Technology and Health Care - Volume 5, issue 6

Authors: Blinowska, K.J. | Durka, P.J. | Skierski, A. | Grandori, F. | Tognola, G.

Article Type: Research Article

Abstract: High resolution time-frequency analysis of OAE signals evoked by stimuli of different strength was performed by means of the Matching Pursuit algorithm. The method relies on adaptive decomposition of a signal into waveforms of well-defined frequency and time localization. Energy of OAE as a function of time and frequency was evaluated for stimuli strength of 35–80 dB SPL. Dynamic characteristics of the signal were constructed. For strong stimuli decrease of the power of high frequency components was found. Matching Pursuit proved to be a method which offers high resolution parametrisation of OAE in time-frequency space and provides excellent possibilities of …investigation of the signal generation mechanisms. Show more

Keywords: Otoacoustic emission, Matching Pursuit, time-frequency methods, Wigner distribution

DOI: 10.3233/THC-1997-5601

Citation: Technology and Health Care, vol. 5, no. 6, pp. 407-418, 1997

Authors: Van de Walle, R. | Lemahieu, I. | Achten, E.

Article Type: Research Article

Abstract: Magnetic resonance (MR) imaging is a non-invasive diagnostic tool which is widely used nowadays. In this paper, the basic principles of MR imaging are explained and it is shown how images can be reconstructed in case of standard 2D Fourier Transform (2DFT) imaging. Several aspects of MR signal encoding are described. Unfortunately, motion of the patient during a magnetic resonance experiment often causes severe artifacts in the images. For example, in 2DFT imaging blurring and ghosting are seen and the appearance of motion artifacts remains one of the major drawbacks in MR imaging. Several methods to reduce motion artifacts …in MR imaging have been proposed in the past. An overview of the principles on which these methods are based is given in this paper. Both post-processing methods and techniques that rely on gating or the use of alternative acquisition schemes such as projection reconstruction are discussed. Show more

Keywords: Magnetic resonance imaging, artifacts, motion, correction, post-processing

DOI: 10.3233/THC-1997-5602

Citation: Technology and Health Care, vol. 5, no. 6, pp. 419-435, 1997

Authors: De Wachter, Dirk S. | Verdonck, Pascal R. | Verhoeven, Ronny F.

Article Type: Research Article

Abstract: To study factors influencing the distribution of local anaesthetics in the subarachnoid space, an in vitro model is constructed which takes into account the natural curvature of the spinal column and the volume occupation of spinal cord and nerve fibres to resemble the in vivo situation. Three Marcaine® solutions of different baricity (1003, 1008, 1030 kg/m3 ) are injected with a 22 G, a 27 G Quincke point needle and a 18 G multiport catheter into three models of non-pathological spinal columns with injection flow speeds of 0.6, 0.2 or 0.1 ml/s. Methylene blue is added for visual and …qualitative assessment of drug distribution. Baricity is the main actor in the spreading of the drug solution. For all other variables, no significant difference is found after ten minutes, though the initial distribution may differ according to the geometry used. A hypobaric solution yields a remarked difference between fast and slower injections. The position of the catheter should be controlled. Show more

Keywords: Local anaesthetics, subarachnoid space, in vitro model, spinal column curvature, catheter injection, baricity

DOI: 10.3233/THC-1997-5603

Citation: Technology and Health Care, vol. 5, no. 6, pp. 437-447, 1997

Authors: Clemente, Fabrizio | Ferrari, Gian Franco | De Lazzari, Claudio | Tosti, Giancarlo

Article Type: Research Article

Abstract: The steep rise in the clinical use of high technology biomedical devices and materials, involving multidisciplinary competencies, points out the problem of mutual standards defining, first of all, functional characteristic and tests able to characterise and qualify devices, materials and minimal safety requirements both for patients and operators. Standards defined by consent of the parties or by law are used to this aim. Fast technical development in specific sectors produces besides lack of rules, which must be quickly filled up. The aim of this paper is both the presentation of the approach to problems related to technical standards for …biomedical devices and the presentation of the set up of a technical standard for mechanical heart assist devices. Show more

Keywords: Quality and safety of medical devices, technical standards, heart assist devices, benchmark, European Directives 90/385 and 93/42

DOI: 10.3233/THC-1997-5604

Citation: Technology and Health Care, vol. 5, no. 6, pp. 449-459, 1997

Authors: Al-Nashash, H. | Lvov, B.

Article Type: Research Article

Abstract: A safe and simple system for the detection of sudden infant death syndrome (SIDS) is proposed. The system consists of an optoelectronic transceiver and electronic circuits capable of detecting infant breath, heart beating and any other infant movement. The system also includes an active alarm circuit. In case of absence of body activity or breathing, the active alarm will give the infant a mild push in order to awaken him or her. If there is no reaction, an audiovisual alarm is activated. Results obtained from six university students and three new born infants show that the system is capable of …detecting apnea and SIDS. Show more

DOI: 10.3233/THC-1997-5605

Citation: Technology and Health Care, vol. 5, no. 6, pp. 461-469, 1997

Authors: Weber, O.M. | Trabesinger, A.H. | Duc, C.O. | Meier, D. | Boesiger, P.

Article Type: Research Article

Abstract: Magnetic resonance spectroscopy (MRS) allows the assessment of chemical substances in living tissue and the detection of biochemical changes associated with certain diseases. In vivo MRS, however, is usually limited in sensitivity and spectral resolution. Many resonance lines originating from metabolites of interest are overlapped by signals of other metabolites and are therefore not visible in conventional MR spectra. In order to overcome this limitation, three localized methods, a technique making use of a spectral difference, a multiple quantum filter technique, and a two-dimensional J -resolved technique, were evaluated theoretically and experimentally for the detection of γ -aminobutyric acid (GABA) …both in vitro and in vivo. All three methods are able to produce the desired results at high metabolite concentrations in vitro. For in vivo measurements the spectral difference method proofed to be most appropriate due to its relatively high sensitivity and its short acquisition time. Show more

Keywords: Magnetic resonance spectroscopy (MRS), editing sequence, multiple quantum filter (MQF), 2D-FT-NMR, brain

DOI: 10.3233/THC-1997-5606

Citation: Technology and Health Care, vol. 5, no. 6, pp. 471-491, 1997