Data processing of stress ECGs using discrete cosine transform

The signal processing steps for the analysis of stress ECGs are aimed at improving the signal to noise ratio (SNR) of recordings in addition to eliminating artifacts due to respiration, movement of arms, etc. In this paper, we bring forth two important applications of the discrete cosine transform (DCT) for noise suppression and removal of baseline wander. The noise suppression algorithm has been framed on the basis of a two step procedure involving singular value decomposition (SVD) smoothing operation in transform domain followed by that in time domain. The mean square error (MSE) resulting from the first step is shown to effectively follow the trend obtained by using an ideal Wiener filter using DCT. In the second step, the degree of closeness to the minimum mean square error (MMSE) of the ideal Wiener filter is improved by subjecting the filtered outputs to a second SVD smoothing operation in time domain. Application of this scheme to noisy records has resulted in near perfect reproduction of the original noise free ECG without significant alterations in its morphological features.     

Compression of ECG signals by optimized quantization of discrete cosine transform coefficients.

This paper presents an ECG compressor based on optimized quantization of Discrete Cosine Transform (DCT) coefficients. The ECG to be compressed is partitioned in blocks of fixed size, and each DCT block is quantized using a quantization vector and a threshold vector that are specifically defined for each signal. These vectors are defined, via Lagrange multipliers, so that the estimated entropy is minimized for a given distortion in the reconstructed signal. The optimization method presented in this paper is an adaptation for ECG of a technique previously used for image compression. In the last step of the compressor here proposed, the quantized coefficients are coded by an arithmetic coder. The Percent Root-Mean-Square Difference (PRD) was adopted as a measure of the distortion introduced by the compressor. To assess the performance of the proposed compressor, 2-minute sections of all 96 records of the MIT-BIH Arrhythmia Database were compressed at different PRD values, and the corresponding compression ratios were computed. We also present traces of test signals before and after the compression/decompression process. The results show that the proposed method achieves good compression ratios (CR) with excellent reconstruction quality. An average CR of 9.3:1 is achieved for PRD equal to 2.5%. Experiments with ECG records used in other results from the literature revealed that the proposed method compares favorably with various classical and state-of-the-art ECG compressors.     

On lossy transform compression of ECG signals with reference to deformation of their parameter values

Electrocardiogram (ECG) signals are the most prominent biomedical signal type used in clinical medicine. Their compression is important and widely researched in the medical informatics community. In the previous literature compression efficacy has been investigated only in the context of how much known or developed methods reduced the storage required by compressed forms of original ECG signals. Sometimes statistical signal evaluations based on, for example, root mean square error were studied. In previous research we developed a refined method for signal compression and tested it jointly with several known techniques for other biomedical signals. Our method of so-called successive approximation quantization used with wavelets was one of the most successful in those tests. In this paper, we studied to what extent these lossy compression methods altered values of medical parameters (medical information) computed from signals. Since the methods are lossy, some information is lost due to the compression when a high enough compression ratio is reached. We found that ECG signals sampled at 400 Hz could be compressed to one fourth of their original storage space, but the values of their medical parameters changed less than 5% due to compression, which indicates reliable results.     

On lossy transform compression of ECG signals with reference to deformation of their parameter values

A prototype computerized system for automatic data collection from multi-vendor infusion devices was constructed. The system was specifically designed around the needs of the critical care environment, and a survey of clinical staff was conducted to determine the functional requirements. Hardware, software and system configuration was based on the Medical Information Bus IEEE 1073 standard for medical device data communications. The infusion devices were configured into device communication controllers (DCC), which were polled at 0.25 Hz by a PC configured as a bedside communication controller (BCC). The system stores data samples after intervals of 1 ml of drug delivery and following any changes in the infusion rate. The system demonstrated significant opportunities for supporting clinical care and for the management of health care technology.     

Accurate identification of waveform of evoked potentials by component decomposition using discrete cosine transform modeling.

This study introduces a method for accurate identification of the waveform of the evoked potentials by decomposing the component responses. The decomposition was achieved by zero-pole modeling of the evoked potentials in the discrete cosine transform (DCT) domain. It was found that the DCT coefficients of a component response in the evoked potentials could be modeled sufficiently by a second order transfer function in the DCT domain. The decomposition of the component responses was approached by using partial expansion of the estimated model for the evoked potentials, and the effectiveness of the decomposition method was evaluated both qualitatively and quantitatively. Because of the overlap of the different component responses, the proposed method enables an accurate identification of the evoked potentials, which is useful for clinical and neurophysiological investigations.     

基于离散余弦变换的空间归一化方法

在分析功能磁共振成像(fMRI)试验数据时,为了在不同被试之间比较实验结果、增加实验数据的可靠性,需要对所有被试的脑解剖学影像在三维空间空间内归一到一个共同的标准模板影像,使得它们之间的解剖结构差异达到最小。过去被广泛使用的基于体素的自动化归一化方法虽然很精确,但很耗时。本文章发展了可以在高速度下达到高精确度归一的基于体素的3D归一化方法,该方法采用了余弦离散变换(DCT),克服了原来方法需要较长计算时间的缺点,在现有普通微机上2分钟之内完成对128×128×30体素尺寸下的三维脑图像归一化,文章对方法和结果进行了讨论。     

Influence of lossy compression on eye movement signals

Eye movements considered in our research are physiological signals that are measured in otoneurological balance tests. They are also investigated in other areas of medicine and in psychology. When great amounts of signals are measured in clinical and research work, signal compression is of great use in storing measurements for later investigations. In this research we assessed the influence of lossy compression on medically interesting parameter values that are computed from eye movement signals. We found that high compression ratios with bit rates lower than 1.5 bits per sample on signals with an original resolution of 13 bits per sample produced results without significant changes to the medical parameters values.     

A hybrid ECG compression algorithm based on singular value decomposition and discrete wavelet transform

Increasing use of computerized ECG processing systems requires effective electrocardiogram (ECG) data compression techniques which aim to enlarge storage capacity and improve data transmission over phone and internet lines. This paper presents a compression technique for ECG signals using the singular value decomposition (SVD) combined with discrete wavelet transform (DWT). The central idea is to transform the ECG signal to a rectangular matrix, compute the SVD, and then discard small singular values of the matrix. The resulting compressed matrix is wavelet transformed, thresholded and coded to increase the compression ratio. The number of singular values and the threshold level adopted are based on the percentage root mean square difference (PRD) and the compression ratio required. The technique has been tested on ECG signals obtained from MIT-BIH arrhythmia database. The results showed that data reduction with high signal fidelity can thus be achieved with average data compression ratio of 25.2:1 and average PRD of 3.14. Comparison between the obtained results and recently published results show that the proposed technique gives better performance.     

A hybrid ECG compression algorithm based on singular value decomposition and discrete wavelet transform

Increasing use of computerized ECG processing systems requires effective electrocardiogram (ECG) data compression techniques which aim to enlarge storage capacity and improve data transmission over phone and internet lines. This paper presents a compression technique for ECG signals using the singular value decomposition (SVD) combined with discrete wavelet transform (DWT). The central idea is to transform the ECG signal to a rectangular matrix, compute the SVD, and then discard small singular values of the matrix. The resulting compressed matrix is wavelet transformed, thresholded and coded to increase the compression ratio. The number of singular values and the threshold level adopted are based on the percentage root mean square difference (PRD) and the compression ratio required. The technique has been tested on ECG signals obtained from MIT-BIH arrhythmia database. The results showed that data reduction with high signal fidelity can thus be achieved with average data compression ratio of 25.2:1 and average PRD of 3.14. Comparison between the obtained results and recently published results show that the proposed technique gives better performance.     

High efficient ECG compression based on reversible round-off non-recursive 1-D discrete periodized wavelet transform

Error propagation and word-length-growth are two intrinsic effects influencing the performance of wavelet-based ECG data compression methods. To overcome these influences, a non-recursive 1-D discrete periodized wavelet transform (1-D NRDPWT) and a reversible round-off linear transformation (RROLT) theorem are developed. The 1-D NRDPWT can resist truncation error propagation in decomposition processes. By suppressing the word- length-growth effect, RROLT theorem enables the 1-D NRDPWT process to obtain reversible octave coefficients with minimum dynamic range (MDR). A non-linear quantization algorithm with high compression ratio (CR) is also developed. This algorithm supplies high and low octave coefficients with small and large decimal quantization scales, respectively. Evaluation is based on the percentage root-mean-square difference (PRD) performance measure, the maximum amplitude error (MAE), and visual inspection of the reconstructed signals. By using the MIT-BIH arrhythmia database, the experimental results show that this new approach can obtain a superior compression performance, particularly in high CR situations.     

高粘度与低粘度骨水泥PVP治疗骨质疏松性椎体压缩骨折疗效及安全性分析

目的对比较经皮椎体成形术(PVP)中使用高粘度骨水泥与低粘度骨水泥治疗骨质疏松性椎体压缩骨折(OVCF)的临床疗效和安全性。方法将68例OVCF行PVP治疗的患者分为高粘度组与低粘度组,分别采用高粘度骨水泥与低粘度骨水泥修复,比较两组患者疼痛缓解(VAS)、脊柱功能改善情况(ODI)、骨水泥渗漏发生率、术后骨水泥肺栓塞发生率及术后邻近椎体骨折发生率情况。结果末次随访,两组VAS、ODI评分均较术前改善,但高粘度组较低粘度组改善更加明显,差异均有统计学意义(0.01)。高粘度组骨水泥渗漏发生为2.9%,明显低于低粘度组(20.6%),差异有统计学意义(x~2=5.100,0.05);高粘度组术后骨水泥肺栓塞发生率为0,明显低于低粘度组(11.8%),差异有统计学意义(x~2=4.250,0.05);高粘度组术后邻近椎体骨折发生率为0,明显低于低粘度组术后邻近椎体骨折发生率(14.7%),差异有统计学意义(x~2=5.397,0.05)。结论经皮椎体成形术中使用高粘度骨水泥疗效显著,术后并发症少。     

PKP微创治疗骨质疏松性胸腰椎压缩性骨折的疗效分析

目的探讨骨质疏松性胸腰椎压缩性骨折经球囊扩张椎体后凸成形术(PKP)治疗后的临床效果及PKP技术的安全性。方法对抚顺市中心医院骨科2011年4月~2013年2月,应用PKP技术治疗40例骨质疏松性胸腰椎压缩骨折的患者进行回顾分析。其中患者中男8例,女32例,伤椎共有43个。分析患者手术前后的临床资料和影像学资料,比较手术前后伤椎前缘高度、脊柱后凸Cobb角、疼痛视觉模拟评分(VAS)、Oswesty功能障碍指数(ODI)以及下腰痛评分(JOA),最终进行数据分析比较。结果所有患者的手术都顺利进行,术后腰背部疼痛的症状得到明显缓解或消失,未出现手术并发症;术后24h VAS和ODI评分低于术前评分,而JOA评分高于术前评分;术后24h伤椎前缘高度高于术前,而Cobb角则低于术前(0.05)。结论 PKP技术治疗骨质疏松性胸腰椎压缩骨折安全而有效。     

医学图像无损压缩与有损压缩技术的进展

本文对医学图像无损压缩和有损压缩的概念和应用进行了分析比较 ,并简要介绍了几种近年来发展的图像无损压缩方法 ,重点介绍了有损压缩中的小波图像压缩技术和分形图像压缩技术。在医学图像的压缩中 ,通过有效地结合无损压缩和有损压缩技术 ,可以在得到医学要求的图像保真度的前提上 ,达到较高的压缩比     

高黏度骨水泥与传统骨水泥治疗骨质疏松性椎体压缩性骨折的疗效比较

目的比较高黏度骨水泥与传统聚甲基丙烯酸甲酯(PMMA)骨水泥治疗骨质疏松性椎体压缩性骨折的疗效,探讨高黏度骨水泥在临床应用中的优势。方法选择2009年7月~2013年7月治疗并获得随访160例骨质疏松性椎体压缩性骨折患者,其中男性64例,女性96例;年龄61~88岁,平均年龄69.1岁。分高黏度骨水泥组[91例(112个椎体)]和传统骨水泥组[69例(86个椎体)]。高黏度骨水泥组,采用以色列Disc-O-Tech公司Confidence骨水泥,施行经皮椎体成形术(PVP);传统骨水泥组,采用PMMA骨水泥,施行PVP。术后对比两组患者视觉疼痛模拟评分(VAS)、责任椎Cobb角的恢复情况及术后骨水泥渗漏情况,并随访观察。结果高黏度骨水泥组与传统骨水泥组VAS评分(1.5±0.8vs1.4±0.9)比较差异无统计学意义(P0.05);高黏度骨水泥组Cobb角恢复优于传统骨水泥组(13.6°±3.1°vs 19.8°±3.0°),差异有统计学意义(P0.05);高黏度骨水泥组渗漏率远低于传统骨水泥组(19.6%vs 41.9%),差异有统计学意义(P0.05)。所有患者术后获得3~48个月(平均16个月)随访,其中3例出现神经根症状,所有患者未出现感染、肺栓塞等并发症。结论高黏度骨水泥与传统PMMA骨水泥相比,在纠正椎体Cobb角及降低骨水泥渗漏发生率方面效果更佳,明显提高了PVP的安全性及有效性。     

骨水泥增强技术治疗骨质疏松性椎体压缩骨折的并发症

背景：椎体成形和椎体后凸成形是治疗骨质疏松性椎体压缩骨折的微创方法。 目的：评价椎体成形和椎体后凸成形治疗骨质疏松性椎体压缩骨折的安全性。 方法：计算机检索Medline、EMBASE、中国知网、维普数据库、万方数据库1990年1月至2012年1月有关椎体成形和椎体后凸成形治疗骨质疏松性椎体压缩骨折并发症的文献。 结果与结论：检索出62篇文献,8 993例患者。椎体成形和椎体后凸成形治疗的穿刺手术并发症与其他并发症差异无显著性意义。椎体成形治疗的骨水泥渗漏率、新发骨折率高于椎体后凸成形治疗(P=0.000 06,P=0.02);二者的相邻椎体骨折率差异无显著性意义。表明椎体成形和椎体后凸成形治疗骨质疏松性椎体压缩骨折的严重并发症非常低,两种治疗方式相邻椎体骨折率、穿刺手术并发症及其他并发症无明显差异,但椎体后凸成形治疗后骨水泥渗漏、新发骨折率低于椎体成形治疗,此次系统评价结果尚需要大样本前瞻性研究证实。     

聚甲基丙烯酸甲酯骨水泥椎体成形修复老年骨质疏松性椎体压缩骨折

背景：经皮穿刺椎体成形骨水泥注射治疗具有微创、时间短、可有效恢复椎体高度、防止椎体进一步塌陷、止痛效果明显等优点,成为治疗老年骨质疏松性压缩骨折的有效方法。 目的：观察老年骨质疏松性压缩骨折经皮椎体成形骨水泥注射的治疗效果。 方法：纳入62例骨质疏松性胸腰椎压缩骨折患者,其中男22例,女40例,年龄55-92岁,累及86椎体,均在C形臂X射线机透视下行经皮椎体成形聚甲基丙烯酸甲酯骨水泥注射治疗。治疗后随访12-36个月,对比治疗前后的目测类比评分、Cobb角与Oswestry功能障碍指数评分。 结果与结论：治疗后随访12-36个月,11例出现并发症,其中骨水泥渗漏7例,临近椎体骨折2例,骨水泥拖尾1例,疼痛缓解不理想1例;末次随访的Cobb角、目测类比评分、Oswestry功能障碍指数评分均较治疗前显著改善(P < 0.05)。表明椎体成形聚甲基丙烯酸甲酯骨水泥注射治疗老年骨质疏松性压缩骨折,不仅能恢复伤椎外形、减少后凸畸形、重建脊柱稳定性,而且能明显减轻骨折所致疼痛,改善患者生活质量,短中期疗效肯定。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

改良小剂量骨水泥椎体成形治疗急性骨质疏松性压缩骨折

背景：经皮椎体成形技术已成为临床治疗脊柱骨质疏松性骨折的有效手段,但存在骨水泥渗漏风险。 目的：探讨改良小剂量骨水泥椎体成形治疗急性骨质疏松性压缩骨折的效果。 方法：选择2008年9月至2011年2月收治的32例骨质疏松性压缩骨折患者进行经皮椎体成形治疗,将患者按照骨水泥注入量分为改良小剂量组和常规剂量组,改良小剂量组骨水泥注入量为2-4 mL,常规剂量组骨水泥注入量为4-6 mL,将同期入院急性骨质疏松压缩骨折因手术禁忌无法进行椎体成形治疗的患者列为对照组。 结果与结论：改良小剂量组和常规剂量组末次随访时疼痛缓解及椎体高度恢复率明显优于对照组(P < 0.05)。改良小剂量组骨水泥渗漏率、末次随访时相邻节段椎体继发骨折发生率明显低于常规剂量组(P < 0.05),末次随访时椎体高度恢复率低于常规剂量组(P < 0.05)。说明椎体成形治疗操作过程中,应用改良小剂量骨水泥方法在达到满意临床效果同时,可有效减少骨水泥渗漏、相邻节段继发骨折等并发症发生率。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

聚甲基丙烯酸甲酯骨水泥椎体成形治疗高龄骨质疏松性胸腰椎骨折

背景：目前经皮椎体成形在临床上治疗骨质疏松性椎体骨折较为广泛应用,而针对高龄患者(65岁以上)在手术的时候存在患者基础病情的限制,关于此方面的细化研究逐渐引起临床医师的重视。目的：对比分析骨水泥椎体成形治疗和常规体位复位保守治疗高龄骨质疏松性胸腰椎骨折的临床疗效。方法：对24例高龄骨质疏松性胸腰椎骨折患者采用自愿的原则分为骨水泥治疗组和保守治疗组,各12例,分别采取聚甲基丙烯酸甲酯骨水泥椎体成形和常规体位复位保守治疗。结果与结论：与保守治疗组相比,骨水泥治疗组患者目测类比评分、Oswesty功能障碍指数和椎体后凸Cobb角明显降低,而伤椎前缘压缩度增加。提示针对高龄骨质疏松性椎体骨折患者,争取稳定病情后行脊柱微创治疗,有利于改善患者的愈合和提高生活质量。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

骨质疏松性椎体压缩骨折椎体成形：漏诊、重度椎体压缩、骨水泥渗漏及再发骨折225例分析

BACKGROUND: Percutaneous vertebroplasty for treatment of osteoporotic vertebral compression fractures has achieved very good results.     

骨折合并脑损伤对骨愈合和骨代谢的影响

背景：骨折周围神经损伤能够有效抑制破骨细胞活动,促进骨折早期愈合。目的：观察了大鼠肢体骨折合并脑损伤对骨密度、骨微结构、骨生物力学特征和骨代谢影响。 方法：63只大鼠随机分为假手术组、单纯骨折组和脑损伤合并骨折组。在术后3周、6周和3个月分批麻醉处死动物保存骨骼和血清标本,检测骨密度、骨微结构和生物力学性能以及血清Ⅰ型胶原氨基末端肽和骨钙素水平的变化。 结果与结论：与单纯骨折组相比,在造模3周和6周后,脑损伤合并骨折组胫骨近端的骨密度、松质骨微结构骨体积分数、骨小梁厚度、胫骨皮质骨截面总面积和骨髓腔面积、胫骨极限载荷和极限应力、血清原氨基末端肽和骨钙素水平均显著增高(P < 0.05),造模后3个月,3组间上述指标均差异无显著性意义。结果证实,脑损伤可增加骨折局部骨密度,改善骨微结构,提高生物力学性能,以此促进骨折局部的骨愈合和骨代谢。中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程