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Edic, P.M.; Saulnier, G.J.; Newell, J.C.; Isaacson, D.
A real-time electrical impedance tomograph
Journal IEEE Transactions on Biomedical Engineering
42
9
SEP
1995
849-859
PM Edic
Rensselaer Polytech Inst
Dept Elect Comp & Syst Engn
Troy, NY 12180 USA
0018-9294
Electrical properties of tissues in the human body can be imaged using a technology known as Electrical Impedance Tomography, In this modality, sinusoidal electrical currents are applied to the body using electrodes attached to the skin, and voltages that are developed on the electrodes are measured. Using these data, a reconstruction algorithm computes the conductivity and permittivity distributions within the body. This paper describes the reconstruction algorithm, image display algorithm, and hardware of a real-time Electrical Impedance Tomograph known as the Real-Time Imaging System. The reconstruction algorithm, executed by a commercially available coprocessor board that resides in a 386-based personal computer, is a modification of the Newton's One Step Error Reconstructor (NOSER) that minimizes algorithm execution time by precomputing many quantities. The image display algorithm, also executed by the coprocessor board, maps the output of the reconstruction algorithm into an image which is displayed using a video graphics board, The architecture of the system and execution times of algorithms implemented by the system are discussed. Using the continuous data acquisition mode of the Real-Time Imaging System, data from the thorax of a normal human subject were collected. Admittivity changes in the chest, as a result of respiration and the cardiac cycle, are presented, Data that were collected from the leg of a normal subject are shown which demonstrate capabilities of the triggered data acquisition mode of the system, allowing data acquisition synchronization with an electrocardiogram. |
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Author(s):
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Edic, P.M.; Saulnier, G.J.; Newell, J.C.; Isaacson, D.
A real-time electrical impedance tomograph
Journal IEEE Transactions on Biomedical Engineering
42
9
SEP
1995
849-859
PM Edic
Rensselaer Polytech Inst
Dept Elect Comp & Syst Engn
Troy, NY 12180 USA
0018-9294
Electrical properties of tissues in the human body can be imaged using a technology known as Electrical Impedance Tomography, In this modality, sinusoidal electrical currents are applied to the body using electrodes attached to the skin, and voltages that are developed on the electrodes are measured. Using these data, a reconstruction algorithm computes the conductivity and permittivity distributions within the body. This paper describes the reconstruction algorithm, image display algorithm, and hardware of a real-time Electrical Impedance Tomograph known as the Real-Time Imaging System, The reconstruction algorithm, executed by a commercially available coprocessor board that resides in a 386-based personal computer, is a modification of the Newton's One Step Error Reconstructor (NOSER) that minimizes algorithm execution time by precomputing many quantities. The image display algorithm, also executed by the coprocessor board, maps the output of the reconstruction algorithm into an image, which is displayed using a video graphics board. The architecture of the system and execution times of algorithms implemented by the system are discussed. Using the continuous data acquisition mode of the Real-Time Imaging System, data from the thorax of a normal human subject were collected. Admittivity changes in the chest, as a result of respiration and the cardiac cycle, are presented. Data that were collected from the leg of a normal subject are shown which demonstrate capabilities of the triggered data acquisition mode of the system, allowing data acquisition synchronization with an electrocardiogram. |
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Erdtsieck, R.J.; Pols, H.A.P.; Valk, N.K.; Vanouwerkerk, B.M.; Lamberts, S.W.J.; Mulder, P.; Birkenhager, J.C.
Treatment of post-menopausal osteoporosis with a combination of growth hormone and pamidronate: A placebo controlled trial
Journal Clinical Endocrinology
43
5
NOV
1995
557-565
JC Birkenhager
Erasmus Univ Rotterdam
Hosp Dijkzigt
Dept Internal Med & Clin Endocrinol 3
POB 1738
3000 Dr Rotterdam, Netherlands
0300-0664
X-RAY ABSORPTIOMETRY; DUAL-PHOTON ABSORPTIOMETRY; BONE- MINERAL CONTENT; LEAN BODY-MASS; POSTMENOPAUSAL OSTEOPOROSIS; BIOELECTRICAL IMPEDANCE; FLUORIDE TREATMENT; DEFICIENT ADULTS; FRACTURE RATE; SHORT-TERM
OBJECTIVE It is known that growth hormone can induce accelerated bone turnover in GH deficient people as well as healthy elderly people. In this study we examined the effect of recombinant human GH (rhGH) on bone mineral mass and bone turnover in the presence of the bone resorption inhibiting agent, pamidronate. Effects on body composition were also studied.
METHODS Twenty-one post-menopausal osteoporotic women were treated with the bisphosphonate pamidronate during 12 months. During the initial 6 months rhGH (0.0675 IU/kg, 3 times/week) was administered in a placebo controlled fashion (10 vs 11 patients).
MEASUREMENTS Bone mineral content (BMC) of the lumbar spine and femoral neck was measured with dual-energy X-ray absorptiometry and BMC of the distal and proximal forearm with single-photon absorptiometry. Body composition was measured with bioelectrical impedance and total body dual- energy X-ray absorptiometry. Serum IGF-l and biochemical indices of bone turnover were also measured.
RESULTS The group treated with rhGH showed a two to three- fold increase in serum IGF-l levels. No effects on bone mineral mass were observed in the group treated with rhGH, either after the initial 6 months of treatment with rhGH or after the total period of 12 months. in women treated with pamidronate, however, a consistent increase of about 5% at the lumbar spine and somewhat less in the distal forearm was reached from 6 months onwards. In neither group was any change observed in BMC at the femoral neck or forearm. Compared to baseline, the biochemical measurements of bone turnover showed a decrease of about 50% in the pamidronate treated group, but this effect was blunted in the group additionally treated with rhGH. The body composition measurements showed clear effects of rhGH administration: a decrease in fat mass of about 5% and an increase in lean body mass of about 3%. However, these effects disappeared after the treatment with rhGH was stopped and both fat mass and lean body mass returned to initial values.
CONCLUSIONS The present study suggests that treatment with rhGH blunted both the pamidronate induced accumulation of bone mineral mass and the reduction of biochemical markers of bone turnover. Furthermore, the positive effect of rhGH on body composition disappears completely after cessation of treatment with rhGH. |
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Erol, R.A.; Mangnall, Y.; Leathard, A.D.; Smallwood, R.H.; Brown, B.H.; Cherian, P.; Bardhan, K.D.
Identifying oesophageal contents using electrical impedance tomography
Journal Physiological Measurement
16
4
NOV
1995
253-261
RA Erol
Univ Sheffield
Royal Hallamshire Hosp
Dept Med Phys & Clin Engn
Sheffield S10 2JF
S Yorkshire, England
0967-3334
electrical impedance tomography; oesophagus; pharynx; swallowing GASTROESOPHAGEAL REFLUX; TIME
Investigations have been carried out using the Sheffield mark II real-time EIT system, to look at changes in conductivity associated with swallowing. A ring of 16 electrodes was placed around the neck of 10 subjects, who then performed swallows with four liquids of different conductivities, ranging from water (sigma = 0.03 mS cm(-1)) to salty soup (sigma = 35.8 mS cm(-1)). Results showed that the conductive and non-conductive liquids could be distinguished. Bolus transit times were calculated from region of interest curves, and the average transit time for the 10 subjects was found to be 320 +/- 100 ms. |
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Erol, R.A.; Smallwood, R.H.; Brown, B.H.; Cherian, P.; Bardhan, K.D.
Detecting oesophageal-related changes using electrical impedance tomography
Journal Physiological Measurement
16
Suppl. 3A
AUG
1995
A143-A152
RA Erol
Royal Hallamshire Hosp
Dept Med Phys & Clin Engn
Glossop Rd
Sheffield S10 2JF
S Yorkshire, England
0967-3334
GASTROESOPHAGEAL REFLUX DISEASE; TIME
Preliminary work has been carried out using the Sheffield mark II real time Err system, looking for changes in conductivity which occur in the stomach and oesophagus following a swallow of a small volume of either a conducting or a non-conducting liquid. This has been done using three different configurations: a conventional transverse array placed around the thorax, a rosette array on the abdomen, and a rosette array placed on the back. Results show a significant difference between the two liquids, which can be detected equally well by the three electrode configurations. |
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Erol, R.A.; Cherian, P.; Smallwood, R.H.; Brown, B.H.; Bardhan, K.D.
Can electrical impedance tomography be used to detect gastro-oesophageal reflux?
Journal Physiological Measurement
17
Suppl. 4A
NOV
1996
A141-A147
RA Erol
Royal Hallamshire Hosp
Dept Med Phys
Glossop Rd
Sheffield S10 2JF
S Yorkshire, England
0967-3334
GASTROESOPHAGEAL REFLUX
A number of experiments have been carried out to investigate the feasibility of using electrical impedance tomography as an alternative method for identifying gastro- oesophageal reflux. Five subjects have been studied using simultaneous EIT and intraoesophageal pH measurements. A refluxogenic meal was given during the course of the recording to induce reflux in the subjects. Results show that there is some change in conductivity in the stomach region during some of the reflux episodes, but EIT is not able to detect all of the pH changes associated with the reflux. Other large conductivity changes, relating to gastric motility can be detected at times when no reflux is occurring. |
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Esposito-Del-Puente-A; Luca-S; De-Filippo-E; Peri-M-R; Caldara-A; Caso-G; Contaldo-F; Valerio-G; Franzese-A; Di-Maio-S; Rubino-A
Familial and environmental influences on body composition and body fat distribution in childhood in Southern Italy.
International Journal of Obesity 18(9): 596-601
1994
English
The aim of this paper was to evaluate the factors affecting body fat excess and distribution in prepubertal age. A cross-sectional survey was carried out on children attending the 4th grade of a primary school in Naples. Eighty-eight per cent of the total sample was examined: 52 girls, 58 boys; mean age = 9.6 yrs (s.e. +- 0.10). Each child underwent a medical examination, anthropometric measurements and bio-impedance analysis of body composition. The parents were asked to fill in a questionnaire that included demographic data, family history, parent's weight and height, child's perinatal history and his or her involvement in sports activities. Data were analyzed by multiple linear regression. The results showed a direct correlation between parental BMI and children's anthropometric measurements: the children's BMI correlated with the fathers' (P = 0.02) and mothers' BMI (P = 0.027); the children's waist/hip ratio correlated with the fathers' BMI (P = 0.07); the children's subscapular skinfolds correlated with the father's (P = 0.07) and mothers' BMI (P = 0.02); the children's triceps skinfolds correlated with the fathers' BMI (P = 0.004). Among congenital factors, sex was shown to be correlated with the children's waist/hip ratio (P = 0.05) with a lower ratio in the female, indicating a sex influence on body fat distribution even in prepubertal age. The children's BMI correlated with their waist/hip ratio (P = 0.001). Children's systolic blood pressure showed a positive correlation with triceps (P = 0.04) and subscapular (P = .05) skinfolds thickness, % FAT-PLI (P = 0.02). No correlation was found between the children's BMI and their weight at birth, a family history of diabetes, hypertension, or hyperlipidemia. Among environmental factors, only the mother's weight gain during pregnancy (P = 0.03) and breast feeding (P = 0.05) showed a reverse correlation with the children's BMI. We foresee the importance of defining a series of factors associated with obesity in pediatric age in different populations. This field of investigation is intriguing because it could lead to a better understanding of the etiology of obesity and could help to establish preventive programs for this Western disease. |
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Eyuboglu, B.M.; Oner, A.F.; Baysal, U.; Biber, C.; Keyf, A.I.; Yilmaz, U.; Erdogan, Y.
Application of electrical impedance tomography in diagnosis of emphysema - A clinical study
Journal Physiological Measurement
16
Suppl. 3A
AUG
1995
A191-A211
BM Eyuboglu
Hacettepe Univ
Dept Elect & Electr Engn
Ankara 06532, Turkey
0967-3334
In this paper, electrical impedance tomography (EIT) ventilation images from a group of 12 patients (11 patients with emphysema and one patient with only chronic obstructive pulmonary disease (COPD) (chronic bronchitis)) and a group of 15 normal subjects were acquired using a Sheffield mark 1 EIT system, at the levels of second, fourth and sixth intercostal spaces. Patients were diagnosed based on CT scans of the thorax, pulmonary function tests and posteroanterior x-ray graphs. One of the patients with emphysema has also a malignant lung tumour. Ventilation-related conductivity changes at total lung capacity (TLC) relative to residual volume were measured quantitatively in EIT images. These quantitative values demonstrate marked differences compared to those values obtained from the a images of 15 normal subjects. The EIT images of the patients were also compared with the cr images. In addition to the visual examination of the EIT images a statistical confidence test is applied to compare the images of the patients with the images of the normal subjects. Prior to statistical analysis all images are normalized with TLC to minimize the effect of mismatch between the TLC of different subjects. A normal mean image is created by averaging the normalized images from the normal subjects, at each intercostal space level. Than a 95% confidence interval is defined for each normal mean image. For each image of the patients, a confidence test image, which represents the deviations from the 95% confidence interval of the normal mean image, is created. The regions with emphysematous bulla and parenchyma are detectable in the confidence test images as regions of positive and negative deviations from the confidence interval of the normal mean, respectively. In the test images, it is possible to differentiate emphysematous parenchyma from emphysematous bulla, tumour structure, and COPD. However, the emphysematous bulla, the tumour structure, and COPD result in the same type of defect in the test images and are therefore indistinguishable from each other. In some cases, off-plane contributions in the EIT images may result in underestimation of the defects. EIT may be a useful screening device in detecting emphysema rather than a diagnostic tool. |
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Eyuboglu, B.M.; Oner, A.F.; Baysal, U.; Biber, C.; Keyf, A.I.; Yilmaz, U.; Erdogan, Y.
Application of electrical impedance tomography in diagnosis of emphysema - A clinical study
Journal Physiological Measurement
16
Suppl. 3A
AUG
1995
A191-A211
BM Eyuboglu
Hacettepe Univ
Dept Elect & Electr Engn
Ankara 06532, Turkey
0967-3334
In this paper, electrical impedance tomography (EIT) ventilation images from a group of 12 patients (11 patients with emphysema and one patient with only chronic obstructive pulmonary disease (COPD) (chronic bronchitis)) and a group of 15 normal subjects were acquired using a Sheffield mark 1 EIT system, at the levels of second, fourth and sixth intercostal spaces. Patients were diagnosed based on CT scans of the thorax, pulmonary function tests and posteroanterior x-ray graphs. One of the patients with emphysema has also a malignant lung tumour. Ventilation-related conductivity changes at total lung capacity (TLC) relative to residual volume were measured quantitatively in EIT images. These quantitative values demonstrate marked differences compared to those values obtained from the a images of 15 normal subjects. The EIT images of the patients were also compared with the cr images. In addition to the visual examination of the EIT images a statistical confidence test is applied to compare the images of the patients with the images of the normal subjects. Prior to statistical analysis all images are normalized with TLC to minimize the effect of mismatch between the TLC of different subjects. A normal mean image is created by averaging the normalized images from the normal subjects, at each intercostal space level. Than a 95% confidence interval is defined for each normal mean image. For each image of the patients, a confidence test image, which represents the deviations from the 95% confidence interval of the normal mean image, is created. The regions with emphysematous bulla and parenchyma are detectable in the confidence test images as regions of positive and negative deviations from the confidence interval of the normal mean, respectively. In the test images, it is possible to differentiate emphysematous parenchyma from emphysematous bulla, tumour structure, and COPD. However, the emphysematous bulla, the tumour structure, and COPD result in the same type of defect in the test images and are therefore indistinguishable from each other. In some cases, off-plane contributions in the EIT images may result in underestimation of the defects. EIT may be a useful screening device in detecting emphysema rather than a diagnostic tool. |
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Eyuboglu, B.M.
An interleaved drive electrical impedance tomography image reconstruction algorithm
Journal Physiological Measurement
17
Suppl. 4A
NOV
1996
A59-A71
BM Eyuboglu
Hacettepe Univ
Dept Elect & Elect Engn
Beytepe
Ankara, Turkey
0967-3334
In this study, a reconstruction algorithm for a 16- electrode interleaved-drive electrical impedance tomography (EIT) system is developed, based on inversion of an analytically calculated sensitivity matrix. The sensitivity matrix is calculated using Geselowitz's lead-sensitivity theorem. Eight interleaved electrodes out of 16 (equally spaced) electrodes are designated as current injection electrodes and the remaining eight electrodes are designated as measurement electrodes. The sensitivity matrix is singular, therefore singular value decomposition (SVD) of the sensitivity matrix, followed by pseudoinversion-with and without truncation-is used to reconstruct images. The algorithm is a single-pass algorithm. Data from a saline filled tank and in viva data during respiration and the cardiac cycle, acquired by using a Sheffield multifrequency system, are used to reconstruct images. The effect of different truncation levels on the reconstructed images is investigated. |
