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Because of the challenges posed by anatomical uncertainties and the low resolution of plain computed tomography (CT) scans, implementing adaptive radiotherapy (ART) for small hepatocellular carcinoma (sHCC) using artificial intelligence (AI) faces obstacles in tumor identification-alignment and automatic segmentation. The current study aims to improve sHCC imaging for ART using a gold nanoparticle (Au NP)-based CT contrast agent to enhance AI-driven automated image processing. The synthesized charged Au NPs demonstrated notable in vitro aggregation, low cytotoxicity, and minimal organ toxicity. Over time, an in situ sHCC mouse model was established for in vivo CT imaging at multiple time points. The enhanced CT images processed using 3D U-Net and 3D Trans U-Net AI models demonstrated high geometric and dosimetric accuracy. Therefore, charged Au NPs enable accurate and automatic sHCC segmentation in CT images using classical AI models, potentially addressing the technical challenges related to tumor identification, alignment, and automatic segmentation in CT-guided online ART.
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Carcinoma Hepatocelular , Oro , Neoplasias Hepáticas , Nanopartículas del Metal , Radioterapia Guiada por Imagen , Tomografía Computarizada por Rayos X , Oro/química , Carcinoma Hepatocelular/radioterapia , Carcinoma Hepatocelular/diagnóstico por imagen , Carcinoma Hepatocelular/patología , Animales , Tomografía Computarizada por Rayos X/métodos , Nanopartículas del Metal/química , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/diagnóstico por imagen , Neoplasias Hepáticas/patología , Ratones , Radioterapia Guiada por Imagen/métodos , Humanos , Medios de Contraste/química , Inteligencia Artificial , Línea Celular TumoralRESUMEN
BACKGROUND: Transcranial direct current stimulation (tDCS) is a non-invasive technique that has demonstrated potential in modulating cortical neuron excitability. The objective of this paper is to investigate the effects of tDCS on characteristic parameters of brain functional networks and muscle synergy, as well as to explore its potential for enhancing motor performance. METHODS: By applying different durations of tDCS on the motor cortex of the brain, the 32-lead electroencephalogram (EEG) of the cerebral cortex and 4-lead electromyography (EMG) signals of the right forearm were collected for 4 typical hand movements which are commonly used in rehabilitation training, including right-hand finger flexion, finger extension, wrist flexion, and wrist extension. RESULTS: The study showed that tDCS can enhance the brain's electrical activity in the beta band of the C3 node of the cerebral cortex during hand movements. Furthermore, the structure of muscle synergy remains unaltered; however, the associated muscle activity is amplified (p < 0.05). CONCLUSIONS: Based on the study results, it can be inferred that tDCS enhances the control strength between the motor area of the cerebral cortex and the muscles during hand movements.
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Corteza Motora , Estimulación Transcraneal de Corriente Directa , Estimulación Transcraneal de Corriente Directa/métodos , Músculos , Mano , Encéfalo , Corteza Motora/fisiología , Estimulación Magnética TranscranealRESUMEN
BACKGROUND AND PURPOSE: By employing three surface-guided radiotherapy (SGRT)-assisted positioning methods, we conducted a prospective study of patients undergoing SGRT-based deep inspiration breath-hold (DIBH) radiotherapy using a Sentine/Catalys system. The aim of this study was to optimize the initial positioning workflow of SGRT-DIBH radiotherapy for breast cancer. MATERIALS AND METHODS: A total of 124 patients were divided into three groups to conduct a prospective comparative study of the setup accuracy and efficiency for the daily initial setup of SGRT-DIBH breast radiotherapy. Group A was subjected to skin marker plus SGRT verification, Group B underwent SGRT optical feedback plus auto-positioning, and Group C was subjected to skin marker plus SGRT auto-positioning. We evaluated setup accuracy and efficiency using cone-beam computed tomography (CBCT) verification data and the total setup time. RESULTS: In groups A, B, and C, the mean and standard deviation of the translational setup-error vectors were small, with the highest values of the three directions observed in group A (2.4 ± 1.6, 2.9 ± 1.8, and 2.8 ± 2.1 mm). The rotational vectors in group B (1.8 ± 0.7°, 2.1 ± 0.8°, and 1.8 ± 0.7°) were significantly larger than those in groups A and C, and the Group C setup required the shortest amount of time, at 1.5 ± 0.3 min, while that of Group B took the longest time, at 2.6 ± 0.9 min. CONCLUSION: SGRT one-key calibration was found to be more suitable when followed by skin marker/tattoo and in-room laser positioning, establishing it as an optimal daily initial set-up protocol for breast DIBH radiotherapy. This modality also proved to be suitable for free-breathing breast cancer radiotherapy, and its widespread clinical use is recommended.
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Neoplasias de la Mama , Contencion de la Respiración , Tomografía Computarizada de Haz Cónico , Posicionamiento del Paciente , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada , Humanos , Femenino , Neoplasias de la Mama/radioterapia , Planificación de la Radioterapia Asistida por Computador/métodos , Estudios Prospectivos , Tomografía Computarizada de Haz Cónico/métodos , Persona de Mediana Edad , Radioterapia de Intensidad Modulada/métodos , Anciano , Radioterapia Guiada por Imagen/métodos , Errores de Configuración en Radioterapia/prevención & control , Adulto , Pronóstico , Marcadores Fiduciales , Órganos en Riesgo/efectos de la radiaciónRESUMEN
BACKGROUND: We retrospectively studied the dosimetry and setup accuracy of deep inspiration breath-hold (DIBH) radiotherapy in right-sided breast cancer patients with regional nodal irradiation (RNI) who had completed treatment based on surface-guided radiotherapy (SGRT) technology by Sentinel/Catalyst system, aiming to clarify the clinical application value and related issues. METHODS: Dosimetric indicators of four organs at risk (OARs), namely the heart, right coronary artery (RCA), right lung, and liver, were compared on the premise that the planning target volume met dose-volume prescription requirements. Meanwhile, the patients were divided into the edge of the xiphoid process (EXP), sternum middle (SM), and left breast wall (LBW) groups according to different positions of respiratory gating primary points. The CBCT setup error data of the three groups were contrasted for the treatment accuracy study, and the effects of different gating window heights on the right lung volume increases were compared among the three groups. RESULTS: Compared with free breath (FB), DIBH reduced the maximum dose of heart and RCA by 739.3 ± 571.2 cGy and 509.8 ± 403.8 cGy, respectively (p < 0.05). The liver changed the most in terms of the mean dose (916.9 ± 318.9 cGy to 281.2 ± 150.3 cGy, p < 0.05). The setup error of the EXP group in the anterior-posterior (AP) direction was 3.6 ± 4.5 mm, which is the highest among the three groups. The right lung volume increases in the EXP, SM, and LBW groups were 72.3%, 69.9%, and 67.2%, respectively (p = 0.08), and the corresponding breath-holding heights were 13.5 ± 3.7 mm, 10.3 ± 2.4 mm, and 9.6 ± 2.8 mm, respectively (p < 0.05). CONCLUSIONS: SGRT-based DIBH radiotherapy can better protect the four OARs of right-sided breast cancer patients with RNI. Different respiratory gating primary points have different setup accuracy and breath-hold height.
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Neoplasias de la Mama , Neoplasias de Mama Unilaterales , Humanos , Femenino , Estudios Retrospectivos , Dosificación Radioterapéutica , Neoplasias de Mama Unilaterales/radioterapia , Neoplasias de la Mama/radioterapia , Planificación de la Radioterapia Asistida por Computador , Contencion de la Respiración , Corazón/efectos de la radiación , Órganos en Riesgo/efectos de la radiaciónRESUMEN
Purpose: Aiming at the motor recovery of patients with unilateral upper limb motor dysfunction after stroke, we propose a mirror therapy (MT) training method, which uses surface electromyography (sEMG) to identify movements on one side and control the other side to perform functional electrical stimulation (FES) while mirror therapy is used. And we verify the effect of this training method by analyzing the activity changes of the sensorimotor cortex. Method: Ten subjects (6 men and 4 women) were randomly divided into two groups according to 3 men and 2 women in each group: the experimental group (n = 5) received FES+MT training, and the control group (n = 5) received MT training. Both groups were trained at a fixed time at 9 : 00 am every day, each time lasting 20 minutes, once a day, 5 days a week, continuous training for 4 weeks, and the training action was elbow flexion training. During the training of the elbow flexion exercise, the experimental group applied FES with a frequency of 30 Hz, a pulse width of 100 µs, and a current of 10 mA to the muscles corresponding to the elbow flexion exercise, and rested for 10 s after 10-s stimulation. We collect the EEG of the elbow flexion motor imagery of all subjects before and after training, and calculate the eigenvalue E, and analyze the effect of FES+MT training on the activity of the cerebral sensorimotor cortex. Results: After repeated measure (RM) two-way ANOVA of the two groups, comparing the subjects' µ rhythm elbow flexion motor imagery eigenvalue E, the experimental group (after training) > the control group (after training) > before training. Conclusion: The FES+MT training method has obvious activation effect on the cerebral sensorimotor cortex.
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Terapia por Estimulación Eléctrica , Corteza Sensoriomotora , Rehabilitación de Accidente Cerebrovascular , Accidente Cerebrovascular , Estimulación Eléctrica , Terapia por Estimulación Eléctrica/métodos , Femenino , Humanos , MasculinoRESUMEN
Feature extraction is essential for classifying different motor imagery (MI) tasks in a brain-computer interface. To improve classification accuracy, we propose a novel feature extraction method in which the connectivity increment rate (CIR) of the brain function network (BFN) is extracted. First, the BFN is constructed on the basis of the threshold matrix of the Pearson correlation coefficient of the mu rhythm among the channels. In addition, a weighted BFN is constructed and expressed by the sum of the existing edge weights to characterize the cerebral cortex activation degree in different movement patterns. Then, on the basis of the topological structures of seven mental tasks, three regional networks centered on the C3, C4, and Cz channels are constructed, which are consistent with correspondence between limb movement patterns and cerebral cortex in neurophysiology. Furthermore, the CIR of each regional functional network is calculated to form three-dimensional vectors. Finally, we use the support vector machine to learn a classifier for multiclass MI tasks. Experimental results show a significant improvement and demonstrate the success of the extracted feature CIR in dealing with MI classification. Specifically, the average classification performance reaches 88.67% which is higher than other competing methods, indicating that the extracted CIR is effective for MI classification.
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Encéfalo/fisiología , Imaginación/fisiología , Modelos Neurológicos , Red Nerviosa/fisiología , Reconocimiento en Psicología/fisiología , Algoritmos , Electroencefalografía , HumanosRESUMEN
Surface electromyography (sEMG) is an electrophysiological reflection of skeletal muscle contractile activity that can directly reflect neuromuscular activity. It has been a matter of research to investigate feature extraction methods of sEMG signals. In this letter, we propose a feature extraction method of sEMG signals based on the improved small-world leaky echo state network (ISWLESN). The reservoir of leaky echo state network (LESN) is connected by a random network. First, we improved the reservoir of the echo state network (ESN) by these networks and used edge-added probability to improve these networks. That idea enhances the adaptability of the reservoir, the generalization ability, and the stability of ESN. Then we obtained the output weight of the network through training and used it as features. We recorded the sEMG signals during different activities: falling, walking, sitting, squatting, going upstairs, and going downstairs. Afterward, we extracted corresponding features by ISWLESN and used principal component analysis for dimension reduction. At the end, scatter plot, the class separability index, and the Davies-Bouldin index were used to assess the performance of features. The results showed that the ISWLESN clustering performance was better than those of LESN and ESN. By support vector machine, it was also revealed that the performance of ISWLESN for classifying the activities was better than those of ESN and LESN.
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Electromiografía , Músculo Esquelético/fisiología , Redes Neurales de la Computación , Algoritmos , HumanosRESUMEN
As an important research direction of human-computer interaction technology, gesture recognition is the key to realizing sign language translation. To improve the accuracy of gesture recognition, a new gesture recognition method based on four channel surface electromyography (sEMG) signals is proposed. First, the S-transform is applied to four channel sEMG signals to enhance the time-frequency detail characteristics of the signals. Then, multiscale singular value decomposition is applied to the multiple time-frequency matrix output of S-transform to obtain the time-frequency joint features with better robustness. The corresponding singular value permutation entropy is calculated as the eigenvalue to effectively reduce the dimension of multiple eigenvectors. The gesture features are used as input into the deep belief network for classification, and nine kinds of gestures are recognized with an average accuracy of 93.33%. Experimental results show that the multiscale singular value permutation entropy feature is especially suitable for the pattern classification of the deep belief network.
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Gestos , Reconocimiento de Normas Patrones Automatizadas , Electromiografía , Entropía , Humanos , Procesamiento de Señales Asistido por ComputadorRESUMEN
Surface electromyography (sEMG) signals are commonly used in activity monitoring and rehabilitation applications as they reflect effectively the motor intentions of users. However, real-time sEMG signals are non-stationary and vary to a large extent within the time frame of signals. Although previous studies have focused on the issues, their results have not been satisfactory. Therefore, we present a new method of conducting feature-level fusion to obtain a new feature space for sEMG signals. Eight activities of daily life (ADLs), including falls, were performed to obtain raw data from EMG signals from the lower limb. A feature set combining the time domain, time-frequency domain, and entropy domain was applied to the raw data to establish an initial feature space. A new projection method, the weighting genetic algorithm for GCCA (WGA-GCCA), was introduced to obtain the final feature space. Different tests were carried out to evaluate the performance of the new feature space. The new feature space created with the WGA-GCCA effectively reduced the dimensions and selected the best feature vectors dynamically while improving monotonicity. The Davies-Bouldin index (DBI) based on fuzzy c-means algorithms of the space obtained the lowest value compared with several fusion methods. It also achieved the highest accuracy when applied to support vector machine classifier.
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Electromiografía , Algoritmos , Entropía , Actividades Humanas , Humanos , Máquina de Vectores de SoporteRESUMEN
As an essential subfield of context awareness, activity awareness, especially daily activity monitoring and fall detection, plays a significant role for elderly or frail people who need assistance in their daily activities. This study investigates the feature extraction and pattern recognition of surface electromyography (sEMG), with the purpose of determining the best features and classifiers of sEMG for daily living activities monitoring and fall detection. This is done by a serial of experiments. In the experiments, four channels of sEMG signal from wireless, wearable sensors located on lower limbs are recorded from three subjects while they perform seven activities of daily living (ADL). A simulated trip fall scenario is also considered with a custom-made device attached to the ankle. With this experimental setting, 15 feature extraction methods of sEMG, including time, frequency, time/frequency domain and entropy, are analyzed based on class separability and calculation complexity, and five classification methods, each with 15 features, are estimated with respect to the accuracy rate of recognition and calculation complexity for activity monitoring and fall detection. It is shown that a high accuracy rate of recognition and a minimal calculation time for daily activity monitoring and fall detection can be achieved in the current experimental setting. Specifically, the Wilson Amplitude (WAMP) feature performs the best, and the classifier Gaussian Kernel Support Vector Machine (GK-SVM) with Permutation Entropy (PE) or WAMP results in the highest accuracy for activity monitoring with recognition rates of 97.35% and 96.43%. For fall detection, the classifier Fuzzy Min-Max Neural Network (FMMNN) has the best sensitivity and specificity at the cost of the longest calculation time, while the classifier Gaussian Kernel Fisher Linear Discriminant Analysis (GK-FDA) with the feature WAMP guarantees a high sensitivity (98.70%) and specificity (98.59%) with a short calculation time (65.586 ms), making it a possible choice for pre-impact fall detection. The thorough quantitative comparison of the features and classifiers in this study supports the feasibility of a wireless, wearable sEMG sensor system for automatic activity monitoring and fall detection.
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Dispositivos Electrónicos Vestibles , Accidentes por Caídas , Actividades Cotidianas , Algoritmos , Electromiografía , Humanos , Reconocimiento de Normas Patrones Automatizadas , Máquina de Vectores de SoporteRESUMEN
Manifold regularization (MR) has become one of the most widely used approaches in the semi-supervised learning field. It has shown superiority by exploiting the local manifold structure of both labeled and unlabeled data. The manifold structure is modeled by constructing a Laplacian graph and then incorporated in learning through a smoothness regularization term. Hence the labels of labeled and unlabeled data vary smoothly along the geodesics on the manifold. However, MR has ignored the discriminative ability of the labeled and unlabeled data. To address the problem, we propose an enhanced MR framework for semi-supervised classification in which the local discriminative information of the labeled and unlabeled data is explicitly exploited. To make full use of labeled data, we firstly employ a semi-supervised clustering method to discover the underlying data space structure of the whole dataset. Then we construct a local discrimination graph to model the discriminative information of labeled and unlabeled data according to the discovered intrinsic structure. Therefore, the data points that may be from different clusters, though similar on the manifold, are enforced far away from each other. Finally, the discrimination graph is incorporated into the MR framework. In particular, we utilize semi-supervised fuzzy c-means and Laplacian regularized Kernel minimum squared error for semi-supervised clustering and classification, respectively. Experimental results on several benchmark datasets and face recognition demonstrate the effectiveness of our proposed method.
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Motor imagery electroencephalography (EEG) has been successfully used in locomotor rehabilitation programs. While the noise-assisted multivariate empirical mode decomposition (NA-MEMD) algorithm has been utilized to extract task-specific frequency bands from all channels in the same scale as the intrinsic mode functions (IMFs), identifying and extracting the specific IMFs that contain significant information remain difficult. In this paper, a novel method has been developed to identify the information-bearing components in a low-dimensional subspace without prior knowledge. Our method trains a Gaussian mixture model (GMM) of the composite data, which is comprised of the IMFs from both the original signal and noise, by employing kernel spectral regression to reduce the dimension of the composite data. The informative IMFs are then discriminated using a GMM clustering algorithm, the common spatial pattern (CSP) approach is exploited to extract the task-related features from the reconstructed signals, and a support vector machine (SVM) is applied to the extracted features to recognize the classes of EEG signals during different motor imagery tasks. The effectiveness of the proposed method has been verified by both computer simulations and motor imagery EEG datasets.
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Electroencefalografía/métodos , Imágenes en Psicoterapia/métodos , Destreza Motora/fisiología , Desempeño Psicomotor/fisiología , Máquina de Vectores de Soporte , HumanosRESUMEN
Maintaining standing balance is essential for people to engage in productive activities in daily life. However, the process of interaction between the cortex and the muscles during balance regulation is understudied. Four balance paradigms of different difficulty were designed by closing eyes and laying sponge pad under feet. Ten healthy subjects were recruited to stand for ten 15 s trials in each paradigm. This study used simultaneously acquired electroencephalography (EEG) and electromyography (EMG) to investigate changes in the human cortico-muscular coupling relationship and functional brain network characteristics during balance control. The coherence and causality of EEG and EMG signals were calculated by magnitude-squared coherence (MSC) and transfer entropy (TE). It was found that changes in balance strategies may lead to a shift in cortico-muscular coherence (CMC) from the beta band to the gamma band when the difficulty of balance increased. As subjects performed the four standing balance paradigms, the causality of the beta band and the gamma band was stronger in the descending neural pathway than that in the ascending neural pathway. A multi-rhythmic functional brain network with 19 EEG channels was constructed and analyzed based on graph theory, showing that its topology also changed with changes in balance difficulty. These results show an active adjustment of the sensorimotor system under different balance paradigms and provide new insights into the endogenous physiological mechanisms underlying the control of standing balance.
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Phase synchronization serves as an effective method for analyzing the synchronization of electroencephalogram (EEG) signals among brain regions and the dynamic changes of the brain. The purpose of this paper is to study the construction of the functional brain network (FBN) based on phase synchronization, with a special focus on neural processes related to human balance regulation. This paper designed four balance paradigms of different difficulty by blocking vision or proprioception and collected 19-channel EEG signals. Firstly, the EEG sequences are segmented by sliding windows. The phase-locking value (PLV) of core node pairs serves as the phase-screening index to extract the valid data segments, which are recombined into new EEG sequences. Subsequently, the multichannel weighted phase lag index (wPLI) is calculated based on the new EEG sequences to construct the FBN. The experimental results show that due to the randomness of the time points of body balance adjustment, the degree of phase synchronization of the datasets screened by PLV is more obvious, improving the effective information expression of the subsequent EEG data segments. The FBN topological structures of the wPLI show that the connectivity of various brain regions changes structurally as the difficulty of human balance tasks increases. The frontal lobe area is the core brain region for information integration. When vision or proprioception is obstructed, the EEG synchronization level of the corresponding occipital lobe area or central area decreases. The synchronization level of the frontal lobe area increases, which strengthens the synergistic effect among the brain regions and compensates for the imbalanced response caused by the lack of sensory information. These results show the brain regional characteristics of the process of human balance regulation under different balance paradigms, providing new insights into endogenous neural mechanisms of standing balance and methods of constructing brain networks.
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X-ray computed tomography (CT) and magnetic resonance (MR) imaging are essential tools in modern medical diagnosis and treatment. However, traditional contrast agents are inadequate in the diagnosis of various health conditions. Consequently, the development of targeted nano-contrast agents has become a crucial area of focus in the development of medical image-enhancing contrast agents. To fully understand the current development of nano-contrast agents, this review provides an overview of the preparation methods and research advancements in CT nano-contrast agents, MR nano-contrast agents, and CT/MR multimodal nano-contrast agents described in previous publications. Due to the physicochemical properties of nanomaterials, such as self-assembly and surface modifiability, these specific nano-contrast agents can greatly improve the targeting of lesions through various preparation methods and clearly highlight the distinction between lesions and normal tissues in both CT and MR. As a result, they have the potential to be used in the early stages of disease to improve diagnostic capacity and level in medical imaging.
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Medios de Contraste , Imagen por Resonancia Magnética , Medios de Contraste/química , Imagen por Resonancia Magnética/métodos , Espectroscopía de Resonancia Magnética , Tomografía Computarizada por Rayos X/métodos , Nanotecnología/métodosRESUMEN
Sign language (SL) has strong structural features. Various gestures and the complex trajectories of hand movements bring challenges to sign language recognition (SLR). Based on the inherent correlation between gesture and trajectory of SL action, SLR is organically divided into gesture-based recognition and gesture-related movement trajectory recognition. One hundred and twenty commonly used Chinese SL words involving 9 gestures and 8 movement trajectories, are selected as research and test objects. The method based on the amplitude state of surface electromyography (sEMG) signal and acceleration signal is used for vocabulary segmentation. The multi-sensor decision fusion method of coupled hidden Markov model is used to complete the recognition of SL vocabulary, and the average recognition rate is 90.41%. Experiments show that the method of sEMG signal and motion information fusion has good practicability in SLR.
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Reconocimiento de Normas Patrones Automatizadas , Lengua de Signos , Humanos , Electromiografía , Gestos , Mano , China , AlgoritmosRESUMEN
Segmentation of skin lesions is a critical step in the process of skin lesion diagnosis. Such segmentation is challenging due to the irregular shape, fuzzy contours and severe noise interference in the skin lesion region. Existing deep learning-based skin lesion segmentation methods are usually computationally expensive, hindering their deployment in dermoscopic devices with poor computational power. To address these challenges, we propose an ultralightweight fully asymmetric convolutional network for skin lesion segmentation, called ULFAC-Net. we use a parallel asymmetric convolutional (PAC) module to extract features instead of the traditional square convolution, and innovatively propose a PAC module with dual attention (Att-PAC) to enhance the feature representation. Based on the PAC and Att-PAC modules, we further propose a lightweight textual information submodule. To balance the number of parameters and performance of the model, we also hand-design an asymmetric encoder-decoder architecture. In this paper, we validate the effectiveness and robustness of the proposed ULFAC-Net on four publicly available skin lesion segmentation datasets (ISIC2018, ISBI2017, ISIC2016 and PH2 datasets). The experimental results show that ULFAC-Net achieves competitive segmentation performance with only 0.842 million(0.842M) parameters and 3.71 gigabytes of floating point operations (GFLOPs) compared to other state-of-the-art methods.
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Enfermedades de la Piel , Humanos , Mano , Extremidad Superior , Procesamiento de Imagen Asistido por ComputadorRESUMEN
Virtual reality (VR) technology, with the advantage of immersive visual experience, has been increasingly applied in the rehabilitation therapy of motor deficits. The functional integration of the mirror neuron system and the sensorimotor cortex under the visual perception of actions is one of the theoretical bases for the application of action observation in the neurorehabilitation of motor deficits. Whether the visual experience changes brought by VR technology can further promote this functional integration to be further confirmed. Using the exact low-resolution brain electromagnetic tomography (eLORETA) source localization method, we calculated and statistically tested the whole brain cortical voxel current density estimation under the Electroencephalogram (EEG) signals collected during action observation under the first-person and third-person perspectives in the VR scene for twenty healthy adults. Furthermore, the functional connectivity between the mirror neuron system and the sensorimotor cortex was analyzed using the lagged phase synchronization method. Under the first-person perspective in the VR scene, the current density changes of the core cortices of the mirror neuron system lead to a larger average event-related potential, more significant suppression in the α1 and α2 frequency bands of EEG signals, and a significant enhancement of functional connectivity between the core cortices of the mirror neuron system and the sensorimotor cortex. These findings indicate that compared with the traditional action observation, the visual reappearance of self-actions in the VR scene further stimulates the activity of the core cortices of the mirror neuron system, and promotes the functional integration of the core cortices of the mirror neuron system and the sensorimotor cortex.
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Ondas Encefálicas/fisiología , Conectoma , Potenciales Evocados/fisiología , Neuronas Espejo/fisiología , Corteza Sensoriomotora/fisiopatología , Realidad Virtual , Percepción Visual/fisiología , Adolescente , Adulto , Electroencefalografía , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
Electromyography (EMG) signals can be used for clinical diagnosis and biomedical applications. It is very important to reduce noise and to acquire accurate signals for the usage of the EMG signals in biomedical engineering. Since EMG signal noise has the time-varying and random characteristics, the present study proposes an adaptive Kalman filter (AKF) denoising method based on an autoregressive (AR) model. The AR model is built by applying the EMG signal, and the relevant parameters are integrated to find the state space model required to optimally estimate AKF, eliminate the noise in the EMG signal, and restore the damaged EMG signal. To be specific, AR autoregressive dynamic modeling and repair for distorted signals are affected by noise, and AKF adaptively can filter time-varying noise. The denoising method based on the self-learning mechanism of AKF exhibits certain capabilities to achieve signal tracking and adaptive filtering. It is capable of adaptively regulating the model parameters in the absence of any prior statistical knowledge regarding the signal and noise, which is aimed at achieving a stable denoising effect. By comparatively analyzing the denoising effects exerted by different methods, the EMG signal denoising method based on the AR-AKF model is demonstrated to exhibit obvious advantages.
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Electromiografía/estadística & datos numéricos , Algoritmos , Ingeniería Biomédica , Biología Computacional , Voluntarios Sanos , Humanos , Masculino , Modelos Estadísticos , Procesamiento de Señales Asistido por Computador , Relación Señal-Ruido , Análisis de OndículasRESUMEN
Electroencephalogram (EEG) and electromyogram (EMG) signals during motion control reflect the interaction between the cortex and muscle. Therefore, dynamic information regarding the cortical-muscle system is of significance for the evaluation of muscle fatigue. We treated the cortex and muscle as a whole system and then applied graph theory and symbolic transfer entropy to establish an effective cortical-muscle network in the beta band (12-30 Hz) and the gamma band (30-45 Hz). Ten healthy volunteers were recruited to participate in the isometric contraction at the level of 30% maximal voluntary contraction. Pre- and post-fatigue EEG and EMG data were recorded. According to the Borg scale, only data with an index greater than 14<19 were selected as fatigue data. The results show that after muscle fatigue: (1) the decrease in the force-generating capacity leads to an increase in STE of the cortical-muscle system; (2) increases of dynamic forces in fatigue leads to a shift from the beta band to gamma band in the activity of the cortical-muscle network; (3) the areas of the frontal and parietal lobes involved in muscle activation within the ipsilateral hemibrain have a compensatory role. Classification based on support vector machine algorithm showed that the accuracy is improved compared to the brain network. These results illustrate the regulation mechanism of the cortical-muscle system during the development of muscle fatigue, and reveal the great potential of the cortical-muscle network in analyzing motor tasks.