Bluetooth Coupling in Hearing Aids: Effect on Audiovisual Speech Recognition and Quality Rating of Compressed Speech in Older Individuals with Sloping Hearing Loss

Abstract Introduction Older individuals often report that they find it difficulty in enjoying watching television since they find it hard to follow the rapid intensity variations, and voice changes from scene to scene. Objective The present study investigated the effect of coupling the hearing aid with the television via Bluetooth on audiovisual speech recognition and quality rating of compressed speech in older individuals with hearing loss. Method Twenty participants in the age range of 60 to 75 years who had moderate to moderately severe sloping sensorineural hearing loss were bilaterally fitted with digital receiver in the canal hearing aids. The hearing aid was coupled with a television via Bluetooth using a streamer. The video recorded stimuli were presented at 65 dB SPL at normal rate, 35% compression and 45% compression conditions. Speech recognition scores and quality ratings were obtained for each condition with and without the Bluetooth streamer connected to the hearing aids. Results Speech recognition scores were significantly better with Bluetooth coupling compared with conventional hearing aid use at 40% compressed speech rate. The quality was also rated higher in almost all parameters across speech rates when Bluetooth was used. Conclusions The improved clarity and nullification of room reverberation offered by Bluetooth coupling can potentially compensate for the age-related temporal processing deficit contributing to ease of listening.

Quality Evaluation of Temporomandibular Joint Images from 3 High-resolution Dynamic Sequences / 中国医学科学院学报

Objective To compare the image quality of three high-resolution dynamic MRI methods for evaluating the motion of temporomandibular joint disc and condyle. Methods Twenty-five patients with suspected temporomandibular joint disorders were examined by single-shot fast spin-echo (SSFSE),fast imaging employing steady-state acquisition (FIESTA),and spoiled gradient echo (SPGR) on the oblique sagittal position.Two radiologists performed subjective and objective evaluation on the images with double-blind method.The subjective evaluation included the signal intensity of mandibular condyle,articular disc,soft tissue around articular disc,and lateral pterygoid muscle,the contrast between articular disc and condyle,the contrast between articular disc and surrounding soft tissue,condylar motion,and disc movement.The objective evaluation indexes included image signal intensity,signal-to-noise ratio (SNR),and contrast-to-noise ratio (CNR).The subjective and objective indexes of the image quality were compared between the three sequences. Results The SSFSE sequence had lower signal intensity of articular disc and higher signal intensity of condyle and surrounding soft tissue than FIESTA and SPGR sequences (all P<0.001).The SPGR sequence showed higher signal intensity of lateral pterygoid muscle than the SSFSE and FIESTA sequences (P=0.017,P<0.001).Among the three sequences,SSFSE sequence showed the clearest articular disc structure (χ2=41.952,P<0.001),the strongest contrast between articular disc and condyle (χ2=35.379,P<0.001),the strongest contrast between articular disc and surrounding soft tissue (χ2=27.324,P<0.001),and the clearest movement of articular disc (χ2=44.655,P<0.001).SSFSE and FIESTA sequences showed higher proportion of disc displacement and reduction than SPGR sequence (all P<0.001).The CNR (χ2=21.400,P<0.001),SNR (χ2=34.880,P<0.001),and condyle signal intensity (F=337.151,P<0.001) demonstrated differences among SSFSE,FIESTA,and SPGR sequences.The CNR of SSFSE sequence was higher than that of FIESTA sequence (P<0.001),while it had no significant difference between SSFSE and SPGR sequences (P=0.472).In addition,the SSFSE sequence had higher SNR and signal intensity than FIESTA and SPGR sequences (all P<0.001). Conclusion The best image quality can be observed from SSFSE sequence where both the structure and movement of temporomandibular joint are well displayed.Therefore,SSFSE is preferred for the examination of temporomandibular joint movement.

Portable Multi Channel EEG Signal Acquisition System / 中国医疗器械杂志

This study introduces a portable multi-channel EEG signal acquisition system. The system is mainly composed of EEG electrode connector, signal conditioning circuit, EEG acquisition part, main control MCU and power supply part. The low-power EEG acquisition front-end ADS1299 and STM32 are used to form the signal acquisition and data communication part. The collected EEG signal can be transmitted to the PC for real-time display. After relevant tests, the system has small volume, low power consumption, high signal-to-noise ratio, and meets the requirements of portable wearable medical devices.

A comparative study of microwire electrode array with built-in and external reference electrodes / 中国应用生理学杂志

Objective: To compare the difference between the built-in and external reference electrode of microwire electrode array in the process of recording rat brain neuron firings, optimizing the production and embedding of the microwire electrode array, and providing a more affordable and excellent media tool for multi-channel electrophysiological real-time recording system. Methods: A 16 channel microwire electrode array was made by using nickel chromium alloy wires, circuit board, electrode pin and ground wires (silver wires). The reference electrode of the microwire electrode array was built-in (the reference electrode and electrode array were arranged in parallel) or external (the reference electrode and ground wire were welded at both ends of one side of the electrode), and the difference between the two electrodes was observed and compared in recording neuronal discharges in ACC brain area of rats. Experimental rats were divided into built-in group and external group, n=8-9. The test indicators included signal-to-noise ratio (n=8), discharge amplitude (n=380) and discharge frequency (n=54). Results: The microwire electrode array with both built-in and external reference electrodes successfully recorded the electrical signals of neurons in the ACC brain region of rats. Compared with the external group, the electrical signals of neurons in built-in group had the advantages of a higher signal-to-noise ratio (P＜0.05), a smaller amplitude of background signals and less noise interference, and a larger discharge amplitude(P＜0.05); there was no significant difference in spike discharge frequency recorded by these two types of electrodes (P＞0.05). Conclusion: When recording the electrical activity of neurons in the ACC brain region of rats, the microwire electrode array with built-in reference electrode recorded electrical signals with higher signal-to-noise ratio and larger discharge amplitude, providing a more reliable tool for multi-channel electrophysiology technology.

Progress in filters for denoising cryo-electron microscopy images / 北京大学学报(医学版)

Cryo-electron microscopy (cryo-EM) imaging has the unique potential to bridge the gap between cellular and molecular biology. Therefore, cryo-EM three-dimensional (3D) reconstruction has been rapidly developed in recent several years and applied widely in life science research to reveal the structures of large macromolecular assemblies and cellular complexes, which is critical to understanding their functions at all scales. Although the technical breakthrough in recent years, for example, the introduction of the direct detection device (DDD) camera and the development of cryo-EM software tools, made the three cryo-EM pioneers share the 2017 Nobel Prize, several bottleneck problems still exist that hamper the further increase of the resolution of single-particle reconstruction and hold back the application of in situ subnanometer structure determination by cryo-tomography. Radiation damage is still the key limiting factor in cryo-EM. In order to minimize the radiation damage and preserve as much resolution as possible, the imaging conditions of a low dose and weak contrast make cryo-EM images extremely noisy with very low signal-to-noise ratios (SNR), generally about 0.1. The high noise will obscure the fine details in cryo-EM images or reconstructed maps. Thus, a method to reduce the level of noise and improve the resolution has become an important issue. In this paper, we systematically reviewed and compared some robust filters in the cryo-EM field of two aspects, single-particle analysis (SPA) and cryo-electron tomography (cryo-ET), and especially studied their applications, such as, 3D reconstruction, visualization, structural analysis, and interpretation. Conventional approaches to noise reduction in cryo-EM imaging include the use of Gaussian, median, and bilateral filters, among other means. A Gaussian filter selects an appropriate filter kernel to conduct spatial convolution with a noisy image. Although noise with larger standard deviations in cryo-EM images can be suppressed and satisfactory performance is achieved in certain cases, this filter also blurs the images and over-smooths small-scale image features. This is especially detrimental when precise quantitative information needs to be extracted. Unlike a Gaussian filter, a median filter is based on the order statistics of the image and selects the median intensity in a window of the adjacent pixels to denoise the image. Although this filter is robust to outliers, it suffers from aliasing problems that possibly result in incorrect information for cryo-EM structure interpretation. A bilateral filter is a nonlinear filter that performs spatial weighted averaging and is more selective in the pixels allowing to contribute to the weighted sum, excluding the high frequency noise from the smoothing process. Thus, this filter can be used to smooth out noise while maintaining the edge details, which is similar to an anisotropic diffusion filter, and distinct from a Gaussian filter but its utility will be limited when the SNR of a cryo-EM image is very low. Generally, spatial filtering methods have the disadvantage of losing image resolution when reducing noise. A wavelet transform can exploit the wavelet's natural ability to separate a signal from noise at multiple image scales to allow for joint resolution in both the spatial and frequency domains, and thus has the potential to outperform existing methods. The modified wavelet shrinkage filter we developed can offer a remarkable improvement in image quality with a good compromise between detail preservation and noise smoothing. We expect that our review study on different filters can provide benefits to cryo-EM applications and the interpretation of biological structures.

Influence of different types of noise on sentence recognition in normally hearing adults / A influência de diferentes tipos de ruídos no reconhecimento de sentenças em adultos normo-ouvintes

ABSTRACT Objective: to analyze speech perception in normally hearing adults when listening in silence and with different types of noise. Methods: 40 individuals of both sexes, aged 18 to 45 years, participated in the study. Speech perception was assessed with the Lists of Sentences in Portuguese test, without a competing noise and with speech-spectrum, babble, and cocktail party noise. A mixed-effects linear regression model and the 95% confidence interval were used. Results: the subjects' performance was worse in the three types of noise than in silence. When comparing the types of noise, differences were found in all combinations (speech-spectrum X babble, speech-spectrum X cocktail party, and babble X cocktail party), with a worse performance in babble, noise, followed by cocktail party. Conclusion: all noises negatively influenced speech perception, with a worse performance in babble, followed by cocktail party and speech-spectrum.

RESUMO Objetivo: analisar a percepção da fala em adultos normo-ouvintes na situação de escuta no silêncio e com diferentes tipos de ruídos. Métodos: participaram 40 indivíduos de ambos os gêneros, de 18 a 45 anos. Foi realizada a avaliação da percepção de fala com o teste Lista de Sentenças para o Português, sem ruído competitivo e com os ruídos: espectro de fala, babble e cocktail party. Foi utilizado modelo de regressão linear com efeitos mistos e adotado intervalo de confiança de 95%. Resultados: houve pior desempenho dos indivíduos com todos os ruídos em comparação a situação de escuta no silêncio. Na comparação entre os tipos de ruídos, também foi constatado diferença em todas as combinações (espectro de fala X babble, espectro de fala X cocktail party e babble X cocktail party), com pior desempenho dos indivíduos com os ruídos babble e cocktail party, respectivamente. Conclusão: todos os ruídos influenciaram negativamente a percepção de fala, com pior desempenho quando utilizado o ruído babble, seguido pelo cocktail party e espectro de fala.

Study of scanning method of T 1WI_Star_VIBE_FS in MRI simulation of neck radiotherapy / 中华放射肿瘤学杂志

Objective:To compare and analyze the image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of T 1WI_Star_VIBE_FS sequence in MRI simulation of neck tumors with different scanning methods, aiming to determine the optimal scanning method. Methods:A retrospective analysis of 78 patients receiving MRI contrast scan was performed. All patients were randomly divided into three groups according to three different scanning methods including bolus mode (group A, n=23), segmentation splicing mode (group B, n=18) and the combination mode (group C, n=37). The image quality, SNR and CNR of the anterior soft tissues of neck were statistically compared. Results:A higher image quality score was obtained in group C. The mean SNR and CNR in three groups were calculated as 214.70±148.78, 91.95±59.26, 307.61±127.80, and 208.74±148.27, 85.79±59.50, 301.58±127.48, respectively. The image quality score, SNR and CNR in group C were significantly better compared with those in group A and B (all P<0.01). Conclusion:Combination of bolus and segmentation splicing modes is a recommended approach in MRI simulation during radiotherapy of neck tumors.

Effect of Quiet and Noise on P300 Response in Individuals with Auditory Neuropathy Spectrum Disorder

Abstract Introduction Auditory neuropathy spectrum disorder (ANSD) is a clinical condition in which individuals have normal cochlear responses and abnormal neural responses. There is a lack of evidence in the literature regarding the neural discrimination skill in individuals with ANSD, especially when the signal is presented in the presence of noise. Objectives The present study was performed with the aim to investigate auditory discrimination skill, in quiet and in the presence of noise, in individuals with ANSD and to compare the findings with normal-hearing individuals. Methods A total of 30 individuals with normal hearing sensitivity and 30 individuals with ANSD in the age range of 15 to 55 years old, with the mean age of 27.86 years old, were the participants. P300 response was recorded from both groups using syllable pairs /ba/-/da/ in oddball paradigm and the syllable /da/ in repetitive paradigm in quiet and at +10 dB signal-to-noise ratio (SNR). Results There was significant prolongation in latency and reaction time, and reduction in amplitude of P300 response and sensitivity in both groups with the addition of noise. The topographic pattern analysis showed activation of the central-parietal-occipital region of the brain in individuals with ANSD, whereas activation of the central-parietal region was observed in individuals with normal hearing. The activation was more diffused in individuals with ANSD compared with that of individuals with normal hearing. Conclusion The individuals with ANSD showed a significantly more adverse effect of noise on the neural discrimination skill than the normal counterpart.

Comparison between STIR and T2-weighted SPAIR sequences in the evaluation of inflammatory sacroiliitis: diagnostic performance and signal-to-noise ratio / Comparação do desempenho diagnóstico e da relação sinal-ruído das sequências SPAIR T2 e STIR na avaliação de sacroiliite inflamatória

Abstract Objective: To compare two different fat-saturated magnetic resonance imaging (MRI) techniques-STIR and T2 SPAIR-in terms of image quality, as well as in terms of their diagnostic performance in detecting sacroiliac joints (SIJ) active inflammation. Materials and Methods: We included 69 consecutive patients with suspected spondyloarthritis undergoing MRI between 2012 and 2014. The signal-to-noise ratio (SNR) was calculated with the method recommended by the American College of Radiology. Two readers evaluated SIJ MRI following ASAS criteria to assess diagnostic performance regarding the detection of active SIJ inflammation. T1 SPIR Gd+ sequence was used as the reference standard. Results: The mean SNR was 72.8 for the T1 SPIR Gd+ sequence, compared with 14.1 and 37.6 for the STIR and T2 SPAIR sequences, respectively. The sensitivity and specificity of STIR and SPAIR T2 sequences did not show any statistically significant differences, for the diagnosis of sacroiliitis with active inflammation. Conclusion: Our results corroborate those in the recent literature suggesting that STIR sequences are not superior to T2 SPAIR sequences for SIJ evaluation in patients with suspected spondyloarthritis. On 1.5-T MRI, T2-weighted SPAIR sequences provide better SNRs than do STIR sequences, which reinforces that T2 SPAIR sequences may be an advantageous option for the evaluation of sacroiliitis.

Resumo Objetivo: O objetivo deste estudo foi comparar a qualidade da imagem das técnicas de saturação de gordura T2 SPAIR e STIR e, adicionalmente, comparar o desempenho diagnóstico das duas sequências para detecção de inflamação ativa nas imagens de ressonância magnética (RM) das sacroilíacas. Materiais e Métodos: Foram incluídos 69 pacientes consecutivos que realizaram RM das articulações sacroilíacas no período de 2012 a 2014. O cálculo da relação sinal/ruído (RSR) foi realizado pelo método do Colégio Americano de Radiologia. O desempenho diagnóstico foi realizado utilizando os resultados da leitura das imagens da sequência T1 SPIR Gd+ como referência. Resultados: A avaliação da RSR mostrou média de 72,8 para a sequência T1 SPIR Gd+. A sensibilidade e a especificidade das sequências STIR e SPAIR 2 para o diagnóstico de sacroiliite com inflamação ativa não apresentaram diferenças estatisticamente significantes. Conclusão: Nossos resultados reforçam a literatura recente sugerindo que não há superioridade da sequência STIR em relação à sequência SPAIR T2 para a avaliação das sacroilíacas em pacientes com espondiloartrite. A sequência SPAIR T2 apresenta melhor RSR em relação à sequência STIR em imagens de RM de 1,5 T, o que reforça que a sequência SPAIR T2 possa ser utilizada como opção vantajosa na avaliação da sacroiliite inflamatória.

A spike denoising method combined principal component analysis with wavelet and ensemble empirical mode decomposition / 生物医学工程学杂志

Spike recorded by multi-channel microelectrode array is very weak and susceptible to interference, whose noisy characteristic affects the accuracy of spike detection. Aiming at the independent white noise, correlation noise and colored noise in the process of spike detection, combining principal component analysis (PCA), wavelet analysis and adaptive time-frequency analysis, a new denoising method (PCWE) that combines PCA-wavelet (PCAW) and ensemble empirical mode decomposition is proposed. Firstly, the principal component was extracted and removed as correlation noise using PCA. Then the wavelet-threshold method was used to remove the independent white noise. Finally, EEMD was used to decompose the noise into the intrinsic modal function of each layer and remove the colored noise. The simulation results showed that PCWE can increase the signal-to-noise ratio by about 2.67 dB and decrease the standard deviation by about 0.4 μV, which apparently improved the accuracy of spike detection. The results of measured data showed that PCWE can increase the signal-to-noise ratio by about 1.33 dB and reduce the standard deviation by about 18.33 μV, which showed its good denoising performance. The results of this study suggests that PCWE can improve the reliability of spike signal and provide an accurate and effective spike denoising new method for the encoding and decoding of neural signal.

Selection and progresses of 31P-MRS scanning sequences / 中国医学影像技术

Phosphorus compounds exist in the tissue of human body,providing important information about microenvironment changes of diseases. Phosphorus magnetic resonance spectroscopy (31P-MRS) is a non-invasive method to observe energy metabolism and biochemical changes of human tissue, which can be utilized in diagnosing disease and monitoring response to therapy. However, the magnetogyric ratio of phosphorus is low, and the in vivo content is relatively low, resulting low signal-to-noise ratio of phosphorus spectrum. It is very important to choose suitable scanning sequence to improve the quality. The characteristics, advantages and disadvantages of sequences used in 31P-MRS were reviewed this article.

A Standard Method for Performance Detection of Fluorescence Imaging System / 中国医疗器械杂志

Fluorescence imaging now becomes an intraoperative navigation technique that gaining popularity in surgery and clinical research. However, at present, there is no mature and reliable method or other related guidance documents for the detection of fluorescence imaging performance. The performance analysis and quality supervision of products on the market could not be performed, which affects their clinical use and image quality. In this paper, a standard method of fluorescence imaging performance testing for fluorescence imaging system is proposed. Several kinds of fluorescence imaging performance parameters affecting fluorescence images are defined strictly. We also recommend scientific and feasible methods for their detections and analyses, which are verified by practical examples. This paper aims to provide a feasible reference standard for fluorescence performance evaluation.

Perception of Tamil Mono-Syllabic and Bi-Syllabic Words in Multi-Talker Speech Babble by Young Adults with Normal Hearing

BACKGROUND AND OBJECTIVES: This study compared the perception of mono-syllabic and bisyllabic words in Tamil by young normal hearing adults in the presence of multi-talker speech babble at two signal-to-noise ratios (SNRs). Further for this comparison, a speech perception in noise test was constructed using existing mono-syllabic and bi-syllabic word lists in Tamil. SUBJECTS AND METHODS: A total of 30 participants with normal hearing in the age range of 18 to 25 years participated in the study. Speech-in-noise test in Tamil (SPIN-T) constructed using mono-syllabic and bi-syllabic words in Tamil was used as stimuli. The stimuli were presented in the background of multi-talker speech babble at two SNRs (0 dB and +10 dB SNR). RESULTS: The effect of noise on SPIN-T varied with SNR. All the participants performed better at +10 dB SNR, the higher of the two SNRs considered. Additionally, at +10 dB SNR performance did not vary significantly for neither mono-syllabic or bi-syllabic words. However, a significant difference existed at 0 dB SNR. CONCLUSIONS: The current study indicated that higher SNR leads to better performance. In addition, bi-syllabic words were identified with minimal errors compared to mono-syllabic words. Spectral cues were the most affected in the presence of noise leading to more of place of articulation errors for both mono-syllabic and bi-syllabic words.

High-Resolution Magnetic Resonance Imaging Using Compressed Sensing for Intracranial and Extracranial Arteries: Comparison with Conventional Parallel Imaging

OBJECTIVE: To compare conventional sensitivity encoding (SENSE) to compressed sensing plus SENSE (CS) for high-resolution magnetic resonance imaging (HR-MRI) of intracranial and extracranial arteries. MATERIALS AND METHODS: HR-MRI was performed in 14 healthy volunteers. Three-dimensional T1-weighted imaging (T1WI) and proton density-weighted imaging (PD) were acquired using CS or SENSE under the same total acceleration factors (AF(t))-5.5, 6.8, and 9.7 for T1WI and 3.2, 4.0, and 5.8 for PD-to achieve reduced scanning times in comparison with the original imaging sequence (SENSE T1WI, AF(t) 3.5; SENSE PD, AF(t) 2.0) using the 3-tesla system. Two neuroradiologists measured signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and used visual scoring systems to assess image quality. Acceptable imaging was defined as a visual score ≥ 2. Repeated measures analysis of variance and Cochran's Q test were performed. RESULTS: CS yielded better image quality and vessel delineation than SENSE in T1WI with AF(t) of 5.5, 6.8, and 9.7, and in PD with AF(t) of 5.8 (p 0.05). SNR and CNR in CS were higher than they were in SENSE, but lower than they were in the original images (p < 0.05). CS yielded higher proportions of acceptable imaging than SENSE (CS T1WI with AF(t) of 6.8 and PD with AF(t) of 5.8; p < 0.0167). CONCLUSION: CS is superior to SENSE, and may be a reliable acceleration method for vessel HR-MRI using AF(t) of 5.5 for T1WI, and 3.2 and 4.0 for PD.

A compact-sized surface EMG sensor for myoelectric hand prosthesis

Myoelectric prosthesis requires a sensor that can reliably capture surface electromyography (sEMG) signal from amputees for its controlled operation. The main problems with the presently available EMG devices are their extremely high cost, large response time, noise susceptibility, less amplitude sensitivity, and larger size. This paper proposes a compact and affordable EMG sensor for the prosthetic application. The sensor consists of an electrode interface, signal conditioning unit, and power supply unit all encased in a single package. The performance of dry electrodes employed in the skin interface was compared with the conventional Ag/AgCl electrodes, and the results were found satisfactory. The envelope detection technique in the sensor based on the tuned RC parameters enables the generation of smooth, faster, and repeatable EMG envelope irrespective of signal strength and subject variability. The output performance of the developed sensor was compared with commercial EMG sensor regarding signal-to-noise ratio, sensitivity, and response time. To perform this, EMG data with both devices were recorded for 10 subjects (3 amputees and 7 healthy subjects). The results showed 1.4 times greater SNR values and 45% higher sensitivity of the developed sensor than the commercial EMG sensor. Also, the proposed sensor was 57% faster than the commercial sensor in producing the output response. The sEMG sensor was further tested on amputees to control the operation of a self-designed 3D printed prosthetic hand. With proportional control scheme, the myoelectric hand setup was able to provide quicker and delicate grasping of objects as per the strength of the EMG signal.

Application of OCT combined with isolated-check visual evoked potential in the diagnosis and treatment of primary open angle glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To analyze the application value of optical coherence tomography(OCT)combined with isolated-check visual evoked potential(Ic-VEP)in the diagnosis and treatment of primary open angle glaucoma(POAG). <p>METHODS: Prospective cohort study. Totally 32 eyes of 32 suspected glaucoma cases, 30 eyes of 30 early POAG cases, 25 eyes of 25 moderate and late POAG cases were selected from the patients treated in our hospital from October 2014 to May 2018 were enrolled, and 30 eyes of 30 normal subjects were selected as control group. All subjects received OCT, Ic-VEP, visual field test, measurement results were analyzed.<p>RESULTS: The sensitivity and specificity of Ic-VEP in diagnose of early POAG was 83% and 93% respectively. The difference between the early POAG group and the suspected glaucoma group was no statistically significant in the signal-to-noise ratio of 8% SNR(<i>P</i>>0.05), but were statistically significant in other groups(<i>P</i><0.05). The differences of 16%SNR and 32%SNR between the control group and the moderate and late POAG group, the suspected glaucoma group and the moderate and late POAG group, the early POAG group and the moderate and late POAG group were statistically significant(<i>P</i><0.01), but were no statistically significant in other groups(<i>P</i>>0.05). The retinal nerve fiber layer(RNFL)thickness parameters in four groups became thinner with the aggravation of the disease, and the differences between the four groups were statistically significant(<i>P</i><0.05). The mean defect of the four groups decreased gradually, there were no significant differences between the suspected glaucoma group and the control group(<i>P</i>=0.08), the differences between the other groups were statistically significant(<i>P</i><0.05). The area under the ROC curve of 8%SNR, mean RNFL and MD in the suspected glaucoma group were 0.824, 0.846 and 0.661 respectively, the early POAG group of those were 0.898, 0.969, 0.889, respectively. <p>CONCLUSION: OCT and Ic-VEP have high diagnostic ability for the early changes of POAG and can evaluate the degree of optic nerve injury, which can be combined used for early diagnosis and efficacy evaluation of POAG.

Effect of Cataract Grade according to Wide-Field Fundus Images on Measurement of Macular Thickness in Cataract Patients

PURPOSE: To investigate the effects of cataract grade based on wide-field fundus imaging on macular thickness measured by spectral domain optical coherence tomography (SD-OCT) and its signal-to-noise ratio (SNR). METHODS: Two hundred cataract patients (200 eyes) with preoperative measurements by wide-field fundus imaging and macular SD-OCT were enrolled. Cataract severity was graded from 1 to 4 according to the degree of macular obscuring by cataract artifact in fundus photo images. Cataract grade based on wide-field fundus image, the Lens Opacity Classification System III, macular thickness, and SD-OCT SNR were compared. All SD-OCT B-scan images were evaluated to detect errors in retinal layer segmentation. RESULTS: Cataract grade based on wide-field fundus imaging was positively correlated with grade of posterior subcapsular cataracts (rho = 0.486, p < 0.001), but not with nuclear opalescence or cortical cataract using the Lens Opacity Classification System III. Cataract grade was negatively correlated with total macular thickness (rho = −0.509, p < 0.001) and SD-OCT SNR (rho = −0.568, p < 0.001). SD-OCT SNR was positively correlated with total macular thickness (rho = 0.571, p < 0.001). Of 200 eyes, 97 (48.5%) had segmentation errors on SD-OCT. As cataract grade increased and SD-OCT SNR decreased, the percentage of eyes with segmentation errors on SD-OCT increased. All measurements of macular thickness in eyes without segmentation errors were significantly greater than those of eyes with segmentation errors. CONCLUSIONS: Posterior subcapsular cataracts had profound effects on cataract grade based on wide-field fundus imaging. As cataract grade based on wide-field fundus image increased, macular thickness tended to be underestimated due to segmentation errors in SD-OCT images. Segmentation errors in SD-OCT should be considered when evaluating macular thickness in eyes with cataracts.

Electron Elimination Method Based on Single Electrode Dielectric Barrier Discharge Ion Source / 分析化学

Based on the electric field shielding and insulation technology, the single electrode dielectric barrier discharge ion source ( DBDI ) has the characteristics of uniform discharging, stability, and high ionization energy, and thus can be used to detect various samples with a large range of polarity. However, the ionization energy is too high to reduce the background signal noise, and thus affects the detection effectiveness to low polarity and low boiling point samples. To enhance the detection effectiveness to these samples, a method of eliminating electrons of single electrode DBDI by using external metal electrodes was developed in this study. Then, the single electrode DBDI was improved by an external needle electrode and an external metal net, respectively. The mechanism of those external metal electrodes was discussed, and the experimental studies were carried out. The results showed that the external metal net technology had an advantage in improving signal to noise ratio ( SNR ) , and the enhancement of SNR for the detection of isoprocarb, perfluorooctanoic acid and SudanⅢwas about 5-6 times. Based on the technology, a method for determination of Sudan Ⅲ in chili powder was developed. The recoveries, RSD and LOD were 83. 7%-94. 6% , 5. 6%-9. 0% and 23 mg/kg, respectively. The external metal electrode technique has broadened the detection range of single electrode DBDI to the field of low polarity, low boiling point and complex samples.

Clinical observation of early detection of open angle glaucoma by the application of isolated-check visual evoked potential / 安徽医科大学学报

Objective To explore the value of qualitative pattern of isolated-check visual evoked potential ( ic-VEP) in the early diagnosis of primary open-angle glaucoma ( POAG) , and to provide an objective and effective basis for the early diagnosis of clinical glaucoma. Methods Sixty-eight patients (82 eyes) with normal POAG were randomly selected. Forty-seven normal individuals (76 eyes) were as control group. Both groups were treated to analyze ic-VEP,the defect of the visual field, the thickness of the retinal nerve fiber layer ( RNFLT) , and the mult-ivariate correlation analysis between ic-VEP, the visual field and RNFLT was performed. The sensitivity and speci-ficity of ic-VEP in the diagnosis of POAG was analysis in this study. Results There were no significant differences in age, diopter and central corneal thickness between glaucoma group and normal control group. However, the in-traocular pressure ( IOP) , the visual field, RNFLT and ic-VEP between two groups were statistically different( P＜0.01) . The correlation analysis of ic-VEP Signal-to-noise ratio ( SNR) with diopter, IOP, the visual field and RN-FLT in the glaucoma group showed that ic-VEP SNR was significantly associated with IOP, the visual field and RN-FLT damage(P＜0.01). The sensitivity of ic-VEP to detect POAG was 90.2% and the specificity was 88.2% . Ic-VEP and the visual field, RNFLT had good consistency. Conclusion Ic-VEP has high sensitivity and accuracy in the diagnosis of primary open-angle glaucoma. Meanwhile ic-VEP SNR is associated with the damage of retinal nerve fiber layer and the visual field damage.

Research on M-sequence coded excitation method for magnetoacoustic imaging / 医疗卫生装备

Objective To solve the problem of the low signal to noise ratio (SNR)and limited imaging quality using single pulse exciting method in magnetoacoustic imaging, as well as the limited imaging speed using wave averaging processing method to magnetoacoustic signal. Methods M-sequence coded exciting method was proposed to enhance SNR imaging efficiency. The SNR improvement and sidelobe level were investigated using M-sequence code by simulation and experiments.Results The SNR of magnetoacoustic signal were 19.4,29.6,and 40.4 dB respectively under 7,31 and 127 bit M-sequence coded excitation. Three bits of M-sequence coded excitation magnetoacoustic signals had the integrated sidelobe level being 14.1,10.0 and 7.6 dB,and the peak sidelobe level being 26.3,24.3 and 21.3 dB.In case the SNR was increased by 40 dB,127 bit of M-sequence coded excitation shortened the sampling and procession time from 53.1 s to 0.520 s when compared with singl-pulse excitation combined with waveform average.Conclusion The coded excitation is significant for magnetoacoustic signal SNR and imaging quality improvement.