Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering最新文献_第3页

Impedance computed tomography using an adaptive smoothing coefficient algorithm. 阻抗计算机断层扫描采用自适应平滑系数算法。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855701316922270

A. Suzuki, A. Uchiyama

{"title":"Impedance computed tomography using an adaptive smoothing coefficient algorithm.","authors":"A. Suzuki, A. Uchiyama","doi":"10.1163/156855701316922270","DOIUrl":"https://doi.org/10.1163/156855701316922270","url":null,"abstract":"In impedance computed tomography, a fixed coefficient regularization algorithm has been frequently used to improve the ill-conditioning problem of the Newton-Raphson algorithm. However, a lot of experimental data and a long period of computation time are needed to determine a good smoothing coefficient because a good smoothing coefficient has to be manually chosen from a number of coefficients and is a constant for each iteration calculation. Thus, sometimes the fixed coefficient regularization algorithm distorts the information or fails to obtain any effect. In this paper, a new adaptive smoothing coefficient algorithm is proposed. This algorithm automatically calculates the smoothing coefficient from the eigenvalue of the ill-conditioned matrix. Therefore, the effective images can be obtained within a short computation time. Also the smoothing coefficient is automatically adjusted by the information related to the real resistivity distribution and the data collection method. In our impedance system, we have reconstructed the resistivity distributions of two phantoms using this algorithm. As a result, this algorithm only needs one-fifth the computation time compared to the fixed coefficient regularization algorithm. When compared to the fixed coefficient regularization algorithm, it shows that the image is obtained more rapidly and applicable in real-time monitoring of the blood vessel.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"22 1","pages":"87-101"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81030216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A computer-controlled system for measuring an impedance locus of palmar skin. 一种测量手掌皮肤阻抗轨迹的计算机控制系统。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855701750383204

H. Isshiki, Y. Yamamoto

引用次数: 3

Analysis of heart rate variability of an anencephalic fetus using a new method to determine a fractal dimension of non-stationary time-serial data. 用一种确定非平稳时间序列数据分形维数的新方法分析无脑胎儿的心率变异性。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855700750265495

H. Shono, M. Shono, T. Iwasaka, H. Sugimori

{"title":"Analysis of heart rate variability of an anencephalic fetus using a new method to determine a fractal dimension of non-stationary time-serial data.","authors":"H. Shono, M. Shono, T. Iwasaka, H. Sugimori","doi":"10.1163/156855700750265495","DOIUrl":"https://doi.org/10.1163/156855700750265495","url":null,"abstract":"Human fetal heart rate (HR) variabilities were analyzed using the QIS-A, which we devised to determine a fractal dimension of non-stationary time series. Fifteen 10-min HR data of an anencephalic fetus at 23 weeks and 3 days of gestation and those of 10 normal fetuses at the same weeks of gestation were obtained by ultrasonic cardiography. The anencephalus preserved the spinal cord, medulla and partial anterior hypothalamus. The fractal scaling exponent alpha of the anencephalus was compared with that of each normal fetus by Student's t-test. In results, the scaling relationship in each case had a crossover pattern characterized by alpha(s) and alpha(l), which were slopes above and below a crossover point, respectively. Differences in mean alpha(s) and mean alpha(l) between the anencephalus and each normal fetus were significant (P < 0.01): mean alpha(s), 1.0 +/- 0.1 (+/-SD) (1/f fluctuation) and 1.6 +/- 0.2 (+/-SEM); mean alpha(l), 1.6 +/- 0.2 (+/-SD) and 1.4 +/- 0.1 (+/-SEM). There were six significant differences in mean crossover point between the anencephalus and each normal fetus: 13.8 +/- 5.7 s (+/-SD) and 15.3 +/- 5.6 s (+/-SEM). These results reveal the relationship between fractal structure of fetal HR variability and the developing central nervous system (CNS). In particular, the 1/f fluctuation of HR variability in an anencephalic fetus from the 1.25 to 13.8 s time scale might have a strong relation to the defect of the CNS.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"10 1","pages":"337-44"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78357899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Characteristics of acoustic noise in echo-planar imaging. 回波平面成像中的噪声特征。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855700750265503

T. Miyati, T. Banno, H. Fujita, M. Mase, H. Narita, M. Imazawa, S. Sanada, K. Koshida, T. Kasuga

{"title":"Characteristics of acoustic noise in echo-planar imaging.","authors":"T. Miyati, T. Banno, H. Fujita, M. Mase, H. Narita, M. Imazawa, S. Sanada, K. Koshida, T. Kasuga","doi":"10.1163/156855700750265503","DOIUrl":"https://doi.org/10.1163/156855700750265503","url":null,"abstract":"Characteristics of the acoustic noise generated by magnetic resonance imagers of different systems and performance levels were studied when operating in echo-planar imaging (EPI) sequence. Continuous equivalent A-weighted sound pressure levels (Leq) and peak impulse sound pressure levels (Lpeak) during EPI were measured in 12 clinical super-conducting MRI systems (0.5-1.5 T). Sound pressure levels and frequency spectra of EPI were compared with those of nine different pulse sequences. EPI sound pressure levels differed among institutions (Leq = 94.2 +/- 2.7 dBA. Lpeak = 109.1 +/- 3.5 dB), but these were within permissible noise exposure levels. Sound pressure levels during EPI were not significantly different from those during other pulse sequences. However, compared to other pulse sequences. EPI had a significantly greater proportion of acoustic noise in the high octave-frequency band. Single-shot EPI had relatively higher frequency noise and greater Leq than multishot EPI, but the difference in Leq decreased when the number of slices in multishot EPI was increased.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"83 1","pages":"345-56"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80388189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Simulation studies of the ischemic vulnerability of the subendocardium. 心内膜下缺血易损性的模拟研究。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855701316922289

T. Ejaz, T. Takemae, Y. Kosugi, M. Hongo

{"title":"Simulation studies of the ischemic vulnerability of the subendocardium.","authors":"T. Ejaz, T. Takemae, Y. Kosugi, M. Hongo","doi":"10.1163/156855701316922289","DOIUrl":"https://doi.org/10.1163/156855701316922289","url":null,"abstract":"Changes in the subendo-subepi flow ratio were studied by using a simple electronic circuit model of the coronary vessel consisting of a resistor, capacitor and field effect transistor in order to provide a better understanding of the ischemic vulnerability of the subendocardium. The simulated subendo-subepi flow ratio was found to be approximately 1.2 under normal condition. Changes in the flow ratio were observed while varying the main arterial resistance, mean arterial pressure and intramyocardial pressure individually. The mean flow in the subendocardium was found to decrease at a rate faster than that in the subepicardium with the increase in the septal arterial resistance and the intramyocardial pressure. The same tendency was also observed while the arterial pressure was lowered. This decrease in the mean subendocardial flow is considered to be the effect of higher end-systolic resistance in the subendocardial venule compared to that in the subepicardial venule. These results would be helpful in understanding the vulnerability of the subendocardium to ischemia and in providing clinical treatment to patients with that disease.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"71 1","pages":"103-15"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81336168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Temperature measurement for energy-efficient ablation by thermal radiation with a microsecond time constant from the corneal surface during ArF excimer laser ablation. ArF准分子激光烧蚀过程中角膜表面微秒时间常数热辐射节能烧蚀温度测量。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/15685570152772441

M. Ishihara, T. Arai, S. Sato, Y. Morimoto, M. Obara, M. Kikuchi

{"title":"Temperature measurement for energy-efficient ablation by thermal radiation with a microsecond time constant from the corneal surface during ArF excimer laser ablation.","authors":"M. Ishihara, T. Arai, S. Sato, Y. Morimoto, M. Obara, M. Kikuchi","doi":"10.1163/15685570152772441","DOIUrl":"https://doi.org/10.1163/15685570152772441","url":null,"abstract":"Measurement of the temperature of the corneal surface during photorefractive keratectomy (PRK) is thought to be useful for monitoring the corneal ablation process, since the photothermal process has been proposed as the major mechanism of ArF excimer laser ablation. For temperature measurement, we measured thermal radiation from the corneal surface during ArF excimer laser ablation using a mercury-cadmium-telluride detector with a 1-micros time constant. To investigate the effects of temperature on ablation depth, the ablation depth of the cornea was measured by microscopy. When corneal ablation was initiated at the fluence of 65 mJ/cm2, the corneal surface temperature rose to 60-70 degrees C. The energy required for a unit-depth ablation (degrees C/microm) was lowest at 120 micro C. Monitoring of transient temperature during PRK provides important information on energy-efficient ablation, which may enable rapid and safe corneal incisions.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"22 1","pages":"167-75"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82560165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 19

Indirect arterial blood pressure measurement at the wrist using a pad-type square cuff and volume-oscillometric method. 使用垫式方袖带和容积振荡法间接测量手腕动脉血压。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/15685570152772478

W. Lu, A. Tsukada, T. Shiraishi, K. Sasaki

{"title":"Indirect arterial blood pressure measurement at the wrist using a pad-type square cuff and volume-oscillometric method.","authors":"W. Lu, A. Tsukada, T. Shiraishi, K. Sasaki","doi":"10.1163/15685570152772478","DOIUrl":"https://doi.org/10.1163/15685570152772478","url":null,"abstract":"Using theoretical and experimental approaches, we examined whether blood pressure at the wrist can be accurately measured by a volume-oscillometric method using a small pad-type square cuff placed above the radial artery (RA). Nuclear magnetic resonance imaging of the wrist allowed us to determine the geometry of two-dimensional (2-D) finite-element models. Finite-element method (FEM) analysis predicted that the pressure transmission ratio (calculated tissue pressure over externally applied pressure; square cuff to RA) was 98.8% for a cuff with a bladder sidelength 0.25 times the wrist diameter placed on the skin surface between the tendons of the brachioradialis muscle (Ta) and the flexor capri radialis muscle (Tb) and over the site (L) at which RA crosses the most protuberant spot on the volar aspect of the distal end of the radius. In addition, FEM analysis using a 3-D finite-element model (constructed by extending the 2-D finite-element model at site L in the longitudinal direction) showed that for all square cuffs with bladder sidelengths greater than or equal to 0.25 times the wrist diameter, the external pressure was transmitted almost completely to RA beneath the cuff center. Moreover, when the bladder sidelength was 0.44 times the wrist diameter, but not 0.29 times the wrist diameter, the mean blood pressure measured at site L in human subjects was similar to that measured at the upper arm. Taken together, the theoretical and the experimental results suggest that (i) blood pressure at the wrist can be measured accurately using a pad-type square cuff placed on the skin surface between Ta and Tb at site L, and (ii) the minimum bladder sidelength for accurate readings is somewhere between one-third and one-half of the wrist diameter.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"20 1","pages":"207-19"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77802914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Selective stimulation of smaller nerve fibers using biphasic rectangular pulses. 用双相矩形脉冲选择性刺激较小的神经纤维。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855700750265486

Q. Shen, D. Jiang, C. Tai

引用次数: 1

Sarcomere lengths of thick skeletal muscle specimens measured under an epi-illumination-type polarization microscope. 用外延照明型偏光显微镜测量厚骨骼肌标本的肌节长度。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2001-01-01 DOI: 10.1163/156855701750383196

K. Akazawa, R. Okuno, T. Hosono

{"title":"Sarcomere lengths of thick skeletal muscle specimens measured under an epi-illumination-type polarization microscope.","authors":"K. Akazawa, R. Okuno, T. Hosono","doi":"10.1163/156855701750383196","DOIUrl":"https://doi.org/10.1163/156855701750383196","url":null,"abstract":"The purpose of this study was to measure sarcomere lengths of thick muscle fiber bundles at resting and at isometric tetanic contractions. We developed a novel measurement system using an epi-illumination-type polarization microscope and an image processing algorithm using an ellipse-type Gabor filter. Images with striation patterns of frog skeletal muscle were obtained by the microscope and the image processing algorithm. Individual lengths of 10 consecutive sarcomeres of a single muscle fiber were measured by gauging each width of the striation pattern, which was proved to be derived from striation structures of the single fiber by performing experiments using different polarization lights and different focus depths. At the resting state, each sarcomere length was identical at the fixed muscle length and in proportion to the length ranging over 91-123% of the natural length. Each sarcomere length was unchanged at the steady state during isometric tetanic contractions. Individual sarcomere lengths in the central part of the skeletal muscle were identical at resting and at isometric tetanic contractions even in the thick muscle fiber specimen.","PeriodicalId":77139,"journal":{"name":"Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering","volume":"21 1","pages":"59-71"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85660583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evaluation of the sharpness of concentric needle electrodes by a penetration test. 用穿透试验评价同心针电极的锐度。

Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering Pub Date : 2000-12-01 DOI: 10.1163/156855700750265512

D. G. Nair, S. Vijayan, R. Sivakumar

引用次数: 0