To develop a totally implantable artificial heart, a new mechanism of pulsatile total artificial heart (TAH), FTPTAH (Flow Transformed Pulsatile Total Artificial Heart), in which a continuous flow from a single centrifugal pump (CFP) was converted to pulsatile flow to perfuse the pulmonary and systemic circulatory system, was proposed. We already reported the results of the first and the second model. There are several problems resulted from the preveous model consisted of a single CFP and one 6-port spool valve driven by a solenoid and a coil spring. 1) maximum output (4.8l/min) was less than that of expected value by the performance of CFP and high flow resistance, 2) the blood mixture of venous and arterial blood could not be controlled, 3) heat generation was occured at the solenoid. To solve these problems, the third model was developed under the hydro-dynamic design, resulting 7.8l/min of pulsatile output. The spool valve deviled into two 3-port spool valves and each valve was driven by two solenoids, which could protect the artrial and venous blood mixture and excessive heat generation.

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A sensor system for automatic discrimination of surgical instruments is proposed. The users are only required to put the instrument on a tray for discrimination. This will work as a sensing head of the autoprocessing system for surgical instrument and will save time and hands of nurses who are engaged in restoring work of washed surgical instruments. In this system, a high frequency electric signal is applied to the instrument from an electrode on the tray and the signal is received by an array of rectangular electrodes located under the tray through capacitances made by the gaps between the instrument and electrodes. Because the amount of capacitance is different depending on the position of instrument, the received signals are also different in the different position though the shapes of the electrode are the same. The received signals on electrodes are collected and reformed to a time serial signal pattern by being switched and sent to the computer for analysis. The differences of signal patterns between instruments are evaluated by correlation coefficient and the possibility of discrimination of most instruments by this system are shown.

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Occlusion characteristics of six infusion pumps commercially available in USA and Japan were examined at 10ml/h flow rate using an infusion analyzer. Flow volume, flow rate and pressure of an infusion pump were measured simultaneously and its occulusion profile was displayed. The time from beginning occlusion to activating alarm, occlusion alarm pressure and bolus volume were calculated from occlusion profiles of each pums. The occlusion alarm pressure of USA were 476-599mmHg and that of Japan pumps were 561-566mmHg. The range of occlusion alarm time were 88-344s (USA) and 478-545s (Japan). Bolus volume were 0.18-0.38ml (USA) and 1.16-1.34ml (Japan). Infusion devices of this country had a longer occasion alarm time and larger bolus volume. Using the evaluation indexes calculated from measured parameters, it was suggested that the cause of this was larger elastisity of Japanese infusion sets. The analysis by this system should be useful in quantitative evaluation the occlusion characteristics of the pumps commercially available or in designing.

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The aim of the paper is to delineate the performance of the lung sound measurement using a air-coupled microphone on the chest wall, more specifically, how the frequency characteristics of the measurement is determined, and how the spatial resolution of the measurement is determined. The system is modelled as the microphone on the free surface of the semi-infinite medium in which the point source is embedded. The theoretical analysis yielded a relatively simple expression for the sensitivity distribution, which implies 1) the sensitivity at the observation point right above the source decreases inversely proportional to the square of the source depth, 2) lateral distribution of the sensitivity on the surface is such that it diminishes to 1/2.83 at the point laterally displaced by the distance equal to the source depth. This means that we can expect fairly good spatial resolution when the source is close to the body surface. The sound pressure transfer function from the embedded spherical source to the air-coupled microphone on the surface is shown to be of the low-pass 2nd order characteristics, of which cut-off frequency is determined by the coupling-chamber dimension. If we want to have the cut-off frequency above 1kHz using the microphone with the aperture of 3.5mm radius, then the depth of the coupling air-chamber must be below 2mm. All those theoretical results were verified with reasonable accuracy on the experimental model using water as the medium. The study seems to give us the answer or clue to most of the fundamental problems in the lung sound measurement on the chest wall, although the model was quite simple.

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Local volume changes of the artery segment under the cuff are caluculated using a static model in which assumed external pressure distributions along the artery and four arterial tube laws are used. Local volume changes of brachial arteries deviled into four sections are measured experimentally using impedance plethysmography. From comparison of analytical and experimental results, individual volume change characteristics in proximal half of the artery under the cuff have been known to be well represented by the static model, if tube law is appropriately selected. Furthermore, validity of the static model, including the tube laws, is shown by compering analytical results with experimental results of Herscovici et al. From the analytical results, it has been known that arterial volume change profiles are strongly affected by arterial tube laws. Therefore, tube laws have to be taken into algorithm determining blood pressure in blood pressure measurement technique using informations about the volume changes.

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In this paper, a new method is proposed for reconstructing the three-dimensional (3D) structure of cerebral arteries from the digital subtraction angiographic (DSA) image sequence, which is taken by the rotational stereo angiographic system. The DSA image sequence is arranged in order of rotation angle to constitute the spatio-temproral image. The sinusoidal movement locus of each vessel can be observed on the transversal sections of spatio-temproral image. We prove that the 3D coordinate of each vessel can be estimated from the parameters of sinusoidal wave form of the movement locus. Such parameters, amplitude and phase in sinusoidal wave form, are obtained by utilizing the voting algorithm anologous to the Hough transform. In this method, an accurate parameter estimation can be performed even from the limited data. The 3D structure of arteries is reconstructed by the 3D coordinate of each vessels. The validity of proposed reconstruction algorithm is confirmed by reprojecting the reconstructed arteries and comparing to the original DSA images. The structure of arterial tree in the reprojected image is closely resembled to that in the corresponding original DSA image. The reconstructed cerebral arteries are displayed by using the computer graphic software, and the 3D structure can be clearly observed from arbitrary view point.

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The present paper deals with relation between a hydrodynamic effect of blood flow and the blood coagulation on artificial organs. In former works, it is considered that the blood coaguration on artificial organs is caused by a biochemical interaction (biocompatibility) and ACT (Activated Coagulation Time) control during extracorporeal circulation. However, the blood coagulation is also under the influence of hydrodynamic effect of blood flows inside of the artificial organs. Therefore quantitative analyses of the flow behavior inside of an artificial organ needs to develop artificial organs, especially for long term use (for example: membrane lung for ECMO). We measured blood flow rate using a velocity vector measurement system (RIX-04) to visualize red blood cell about 1.5-3mm on TV monitor (14 inch) magnified 400 times by CCD microscope. The method of the determination of velocity vector is a two-dimensional correlation technique of binary video data. The three ex-vivo tests were conducted. In experiments, we use flow visuarization models made of artificial materials. The results are as follows: 1. There is a relation between blood flow rate and aggregation of red blood cells. 2. There is a relation between Ht. and rate of blood cell movement. The moving rate of red blood cells (absolute value) after the pump stop are 1.49±0.098, 1.26±0.031, 1.18±0.061 and 0.803±0.19mm/min at Ht. 36, 26, 23 and 17%. These data have significant difference (1%). 3. There is a relation between aggregation section and blood clotting section. 4. We could analyze blood flow inside of the flow visualization models using the velocity vector measurement system. In conclusion, we could consider high Ht. and low blood flow rate at the stagnation point inside of artificial organs formed thrombus easily.

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New high-resolution 12″ x-ray image intensifier (I. I.) has been developed exclusively for use with a 2048×2048-matrix real-time II-TV digital radiography (DR) system. The basic imaging properties of a 100-mm roll-film system and DR system using this I. I. were examined to determine the effects of physical parameters on the quality of the GI-tract images, and also to explore the clinical usefulness of the system. We found that the resolution of the 100-mm roll-film system at 7″ I. I. mode is superior to that of screen-film system. The incident exposures for these systems with 12″ I. I. mode were approximately 1/12 of that for the screen-film system (HR4/HRS). The small x-ray focus of 0.2mm can be employed with the I. I. system, so the effect of geometric unsharpness can be reduced. Therefore, it was possible to apply the magnification technique. The ROC analysis indicates that the image obtained with the DR system at 7″ I. I. mode under the condition with less than half exposure relative to the screen-film system provides similar detectability to the image with the screen-film system (HRS/HR6). It was found that these 100-mm roll-film and DR systems can be applied not only to the mass screening but to the accurate GI-tract examinations.

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The purpose of the study is to apply a neural network to detect changes of trabecular patterns on skeletal radiographs due to osteoporosis. Regions of interest (ROIs)(64×64 pixels, 6.4×6.4mm²) near the center of the vertebral body were extracted from digitized bone radiographs. After background trend corrections, texture measures were calculated in terms of standard deviations (total, horizontal, and vertical directions) and pixel values (maximum and minimum), all of which were used as input to the input layer of the neural network. The network was trained with a back-propagation technique to discriminate textural differences between the normal and the diseased cases. A data base of 46 bone radiographs was used in this study. Half of the cases was used as the training set, and the other half was used as the testing set. The neural network correctly classified about 90% of the cases, using the diagnosis made by an experienced physician as a standard for comparison. Our results suggest that a neural network analysis is useful to discriminate textural variations of trabecular patterns and may be effective for computer-aided diagnosis of osteoporosis.

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