基于子波变换及其"WD倒谱"法的肾组织超声散射微结构特征分析

本文提出了一种对超声散射信号分析的新方法--"WD倒谱"法,并分别利用该方法和子波变换法对人体正常肾和肾肿瘤组织的超声回波信号进行了分析,对软组织中散射子的平均间距进行了估计,结果表明:两种肾组织散射子的平均间距明显不同;子波变换及其"WD倒谱"能很好地反映软组织的微观结构特征,初步说明两种方法是软组织回波信号分析与软组织散射子平均间距定征的有效方法,但"WD倒谱"提高了子波变换对平均间距估计的分辨率.     

基于子波变换及其“WD倒谱”法的肾组织超声散射微结 …

本文提出了一种对超声散射信号分析的新方法－－“ＷＤ倒谱”法,并分别利用该方法和子波变换法对人体正常肾和肾肿瘤组织的超声回波信号进行了分析,对软组织中散射子的平均间距进行了估计,结果表明：两种肾组织散射子的平均间距明显不同;子波谱换及其“ＷＤ倒谱”能很即地反映软组织的微观结构特征,初步说明两种方法是软组织回波信号分析与软组织散射子平均间距定征的有效方法,但“ＷＤ倒谱”提高了子波变换对平均间距估计的分     

Chirp-Z变换频谱细化倒谱定征生物软组织散射子平均间距的研究

用信号处理方法,提取生物软组织声散射特征,从而对生物组是进行鉴别,是超声医学的基础研究一直关注的重要课题,生物软组织的超声散射主要由组织内部的散射子引起,散射子平均间距与组织的微结构特征相关。我们分析和总结了一般基于FFT倒谱,AR倒谱等算法波动性较大、分辨率不高产生的原因,提出利用Chirp-Z变换频谱得到细化倒谱,在超声检测中估计生物软组织散射子平均间距及其变化的新方法,并利用该方法对仿体和生物软组织的回波信号进行了分析。结果表明:该方法是软组织的超声散射信号分析和散射子平均间距定征的一种有效方法。     

生物组织散射元平均间距估计的方法及其应用

超声背向散射信号基本上是一个随机信号，它的统计量中蕴含着有关组织散射元的数目，平均间距和散元散射截面等方面的信息。生物组织散射元平均间距是描述生物组织微观结构和超声散射特性和重要参数。     

超声换能器焦区内软组织背散射信号频移与散射子粒径的相关性研究

基于超声波在生物软组织中的传播机理,研究聚焦超声换能器焦区内软组织超声背散射信号中心频率的偏移量与组织超声特征散射子粒径的相关性.通过计算机模拟实验,探讨了组织的衰减系数和超声特征散射子的数浓度(单位体积内散射子的个数)以及换能器的中心频率、带宽和聚焦性等参数对频移量的影响.模拟结果表明,换能器焦区内软组织超声背散射信...     

基于简易反向滤波跟踪算法分析松质骨的微结构特征

平均散射元间距（MSS）已被众多研究者用于分析准规则组织的微结构特征，平均骨小梁间距（MTBS）是诊断骨质疏松症的重要参数之一。本研究提出一种基于简易反向滤波跟踪（SIFT）的算法，用于估计平均骨小梁间距。对计算机仿真信号和离体牛胫骨松质骨的超声背散射信号分别进行分析处理。实验结果表明，SIFT算法能简单而有效地减小测量系统和传播介质特性的干扰，并且在较强噪声存在的情况下，SIFT算法比AR倒谱法的估计结果更为精确。因此，SIFT算法可用于估计平均骨小梁间距，从而反映松质骨的微结构特征。     

估计骨小梁间距的信号处理方法

骨小梁间距是评价松质骨微结构状况的主要参数之一。介绍了基于超声背散射信号估计骨小梁平均间距的信号处理方法：倒谱分析法和奇异谱分析法以及谱自相关技术和二次变换处理方法等其它散射体元平均间距估计方法。对各种方法的优缺点进行了论述，提出了今后研究的一些建议。     

中性粒细胞分布数据序列小波变换研究

目的　研究小波分析结合复倒谱处理血膜中中性粒细胞分布数据信号的新方法及临床意义。方法　利用“虚拟盒计数法”方法采集血膜中的细胞分布数据信号 ,然后进行小波变换结合复倒谱分析方法处理。结果　提出血膜中细胞分布状态的“密集子”新概念。计算出小波变换复倒谱主极大值 ,并以此作为不同情况下血膜中中性粒细胞分布“密集子”间距的准确参数。结论　方法简单 ,能较好的反映血膜中细胞分布状态的微观组织结构特征 ,是血膜中细胞“密集子”表达定征的一种有效方法     

连体乳腺正常与病变组织微观结构变化的AR倒谱分析

乳腺组织微观结构的准周期性可以利用散射体平均间距来描述,本文利用ＡＲ倒谱方法对连体正常与病变乳腺组织的散射体平均间距进行了估计,得到了正常乳腺组织的散射体平均间距约为１２５±０２１ｍｍ,各类病变组织的平均间距较正常组织有明显的特异性,所得结果与乳腺组织的微观结构特征相符     

猪的软组织超声背向散射的初步研究

本文探讨了超声背向散射系数的测量原理,在远场测量的情况下推导出了由平均背向散射传递函数求平均背向散射系数的一般公式,报道了我们已建立的背向散射测量系统及利用此系统对一些动物软组织样品所作的测量结果。     

二维数字化超声软组织应变成像系统的研制

利用超声散射回波测量生物组织在静态压缩情况下弹性系数的超声弹性成像方法得到了很大的发展.利用国产高速数据采集卡以及商业线阵B型超声诊断仪,建立了一套二维数字化超声软组织应变成像系统.应用这一系统获得了数字化的射频组织超声散射回波信号,并对组织内的应变分布进行成像.实验结果表明,该应变成像系统在获得传统B型超声图像的同时,可以获得组织内部的应变分布图像,从而获取在B超图像上无法得到的组织弹性变化.这一系统的研制成功,不仅为超声弹性成像技术在医学临床上的应用研究打下了基础,同时也为扩宽普通商业B超的应用范围提供了途径.     

利用超声回波特征无创监测微波热疗的实验研究

寻找一种合适的方法区别正常组织与坏死组织,是癌微波热疗应用中所面临的重要难题.本研究探讨微波热疗过程中组织回波时域的变化,以寻找合适的参数,无创监测热疗组织状态的变化.在原理分析的基础上设计了实验系统,采用微波介入的加热方式,采集超声回波信号,对变性区域做回波幅值时域积分、幅值平方时域积分(能量)和损伤数字减影积分,并分析它们的变化趋势.实验结果表明:生物组织回波的不同方式积分值与加热过程中的组织变性具有相关性,微波热疗前后组织回波的幅值、能量、不均匀性均有增大的趋势.利用超声背向散射积分和反应不均匀度的参数进行监测,可得到较理想的结果.     

Estimation of tissue parameters derived from reflected ultrasound

We propose a method of estimating two tissue parameters, that is, the reflection coefficient and attenuation coefficient from the reflected ultrasound for the purpose of improving the resolution of ultrasonic images and obtaining information on tissue characterization. The reflection coefficient is estimated by deconvolution technique using Kalman filter taking into account the distortion of the propagating pulse due to the frequency-dependent attenuation. The attenuation is estimated by adaptive processings based upon the criterion function calculated using estimates of the reflection coefficient. Simulated signals are used to investigate the ability of this method. Additionally, actual reflected signals from soft tissues are processed by the method. The results show that the method can be applied in clinical cases.     

Long-term ECG signal feature extraction

This paper proposes a cepstrum coefficient method applying the dynamic time warping technique to extract the feature vectors from long-term ECG signals. Utilizing this method, one can identify the characteristics hidden in an ECG signal; and then classify the signal as well as diagnose the abnormalities. To evaluate this method, the Normal and PACED BEAT data from the MIT/BIH database are used. The results show that the proposed method successfully extracts the corresponding feature vectors, distinguishes the difference and classifies both signals.     

Long-term ECG signal feature extraction

This paper proposes a cepstrum coefficient method applying the dynamic time warping technique to extract the feature vectors from long-term ECG signals. Utilizing this method, one can identify the characteristics hidden in an ECG signal; and then classify the signal as well as diagnose the abnormalities. To evaluate this method, the Normal and PACED BEAT data from the MIT/BIH database are used. The results show that the proposed method successfully extracts the corresponding feature vectors, distinguishes the difference and classifies both signals.     

4193delC, a common mutation causing Wilson's disease in Saudi Arabia: rapid molecular screening of patients and carriers.

BACKGROUND: In patients with Wilson's disease (WD), an autosomal recessive disorder, toxic accumulation of copper results in fatal liver disease and irreversible neuronal degeneration. ATP7B, the gene mutated in WD, contains 21 exons and encodes a copper transporting ATPase. A novel disease causing mutation (4193delC) in exon 21 of the ATP7B gene has previously been detected by heteroduplex analysis and DNA sequencing. AIMS: To screen for the above mutation in patients with WD and carriers using an amplification refractory mutation system (ARMS). METHODS: ARMS was used to screen for the 4193delC mutation in 30 patients with WD and their relatives. RESULTS: A homozygous mutation was detected in 16 of 30 patients with WD. CONCLUSIONS: This polymerase chain reaction based method, which has been known for years, is a simple, inexpensive, and rapid method for screening common and specific mutations in patients with WD and carriers.     

Value of histochemical stains for copper in the diagnosis of Wilson's disease

Aims : The histochemical demonstration of hepatic copper is important in the diagnosis of Wilson's disease (WD). Conflicting results have been published with regard to the ability of different histochemical methods to demonstrate copper storage in the liver. Therefore, we evaluated the diagnostic value of three available histochemical methods in a large series of patients affected by WD.  

Methods and results

Seventy-nine consecutive liver needle biopsies, from 74 patients, 39 males and 35 females, aged 4–60 years (mean age 28.5 years) were stained with orcein, rhodanine and using Timm's method. On the basis of the histological picture, liver biopsies were subdivided into three groups: group A, steatosis; group B, interface hepatitis; group C, chronic hepatitis with bridging fibrosis and/or cirrhosis. In group A, 30.4% of the cases were positive using Timm's method, vs 13.2% using the rhodanine and 17.5% using the orcein method. In group B, Timm's method was positive in 40.1% while rhodanine and orcein showed positivity in 26.7%. In group C, the Timm's method stained 58.6%, rhodanine 36.6% and orcein 29.3% positively.  

Conclusions

Our data show that: (1) Timm's silver stain is the most sensitive method for the demonstration of copper in all cases of WD; (2) rhodanine and orcein have minor value in the diagnosis of WD, especially in the early stages of the disease; (3) to increase the diagnostic value of histochemistry for copper multiple histochemical stains in serial sections are required; and (4) although hepatic copper concentration is highest in the early stages of WD, the histochemical demonstration fails in a large number of cases.