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1.
Brief Bioinform ; 23(3)2022 05 13.
Artículo en Inglés | MEDLINE | ID: mdl-35325050

RESUMEN

DNA N6-methyladenine (6mA) is produced by the N6 position of the adenine being methylated, which occurs at the molecular level, and is involved in numerous vital biological processes in the rice genome. Given the shortcomings of biological experiments, researchers have developed many computational methods to predict 6mA sites and achieved good performance. However, the existing methods do not consider the occurrence mechanism of 6mA to extract features from the molecular structure. In this paper, a novel deep learning method is proposed by devising DNA molecular graph feature and residual block structure for 6mA sites prediction in rice, named MGF6mARice. Firstly, the DNA sequence is changed into a simplified molecular input line entry system (SMILES) format, which reflects chemical molecular structure. Secondly, for the molecular structure data, we construct the DNA molecular graph feature based on the principle of graph convolutional network. Then, the residual block is designed to extract higher level, distinguishable features from molecular graph features. Finally, the prediction module is used to obtain the result of whether it is a 6mA site. By means of 10-fold cross-validation, MGF6mARice outperforms the state-of-the-art approaches. Multiple experiments have shown that the molecular graph feature and residual block can promote the performance of MGF6mARice in 6mA prediction. To the best of our knowledge, it is the first time to derive a feature of DNA sequence by considering the chemical molecular structure. We hope that MGF6mARice will be helpful for researchers to analyze 6mA sites in rice.


Asunto(s)
Retraso en el Despertar Posanestésico , Oryza , Adenina , ADN/genética , Metilación de ADN , Retraso en el Despertar Posanestésico/genética , Oryza/genética
2.
Sensors (Basel) ; 24(2)2024 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-38257516

RESUMEN

Compliance control strategies have been utilised for the ultraprecision polishing process for many years. Most researchers execute active compliance control strategies by employing impedance control law on a robot development platform. However, these methods are limited by the load capacity, positioning accuracy, and repeatability of polishing mechanisms. Moreover, a sophisticated actuator mounted at the end of the end-effector of robots is difficult to maintain in the polishing scenario. In contrast, a hybrid mechanism for polishing that possesses the advantages of serial and parallel mechanisms can mitigate the above problems, especially when an active compliance control strategy is employed. In this research, a high-frequency-impedance robust force control strategy is proposed. It outputs a position adjustment value directly according to a contact pressure adjustment value. An open architecture control system with customised software is developed to respond to external interrupts during the polishing procedure, implementing the active compliance control strategy on a hybrid mechanism. Through this method, the hybrid mechanism can adapt to the external environment with a given contact pressure automatically instead of relying on estimating the environment stiffness. Experimental results show that the proposed strategy adapts the unknown freeform surface without overshooting and improves the surface quality. The average surface roughness value decreases from 0.057 um to 0.027 um.

3.
BMC Nurs ; 17: 50, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30519146

RESUMEN

BACKGROUND: To adopt a healthy lifestyle is considered an essential component of nursing education. Self-rated health is a subjective assessment of health status and is consistent with objective health status. Previous studies have shown an association between self-rated health and engagement in a healthy lifestyle. Nursing students need to feel good about their subjective health status and to be able to adopt health improvements in their lifestyle before attempting to disseminate health messages to clients. The aims of this study were to compare the difference in self-rated health and health promotion lifestyle profile between senior and junior nursing students, describe correlations between self-rated health and health promotion lifestyle profile, and identify the predictors of self-rated health. METHODS: A cross-sectional descriptive survey was adopted. The study sample consisted of 314 junior and senior year nursing students from a tertiary institution. The self-reported questionnaire consisted of a single-item question to examine their self-rated health. The Health Promoting Lifestyle Profile-II: Chinese version short form (HPLP-IICR) was used to investigate the health-promoting lifestyles of the students. Descriptive statistics, Mann-Whitney U test, Chi-square test, Fisher's exact test, Spearman's correlation, and ordinal logistic regression were used to analyze the data. RESULTS: The median scores for self-rated health were 3 (Mean 3.26, IQR 3-4) and 3 (Mean 3.19, IQR 3-4) out of 5 for Year 2 and Year 5 students, respectively, with no significant difference between the two groups. The two groups of students showed no significant differences in overall score and in most subscales of the HPLP-IICR. An ordinal logistic regression showed that those students with higher health management score (OR: 1.12, 95% CI: 1.04-1.21) and who had experienced no family conflicts in the recent month than having family conflict (OR: 1.64, 95% CI: 1.01-2.66) were more likely to have higher self-rated health. CONCLUSION: Nursing education and clinical practice can undoubtedly increase the health knowledge of students, but may not lead to changes in actual health-promoting behaviours. Students with a higher health management score and no family conflicts are more likely to give a positive appraisal of their health status.

4.
Artículo en Inglés | MEDLINE | ID: mdl-38607717

RESUMEN

Photometric stereo recovers the surface normals of an object from multiple images with varying shading cues, i.e., modeling the relationship between surface orientation and intensity at each pixel. Photometric stereo prevails in superior per-pixel resolution and fine reconstruction details. However, it is a complicated problem because of the non-linear relationship caused by non-Lambertian surface reflectance. Recently, various deep learning methods have shown a powerful ability in the context of photometric stereo against non-Lambertian surfaces. This paper provides a comprehensive review of existing deep learning-based calibrated photometric stereo methods utilizing orthographic cameras and directional light sources. We first analyze these methods from different perspectives, including input processing, supervision, and network architecture. We summarize the performance of deep learning photometric stereo models on the most widely-used benchmark data set. This demonstrates the advanced performance of deep learning-based photometric stereo methods. Finally, we give suggestions and propose future research trends based on the limitations of existing models.

5.
IEEE Trans Med Imaging ; 43(7): 2679-2692, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38421850

RESUMEN

In medical image analysis, anatomical landmarks usually contain strong prior knowledge of their structural information. In this paper, we propose to promote medical landmark localization by modeling the underlying landmark distribution via normalizing flows. Specifically, we introduce the flow-based landmark distribution prior as a learnable objective function into a regression-based landmark localization framework. Moreover, we employ an integral operation to make the mapping from heatmaps to coordinates differentiable to further enhance heatmap-based localization with the learned distribution prior. Our proposed Normalizing Flow-based Distribution Prior (NFDP) employs a straightforward backbone and non-problem-tailored architecture (i.e., ResNet18), which delivers high-fidelity outputs across three X-ray-based landmark localization datasets. Remarkably, the proposed NFDP can do the job with minimal additional computational burden as the normalizing flows module is detached from the framework on inferencing. As compared to existing techniques, our proposed NFDP provides a superior balance between prediction accuracy and inference speed, making it a highly efficient and effective approach. The source code of this paper is available at https://github.com/jacksonhzx95/NFDP.


Asunto(s)
Algoritmos , Puntos Anatómicos de Referencia , Procesamiento de Imagen Asistido por Computador , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Puntos Anatómicos de Referencia/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos
6.
Eur Urol ; 2024 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-38692956

RESUMEN

BACKGROUND: Conventionally, standard resection (SR) is performed by resecting the bladder tumour in a piecemeal manner. En bloc resection of the bladder tumour (ERBT) has been proposed as an alternative technique in treating non-muscle-invasive bladder cancer (NMIBC). OBJECTIVE: To investigate whether ERBT could improve the 1-yr recurrence rate of NMIBC, as compared with SR. DESIGN, SETTING, AND PARTICIPANTS: A multicentre, randomised, phase 3 trial was conducted in Hong Kong. Adults with bladder tumour(s) of ≤3 cm were enrolled from April 2017 to December 2020, and followed up until 1 yr after surgery. INTERVENTION: Patients were randomly assigned to receive either ERBT or SR in a 1:1 ratio. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was 1-yr recurrence rate. A modified intention-to-treat analysis on patients with histologically confirmed NMIBC was performed. The main secondary outcomes included detrusor muscle sampling rate, operative time, hospital stay, 30-d complications, any residual or upstaging of disease upon second-look transurethral resection, and 1-yr progression rate. RESULTS AND LIMITATIONS: A total of 350 patients underwent randomisation, and 276 patients were histologically confirmed to have NMIBC. At 1 yr, 31 patients in the ERBT group and 46 in the SR group developed recurrence; the Kaplan-Meier estimate of 1-yr recurrence rates were 29% (95% confidence interval, 18-37) in the ERBT group and 38% (95% confidence interval, 28-46) in the SR group (p = 0.007). Upon a subgroup analysis, patients with 1-3 cm tumour, single tumour, Ta disease, or intermediate-risk NMIBC had a significant benefit from ERBT. None of the patients in the ERBT group and three patients in the SR group developed progression to muscle-invasive bladder cancer; the Kaplan-Meier estimates of 1-yr progression rates were 0% in the ERBT group and 2.6% (95% confidence interval, 0-5.5) in the SR group (p = 0.065). The median operative time was 28 min (interquartile range, 20-45) in the ERBT group and 22 min (interquartile range, 15-30) in the SR group (p < 0.001). All other secondary outcomes were similar in the two groups. CONCLUSIONS: In patients with NMIBC of ≤3 cm, ERBT resulted in a significant reduction in the 1-yr recurrence rate when compared with SR (funded by GRF/ECS, RGC, reference no.: 24116518; ClinicalTrials.gov number, NCT02993211). PATIENT SUMMARY: Conventionally, non-muscle-invasive bladder cancer is treated by resecting the bladder tumour in a piecemeal manner. In this study, we found that en bloc resection, that is, removal of the bladder tumour in one piece, could reduce the 1-yr recurrence rate of non-muscle-invasive bladder cancer.

7.
Artículo en Inglés | MEDLINE | ID: mdl-37037244

RESUMEN

Weakly supervised video anomaly detection (WS-VAD) aims to identify the snippets involving anomalous events in long untrimmed videos, with solely video-level binary labels. A typical paradigm among the existing WS-VAD methods is to employ multiple modalities as inputs, e.g., RGB, optical flow, and audio, as they can provide sufficient discriminative clues that are robust to the diverse, complicated real-world scenes. However, such a pipeline has high reliance on the availability of multiple modalities and is computationally expensive and storage demanding in processing long sequences, which limits its use in some applications. To address this dilemma, we propose a privileged knowledge distillation (KD) framework dedicated to the WS-VAD task, which can maintain the benefits of exploiting additional modalities, while avoiding the need for using multimodal data in the inference phase. We argue that the performance of the privileged KD framework mainly depends on two factors: 1) the effectiveness of the multimodal teacher network and 2) the completeness of the useful information transfer. To obtain a reliable teacher network, we propose a cross-modal interactive learning strategy and an anomaly normal discrimination loss, which target learning task-specific cross-modal features and encourage the separability of anomalous and normal representations, respectively. Furthermore, we design both representation-and logits-level distillation loss functions, which force the unimodal student network to distill abundant privileged knowledge from the well-trained multimodal teacher network, in a snippet-to-video fashion. Extensive experimental results on three public benchmarks demonstrate that the proposed privileged KD framework can train a lightweight yet effective detector, for localizing anomaly events under the supervision of video-level annotations.

8.
Artículo en Inglés | MEDLINE | ID: mdl-37922172

RESUMEN

In this paper, we propose a novel method, namely GR-PSN, which learns surface normals from photometric stereo images and generates the photometric images under distant illumination from different lighting directions and surface materials. The framework is composed of two subnetworks, named GeometryNet and ReconstructNet, which are cascaded to perform shape reconstruction and image rendering in an end-to-end manner. ReconstructNet introduces additional supervision for surface-normal recovery, forming a closed-loop structure with GeometryNet. We also encode lighting and surface reflectance in ReconstructNet, to achieve arbitrary rendering. In training, we set up a parallel framework to simultaneously learn two arbitrary materials for an object, providing an additional transform loss. Therefore, our method is trained based on the supervision by three different loss functions, namely the surface-normal loss, reconstruction loss, and transform loss. We alternately input the predicted surface-normal map and the ground-truth into ReconstructNet, to achieve stable training for ReconstructNet. Experiments show that our method can accurately recover the surface normals of an object with an arbitrary number of inputs, and can re-render images of the object with arbitrary surface materials. Extensive experimental results show that our proposed method outperforms those methods based on a single surface recovery network and shows realistic rendering results on 100 different materials. Our code can be found in https://github.com/Kelvin-Ju/GR-PSN.

9.
Artículo en Inglés | MEDLINE | ID: mdl-36094995

RESUMEN

The popularity of wearable devices has increased the demands for the research on first-person activity recognition. However, most of the current first-person activity datasets are built based on the assumption that only the human-object interaction (HOI) activities, performed by the camera-wearer, are captured in the field of view. Since humans live in complicated scenarios, in addition to the first-person activities, it is likely that third-person activities performed by other people also appear. Analyzing and recognizing these two types of activities simultaneously occurring in a scene is important for the camera-wearer to understand the surrounding environments. To facilitate the research on concurrent first-and third-person activity recognition (CFT-AR), we first created a new activity dataset, namely PolyU concurrent first-and third-person (CFT) Daily, which exhibits distinct properties and challenges, compared with previous activity datasets. Since temporal asynchronism and appearance gap usually exist between the first-and third-person activities, it is crucial to learn robust representations from all the activity-related spatio-temporal positions. Thus, we explore both holistic scene-level and local instance-level (person-level) features to provide comprehensive and discriminative patterns for recognizing both first-and third-person activities. On the one hand, the holistic scene-level features are extracted by a 3-D convolutional neural network, which is trained to mine shared and sample-unique semantics between video pairs, via two well-designed attention-based modules and a self-knowledge distillation (SKD) strategy. On the other hand, we further leverage the extracted holistic features to guide the learning of instance-level features in a disentangled fashion, which aims to discover both spatially conspicuous patterns and temporally varied, yet critical, cues. Experimental results on the PolyU CFT Daily dataset validate that our method achieves the state-of-the-art performance.

10.
IEEE Trans Med Imaging ; 41(7): 1610-1624, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35041596

RESUMEN

Volume Projection Imaging from ultrasound data is a promising technique to visualize spine features and diagnose Adolescent Idiopathic Scoliosis. In this paper, we present a novel multi-task framework to reduce the scan noise in volume projection images and to segment different spine features simultaneously, which provides an appealing alternative for intelligent scoliosis assessment in clinical applications. Our proposed framework consists of two streams: i) A noise removal stream based on generative adversarial networks, which aims to achieve effective scan noise removal in a weakly-supervised manner, i.e., without paired noisy-clean samples for learning; ii) A spine segmentation stream, which aims to predict accurate bone masks. To establish the interaction between these two tasks, we propose a selective feature-sharing strategy to transfer only the beneficial features, while filtering out the useless or harmful information. We evaluate our proposed framework on both scan noise removal and spine segmentation tasks. The experimental results demonstrate that our proposed method achieves promising performance on both tasks, which provides an appealing approach to facilitating clinical diagnosis.


Asunto(s)
Escoliosis , Adolescente , Algoritmos , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Escoliosis/diagnóstico por imagen , Columna Vertebral/diagnóstico por imagen , Ultrasonografía
11.
IEEE Trans Image Process ; 30: 6081-6095, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34185645

RESUMEN

Invertible image decolorization is a useful color compression technique to reduce the cost in multimedia systems. Invertible decolorization aims to synthesize faithful grayscales from color images, which can be fully restored to the original color version. In this paper, we propose a novel color compression method to produce invertible grayscale images using invertible neural networks (INNs). Our key idea is to separate the color information from color images, and encode the color information into a set of Gaussian distributed latent variables via INNs. By this means, we force the color information lost in grayscale generation to be independent of the input color image. Therefore, the original color version can be efficiently recovered by randomly re-sampling a new set of Gaussian distributed variables, together with the synthetic grayscale, through the reverse mapping of INNs. To effectively learn the invertible grayscale, we introduce the wavelet transformation into a UNet-like INN architecture, and further present a quantization embedding to prevent the information omission in format conversion, which improves the generalizability of the framework in real-world scenarios. Extensive experiments on three widely used benchmarks demonstrate that the proposed method achieves a state-of-the-art performance in terms of both qualitative and quantitative results, which shows its superiority in multimedia communication and storage systems.

12.
Bioinformatics ; 22(22): 2722-8, 2006 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-17000749

RESUMEN

MOTIVATION: Promoter prediction is important for the analysis of gene regulations. Although a number of promoter prediction algorithms have been reported in literature, significant improvement in prediction accuracy remains a challenge. In this paper, an effective promoter identification algorithm, which is called PromoterExplorer, is proposed. In our approach, we analyze the different roles of various features, that is, local distribution of pentamers, positional CpG island features and digitized DNA sequence, and then combine them to build a high-dimensional input vector. A cascade AdaBoost-based learning procedure is adopted to select the most 'informative' or 'discriminating' features to build a sequence of weak classifiers, which are combined to form a strong classifier so as to achieve a better performance. The cascade structure used for identification can also reduce the false positive. RESULTS: PromoterExplorer is tested based on large-scale DNA sequences from different databases, including the EPD, DBTSS, GenBank and human chromosome 22. Experimental results show that consistent and promising performance can be achieved.


Asunto(s)
Biología Computacional/métodos , Islas de CpG , Regiones Promotoras Genéticas , Análisis de Secuencia de ADN/métodos , Algoritmos , Animales , Interpretación Estadística de Datos , Bases de Datos Genéticas , Bases de Datos de Proteínas , Humanos , Reconocimiento de Normas Patrones Automatizadas , Lenguajes de Programación , Análisis de Secuencia de Proteína , Programas Informáticos
13.
IEEE Trans Image Process ; 15(9): 2481-92, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16948295

RESUMEN

In this paper, a novel Gabor-based kernel principal component analysis (PCA) with doubly nonlinear mapping is proposed for human face recognition. In our approach, the Gabor wavelets are used to extract facial features, then a doubly nonlinear mapping kernel PCA (DKPCA) is proposed to perform feature transformation and face recognition. The conventional kernel PCA nonlinearly maps an input image into a high-dimensional feature space in order to make the mapped features linearly separable. However, this method does not consider the structural characteristics of the face images, and it is difficult to determine which nonlinear mapping is more effective for face recognition. In this paper, a new method of nonlinear mapping, which is performed in the original feature space, is defined. The proposed nonlinear mapping not only considers the statistical property of the input features, but also adopts an eigenmask to emphasize those important facial feature points. Therefore, after this mapping, the transformed features have a higher discriminating power, and the relative importance of the features adapts to the spatial importance of the face images. This new nonlinear mapping is combined with the conventional kernel PCA to be called "doubly" nonlinear mapping kernel PCA. The proposed algorithm is evaluated based on the Yale database, the AR database, the ORL database and the YaleB database by using different face recognition methods such as PCA, Gabor wavelets plus PCA, and Gabor wavelets plus kernel PCA with fractional power polynomial models. Experiments show that consistent and promising results are obtained.


Asunto(s)
Algoritmos , Inteligencia Artificial , Biometría/métodos , Cara/anatomía & histología , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Reconocimiento de Normas Patrones Automatizadas/métodos , Simulación por Computador , Humanos , Almacenamiento y Recuperación de la Información/métodos , Modelos Biológicos , Modelos Estadísticos , Dinámicas no Lineales , Análisis de Componente Principal , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
14.
IEEE Trans Image Process ; 15(5): 1182-91, 2006 May.
Artículo en Inglés | MEDLINE | ID: mdl-16671299

RESUMEN

A different contour search algorithm is presented in this paper that provides a faster convergence to the object contours than both the greedy snake algorithm (GSA) and the fast greedy snake (FGSA) algorithm. This new algorithm performs the search in an alternate skipping way between the even and odd nodes (snaxels) of a snake with different step sizes such that the snake moves to a likely local minimum in a twisting way. The alternative step sizes are adjusted so that the snake is less likely to be trapped at a pseudo-local minimum. The iteration process is based on a coarse-to-fine approach to improve the convergence. The proposed algorithm is compared with the FGSA algorithm that employs two alternating search patterns without altering the search step size. The algorithm is also applied in conjunction with the subband decomposition to extract face profiles in a hierarchical way.


Asunto(s)
Algoritmos , Inteligencia Artificial , Cara/anatomía & histología , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Almacenamiento y Recuperación de la Información/métodos , Reconocimiento de Normas Patrones Automatizadas/métodos , Humanos
15.
IEEE Trans Cybern ; 46(2): 546-57, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25781973

RESUMEN

It is often a difficult task to accurately segment images with intensity inhomogeneity, because most of representative algorithms are region-based that depend on intensity homogeneity of the interested object. In this paper, we present a novel level set method for image segmentation in the presence of intensity inhomogeneity. The inhomogeneous objects are modeled as Gaussian distributions of different means and variances in which a sliding window is used to map the original image into another domain, where the intensity distribution of each object is still Gaussian but better separated. The means of the Gaussian distributions in the transformed domain can be adaptively estimated by multiplying a bias field with the original signal within the window. A maximum likelihood energy functional is then defined on the whole image region, which combines the bias field, the level set function, and the piecewise constant function approximating the true image signal. The proposed level set method can be directly applied to simultaneous segmentation and bias correction for 3 and 7T magnetic resonance images. Extensive evaluation on synthetic and real-images demonstrate the superiority of the proposed method over other representative algorithms.

16.
Technol Cancer Res Treat ; 15(1): 44-54, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25520271

RESUMEN

OBJECTIVE: This preliminary study aims to verify the effectiveness of the additional information provided by spectral computed tomography (CT) with the proposed computer-aided diagnosis (CAD) scheme to differentiate pancreatic serous oligocystic adenomas (SOAs) from mucinous cystic neoplasms of pancreas cystic lesions. MATERIALS AND METHODS: This study was conducted from January 2010 to October 2013. Twenty-three patients (5 men and 18 women; mean age, 43.96 years old) with SOA and 19 patients (3 men and 16 women; mean age, 41.74 years old) with MCN were included in this retrospective study. Two types of features were collected by dual-energy spectral CT imaging as follows: conventional and additional quantitative spectral CT features. Classification results of the CAD scheme were compared using the conventional features and full feature data set. Important features were selected using support vector machine classification method combined with feature-selection technique. The optimal cutoff values of selected features were determined through receiver-operating characteristic curve analyses. RESULTS: Combining conventional features with additional spectral CT features improved the overall accuracy from 88.37% to 93.02%. The selected features of the proposed CAD scheme were tumor size, contour, location, and low-energy CT values (43 keV). Iodine-water basis material pair densities in both arterial phase (AP) and portal venous phase (PP) were important factors for differential diagnosis of SOA and MCN. The optimal cutoff values of long axis, short axis, 40 keV monochromatic CT value in AP, iodine (water) density in AP, 43 keV monochromatic CT value in PP, and iodine (water) density in PP were 3.4 mm, 3.1 mm, 35.7 Hu, 0.32533 mg/mL, 39.4 Hu, and 0.348 mg/mL, respectively. CONCLUSION: The combination of conventional features and additional information provided by dual-energy spectral CT shows a high accuracy in the CAD scheme. The quantitative information of spectral CT may prove useful in the diagnosis and classification of SOAs and MCNs with machine learning algorithms.


Asunto(s)
Adenoma/diagnóstico por imagen , Neoplasias Quísticas, Mucinosas y Serosas/diagnóstico por imagen , Neoplasias Pancreáticas/diagnóstico por imagen , Adulto , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis de Componente Principal , Curva ROC , Estudios Retrospectivos , Máquina de Vectores de Soporte , Tomografía Computarizada por Rayos X
17.
J Endourol ; 30(2): 160-4, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26414736

RESUMEN

OBJECTIVE: Traditionally, fluoroscopy or ultrasound (US) or both are used for guiding tract creation during percutaneous nephrolithotomy (PCNL). However, the use of fluoroscopy inevitably incurs radiation exposure, which should be cut down as much as possible in view of its potential adverse effects on health: both deterministic effects and stochastic effects. Conventional US guidance, being radiation free, can serve the purpose, but it is difficult to visualize the needle tract during screening without a needle-guiding system fixed to the transducer, and hence, there is a lack of predictability and sense of security. The objective of this study is to assess the feasibility of using US with navigation system (USNS) to solve the above problems. PATIENTS AND METHODS: In 2014, we performed PCNL on 18 patients with USNS guidance. During the puncture step, the magnetic field-based navigation US could help visualize the position of the needle tract in relation to the target calix. The procedure was done in free hand without the usage of needle-guiding system attached to the transducer. Needle deviation could be detected and adjusted immediately to achieve precise puncture. RESULTS: Of the 18 patients, 83.3% (15/18) of them had their punctures effectively done with a single attempt. Three puncture procedures were performed by two urologic trainees without any previous USNS experience. The mean fluoroscopy time during dilatation was 74.6s, with no radiation at all during the puncture step. The stone clearance rate was 72.2%, with 66.7% (12/18) being tubeless procedures. The mean length of hospital stay was 4.8 days. No immediate complications related to the puncture procedure were found. CONCLUSIONS: USNS can provide radiation-free guidance for tract creation in PCNL. It is predictable, precise, reliable, and safe. Most importantly, the technique is easy to learn, particularly for urologists who are new to PCNL.


Asunto(s)
Cálculos Renales/cirugía , Riñón/cirugía , Campos Magnéticos , Nefrostomía Percutánea/métodos , Cirugía Asistida por Computador/métodos , Adulto , Anciano , Estudios de Cohortes , Femenino , Fluoroscopía , Hong Kong , Humanos , Riñón/diagnóstico por imagen , Cálculos Renales/diagnóstico por imagen , Tiempo de Internación , Masculino , Persona de Mediana Edad , Agujas , Estudios Prospectivos , Punciones , Transductores , Ultrasonografía , Urología
18.
IEEE Trans Image Process ; 24(8): 2317-27, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25781876

RESUMEN

Face recognition methods, which usually represent face images using holistic or local facial features, rely heavily on alignment. Their performances also suffer a severe degradation under variations in expressions or poses, especially when there is one gallery per subject only. With the easy access to high-resolution (HR) face images nowadays, some HR face databases have recently been developed. However, few studies have tackled the use of HR information for face recognition or verification. In this paper, we propose a pose-invariant face-verification method, which is robust to alignment errors, using the HR information based on pore-scale facial features. A new keypoint descriptor, namely, pore-Principal Component Analysis (PCA)-Scale Invariant Feature Transform (PPCASIFT)-adapted from PCA-SIFT-is devised for the extraction of a compact set of distinctive pore-scale facial features. Having matched the pore-scale features of two-face regions, an effective robust-fitting scheme is proposed for the face-verification task. Experiments show that, with one frontal-view gallery only per subject, our proposed method outperforms a number of standard verification methods, and can achieve excellent accuracy even the faces are under large variations in expression and pose.


Asunto(s)
Identificación Biométrica/métodos , Cara/anatomía & histología , Procesamiento de Imagen Asistido por Computador/métodos , Piel/anatomía & histología , Algoritmos , Bases de Datos Factuales , Humanos , Análisis de Componente Principal
19.
IEEE Trans Cybern ; 45(8): 1575-86, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25291809

RESUMEN

The human visual system (HVS) can reliably perceive salient objects in an image, but, it remains a challenge to computationally model the process of detecting salient objects without prior knowledge of the image contents. This paper proposes a visual-attention-aware model to mimic the HVS for salient-object detection. The informative and directional patches can be seen as visual stimuli, and used as neuronal cues for humans to interpret and detect salient objects. In order to simulate this process, two typical patches are extracted individually and in parallel from the intensity channel and the discriminant color channel, respectively, as the primitives. In our algorithm, an improved wavelet-based salient-patch detector is used to extract the visually informative patches. In addition, as humans are sensitive to orientation features, and as directional patches are reliable cues, we also propose a method for extracting directional patches. These two different types of patches are then combined to form the most important patches, which are called preferential patches and are considered as the visual stimuli applied to the HVS for salient-object detection. Compared with the state-of-the-art methods for salient-object detection, experimental results using publicly available datasets show that our produced algorithm is reliable and effective.


Asunto(s)
Atención/fisiología , Procesamiento de Imagen Asistido por Computador/métodos , Modelos Neurológicos , Percepción Visual/fisiología , Algoritmos , Bases de Datos Factuales , Humanos , Estimulación Luminosa
20.
Comput Biol Med ; 63: 124-32, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26073099

RESUMEN

Bladder cancer is a common cancer in genitourinary malignancy. For muscle invasive bladder cancer, surgical removal of the bladder, i.e. radical cystectomy, is in general the definitive treatment which, unfortunately, carries significant morbidities and mortalities. Accurate prediction of the mortality of radical cystectomy is therefore needed. Statistical methods have conventionally been used for this purpose, despite the complex interactions of high-dimensional medical data. Machine learning has emerged as a promising technique for handling high-dimensional data, with increasing application in clinical decision support, e.g. cancer prediction and prognosis. Its ability to reveal the hidden nonlinear interactions and interpretable rules between dependent and independent variables is favorable for constructing models of effective generalization performance. In this paper, seven machine learning methods are utilized to predict the 5-year mortality of radical cystectomy, including back-propagation neural network (BPN), radial basis function (RBFN), extreme learning machine (ELM), regularized ELM (RELM), support vector machine (SVM), naive Bayes (NB) classifier and k-nearest neighbour (KNN), on a clinicopathological dataset of 117 patients of the urology unit of a hospital in Hong Kong. The experimental results indicate that RELM achieved the highest average prediction accuracy of 0.8 at a fast learning speed. The research findings demonstrate the potential of applying machine learning techniques to support clinical decision making.


Asunto(s)
Cistectomía , Bases de Datos Factuales , Modelos Biológicos , Máquina de Vectores de Soporte , Neoplasias de la Vejiga Urinaria/mortalidad , Neoplasias de la Vejiga Urinaria/cirugía , Anciano , Supervivencia sin Enfermedad , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Tasa de Supervivencia
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