基于改进阈值的VGG网络的新冠肺炎CT图像自动诊断算法

肺部CT能够较准确地鉴定新冠肺炎病例,但医生工作量较大,本研究提出一种基于改进阈值的VGG网络的新冠肺炎CT图像自动诊断算法,通过该模型可快速准确地完成新冠肺炎病例的自动识别,为进一步控制其传播提供帮助。通过比较卷积神经网络VGG中的VGG-11、VGG-13、VGG-16,获得准确率较高的新冠肺炎CT图像自动诊断模型VGG-13,并在此基础上通过改进阈值的方式使准确率由86%提高到了89%,进一步提高诊断的准确性。     

基于3D ResUnet网络的肺结节分割

目的:将深度残差结构和U-Net网络结合形成新的网络ResUnet,并利用ResUnet深度学习网络结构对胸部CT影像进行图像分割以提取肺结节区域。方法:使用的CT影像数据来源于LUNA16数据集,首先对CT图像预处理提取出肺实质,然后对其截取立体图像块并进行数据增强来扩充样本数,形成相应的肺结节掩膜图像,最后将生成的样本输入到ResUnet模型中进行训练。结果:本研究模型最终的精度和召回率分别为35.02%和97.68%。结论:该模型能自动学习肺结节特征,为后续的肺癌自动诊断提供可靠基础,减少临床诊断的成本并节省医生诊断的时间。 【关键词】肺结节;分割;深度残差结构;召回率;ResUnet     

基于深度学习的儿童肺炎检测模型建立及应用

目的:基于深度学习根据儿童胸部X光正位数字影像构建肺炎自动判别模型,辅助临床诊断,提高影像诊断效率。方法:首先通过选取公开数据集5 856张儿童胸片（肺炎4 273张,正常1 583张）,分为训练集、验证集和测试集,基于Resnet-50神经网络构建儿童肺炎自动判别模型,利用验证集选取最优模型,在测试集上做内部独立验证。进一步收集6家医疗单位共611张儿童胸片（肺炎300张,正常311张）进行外部验证,并根据验证结果对模型进行微调后再次测试,使模型更适合临床使用。结果:基于深度学习技术和公开数据集数据构建儿童肺炎自动判别模型,准确率为98.48%,精确率为99.54%,召回率为98.81%,F1-score为98.86%,AUC为0.999。外部验证初始结果准确率为59.90%,选用部分外部验证数据微调模型后,独立测试准确度提升至85.00%。结论:基于深度学习根据公开数据集构建肺炎自动判别模型具有可行性,准确率达98.48%,在实际临床使用时应根据具体使用条件选取适量数据集对模型进行微调。     

基于栈式深度多项式网络集成学习框架的帕金森病计算机辅助诊断

特征表达是基于磁共振成像(MRI)的帕金森病(PD)计算机辅助诊断系统诊断准确性的重要决定因素。深度多项式网络(DPN)是一种新的有监督深度学习算法,对于小数据集具有良好的特征表达能力。本文提出一种面向PD计算机辅助诊断的栈式DPN(SDPN)集成学习框架,以有效提高基于小数据的PD辅助诊断准确性。本框架对所提取的MRI特征的每一个特征子集分别通过SDPN得到新的特征表达,然后采用支持向量机(SVM)对每个子集进行分类,再对所有分类器进行集成学习,得到最终的PD诊断结果。通过对公开的帕金森病数据库PPMI进行实验,基于脑网络特征的分类精度、敏感度和特异性分别为90.15%、85.48%和93.27%;而基于多视图脑区特征的分类精度、敏感度和特异性分别为87.18%、86.90%和87.27%。与在PPMI数据库中的MRI数据集进行实验的其他算法研究相比,本文所提出的算法获得了更好的分类结果。本文研究表明了所提出的SDPN集成学习框架的有效性,具有应用于PD计算机辅助诊断的可行性。     

基于眼肌语义分割和特征提取的甲状腺相关眼病诊断算法研究

目的 甲状腺相关眼病(thyroid-associated ophthalmopathy, TAO)是常见的眼病之一，通过CT图像进行诊断和筛查对治疗有着重要意义，但传统方法依赖有经验的医生对CT进行分析和诊断，尚无有效的自动化方法。为此本文提出一种可以从CT图像中自动提取特征进行TAO诊断的方法，辅助医生进行诊断。方法 设计了Unet-Orbit分割网络对CT中的眼肌进行图像分割，随后采用影像组学工具(PyRadiomics)从分割结果中的眼肌区域提取数值化特征。为了更好地利用影像组学的特征，设计了一个特征提取网络，采用自动编码器框架。将不同的眼肌提取到的特征，通过特征合并和变换进一步得到一组新特征。最后采用来自上海交通大学医学院附属第九人民医院的1 912个CT图像数据集，对使用原始影像组学特征的分类器与使用特征提取网络后的特征的分类器进行了比较。结果 在医院数据集上，该模型的诊断准确率、灵敏度和特异性分别为87.34%、84.73%和89.96%。结论 语义分割网络可以高效分割眼肌区域，特征提取网络得到的新特征可以提升多种不同分类器在TAO诊断的准确率，可能为TAO的诊断提供一个...     

基于空洞空间金字塔池化的U-Net网络在肺部图像分割上的应用

目的：胸部X线图像中肺野的自动分割是相关疾病筛查和诊断的关键步骤,为了适应计算机辅助诊断系统的要求,提出一种基于空洞空间金字塔池化的U-Net网络对胸部X线图像中肺野进行自动分割。方法：在编码和解码之间引入带有空洞卷积的空间金字塔池化用于扩大接受域;同时,在多个尺度上获取图像上下文信息,用于从胸片中分割肺野,使用Montgomery数据集及深圳数据集进行验证。根据医学图像分割常用指标准确性、Dice相似系数及交并比评价基于空洞空间金字塔池化的U-Net网络分割肺野的性能。结果：验证准确性为98.29%,Dice相似系数为96.61%,交并比为93.47%。结论：本文提出一种基于空洞空间金字塔池化的U-Net网络用于分割肺野,相较于其他方法学习到更多边缘分割特征,取得更好的分割结果。     

基于多维信息融合的无监督快速肺部血管分割算法

肺部CT图像中血管的分割在疾病的诊断和外科治疗中起着重要作用。在医学图像相关任务中，深度学习因其强大的表现能力和辨别学习能力，被广泛应用。然而基于深度学习的方法需要昂贵的GPU和大量有标签的数据。为了更好地平衡肺部CT图像血管分割的准确性和效率，提出了一种基于多维信息融合的快速有效的血管分割算法(MDF),该算法设计2D分割分支和3D分割分支来充分利用2D和3D信息，在最后的分割结果中对多个分支的结果进行合并，能够快速有效地融入到传统无监督算法。与此同时，MDF具有强大并行能力，能够在低端显卡上被显著加速。选取VESSEL12挑战的23例数据以及CARVE14挑战赛的55例数据对所提出的基于多维信息融合的血管分割算法进行了全面评估。实验结果表明，MDF与其他无监督算法相比有着更高的精度，在CARVE14数据集上血管的DSC系数达到了0.716。除此之外，通过GPU并行优化，运行速度大约为基于Hession矩阵的Frangi多尺度算法的20倍。与深度学习算法相比，MDF在不同数据集上的泛化能力更强。     

基于深度可分离稠密网络的新型冠状病毒肺炎X线图像检测方法研究

新型冠状病毒肺炎肆虐全球,为了更加快速地诊断新型冠状病毒肺炎(COVID-19),本文提出一种深度可分离稠密网络DWSDenseNet,以2 905例COVID-19胸部X线平片影像作为实验数据集,在网络训练前使用限制对比度自适应直方图均衡化(CLAHE)算法对图像进行预处理,增强图像的对比度,将预处理之后的图像放入训练网络中,采用Leaky ReLU作为激活函数,调整参数以达到最优。本文引入VGG16、ResNet18、ResNet34、DenseNet121和SDenseNet模型进行比较,所提出的网络在三分类实验中相较于ResNet34在准确率、灵敏度和特异性上分别提高了2.0%、2.3%、1.5%。相对于改进前的SDenseNet网络,本文模型的参数量减少了43.9%,但分类效果并未下降。通过对比实验可以发现,本文所提出的深度可分离稠密网络对COVID-19胸部X线平片影像数据集具有良好的分类效果,在保证准确率的情况下,深度可分离卷积能够有效地降低模型参数量。     

基于深度学习的低剂量CT图像去噪

目的:提出一种基于深度学习的方法用于低剂量CT（LDCT）图像的噪声去除。方法:首先进行滤波反投影重建,然后利用多尺度并行残差U-net（MPR U-net）的深度学习模型对重建后的LDCT图像进行去噪。实验数据采用LoDoPaB-CT挑战赛的医学CT数据集,其中训练集35 820张图像,验证集3 522张图像,测试集3 553张图像,并采用峰值信噪比（PSNR）与结构相似性系数（SSIM）来评估模型的去噪效果。结果:LDCT图像处理前后PSNR分别为28.80、38.22 dB,SSIM分别为0.786、0.966,平均处理时间为0.03 s。结论:MPR U-net深度学习模型能较好地去除LDCT图像噪声,提升PSNR,保留更多图像细节。     

基于Gabor小波和深度置信网络的肺结节良恶性分类研究

目的从频率域角度研究孤立性肺结节纹理特征,探讨深度置信网络对其良恶性的分类效果,达到辅助医生提高早期肺癌诊断准确率的目的。方法首先,利用Gabor小波对1012例患者的1072张孤立性肺结节CT图像提取纹理特征,用受限玻尔兹曼机对特征向量进行编码,学习数据本质特征;然后,用得到的纹理特征向量集训练深度置信网络,构建分类模型;最后,通过K折交叉验证法从准确性、ROC曲线下面积(AUC值)以及时间成本方面对本文提出的研究方法进行评估。结果经Gabor小波变换并构建DBN分类模型的准确度为83.75%,测试集的AUC值为0.78。与传统支持向量机分类模型相比,所提方法的准确度上升了0.56%,时间成本缩减了一半。结论利用Gabor小波从频率域提取纹理特征,结合深度置信网络构建分类模型能够取得较好的分类效果,一定程度上能够为临床诊断肺结节的良恶性提供参考。     

Auxiliary Diagnosis for COVID-19 with Deep Transfer Learning

To assist physicians identify COVID-19 and its manifestations through the automatic COVID-19 recognition and classification in chest CT images with deep transfer learning. In this retrospective study, the used chest CT image dataset covered 422 subjects, including 72 confirmed COVID-19 subjects (260 studies, 30,171 images), 252 other pneumonia subjects (252 studies, 26,534 images) that contained 158 viral pneumonia subjects and 94 pulmonary tuberculosis subjects, and 98 normal subjects (98 studies, 29,838 images). In the experiment, subjects were split into training (70%), validation (15%) and testing (15%) sets. We utilized the convolutional blocks of ResNets pretrained on the public social image collections and modified the top fully connected layer to suit our task (the COVID-19 recognition). In addition, we tested the proposed method on a finegrained classification task; that is, the images of COVID-19 were further split into 3 main manifestations (ground-glass opacity with 12,924 images, consolidation with 7418 images and fibrotic streaks with 7338 images). Similarly, the data partitioning strategy of 70%-15%-15% was adopted. The best performance obtained by the pretrained ResNet50 model is 94.87% sensitivity, 88.46% specificity, 91.21% accuracy for COVID-19 versus all other groups, and an overall accuracy of 89.01% for the three-category classification in the testing set. Consistent performance was observed from the COVID-19 manifestation classification task on images basis, where the best overall accuracy of 94.08% and AUC of 0.993 were obtained by the pretrained ResNet18 (P < 0.05). All the proposed models have achieved much satisfying performance and were thus very promising in both the practical application and statistics. Transfer learning is worth for exploring to be applied in recognition and classification of COVID-19 on CT images with limited training data. It not only achieved higher sensitivity (COVID-19 vs the rest) but also took far less time than radiologists, which is expected to give the auxiliary diagnosis and reduce the workload for the radiologists.     

基于深度特征融合的肺炎影像识别研究

在新型冠状病毒肺炎(COVID-19)疫情背景下,肺炎影像快速准确诊断显得尤为重要.针对肺炎影像纹理及细粒度特征受噪声影响大、常规手段识别率低等问题,本研究构建了一种新的基于跨层连接机制的多主干网络特征融合卷积模型.依托并行特征挖掘思路,利用多尺度感受野挖掘融合来捕获医学图像的局部细节,实现对COVID-19医学影像的...     

U-Net改进及其在新冠肺炎图像分割的应用

CT成像已成为检测新型冠状病毒肺炎（COVID-19）最重要的步骤之一。针对手动分割患者胸部CT图像中毛玻璃混浊区域繁琐的问题提出了一种自注意力循环残差U型网络模型来实现COVID-19患者肺部CT图像的自动分割,辅助医生诊断。在U-Net模型的基础上引入了循环残差模块和自注意力机制来加强对特征信息的抓取从而提升分割精度。在公开数据集上的分割实验结果显示,该算法的Dice系数、敏感度和特异度分别达到了85.36%、76.64%和76.25%,与其他算法相比具有良好的分割效果。     

Quantitative Assessment of Chest CT Patterns in COVID-19 and Bacterial Pneumonia Patients: a Deep Learning Perspective

BackgroundIt is difficult to distinguish subtle differences shown in computed tomography (CT) images of coronavirus disease 2019 (COVID-19) and bacterial pneumonia patients, which often leads to an inaccurate diagnosis. It is desirable to design and evaluate interpretable feature extraction techniques to describe the patient''s condition.MethodsThis is a retrospective cohort study of 170 confirmed patients with COVID-19 or bacterial pneumonia acquired at Yeungnam University Hospital in Daegu, Korea. The Lung and lesion regions were segmented to crop the lesion into 2D patches to train a classifier model that could differentiate between COVID-19 and bacterial pneumonia. The K-means algorithm was used to cluster deep features extracted by the trained model into 20 groups. Each lesion patch cluster was described by a characteristic imaging term for comparison. For each CT image containing multiple lesions, a histogram of lesion types was constructed using the cluster information. Finally, a Support Vector Machine classifier was trained with the histogram and radiomics features to distinguish diseases and severity.ResultsThe 20 clusters constructed from 170 patients were reviewed based on common radiographic appearance types. Two clusters showed typical findings of COVID-19, with two other clusters showing typical findings related to bacterial pneumonia. Notably, there is one cluster that showed bilateral diffuse ground-glass opacities (GGOs) in the central and peripheral lungs and was considered to be a key factor for severity classification. The proposed method achieved an accuracy of 91.2% for classifying COVID-19 and bacterial pneumonia patients with 95% reported for severity classification. The CT quantitative parameters represented by the values of cluster 8 were correlated with existing laboratory data and clinical parameters.ConclusionDeep chest CT analysis with constructed lesion clusters revealed well-known COVID-19 CT manifestations comparable to manual CT analysis. The constructed histogram features improved accuracy for both diseases and severity classification, and showed correlations with laboratory data and clinical parameters. The constructed histogram features can provide guidance for improved analysis and treatment of COVID-19.     

Efficient COVID-19 Segmentation from CT Slices Exploiting Semantic Segmentation with Integrated Attention Mechanism

Coronavirus (COVID-19) is a pandemic, which caused suddenly unexplained pneumonia cases and caused a devastating effect on global public health. Computerized tomography (CT) is one of the most effective tools for COVID-19 screening. Since some specific patterns such as bilateral, peripheral, and basal predominant ground-glass opacity, multifocal patchy consolidation, crazy-paving pattern with a peripheral distribution can be observed in CT images and these patterns have been declared as the findings of COVID-19 infection. For patient monitoring, diagnosis and segmentation of COVID-19, which spreads into the lung, expeditiously and accurately from CT, will provide vital information about the stage of the disease. In this work, we proposed a SegNet-based network using the attention gate (AG) mechanism for the automatic segmentation of COVID-19 regions in CT images. AGs can be easily integrated into standard convolutional neural network (CNN) architectures with a minimum computing load as well as increasing model precision and predictive accuracy. Besides, the success of the proposed network has been evaluated based on dice, Tversky, and focal Tversky loss functions to deal with low sensitivity arising from the small lesions. The experiments were carried out using a fivefold cross-validation technique on a COVID-19 CT segmentation database containing 473 CT images. The obtained sensitivity, specificity, and dice scores were reported as 92.73%, 99.51%, and 89.61%, respectively. The superiority of the proposed method has been highlighted by comparing with the results reported in previous studies and it is thought that it will be an auxiliary tool that accurately detects automatic COVID-19 regions from CT images.     

基于特征融合的U-Net肺自动分割方法

目的:将肺部颜色特征与纹理特征融合形成一种更有效的特征,并利用改进的U-Net深度学习网络结构对肺部CT影像进行图像分割以准确提取肺实质区域。方法:使用的CT影像数据来源于LIDC-IDRI数据库,首先通过色彩空间转换、高阶邻域统计的方法分别提取颜色特征和纹理特征,然后采用加权平均直方图融合两类特征,最后将特征输入改进后的U-Net模型,进行1 000次CT扫描测试,以达到完整的肺实质输出。结果:该方法最终的骰子系数、灵敏度、特异性分别为93%、96%和97%。结论:本方法较单一特征分割方法具有较高的分割精度,有效提高肺实质的分割精度,可为后续的肺部疾病自动诊断提供可靠基础,减少临床诊断的成本并节省医生诊断时间。     

非对称卷积核YOLO V2网络的CT影像肺结节检测

肺癌一直是严重威胁人类健康的疾病之一,肺结节作为早期肺癌的一个重要征象,在肺癌的早期诊断与治疗中具有重要的意义。传统的CT影像肺结节检测方法不仅步骤繁琐、处理速度慢,而且对于结节的检出率及定位精度都亟待提高。提出一种基于非对称卷积核YOLO V2网络的CT影像肺结节检测方法:首先将连续的CT序列叠加构造为伪彩色数据集,以增强病变和健康组织的差异;然后将含有非对称卷积核的inception V3模块引入到YOLO V2网络中,构造出一种适用于肺结节检测的深度网络,一方面利用YOLO V2网络在目标检测上的优势,另一方面通过inception V3模块在网络的宽度与深度上进行扩增,以提取更加丰富的特征;为进一步提高结节的定位精度,对损失函数的设计与计算方法也进行一定的改进。为验证所提检测模型的性能,从LIDC-IDRI数据集中选取1 010个病例的CT图像用于训练和测试,在大于3 mm的肺结节中,检测敏感度为94.25%,假阳性率为8.50%。实验表明,所提出的肺结节检测方法不仅可以简化肺部CT图像的处理过程,而且在结节检测率及定位精度方面均优于传统方法,可为肺结节检测提供一种新思路。     

基于改进型V-net卷积神经网络的胃壁分割方法

实现上腹部CT影像的胃壁分割与中心线提取是成功实现早期胃癌筛查和辅助T分期的前提。基于改进型V-net的胃壁分割方法加入了全局平均权重模块的全卷积神经网络框架,有效解决了神经网路下采样过程中信息丢失的问题。此外,本文在原水平集方法的基础上,提出了正则化水平集损失函数。该损失函数有效抑制了全卷积网络胃壁边缘特征丢失率和因数据量较少而引起的过拟合问题,提高了神经网络对上腹部CT影像中胃壁的识别精度。实验表明,在上腹部CT影像数据集中本文方法分割准确度Dice系数高达0.916 5,IOU达到了0.822 3。该方法的Dice相对于3D V-net方法准确度提高了近6%,同时比CE-net和Dense U-net方法的准确率分别提高了2.7%和3.1%。