducibility, signal-to-noise ratio, and speed of application. Some of its advantages over currently employed systems include a rational physical basis, corrections for torso shape, avoidance of left arm, insensitivity to individual variability of ventricle location, and accuracy comparable to applicability of 3-dimensional torso-model data to the human subject. Detailed description of electrode placement, practical procedures, and useful technics is included.

A new quantitative basis for electrocardiographic theory: the normal QRS complex.

A theory of electrocardiography based on a fixed-location, eccentric-dipole representation of ventricular depolarization and a homogeneous, resistive, linear medium in the shape of the human torso yields quantitative predictions of instantaneous amplitude and shape of QRS body surface potentials on one normal human subject to an accuracy of approximately ±15 per cent for electrodes dispersed over the entire torso.

The image surface of a homogeneous torso

The image surface is a geometric representation of the relationship between a fixed-position current dipole inside a volume conductor and the electric potential it produces on the boundary of the conductor. It is a powerful means of conveying a wealth of information concerning some basic problems in electrocardiography, in terms of familiar heart-vector projection ideas. It gives deep insight into the nature of the relationship between torso surface voltages and the internal heart generator. A detailed image surface is presented in quantitative terms for a specific human torso shape and dipole position in order to illustrate its remarkable properties. Applications to the frontal-plane, Wilson central-terminal voltage and spatial vectorcardiography systems reveal shortcomings of current practices. Examples of possible research investigations suggested by the image surface are presented.