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Babor, T.F.; Longabaugh, R.; Zweben, A.; Fuller, R.K.; Stout, R.L.; Anton, R.F.; Randall, C.L Issues in the definition and measurement of drinking outcomes in alcoholism treatment research This article reviews methodological and conceptual issues regarding the choice of drinking outcome measures in alcoholism treatment research. The following issues are discussed: Should drinking outcomes be conceptualized in terms of an underlying unitary disorder, or should provision be made for independent outcomes that cover a wide variety of dimensions? Which drinking outcomes are typically measured in treatment evaluation studies and how are they operationalized? What are the empirical associations among drinking outcome measures? If multiple outcomes are measured, which should be given primary importance? Over what period of time should treatment outcome be evaluated? What procedures can be used to detect, correct or prevent the response bias associated with verbal report methods? Because outcome measures need to fit the hypotheses and practical needs of a particular study, it is unlikely that complete standardization can be achieved across all studies. Nevertheless, given the importance of drinking outcomes and the need for economy, two primary dependent measures are recommended: (1) proportion of available drinking days abstinent; and (2) intensity of drinking, as defined by the total amount consumed (in ounces absolute alcohol) during the follow-up period divided by the number of actual drinking days. This article also proposes a strategy that may help to guide the selection of outcome measures in future research. |
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Basarabhorwath, I.; Piotrowski, J.; Mcewan, P.M. Calculated measures of performance in electrical impedance tomography using a finite-element model A two-dimensional finite-element model of an electrical impedance tomographic phantom has been investigated. It is perceived that an understanding of the basic measurement system will enable the design of improved data collection hardware, e.g. the number and size of the electrodes. The presented model has sixteen electrodes spaced equidistantly on the perimeter and a centrally placed anomaly. The system is excited using the adjacent-electrode constant-current drive scheme. The size and conductivity of the anomaly are varied in order to investigate how the measurement system will behave to changes in input. Measures of the system's sensitivities to these Variations in the anomaly are defined. The four measures derived from the calculated boundary voltages are contrast sensitivity, spatial or radial sensitivity, visibility and rms voltage difference. Results are presented for the four measures, showing how they vary with the parameters of the anomaly. In particular, these results show that there is a clear and distinct difference between spatial and contrast sensitivity. The relationship between the calculated visibility values and the conductivity contrast of the anomaly differs from that predicted theoretically, but is in agreement with the measured relationship. It can also be seen that the presented model is more than twice as sensitive to changes in an anomaly that is more resistive as compared to one that is more conductive than the background or surrounding material. |
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Battistini, N.; Facchini, F.; Bedogni, G.; Severi, S.; Fiori, G.; Pettener, D. The prediction of extracellular and total body water from bioelectric impedance in a non-Caucasian population from Central Asia The availability of only a small number of studies on bioelectric impedance analysis (BIA) in non-Caucasian ethnic groups appears to limit reliable utilization of this method in anthropological field studies. In this study, 28 male Turkish-Mongolian subjects native of Kazakhstan (Central Asia) underwent total body water (TBW) and extracellular water (ECW) assessment by deuterium oxide (D2O) and sodium bromide (NaBr) dilution respectively. Bioelectric impedance (BI) was recorded at multiple frequencies. ECW and TBW were calculated from BI at 1 and 00 kHz respectively by applying formulae developed on a sample of Caucasian subjects with a hydration status similar to that of the study population. TBW predicted from BI at 100 kHz (37.5+/-3.31)was highly correlated and not significantly different from that obtained by D2O dilution (39.0+/-4.11, r=0.894, p<0.0001, SEE=1.91). Similarly, ECW predicted from BI at 1 kHz(15.1+/-1.2]) was highly correlated and not significantly different from that obtained by NaBr dilution (15.0+/-1.61, r=0.847, p<0.0001, SEE=0.81). It is concluded that selected predictive formulae developed on Caucasian subjects may provide a precise and accurate assessment of ECW and TBW in Turkish- Mongolian populations. |
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Battistini, N.; Virgili, F.; Severi, S.; Brambilla, P.; Manzoni, P.; Beccaria, L.; Chiumello, G. Relative expansion of extracellular water in obese vs normal children This preliminary communication reports data regarding the distribution between intracellular (ICW) and extracellular (ECW) water compartments in a group of 21 prepubertal young obese children of both sexes in comparison with a group of 18 normal children weight matched for age. Our data indicate that obesity is associated with a highly significant relative expansion of extracellular water (ECW/ICW = 0.61 +/- 0.19 and 0.76 +/- 0.09 in control and obese subjects, respectively; P < 0.0015). This observation, hich has been already reported in adult women, suggests that some disturbances of water homeostasis have an early onset and stress the need for an early control of energy imbalance in children. These findings are of great concern also in the field of human body composition, suggesting the opportunity for a critical reevaluation of the assumed constancy of some human body characteristics. Body composition methodologies developed for ''normal'' populations would require adjustment for use in the obese population, since a considerable error would be introduced. |
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Bayford, R.; Hanquan, Y.; Boone, K.; Holder, D.S. Experimental validation of a novel reconstruction algorithm for electrical impedance tomography based on backprojection of Lagrange multipliers A novel approach to image reconstruction for electrical impedance tomography (EIT) has been developed. It is based on a constrained optimization technique for the reconstruction of difference resistivity images without finite-element modelling. It solves the inverse problem by optimizing a cost function under constraints, in the form of normalized boundary potentials. Its application to the neighbouring data collection method is presented here. Mathematical models are developed according to specified criteria. These express the reconstructed image in terms of one-dimensional Lagrange multiplier functions. The reconstruction problem becomes one of estimating these functions from normalized boundary potentials. This model is based on a cost criterion of the minimization of the variance between the reconstructed and the true resistivity distributions. The algorithm was tested on data collected in a cylindrical saline-filled tank. A polyacrylamide rod was placed in various positions with or without a peripheral plaster of Paris ring in place. This was intended to resemble the conditions during Err of epileptic seizures recorded with scalp or cortical electrodes in the human head. One advantage of this approach is that compensation for non- uniform initial conditions may be made, as this is a significant problem in imaging cerebral activity through the skull. |
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Bayford, R.; Hanquan, Y.; Boone, K.; Holder, D.S. Experimental validation of a novel reconstruction algorithm for electrical impedance tomography based on backprojection of Lagrange multipliers A novel approach to image reconstruction for electrical impedance tomography (EIT) has been developed. It is based on a constrained optimization technique for the reconstruction of difference resistivity images without finite-element modelling. It solves the inverse problem by optimizing a cost function under constraints, in the form of normalized boundary potentials. Its application to the neighbouring data collection method is presented here. Mathematical models are developed according to specified criteria. These express the reconstructed image in terms of one-dimensional Lagrange multiplier functions. The reconstruction problem becomes one of estimating these functions from normalized boundary potentials. This model is based on a cost criterion of the minimization of the variance between the reconstructed and the true resistivity distributions. The algorithm was tested on data collected in a cylindrical saline-filled tank. A polyacrylamide rod was placed in various positions with or without a peripheral plaster of Paris ring in place. This was intended to resemble the conditions during Err of epileptic seizures recorded with scalp or cortical electrodes in the human head. One advantage of this approach is that compensation for non- uniform initial conditions may be made, as this is a significant problem in imaging cerebral activity through the skull. |
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Bayford, R.H.; Boone, K.G.; Hanquan, Y.; Holder, D.S. Improvement of the positional accuracy of EIT images of the head using a Lagrange multiplier reconstruction algorithm with diametric excitation A novel algorithm for the reconstruction of dynamic images using diametric excitation has been developed. The algorithm is specifically designed to image impedance changes in the brain using boundary data obtained from scalp electrodes by incorporating a priori information. The priority information is obtained by serving the forward problem using a finite-element model (FEM) which includes the discontinuity of the skull resistivity. The advantages with this new approach are that the sensitivity and accuracy of the location of the impedance changes are improved compared to methods based on adjacent excitation. |
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Bedogni, G.; Merlini, L.; Ballestrazzi, A.; Severi, S.; Battistini, N. Multifrequency bioelectric impedance measurements for predicting body water compartments in Duchenne muscular dystrophy Body hydration and extra- to intra-cellular water ratio (EGW: ICW) have been studied in 12 duchenne muscular dystrophy (DMD) patients and 15 healthy controls. Subjects underwent total body water (TBW) and extracellular water (ECW) assessment by deuterium and bromide dilution, respectively. Multifrequency bioelectric impedance analysis (MFBIA) was performed on all subjects with the aim to establish its accuracy in predicting TBW and ECW in DMD. Body hydration was lower (51.8 +/- 2.8 vs 58.5 +/- 5.9%, P < 0.01) and the ECW: ICW ratio higher (1.15 +/- 0.25 vs 0.70 +/- 0.23, P < 0.001) in DMD than in control subjects. Hence, control-generated formulae for predicting TBW and ECW from MFBIA gave inaccurate results in DMD subjects. Population-specific formulae were developed to obtain an accurate prediction of body water compartments in DMD patients. |
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Bellu, R.; Ortisi, M.T.; Agostoni, C.; Riva, E.; Giovannini, M. Total body electrical conductivity derived measurement of the body composition of breast or formula-fed infants at 12 months Recent studies found a difference in body composition determined by skinfold thickness measurements between breast-fed and formula-fed infants in the first year of life. We therefore investigated the body composition of 79 infants at 12 months measured by total body electrical conductivity (TOBEC) and compared with early feeding mode (breast-feeding for at least 6 months versus formula-feeding or breast-feeding or for less than or equal to 2 months). Lower weight, stature and cranial circumference were associated with breast-feeding when the variables were compared using an ANOVA model. The groups did not significantly differ in terms of fat-free mass, but body- fat mass was lower among breast-fed infants. Multiple regression analysis showed a significant correlation between body fat mass and duration of breast-feeding and lower amounts of body fat correlated with a longer period of breast-feeding. Copyright (C) 1996 Elsevier Science Inc. |
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- Bioelectrical impedance analysis in body composition measurement NIH Technology Assessment Conferences and Workshops are convened to evaluate available scientific information related to a biomedical technology. The resultant NIH Technology Assessment Statements and published reports are intended to advance understanding of the technology or issue in question and to be useful to health professionals and the public. Some Technology Assessment Conferences and Workshops adhere to the NIH Consensus Development Conference (CDC) format because the process is altogether appropriate for evaluating highly controversial, publicized, or politicized issues. In the CDC format, NIH Technology Assessment Statements are prepared by a nonadvocate, non-Federal panel of experts, based on (1) presentations by investigators working in areas relevant to the consensus questions during a 1 1/2-day public session, (2) questions and statements from conference attendees during open discussion periods that are part of the public session, and (3) closed deliberations by the panel during the remainder of the second day and morning of the third. Each statement is an independent report of the panel and is not a policy statement of the NIH or the Federal Government. Other Technology Assessment Conferences and Workshops are organized around unique formats. Usually, speakers present findings or perspectives on the issue. Policy implications may be discussed. The public is invited to address questions to the speakers. A report of the findings can emerge in one of a variety of formats including publication in a clinical or scientific journal. |
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Bitar, A.; Vermorel, M.; Fellmann, N.; Coudert, J. Twenty-four-hour energy expenditure and its components in prepubertal children as determined by whole-body indirect calorimetry and compared with young adults The aim of the present study was to compare total daily and circadian variations of energy expenditure (EE) in 21 prepubescent 10-y-old children (12 boys and 9 girls) and 18 23-y-old adults (9 men and 9 women) under the same conditions by using two large calorimetric chambers. The volunteers followed similar activity programs with four periods of exercise on a cyclergometer. Total daily and sleeping EE adjusted for differences in fat-free mass (FFM) and age were significantly higher in children than in adults by 35% and 27%, respectively (P < 0.001). EE during sleep decreased by 2% per hour in both age groups. Heart rate was significantly higher in girls than in boys. The energy cost of cycling, adjusted for differences in FFM and external mechanical power, was not significantly different in children and adults. The differences in EE between children and adults may partly result from a higher proportion of internal organs in the FFM. |
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Blad B Clinical applications of characteristic frequency measurements: Preliminary in vivo study. In vivo electrical impedance tomography images have been available for some years, and most of them show variation in impedance amplitude between two different states, for example between inspiration and expiration of the lungs. A refinement of the tomography technique has made it possible to show images of the complex impedance of the body. If several frequencies are used, more information on the investigated tissues can be collected, and new areas made available for investigation. It has been shown that tissues exhibit a characteristic frequency that can be derived from the maximum magnitude of the (negative) reactance. The characteristic frequency-related images can be calculated from several imaginary part curves obtained using the back-projection technique. The paper shows in vivo impedance spectra from different parts of the body, determines the characteristic frequency of the different in vivo measurements and suggests different applications of characteristic frequency imaging. Several data sets are collected to show the reproducibility of the measurements. |
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Blad, B.; Baldetorp, B. Impedance spectra of tumour tissue in comparison with normal tissue; A possible clinical application for electrical impedance tomography Electrical characteristics of living tissues have been investigated for a long time in the search for further methods to complement the traditional investigations of pathology and physiology. Tumour tissue has been shown to exhibit a larger permittivity and conductivity than normal tissues. This might be associated with the fact that tumour cells have a higher water content and sodium concentration than normal cells, as well as different electrochemical properties of their cell membranes. To our knowledge only a few contributions on this subject have been published. This study describes an additional application on measurements of the complex impedance of tumour and normal tissues, in order to compare the impedance features of the two tissue types. The tissue sample is placed in a measuring cell in which the temperature is controlled. The measuring cell is connected to an impedance meter able to measure the complex impedance in terms of real and imaginary part curves for frequencies from 1.5 kHz to 700 kHz. The four-electrode principle is used with the current injected by the outer electrodes and the voltage difference measured between the inner electrodes. The current can be altered up to 1 mA. The instrument can be calibrated with known resistance and capacitance networks connected to the input of the instrument in order to minimize the measurement errors. The calibration routine uses a polynomial adaptation and can be applied interactively. Measurements performed by the instrument show promising results. Preliminary results show that this method can be extended to a new application for detection of tumour tissue by electrical impedance tomography (EIT). |
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Bonora, E.; Targher, G.; Branzi, P.; Zenere, M.; Saggiani, F.; Zenti, M.G.; Travia, D.; Tonoli, M.; Muggeo, M.; Cigolini, M. Cardiovascular risk profile in 38-year and 18-year-old men. Contribution of body fat content and regional fat distribution OBJECTIVE: To evaluate whether young and middle-age men differ in blood pressure and serum lipid profiles and, if so, to what extent these differences are dependent on total body fat, regional fat distribution, plasma insulin and behavioural variables. |
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Boone, K.G.; Holder, D.S. Current approaches to analogue instrumentation design in electrical impedance tomography Electrical impedance tomography (EIT) is a novel medical imaging method, which allows reconstructed tomographic images of the internal impedance of a subject to be made with the use of a ring of electrodes. High precision impedance measurements are needed, because the image reconstruction process is ill-conditioned and small errors in measurement can lead to large errors in the final image. In practice, there are formidable instrumentation problems, due to the interaction of finite current drive output impedance, recording amplifier common mode rejection, and unequal skin-electrode impedances. A number of different EIT systems have been constructed or are under development. These employ differing strategies, such as additional electrodes, multiple electrode current injection, or recording at multiple frequencies, to improve image accuracy. This paper reviews the nature of the instrumentation problems and the designs employed by differing groups in attempting to overcome them. |
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Boone KG, Holder DS Effect of skin impedance on image quality and variability in electrical impedance tomography: A model study. A computer simulation is used to investigate the relationship between skin impedance and image artefacts in electrical impedance tomography. Sets of electrode impedance are generated with a pseudo-random distribution and used to introduce errors in boundary voltage measurements. To simplify the analysis, the non-idealities in the current injection circuit are replaced by a fixed common-mode error term. The boundary voltages are reconstructed into images and inspected. Where the simulated skin impedance remains constant between measurements, large impedances (2k Omega) do not cause significant degradation of the image. Where the skin impedances 'drift' between measurements, a drift of 5% from a starting impedance of 100 Omega is sufficient to ause significant image distortion. If the skin impedances vary randomly between measurements; they have to be less than 10 Omega to allow satisfactory images. Skin impedances' are typically 100-200 Omega at 50 kHz on unprepared skin. These values are sufficient to cause Image distortion if they drift over time. It is concluded that the patient's skin should be abraded to reduce impedance, and measurements should be avoided in the first 10 min after electrode placement. |
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Borgonovo, G.; Desalvo, L.; Adami, G.F.; Mattioli, F.P. Perioperative artificial nutrition in elective adult surgery |
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Bracco, D.; Thiebaud, D.; Chiolero, R.L.; Landry, M.; Burckhardt, P.; Schutz, Y. Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whale body value (100.5 +/- 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual- energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but-represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length(2)/impedance) and FFM (r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 +/- 23 cm for the arm and 193 +/- 39 cm for the leg at 50 kHz) but was higher for the trunk (457 +/- 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women. |
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Bradbury-M-G; Brocklebank-J-T; Dyson-E-H; Goutcher-E; Cohen-A-T Volumetric control of continuous haemodialysis in multiple organ failure. A system for precise volumetric control of continuous hemodialysis and its use in providing renal replacement treatment in the intensive care unit to 10 children with multiple organ failure are described. The system, termed slow efficient dialysis, provided effective clearance of urea, creatinine, potassium, and phosphate. It provided precise control of the volume of ultrafiltrate removed in a prospective manner ('dial up' fluid balance) to reduce |
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Bradbury-M-G; Smye-S-W; Brocklebank-J-T Assessment of the sensitivity of bioimpedance to volume changes in body water. The sensitivity of whole-body electrical impedance measurements to changes in the volume of total body water in 12 children undergoing haemodialysis has been assessed. The impedance (I) of each child was measured at 20-min intervals during dialysis using the standard four-electrode technique to apply a constant current ( 800 mu-A, 50 kHz) between the wrist and ankle on the nonfistula side of the patient. The ultrafiltration volume (U) was also recorded. A simple electrical model suggests that U = aHt-2 ((1/I- 0)-(1/I)), where I-0 is the whole body impedance at the start of dialysis, a is a constant and Ht is patient height. No significant changes in I were measured on 4 patients under-going dialysis |
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Bradbury-M-G; Smye-S-W; Brocklebank-J-T Assessment of the sensitivity of bioimpedance to volume changes in body water. The sensitivity of whole-body electrical impedance measurements to changes in the volume of total body water in 12 children undergoing haemodialysis has been assessed. The impedance (I) of each child was measured at 20-min intervals during dialysis using the standard four-electrode technique to apply a constant current ( 800 mu-A, 50 kHz) between the wrist and ankle on the nonfistula side of the patient. The ultrafiltration volume (U) was also recorded. A simple electrical model suggests that U = aHt-2 ((1/I- 0)-(1/I)), where I-0 is the whole body impedance at the start of dialysis, a is a constant and Ht is patient height. No significant changes in I were measured on 4 patients under-going dialysis without ultrafiltration, whereas in 8 patients undergoing ultrafiltration and dialysis I increased. Linear regression analysis and the above equation gave a mean value for a = 0.566 1 Ohm/cm-2 (coefficient of variation = 3%), (mean r = 0.97), values comparable to those values obtained from isotope dilution studies. Predicted fluid loss in 8 patients following a single dialysis session gave a mean overestimate of 4.3% (limits of agreement 27.3% and -19.7%), although in 6 of the patients agreement was to within 6%. Changes in impedance reflect changes in total body water in children undergoing haemodialysis and are relatively insensitive to factors such as the possible differences in electrolyte levels between these patients. |
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Brizzolara, A.; Barbieri, M.P.; Adezati, L.; Viviani, G.L. Water distribution in insulin-dependent diabetes mellitus in various states of metabolic control Alterations in water compartments have been described in insulin-dependent diabetes mellitus (IDDM). Both insulin and lack of natriuretic counteracting response lead to water expansion, while hyperglycemica-induced osmotic diuresis leads to water depletion, Both total body water and water distribution in the extra-intracellular space, as well as their relationships to metabolic control, were investigated in 15 controls (30.1 +/- 1.4 years) and in 26 IDDM patients (31.3 +/- 1.6, diabetes duration 11.3 +/- 1.4 years) who were neither hypertensive nor proteinuric. The amounts of total body water (TBW) and extracellular water (ECW) were predicted by impedance measurements at 100 KHz and at 1 KHz. The amount of intracellular water (ICW) was computed as the difference between the two. Water distribution was estimated by measuring the ratio between low- and high-frequency impedance and by computing the ratio between ECW and ICW. The IDDM patients were divided into four groups on the basis of reference HbA(1c) mean and SD: A less than or equal to mean + 2 SD < B less than or equal to mean + 4 SD < C less than or equal to mean + 6SD < D. The groups were comparable with sodium intake, insulin dosage, fasting glycemia and laboratory hydration markers. As compared to controls, impedance values at 1, 5, 10, 50 and 100 KHz were significantly lower in diabetic patients and the difference within group D increased as the frequency increased: -3.9% at 1 KHz, -10.1% at 100 KHz. As compared to controls, groups A, B and C showed higher TBW, ECW and ICW while water distribution was normal, and group D showed higher TBW and ICW but normal ECW and a different water distribution. In all IDDM patients, HbA(1c) correlated with ECW (r = -0.49) and distribution ratios (r = 0.42, impedance; r = 0.40, ECW/ICW ratio). These observations suggest that good or moderate long-term control IDDM patients have proportionately normal distributions of ECW and ICW excess. However, water excess in poor control IDDM patients was only found in the ICW space. |
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Brown, B.H.; Leathard, A.D.; Lu, L.; Wang, W.; Hampshire, A. Measured and expected Cole parameters from electrical impedance tomographic spectroscopy images of the human thorax Electrical impedance tomographic spectroscopy (Errs) images have been recorded from a group of 12 normal subjects using frequencies from 9.6 kHz to 1.2 MHz. The impedance changes with frequency have been modelled on a pixel by pixel basis to produce parametric images as a means of characterizing tissue. The modelling was based on the Cole equation. The lungs are seen as areas of high characteristic frequency and low time constants SC and RS. The R/S images are much less uniform over the region of the lungs. Values characterizing the lung and cardiac regions are given. The results appear to be consistent with a model for the lungs whereby the model parameters can be related to alveolar structure and composition. |
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Brown, B.H.; Leathard, A.D.; Lu, L.; Wang, W.; Hampshire, A. Measured and expected Cole parameters from electrical impedance tomographic spectroscopy images of the human thorax Electrical impedance tomographic spectroscopy (Errs) images have been recorded from a group of 12 normal subjects using frequencies from 9.6 kHz to 1.2 MHz. The impedance changes with frequency have been modelled on a pixel by pixel basis to produce parametric images as a means of characterizing tissue. The modelling was based on the Cole equation. The lungs are seen as areas of high characteristic frequency and low time constants SC and RS. The R/S images are much less uniform over the region of the lungs. Values characterising the lung and cardiac regions are given. The results appear to be consistent with a model for the lungs whereby the model parameters can be related to alveolar structure and composition. |
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Brown, B.H.; Flewelling, R.; Griffiths, H.; Harris, N.D.; Leathard, A.D.; Lu, L.; Morice, A.H.; Neufeld, G.R.; Nopp, P.; Wang, W. EITS changes following oleic acid induced lung water We present the results of using electrical impedance tomographic spectroscopy (EITS) to follow the changes in lung water induced by oleic acid. Measurements were made on three goats before and after the injection of oleic acid. In addition to the EITS measurements, lung water was also measured using a double-indicator technique. Large falls in lung electrical impedance were seen as a result of the increase in lung water but the size of the fall was a function of the frequency at which the measurements were made. These changes have been modelled using the Cole equation. Four-electrode measurements were also made on two extracted porcine lungs and Cole equation modelling carried out following the introduction of saline into the lungs. Results were similar in the two sets of animal experiments. |
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Brummer, R.J.M.; Lonn, L.; Bengtsson, B.A.; Kvist, H.; Bosaeus, I.; Sjostrom, L. Comparison of different body composition models in acromegaly The aberrant body composition of 10 patients with active acromegaly was used to evaluate the validity and limitations of several models and methods to assess body composition. Body composition was determined using either a two-compartment model, dividing the body in a body fat (BF) compartment and a fat-free mass (FFM) compartment, or a four-compartment model in which the FFM compartment comprises the three following components: body cell mass, extracellular water and the fat-free extracellular solids. The measurement techniques consisted of anthropometry, bioelectrical impedance analysis (BIA) - applying various established regression equations - tritiated water dilution, whole body K-40-counting, and whole body computed tomography (CT). This latter method was used as the reference technique. Assessment of total body water using BIA - applying the RJL or Kushner equation - correlated significantly with the assessment using tritiated water dilution (P < 0.01). Body fat assessment using the two-compartment model based on either tritiated water dilution or BIA - applying the RJL or Lukaski equation - as well as body fat assessment using the four-compartment model based on tritiated water dilution and whole body K-40-counting were significantly correlated with body fat assessment using CT (P < 0.01) and resulted in good agreement with each other with respect to the absolute values of the body fat determination. BIA using other regression equations overestimated body fat by 7.2-13.7 kg. Whole body K-40-counting was significantly correlated with CT-determined muscle plus skin volume (P < 0.001). CT-calibrated anthropometric predictions significantly overestimated body fat. It is concluded that in patients with active acromegaly, the determination of body composition using either certain two-compartment models based on measurement of total body water or bioelectrical impedance, or a four-compartment model based on total body water and total body potassium measurements show good agreement with CT-determined body composition. |
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Buscemi, S.; Caimi, G.; Verga, S. Resting metabolic rate and postabsorptive substrate oxidation in morbidly obese subjects before and after massive weight loss OBJECTIVE: To investigate the changes of resting metabolic rate (RMR) and postabsorptive oxidation of carbohydrates (CHO), lipids (LIP) and proteins (PT) in morbidly obese subjects after long-term stable massive weight reduction. |
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Busetto-L; Perini-P; Giantin-V; Valente-P; Segato-G; Belluco-C; Favretti-F; Enzi-G Relationship between energy expenditure and visceral fat accumulation in obese women submitted to adjustable silicone gastric banding (ASGB). OBJECTIVE: To analyze the relationship between visceral fat accumulation and resting energy expenditure in obese women and to evaluate the effects of a severe weight loss both on energy expenditure and on fat distribution. |
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Busetto-L; Perini-P; Giantin-V; Valente-P; Segato-G; Belluco-C; Favretti-F; Enzi-G Relationship between energy expenditure and visceral fat accumulation in obese women submitted to adjustable silicone gastric banding (ASGB). OBJECTIVE: To analyze the relationship between visceral fat accumulation and resting energy expenditure in obese women and to evaluate the effects of a severe weight loss both on energy expenditure and on fat distribution. |