Technology and Health Care - Volume 3, issue 2

Authors: Schneider, P. | Butz, S. | Allolio, B. | Börner, W. | Klein, K. | Lehmann, R. | Petermann, K. | Tysarczyk-Niemeyer, G. | Wüster, Chr. | Zander, C. | Ziegler, R. | Reiners, Chr.

Article Type: Research Article

Abstract: The wide spread use of bone densitometers in Germany and other European countries has required the establishment of a validated reference population data base. A semi anthropomorphic forearm cross-calibration phantom (EFP), developed during a concerted research action of the European Union’s programme in Biomedical Engineering (COMAC-BME), was used to cross-calibrate the peripheral quantitative computer tomography (pQCT) devices at four German centers participating in the multicenter study. In total, 723 women and 208 men were included in the normal data base. No significant regional differences were found between the data of the different centers. In addition to the manufacturers calibration standard, …proper calibration of the pQCT devices could be monitored during collection of the normal female and male data base. As a merit of the COMAC-BME study the measurements obtained with all pQCT devices thus ensured an uniform reference data base for distal radius measurements in Germany. Show more

Keywords: Osteoporosis, Bone densitometry, Peripheral quantitative computer tomography

DOI: 10.3233/THC-1995-3201

Citation: Technology and Health Care, vol. 3, no. 2, pp. 69-73, 1995

Authors: Dumay, Adrie C.M.

Article Type: Review Article

Abstract: Virtual Environments allow a human to interact with a (computer) system in such a way that a high level of presence in a computer-synthesised world is experienced. In principle, all human senses are involved with the interaction. Many applications may benefit from this type of human-machine interfacing, however, few have emerged so far for medicine. In this paper we elaborate on some realistic potential applications of Virtual Environment technology in the field of medicine. These applications can be found in education/training, therapy, surgery, rehabilitation, diagnosis, telemedicine and biomechanics. The value to be added to these applications by VE technology lies …in the fact that patient data or patient models may be moderated to the physician in a more intuitive and natural manner. Despite these potentials, the short-term feasibility of these applications can be put into question for various reasons. Firstly, the current generation of display devices have a resolution that may show to be too low to achieve a sufficiently high degree of realism for medical applications. Secondly, there are no commercially-available actuators for tactile and force feedback which the physician desperately need for the simulation of the contact with the (virtual) patient. Thirdly, the enormous computing power required for these applications (still) needs a considerable investment. With these limitations in mind, we believe that we are at the cradle of a whole new generation of VE applications in medicine. Show more

Keywords: Medicine, Virtual Environments, Simulation technology, Training, Education

DOI: 10.3233/THC-1995-3202

Citation: Technology and Health Care, vol. 3, no. 2, pp. 75-89, 1995

Authors: Brunie, Lionel | Leitner, Frank | Berthommier, F. | Cinquin, P. | Demongeot, J.

Article Type: Research Article

Abstract: Our medical objective is to match multimodal 3D medical images into a coherent model of the patient, from which diagnosis can be assessed and therapeutics guided. 3D image segmentation is absolutely necessary to reach this objective. We investigate two complementary approaches for segmenting 3D medical images. First we present some definitions, basic properties and recent theoretical results about formal neural networks, and show that these results can be applied to brain tumour segmentation. A variational approach (called the ’snake spline’ method) is then detailed. We finally show how segmented 3D images can be used for multi modal image matching.

Keywords: Medical imaging, Neural networks, 3D image segmentation, Multimodal image fusion, Computer-assisted surgery

DOI: 10.3233/THC-1995-3203

Citation: Technology and Health Care, vol. 3, no. 2, pp. 91-99, 1995

Authors: Yova, D. | Gonis, H. | Politopoulos, C. | Agapitos, E. | Kavantzas, N. | Loukas, S.

Article Type: Research Article

Abstract: Fluorescence spectroscopy presents great interest for the diagnosis of atherosclerosis. Nevertheless there are some difficulties in the interpretation of diagnostic information. This could be overcome by precise methods of extraction of the diagnostic parameters and convenient statistical analysis, which are the subject of this work. Fluorescence excitation-emission matrices from different categories of coronary arteries were developed and used to derive the optimum excitation wavelength on the one hand and to assign the spectra to specific chromophores on the other hand. Simple dimensionless functions (F) were formed by the ratio of the intensities at selected wavelength and the logistic model …was used for statistical analysis. Decision surfaces were drawn and it was estimated that the probability of correct classification is 88%. The algorithm correctly diagnoses 97% of healthy from diseased samples and 80% of fibrous from calcified coronary arteries. Show more

Keywords: Fluorescence, Diagnostics, Spectroscopy, Atherosclerosis

DOI: 10.3233/THC-1995-3204

Citation: Technology and Health Care, vol. 3, no. 2, pp. 101-109, 1995

Authors: Curcie, David J. | Craelius, William

Article Type: Research Article

Abstract: Thermal dependence of tissue resistivity was incorporated into a compartmental tissue model that predicted the interaction between power delivery from electrosurgical units (ESUs) and tissue heating. Simulations showed that as tissue resistance declines with heating, a positive feedback loop from tissue to generator is created that can promote alternate site burning. This study describes how the thermal behaviour of tissue resistance influences the output of microprocessor-controlled thermal generators, especially when used in the monopolar mode.

Keywords: Electrical surgical unit, Tissue heating, Alternate site burns

DOI: 10.3233/THC-1995-3205

Citation: Technology and Health Care, vol. 3, no. 2, pp. 111-116, 1995

Authors: Mitsubayashi, Kohji | Ogasawara, Katsunori | Yokoyama, Kenji | Takeuchi, Toshifumi | Tsuru, Tadahiko | Karube, Isao

Article Type: Research Article

Abstract: Tear fluid conductivity was measured by a non-invasive method. A flexible 3 mm-wide conductimetric sensor was placed inside the human subjects temporal lower cul-de-sac (similar to Schirmer test strip), and used to evaluate electrolyte concentration and turnover rate in tear for normal, healthy subjects aged between 30 to 85 years in a normal, light indoor environment. The tear electrolyte concentration was calculated from tear conductivity to give a mean value of 297 mEq/l (S.D. 30 mEq/l; n = 29) which was consistently with previously reported values. Tear turnover rate was calculated by a single exponential equation of tear conductivity change, …following the application to the eye-drops of 40.0 g/l sodium chloride solution. The mean turnover rate was 44.2% per minute (S.D. = 13.3% per minute; n = 30), being in agreement with previously reported values. Show more

Keywords: Flexible conductimetric sensor, Tear conductivity, Tear electrolyte, Tear turnover rate

DOI: 10.3233/THC-1995-3206

Citation: Technology and Health Care, vol. 3, no. 2, pp. 117-121, 1995

Authors: Tombros, S. | Tselikis, G. | Marakas, S. | Protonotarios, E. | Koutsouris, D. | Toutouzas, P.

Article Type: Research Article

Abstract: Every aspect of cardiac function such as contractibility, depolarization and repolarization of cardiac cells, firing rate of pacemaker cells, is under a complex neurohumoral regulation. Especially the autonomic neuron system through the interplay of its two opposing components, sympathetic and parasympathetic (vagal), is controlling cardiac function on a beat to beat basis. Moreover, the interaction of sympathetic and parasympathetic systems is a non-linear function, with sympathetic tone modulating the responce of vagal activation. It has been shown that the power of frequency components and especially the ratio of low to high frequency power spectra of heart rate variability are reliable …indicators of sympathovagal balance (A. Malliani et al. 1991. Cardiovascular Neural regulation explored in the frequency domain. Circulation, 84 (2) 482–484. The most known algorithms of linear and non-linear signal processing have been applied to the ECG data recorded from healthy and high risk individuals. These methods together with the study and analysis of QRS frequency spectrum will lead to very useful conclusions with diagnostic and prognostic information. In this paper we will briefly describe the mathematical aspect of these algorithms presenting their results for normal and pathological ECG signals. Show more

Keywords: ECG, Linear/Non-linear processing, Cardiac function, Computer modelling

DOI: 10.3233/THC-1995-3207

Citation: Technology and Health Care, vol. 3, no. 2, pp. 123-130, 1995

Article Type: Calendar

DOI: 10.3233/THC-1995-3208

Citation: Technology and Health Care, vol. 3, no. 2, pp. 131-131, 1995