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.     

Modelling non-invasive brain stimulation in cognitive neuroscience

Non-invasive brain stimulation (NIBS) is a method for the study of cognitive function that is quickly gaining popularity. It bypasses the correlative approaches of other imaging techniques, making it possible to establish a causal relationship between cognitive processes and the functioning of specific brain areas. Like lesion studies, NIBS can provide information about where a particular process occurs. However, NIBS offers the opportunity to study brain mechanisms beyond process localisation, providing information about when activity in a given brain region is involved in a cognitive process, and even how it is involved. When using NIBS to explore cognitive processes, it is important to understand not only how NIBS functions but also the functioning of the neural structures themselves. We know that NIBS techniques have the potential to transiently influence behaviour by altering neuronal activity, which may have facilitatory or inhibitory behavioural effects, and these alterations can be used to understand how the brain works. Given that NIBS necessarily involves the relatively indiscriminate activation of large numbers of neurons, its impact on a neural system can be easily understood as modulation of neural activity that changes the relation between noise and signal. In this review, we describe the mutual interactions between NIBS and brain activity and provide an updated and precise perspective on the theoretical frameworks of NIBS and their impact on cognitive neuroscience. By transitioning our discussion from one aspect (NIBS) to the other (cognition), we aim to provide insights to guide future research.     

不同原因内耳损伤下畸变产物耳声发射的改变

目的研究不同原因内耳损伤下畸变产物耳声发射(distortion product otoacoustic emissions,DPOAE)改变的特点.方法对耳科正常人、噪声暴露工人和应用顺铂化疗的妇科肿瘤患者进行DPOAE(0.5～16 kHz)、常频纯音测听(0.5～8 kHz)及扩展高频测听(9～16 kHz)检查.对DPOAE幅值与纯音听阈进行比较分析.结果在噪声性和顺铂耳毒性损伤下,常频DPOAE表现为3～6 kHz幅值降低,早于对应常频纯音听阈变化.扩展高频DPOAE幅值均有下降,但频率区域不同,噪声组只在11.2 kHz处下降明显,其他频率变化不大,尤其是12.5 kHz、14 kHz、16 kHz三个频率几无变化;药物组除16 kHz外各频率均幅值下降.结论常频DPOAE比常频纯音测听和扩展高频DPOAE敏感,因此,在噪声、顺铂等引起的耳蜗性听力损害的早期监测中,优于常频纯音测听和扩展高频DPOAE.     

Poorly selective cation channels in the skin of the larval frog (Stage≤XIX)

The abdominal skin of bullfrog larvae (Rana catesbeiana) was placed in an Ussing-type chamber, and its transepithelial electrical parameters were recorded with mucosal solutions of different ionic composition. With K⁺-like cations (K⁺, NH ₄ ⁺ , Rb⁺, Cs^–) the power spectra of the fluctuations in short-circuit current displayed a Lorentzian component (f _c =30–40 Hz). The relaxation noise could be suppressed by addition of the K⁺-channel blockers Ba²⁺ and TEA to the mucosal solution. Also, in presence of the ionophore antibiotic nystatin the Lorentzian noise was abolished. The Na⁺-channel probes amiloride and benzimidazolyl-2-guanidine (BIG) both enhanced the relaxation noise obtained with the K⁺-like cations but, with Na⁺, and Li⁺, also caused the rise of a relaxation component above the background noise. In presence of amiloride or BIG, the addition of Ba²⁺, TEA and nystatin still abolished the Lorentzian noise. It can be concluded that the relaxation-noise source is located in the apical cell membranes of the tadpole skin. These spontaneously fluctuating cation channels do not seem to strictly discriminate between K⁺-like ions (K⁺, NH ₄ ⁺ , Rb⁺, Cs⁺) and Na⁺-like ions (Na⁺, Li⁺). On the other hand, well-known specific probes for K⁺ channels (Ba²⁺, TEA) and for Na⁺ channels (amiloride, BIG) interact with this apical cation channel. It is possible that the poorly selective channel plays a role in the ontogenesis of the specific Na⁺ transport in the maturing frog skin.     

Reduction of noise due to systematic uncertainties in In SPECT imaging using information theory

SPECT images using radiopharmaceuticals are limited by noise caused by both random and systematic uncertainties. All the efforts so far have been directed only to minimize the random uncertainty and no attempt has ever been made to minimize the noise due to systematic uncertainty. As these radiopharmaceuticals encounter many systematic uncertainties during their formation, we constructed the covariance matrix with some of these systematic uncertainties for the gamma count rate of ^113mIn. We describe the algorithm we have developed based on the technique of determinant inequalities and the concept of minimization of mutual information to process the covariance matrix element by element to minimize the noise caused by systematic uncertainty in the SPECT imaging of ^113mIn and its utility to experimentalists to design and improve their process of measurement and instrumentation.     

手术室噪声污染的原因分析及护理对策

目的：探讨手术室环境噪声污染的原因,制定相应的护理对策。方法：选择120例手术患者为观察组,对手术室采取降噪措施;120例手术患者为对照组,对手术室噪声未加任何控制。比较手术后两组患者手术后的心率、血压、焦虑发生、拆线时间、满意度等情况。结果：观察组手术后心率、血压明显低于对照组,焦虑发生例数明显少于对照组,拆线时间明显短于对照组,满意度明显高于对照组,以上差异有统计学意义（P（0.01）。结论：应重视手术室环境对患者健康的影响,针对手术中噪声的来源,采取相应的护理措施,减少噪声对患者的不良心理刺激,增强患者安全感,缓解其焦虑、恐惧的情绪,共同为患者创造一个安全、舒适、整洁、安静的手术环境。