限窗滑动线性傅里叶拟合在人体震颤预估滤波中的应用

背景：为抑制人体的震颤运动,各国研究人员试图设计出一套可穿戴机器人辅助抑震系统。目的：分析介绍了针对震颤滤波预估常用的线性傅里叶拟合算法及其衍生算法,并在此基础上提出了改进算法。方法：提出一种引入了加权线性傅里叶拟合算法变基频带限线性傅里叶拟合改进算法,迭代的过程中可随着对象的改变而发生改变,频带设定了一定约束条件以保证算法的滤波特性,限制了频带的变化范围,即限定了一个大的通频带,通频窗口只能在所设定的这个范围内进行滑动,所提出的这种算法为限窗滑动的线形傅里叶拟合。结果及结论：该算法的适应性得到了拓宽,对震颤滤波预估具有更强的适应性与准确性。     

基于频域时域相结合的医学图像配准算法

为解决存在平移变换和旋转变换的2幅刚性医学图像的配准问题,结合图像信号傅里叶变换的平移特性和旋转特性,提出了一种基于频域与时域相结合的医学图像配准算法.该算法将旋转调整和平移调整分而治之,首先以图像信号的幅度谱巨相关确定旋转参数,再以图像的时域体素互相关确定平移参数.将该算法用于对核医学图像配准及多模态医学图像配准实验,结果表明该算法是一种速度快、精度高、鲁棒性好的医学图像配准方法.     

磁共振T2-Map的单、双指数拟合方法

目的 探讨MR图像单指数和双指数拟合的T2-Map方法,获得每个像素点的T2信息.方法 对不同TE条件下的一系列MR图像利用单、双指数拟合方法得到T2-Map图像.采用线性拟合和非线性回归方法实现对MR图像的每个像素点的单指数拟合和定点双指数拟合,得到T2-Map图像;上述计算过程是在MATLAB平台上开发T2-Map的计算软件,根据应用需求设计并实现计算、显示和存储等功能.结果 得到了单、双指数拟合方法的T2-Map计算软件,可用于计算不同组织的T2值,得到T2-Map.结论 利用单指数线性拟合方法得到T2-Map图像方便、快捷,但不能很好地反映一些组织成分混合较多的区域;在出现组织明显混合的情形时,双指数拟合的方法可以计算出两个不同的T2值,使得分析结果更加精确,但是计算速度较慢,双指数T2-Map是单指数T2-Map计算方法的有益补充.     

一种改进的定量磁化率成像多回波场图拟合算法

目的开发并验证一种基于相位线性度的多回波场图拟合算法,以提高定量磁化率分布图的图像质量。材料与方法提出了一种多回波场图拟合的改进算法,其通过场图线性拟合的残差来判断数据点相位的可靠性。采集15名健康被试的模图和相位图,分别采用常规算法和改进算法拟合得到场图,再经过场图解缠绕、背景场去除和磁化率反演等步骤获得磁化率分布图。选取黑质、红核、尾状核、苍白球和壳核作为感兴趣区,对比研究了两种算法得到的磁化率分布图上感兴趣区的噪声水平。结果采用改进的场图拟合算法后,定量磁化率图像质量得到明显提高,伪影得到明显抑制。双侧黑质、右侧红核等区域的噪声水平显著下降。结论该文提出的一种改进的定量磁化率成像多回波场图拟合算法可以提高磁化率分布图的图像质量。     

TCD傅里叶分析观察硝酸甘油对老年人脑血管的影响

目的：了解老年人脑血管的功能状态及ＴＣＤ傅里叶分析在鉴别药物性头痛中的意义。方法：对４２例老年冠心病患者（其中２２例有明确的含服硝酸甘油后头痛史）含服硝酸甘油０．５ｍｇ前后进行ＴＣＤ检查及傅里叶分析。结果：老年冠心病患者脑血流量低。服药后大脑中动脉（ＭＣＡ）的平均峰流速（Ｖｍ）、空间平均流速（ＳＭＶ）及血压、心率均无明显变化（Ｐ＞０．０５）。头痛组ＭＣＡ的相对横截面积（ＲＣ－ＳＡ）增大，相对流量（ＲＶＦ）增加。与无头痛组比Ｐ＜０．００１。结论：老年冠心病患者由于动脉硬化，对硝酸甘油扩张脑血管作用不敏感，而硝酸甘油致偏头痛时有局部的脑血管扩张，脑血流量增加。ＴＣＤ傅里叶分析可反映老年人脑血管的功能状态，并可做为鉴别老年人药物性头痛的一种可靠的方法。     

傅里叶变换红外光谱分析在医药领域的应用进展

傅里叶变换红外光谱仪（FTIR）于20世纪70年代诞生,它是由光源（碳棒、高压汞灯）、迈克尔逊（michelson）干涉仪、样品室、检测器、计算机系统和记录显示装置等几部分组成。傅里叶变换红外光谱仪不仅具有很高的分辨率和扫描速度,且不仅限于中红外（MIR）区段的使用,而且分束器的应用可将其光谱范围覆盖到从紫外到远红外的区段。     

临床实验室线性评价方案

线性范围(Linearity range)是分析方法的一个重要技术指标,它能判断对某一分析方法(试剂或仪器)测得的浓度或活性值与设定的浓度或活性值之间的比例关系的范围[1]。而检测线性范围是通过可接受的分析测定范围的高和低值拟合成一条直线,然后应用目测定法、最小二剩法、NCCLS EP6     

面向两自由度下肢康复训练机器人平滑运动轨迹优化方法

目的：针对下肢康复机器人周期衔接不够平滑的问题，本文提出面向两自由度（2-DOF）下肢康复训练机器人在不同康复训练任务目标下的平滑运动轨迹优化方法。方法：首先针对自研的下肢康复机器人建立了2-DOF运动学模型，然后根据不同康复训练任务目标选用傅里叶法与特征点正弦法对求解的关节运动轨迹进行优化。结果：基于傅里叶拟合法的轨迹优化方法获得的关节训练活动度与速度相对较小，而基于特征点正弦拟合法的轨迹优化方法获得的关节训练活动度与速度相对较大。结论：提出的两种基于傅里叶拟合与基于特征点正弦拟合对角度—时间曲线的优化方法均能够使机器人轨迹与运动特征发生改变，并有效地应对康复机器人在周期衔接时的加速度突变问题，使下肢康复机器人的运行更加平稳，在临床康复训练过程对于不同训练任务的患者可采用不同的轨迹优化方法。     

准静态弹性成像技术检测聚焦超声致离体组织损伤

目的 用准静态弹性成像检测聚焦超声(FUS)在离体组织中形成的损伤。方法 在仿体实验中采取多种方法提高运动估计的精度。通过分段线性拟合等算法对位移数据进行后处理,优化位移估计结果,采用基于小波变换的数字低通差分算法抑制应变估计中高频噪声的干扰。在此基础上用准静态弹性成像检测FUS在离体猪肌肉组织中形成的损伤。结果 采用分段线性拟合算法和基于小波变换的数字低通差分算法可显著改善运动估计的准确性。弹性成像可检测小剂量FUS辐照后在组织内形成的损伤,主要表现为损伤区域的力学特性与周围组织具有明显差异。结论 弹性成像可用于评价FUS形成的组织损伤。     

叶九斤以通降法治疗脾胃病经验

总结叶九斤主任运用通降法治疗脾胃病的经验,提出治疗各型脾胃病,以明辨寒热虚实为基础,在温清补泻诸多治法中酌加通降之品,以顺应胃气通降之特性,而获良效。临证中具体通降之法有:温中通降法、补虚通降法、泄浊通降法、理气通降法、苦辛通降法。     

Validity of the adaptive filter for accurate measurement of cardiac output in impedance cardiography

The purpose of this study was to assess the validity of an adaptive filter, the scaled Fourier linear combiner (SFLC), in the impedance cardiography (ICG). Eight healthy males underwent constant-load bicycle exercise at different intensities from unloaded to near maximal intensity. The stroke volume (SV) and cardiac output (Q) measured by ICG at each condition were compared with those by the CO2 rebreathing method. We found that the noises were greatly reduced in the impedance waveform and that the inflection points, so-called the B- and X-points, were clearly detected even during strenuous exercise using the SFLC. Although a high correlation was observed between Qs measured by the two methods, the mean values of Qs in each method differed significantly and the regression line also differed significantly from the identity line. Likewise, a significant correlation was observed between SVs obtained by the two methods, but a significant difference in the group mean values and a trend of the regression line were observed. These findings suggest that the use of SFLC in ICG improves the performance in eliminating the noises and in detecting the inflection points in the waveform, thereby contributing to the accurate and beat-to-beat measurements of SV and Q especially during exercise.     

Beat-to-beat evaluation of systolic time intervals during bicycle exercise using impedance cardiography

In order to elucidate the beat-to-beat changes of the systolic time intervals (STI) during exercise, we proposed new techniques relating to an adaptive filter and detection algorithms for B- and X-points in the impedance cardiograph (ICG). Six male subjects underwent a ramp bicycle exercise up to maximum intensity during which an ECG, ICG and phonocardiogram (PCG) were continuously measured. Following the application of an adaptive filter, the scaled Fourier linear combiner (SFLC), to the first derivative (dZ/dt) of the base impedance (deltaZ) and PCG waveforms, the B- and X-points were automatically determined. For the B-point detection we used three criteria: the zero-crossing point (B(zero)), the 15% response point (B15%) of the negative peak of the dZ/dt (dZ/dt(min)) and a new algorithm (B(new)). The X-point was separately determined by using the ICG and PCG waveforms. It was found that the shape of the dZ/dt waveform directly affected the determination of the B- and X-points. The B-points determined using B(zero) and B15%, criteria were sometimes unstable caused by the location of a notch preceding the dZ/dt(min) compared to the B(new). The time difference between the X-points measured by the ICG and PCG was mostly within +/- 20 milliseconds but statistically significant. Although a wide variation was seen in R-R intervals, the STI were more stable. The relationships between HR and STI from rest to maximal exercise showed a gentle curvilinear relationship. It is suggested that the STI can be obtained precisely on a beat-to-beat basis by using the adaptive filter and detection algorithms for the inflection points of the ICG even during maximum exercise.     

Does texture analysis improve breast ultrasound precision?

OBJECTIVE: To evaluate the possibility of distinguishing between benign and malignant breast tumors using a computer-aided evaluation of echogenicity and echostructure of ultrasound findings at certain focal points. STUDY DESIGN: The ultrasound images from 89 cases of breast tumor were documented under standardized conditions using a linear array machine and 7.5 MHz transducer. In each sonographic image, the maximum area of the 'region of interest' of the tumor was marked and then subjected to consecutive statistical analysis and correlation with the histological findings. For evaluation of tumor status eight parameters of first and second order texture statistics (gray level histogram, Fourier analysis, co-occurrence matrix) were applied. RESULTS: Benign tumors were clearly distinguished from carcinomas in the evaluation of the co-occurrence matrix and the Fourier analysis on the basis of Wilcoxon and Student t-test (P < 0.05) but not in the gray level histogram. Using logistic regression a sensitivity of 73.8% and a specificity of 54.2% were obtained. A statistically significant difference between benign tumors and moderately differentiated together with poorly differentiated carcinomas could be demonstrated. CONCLUSION: This study concludes that texture analysis appears to distinguish between benign and most malignant tumors. A computer texture analyzing system is able to improve the subjective assessment of ultrasound images of the breast but can not replace it. Where the limits of subjective assessment of a given tumor are reached, computerized texture analysis will provide additional information in the differentiation of benign from malignant findings.     

Results of respiratory mechanics analysis in the critically ill depend on the method employed

OBJECTIVE: To compare the measurements of total resistance and dynamic elastance determined by different techniques of respiratory mechanics analysis based on the time or frequency domains. DESIGN: Prospective study. SETTING: A 12-bed medical and surgical intensive care unit in a 700-bed university hospital. PATIENTS: Eighteen sedoparalyzed patients who needed controlled mechanical ventilation for acute or chronic acute respiratory failure. MEASUREMENTS: The total resistance and dynamic elastance in the time domain were determined by the occlusion technique and by multiple linear regression. The Fourier analysis was used to study the impedance of the respiratory system for elastance and resistance values in the frequency domain. RESULTS: The ANOVA analysis of the elastance variable showed no statistical differences (Ef: 41.4+/-19.0 cmH(2)O/l, Emlr: 40.8+/-17.2 cmH(2)O/l Edyn,occ: 39.5+/-14.0 cmH(2)O/l; ns) and the correlation was very good (r=0.8-0.9). The total resistances were less with multiple linear regression (13.5+/-9.3 cmH(2)O/l per s, p<0.05) than Rmax (17.0+/-11.9 cmH(2)O/l per s) or Rf (17.6+/-10.2 cmH(2)O/l per s). There were no differences between Rmax and Rf (p=0.7) and the correlation between resistances was 0.7-0.9. The agreement analysis for variables without statistical differences showed the following limits: Edyn,occ-f: -17 to 13 cmH(2)O/l; Edyn,occ-mlr: -12 to 9 cmH(2)O/l; Emlr-f: -6 to 8 cmH(2)O/l; Rmax-f: -18 to 19 cmH(2)O/l per s. This last range was related to the autoPEEP level (r=0.9). CONCLUSION: The wide agreement limits show that respiratory mechanics analysis is very dependent on the measurement technique used, particularly for resistance, perhaps due to the higher dependence on frequency.     

壳聚糖/介孔生物活性玻璃多孔膜的制备和表征

背景:壳聚糖和介孔生物玻璃都具有良好的生物相容性和止血性能,但壳聚糖止血作用有限,介孔生物玻璃粉体方式止血,给应用带来不便。目的:制备壳聚糖/介孔生物玻璃复合多孔膜并检测材料的性能。方法:采用冷冻干燥法制备壳聚糖/介孔生物玻璃复合多孔膜。结果与结论:通过冷冻干燥法可以实现壳聚糖和介孔生物玻璃的均匀复合。制备的复合多孔膜的孔隙分布较均匀;多孔膜具有很好的吸水性,吸水率的大小与壳聚糖和介孔生物玻璃质量比相关;多孔膜的孔隙率高。     

Echocardiographic quantification of left ventricular asynergy in coronary artery disease with Fourier phase imaging

Background: Visual evaluation of wall motion is subjective and may be difficult in patients with impaired left ventricular function. Current algorithms used to analyze wall motion usually neglect motion asynchrony that may be profoundly altered in coronary artery disease. This study was to investigate whether the extent of left ventricular asynergy can be used to quantify the severity of regional myocardial dysfunction by the use of Fourier phase imaging. Methods: Echocardiographic cine loops of 21 patients with ischemic cardiomyopathy (EF 40%) were mathematically transformed using a first-harmonic Fourier algorithm displaying the sequence of wall motion as phase angles in parametric images and regional phase histograms. Segmental fractional area shortening (FAC) and qualitative assessment of regional wall motion based on visual inspection served as reference method. Results: There was an inverse linear relationship between FAC and phase angles (r = –0.75, p < 0.01). Normal endocardial motion yielded low phase angles (mean 16 ± 15° SD). With an increase in wall motion abnormalities, phase angles were progressively delayed by 56 ± 38° in hypokinetic, by 88 ± 38° in akinetic, and by 143 ± 33° (p < 0.001) in dyskinetic segments. Conclusions: These results demonstrate that left ventricular asynchrony is an indicator of regional myocardial dysfunction in coronary artery disease. Echocardiographic Fourier phase imaging can be used to quantify wall motion displaying contraction sequence in a simple and objective format.     

Noninvasive temperature estimation using sonographic digital images.

OBJECTIVE: The purpose of this study was to develop and evaluate a speckle-tracking method for tissue temperature estimation due to heating fields using digital sonographic images. METHODS: The temperature change estimation method is based on the thermal dependence of the ultrasound speed and the thermal expansion of the medium. Local changes in the speed of sound due to changes in the temperature produce apparent displacement of the scatterers, and the expansion introduces physical displacement. In our study, a new technique has been introduced in which the axial physical displacements were obtained from digital sonographic images. The axial speckle pattern displacement was determined with a cross-correlation algorithm. The displacement data were then used for computing the temperature changes. To monitor the temperature in real time, the computational time was decreased by restricting the search region in the cross-correlation algorithm and carrying out the cross-correlation function in the frequency domain via a fast Fourier transform algorithm. RESULTS: Experiments were performed on tissue-mimicking phantoms. The imaging probe was a commercial linear array working at 10 MHz. In addition, the temperature changes during heating were measured invasively by negative temperature coefficient thermistors. There was good agreement between ultrasonic temperature estimations and invasive temperature measurements. CONCLUSIONS: The proposed method verifies the capability of the speckle-tracking algorithm for determining both the magnitude and direction of displacement. The average error was 0.2 degrees C; the maximum error was 0.53 degrees C; and the SD was 0.19 degrees C. Therefore, the proposed algorithm is capable of extracting the temperature information from sonographic digital images.     

Computerized evaluation of blood flow measurement indices using doppler ultrasound

The study involved computer-assisted analysis of Doppler blood flow signals from an in vitro experimental system utilizing a calibrated occlusive pulsatile pump, vinyl tubings of various dimensions, and human blood. The power spectra of these signals were obtained using the Fast Fourier Transform, and the peak and mean frequencies along with the first moments of the Fourier spectra around the zero-frequency axis were computed. These indices were evaluated using different flow rates and tubal dimensions. It was experimentally verified that the first moment provided a more linear measure of volume flow rate than that estimated by peak and mean velocities. Although the first moment cannot measure the absolute flow rate, it may serve as a better indicator of relative flow changes than the other two indices.     

丝素/褐藻多糖硫酸酯复合膜的理化性质

背景:丝素膜α-螺旋的结构是水溶性的而且不稳定,不能直接作为医用材料,具而β-折叠构象更为稳定.目的:利用褐藻多糖硫酸酯导致丝素膜的构象转变来制备β折叠构象的丝素膜,观察膜的理化件质.设计、时间及地点:生物材料复合膜的理化性质观察实验,于2003-11/2006-08在中科院北京化学所、承德石油高等专科学校化学实验中心完成.材料:褐藻多糖硫酸酯,从海带中提取,在承德石油高等专科学校化学实验中心完成,蚕丝购于中国进出口公司.方法:将丝素溶液和褐藻多糖硫酸酯的水溶液按一定比例混合,静置脱泡后,注入聚乙烯模具内,于25℃.相对湿度65%的环境干燥成膜,当褐藻多糖硫酸酯含量≤20%时,成膜性较好.根据复合膜中褐藻多糖硫酸酯和丝素的质量比0∶100、5∶95、10∶90、20∶80、100∶0,将膜分别标记.主要观察指标:采用红外光谱、X射线衍射、热失重分析表征观察制成膜的理化性质.结果:红外光谱、X射线衍射结果表明,由于褐藻多糖硫酸酯的引入,促使了丝素β-折替构象的形成.丝素从无规线团转变为β-折叠构象归结于丝素与褐藻多糖硫酸酯之间存在着氢键的相互作用.热失重分析表明,具有β-折叠结晶结构的丝素复合膜热稳定性要比无定形丝素膜高.结论:利用褐藻多糖硫酸酯导致丝素膜的构象转变来制备β折叠构象的丝素膜,构象的转变可通过红外光谱、X射线衍射证实.具有β-折叠结晶结构的丝素膜的热稳定性要比无定形丝素膜高.