迭代重建技术在CT检查青年骶髂关节中的应用

目的探讨自适应统计迭代重建(ASIR)技术对青年患者骶髂关节CT图像噪声和质量的影响。方法应用宝石能谱CT(Discovery CT 750HD)对30例青年患者行骶髂关节CT螺旋扫描。分别采用传统滤过反投影法(FBP组)和ASIR算法对原始投影数据进行重建,后者以10%为间隔在10%～100%间重建10组图像(ASIR组)。比较不同重建图像在同一层面的图像标准差(SD值)及平均CT值,并计算SNR和对比噪声比(CNR)。采用Likert 5分制评估图像质量,通过Kappa方法评价观察者间的一致性。对FBP图像和10组ASIR图像测量结果进行方差分析,对图像噪声和ASIR取值进行相关分析。结果客观分析:①10%～100%ASIR图像的SD值小于FBP组(P<0.05),对应图像的SD值分别降低5.79%、11.44%、16.92%、21.78%、26.85%、32.12%、37.45%、40.32%、43.89%、47.27%;而图像CT值差异无统计学意义;②30%～100%ASIR各组图像SNR值高于FBP组(P均<0.05);③40%～100%ASIR各组图像CNR值高于FBP组(P均<0.05);④40%、50%、60%ASIR各组间SD值、SNR值及CNR值差异均无统计学意义(P>0.05);⑤图像噪声与ASIR百分比呈负相关(r=-0.613,P<0.05)。主观分析:①图像评定结果的观察者间一致性中等(Kappa=0.483);②30%～70%ASIR图像评分值高于FBP组(P<0.05),其中40%、50%、60%ASIR图像评分较高。结论与FBP相比,ASIR技术可降低青年骶髂关节CT噪声,有效改善图像质量;ASIR取值为40%～60%时可获得最佳图像质量。     

耳塞型耳机对青年听力的影响

为探讨使用耳塞型耳机对青年听力的影响 ,采用FONIXAFA -18型临床诊断听力计在隔声室对 10 2例2 0 4耳不同程度使用耳塞型耳机的健康青年和 38例 76耳不使用者做纯音听阈测试。结果显示 :使用耳塞型耳机者全频段听阈均有提高 ,与非使用者相比有显著的统计学差异 (P <0 .0 0 1) ;且短时间使用者与长时间使用者之听阈除 2 5 0Hz外 ,其它频率均有差异 (P <0 .0 1)。提示 :使用耳塞型耳机可导致噪声性听力下降     

Fast and reliable QRS alignment technique for high-frequency analysis of signal-averaged ECG

The process of QRS alignment as required in signal-averaged ECG can impose serious limitations on the spectral range of the signal output. This effect depends basically on the particular alignment technique being used and on the level and type of noise present in the recorded ECG. In clinical studies where a wide-band (1000 Hz) ECG averager is required, the conventional QRS alignment technique, based on maximum coherence matching (MCM) with a template beat, may not perform consistently well. An alternative QRS alignment technique based on the accurate detection of a single fiducial point (SFP) in the bandpass filtered (3–30 Hz) QRS complex was developed. Using computer simulation methods, a comparative assessment of the frequency bandwidths (3 dB points) offered by both MCM and SFP techniques as a function of noise level (15–100 μ RMS) and type (EMG and 50 Hz interference), was carried out. The results of the comparative assessment indicated a better performance by the SFP technique in all cases of noise. Hence, the SFP technique would perform more reliably for high-frequency analysis of a noisy ECG, especially when 50 Hz interference is high. Furthermore, SFP is considerably faster than MCM (about four times) when implemented digitially, and its analogue realisation is feasible. The SFP technique is suitable for late-potential analysis in the signal-averaged ECG.     

Reproducible increases in blood pressure during intermittent noise exposure: underlying haemodynamic mechanisms specific to passive coping

Summary The purpose of the present study was to investigate the reproducibility of the increases in blood pressure found in our recent study on exposure to intermittent noise, to confirm the haemodynamic mechanism raising blood pressure (via an increase in peripheral vascular resistance expected to be specific to passive coping), and to assess baroreceptor cardiac reflex sensitivity in connection with the blood pressure elevation. A group of 16 young normotensive men participated in the experiment and underwent a 10-min intermittent exposure to pink noise at 100 dB (sound pressure level). The subjects also underwent three other stresses: a 1-min cold pressor test, a 3-min isometric handgrip and 3-min of mental arithmetic. The results indicated that blood pressure was elevated reproducibly for most of the noise exposure periods and that peripheral vascular resistance increased simultaneously, as expected. Baroreflex sensitivity was not suppressed. The results, as a whole, were in agreement with our recent findings for exposure to a similar type of noise and thus the reproducibility was corroborated. The mechanism raising blood pressure was similar in the cold pressor test. Conversely, during the isometric handgrip and mental arithmetic, blood pressure elevations were attributable mainly to increases in cardiac output. The implications of the opposing haemodynamic mechanisms raising blood pressure among the four stressful tasks have been discussed in relation to active versus passive coping required for each task. Differences in the magnitude of suppression observed in baroreflex sensitivity among the tasks have also been discussed in the context of defence reactions.     

强脉冲噪声暴露对豚鼠耳蜗Corti隧道中传出神经纤维损伤的定量观察

目的　探索爆震后豚鼠耳蜗 Corti隧道中传出神经纤维损伤情况。方法　复制强脉冲噪声致聋豚鼠模型 ,暴露后 3,2 1 d进行耳蜗乙酰胆碱脂酶染色、铺片 ,计算机辅助定量研究穿越耳蜗 Corti隧道中传出神经纤维。结果　暴露后穿越耳蜗 Corti隧道中传出神经纤维损伤主要发生在耳蜗第一回和第二回 ,暴露后各组耳蜗第一回、第二回每 0 .2 4mm穿越耳蜗 Corti隧道中传出神经纤维数分别为 :暴露后 3d组 (9.6± 4.2 )、(8.8± 3.4)根 ;暴露后 2 1 d组 (1 1 .4± 3.2 )、(1 0 .6± 2 .5 )根 ;而正常对照组(2 3.2± 3.2 )、(2 0 .7± 2 .9)根 ;两实验组与正常对照组间统计学差异有显著意义。结论　强脉冲噪声暴露后耳蜗 Corti隧道中传出神经纤维变性坏死     

Improved signal and reduced noise in neural recordings from close-spaced electrode arrays using independent component analysis as a preprocessor

Noise can greatly complicate the isolation of individual cell action potential waveforms for the sake of electrophysiological analysis. For an experiment involving recording in the thalamus/subthalamus areas of a rat brain, a hybrid hardware/software method was utilized to improve the signal-to-noise quality of the recorded signal on each recording channel. The procedure uses closely spaced recording electrode arrays and independent component analysis (ICA) to fortify the signal energy of a single spike by combining input from several channels, and concurrently to reduce the noise on each channel by isolating common mode components such as artifacts, slow waves, and correlated distant spike activation. In the next step, a wavelet denoising-based signal-to-noise assessment is used to quantify the improvement in data quality for each data record. The data presented here demonstrate that this method, which can be applied off-line as a preprocessor to other time domain or transform domain spike sorting methods, is consistently effective at improving data quality and facilitating subsequent detection and classification of neurons.     

三种鼠对脉冲噪音损伤敏感性的研究

目的 研究豚鼠、大鼠和小鼠对脉冲噪音暴露的敏感性。方法 共分6组,第1组豚鼠(n=5)给予160 dB SPL50次脉冲噪音暴露;第2组豚鼠(n=5)予160 dB SPL 100次脉冲噪音暴露;第3组豚鼠(n=5)给予160 dB SPL 200次脉冲噪音暴露;第4组豚鼠(n=6)给予160 dB SPL 400次脉冲噪音暴露。第5组10只Sprague-Dawley大鼠给予160 dB SPL 50次脉冲噪音暴露。第6组10只小鼠(Bagg Albino雌鼠与DBA雄鼠杂交)予160 dB SPL 50次脉冲噪音暴露。脑干诱发电位检测在脉冲噪音前,噪音后立刻、1 d、1、2、4周。结果 给予160 dB SPL50次脉冲噪音暴露后,大鼠和小鼠都显示暂时和永久的阈值漂移,豚鼠无暂时和永久的阈值漂移,给予160 dB SPL 400次脉冲噪音暴露后显示暂时和永久的阈值漂移。结论 豚鼠、大鼠和小鼠对脉冲噪音敏感性不同,豚鼠对脉冲噪音不如大鼠小鼠敏感,而大鼠比小鼠更敏感。     

某造船企业噪声作业工人纯音测听结果分析

目的：探讨生产性噪声对作业工人听力的影响。方法对某造船企业94名噪声作工人进行在岗期间纯音电测听检查,测听数据进行统计分析。结果听力损失37人(占受检人数的39.36%),其中轻度听力损失36人,中度听力损失1人。听力损失随工龄增加而升高,不同工龄组间听力损失比较有统计学意义(P<0.05)。结论听力损失随接触噪工龄的增加呈上升趋势。建议企业加强监督和管理,做好作业工人职业危害宣传教育和个人防护,建立和完善职业健康监护档案,控制职业性噪声聋发生。