USING DEEP LEARNING FOR ANOMALY DETECTION IN RADIOLOGICAL IMAGES

本文讨论了深度学习在医疗数据应用中遇到的问题,特别是处理罕见疾病诊断时数据量有限的情况。COSMONiO Health Lab通过设计激活学习系统来解决这一挑战,旨在使用较小的数据集进行高精度预测。文中还探讨了深度学习的关键进展、如何帮助诊断罕见疾病、预测准确性的主要挑战以及COSMONiO NOUS平台的应用前景。

关注Deep Learning在医疗数据中的应用,指出了Deep Learning在医疗数据应用中遇到的问题,即不能像处理图片数据那样,输入大量训练数据,而是相对数据量的缺乏;注意到人类的学习过程,当教小孩读和写的时候,它是一个学生和老师交互反馈的过程,受此启发,可设计一个激活学习系统,让用户反馈起一定作用。

原文及链接:
https://re-work.co/blog/deep-learning-healthcare-ioannis-katramados-cosmonio-nous

Deep learning is usually linked to big data, but in a medical context radiologists often need help in diagnosing rare conditions that have limited historical data. Can deep learning prove a useful tool in such cases?

Ioannis Katramados founded COSMONiO Health Lab in 2015 with a vision to develop intelligent medical technologies based on deep learning. COSMONiO’s focus is on designing NOUS, an embedded deep neural network platform that aims to make high-accuracy predictions using significantly smaller training datasets. To achieve this the lab collaborates closely with UMC Groningen, one of the leading university hospitals in the Netherlands, where their research is currently focussing on performing automated anomaly detection on thoracic X-rays.

I caught up with him ahead of his presentation on ‘Anomaly Detection in Radiological Images Using Deep Learning’ at the RE•WORK Deep Learning in Healthcare Summit on 7-8 April.

What are the key factors that have enabled recent advancements in deep learning?
The single most significant factor is the availability of low-cost GPUs. These allow us to train complex deep neural networks significantly faster than before. Since engineering often relies on trial and error, it makes sense that shorter training times enable deep learning engineers to perform more experiments even using a standard desktop PC. Alongside the contribution of GPUs, I should also acknowledge the importance of having great open-source libraries available from a wide range of academic institutes and companies.

How can deep learning methods help to diagnose rare conditions with limited historical data?
This is the main question that COSMONiO is trying to answer. There is no doubt that deep neural networks need a lot of data to become effective. However, when it comes to image classification we usually try to feed a vast amount of pre-labelled images to the neural network. But when big data is simply unavailable we have to invent other ways of training our algorithms. One way is to copy the human model, for example, when children are being taught to read and write. It is an interactive process involving the child and the teacher. In practice this means that we need better active learning systems, where user feedback plays an important role.

What are the main challenges to using a deep neural network platform to make high-accuracy predictions?
As with humans, the quality of predictions depends on the quality of the acquired knowledge. So one of the biggest challenges is the development of deep-learning frameworks that can handle noisy and inaccurate data more effectively, without relying on huge training databases. In this case, user feedback will be increasingly important, but of course we have to go beyond existing point-and-click feedback techniques that make this a laborious process.

What additional applications can COSMONiO NOUS be used for?
NOUS is an embedded deep learning platform that allows real-time training of neural networks. The hardware is based on cutting-edge NVIDIA technologies, while an incredible amount of innovation has gone into the software. We are currently developing a new deep learning engine that significantly reduces the computational overhead of training neural networks. This means that in the future we will be able to embed artificial brains in small devices that can learn throughout their lifetime. For non-embedded applications we will see a sharp increase in training speed and performance.

What developments can we expect to see in deep learning in the next 5 years?
1) E-brain hardware modules, 2) A deep-learning OS that writes its own software, 3) A revolutionary GUI for visualising deep neural networks. I am sure all three will happen sooner than we think.

Ioannis Katramados will be speaking at the RE•WORK Deep Learning in Healthcare Summit, in London on 7-8 April 2016. Other speakers include Alex Jaimes, CTO & Chief Scientist of AiCure; Brendan Frey, President & CEO of Deep Genomics; Ekaterina Volkova-Volkmar, Researcher at Bupa; Jeffrey de Fauw, Research Engineer at Google DeepMind and more.

### 混合模型在航天器异常检测中的应用 残差图学习(Residual Graph Learning)结合深度学习和图神经网络(Graph Neural Networks, GNNs),为航天器异常检测提供了一种新颖且高效的方法。这种方法通过构建残差图,将时间序列数据映射到图结构中,并利用图神经网络来捕捉复杂的时间依赖性和空间相关性[^1]。 #### 残差图的构建 残差图的核心思想是基于重建误差构建节点之间的关系。对于航天器传感器数据的时间序列,每个时间点可以被视为一个节点,而节点之间的边权重则由重建误差决定。重建误差越大的节点对,其边权重越高,这表明它们之间的异常可能性更大[^2]。 #### 深度学习与图神经网络的结合 为了进一步提升异常检测的效果,可以使用深度学习模型(如自编码器或变分自编码器)生成初始的重建误差。随后,将这些误差作为输入传递给图神经网络,以捕捉全局和局部的异常模式。这种方法不仅能够处理单个传感器的异常,还能发现多个传感器之间的联合异常[^3]。 ```python import torch import torch.nn as nn import torch.optim as optim # 定义自编码器模型 class AutoEncoder(nn.Module): def __init__(self, input_dim, hidden_dim): super(AutoEncoder, self).__init__() self.encoder = nn.Sequential( nn.Linear(input_dim, hidden_dim), nn.ReLU() ) self.decoder = nn.Sequential( nn.Linear(hidden_dim, input_dim), nn.Sigmoid() ) def forward(self, x): encoded = self.encoder(x) decoded = self.decoder(encoded) return decoded # 定义图神经网络模型 class GraphNeuralNetwork(nn.Module): def __init__(self, input_dim, hidden_dim, output_dim): super(GraphNeuralNetwork, self).__init__() self.gnn_layer = nn.Linear(input_dim, hidden_dim) self.output_layer = nn.Linear(hidden_dim, output_dim) def forward(self, x): x = torch.relu(self.gnn_layer(x)) x = self.output_layer(x) return x # 初始化模型 input_dim = 10 # 假设输入维度为10 hidden_dim = 5 output_dim = 1 autoencoder = AutoEncoder(input_dim, hidden_dim) gnn = GraphNeuralNetwork(hidden_dim, hidden_dim, output_dim) # 定义优化器和损失函数 criterion = nn.MSELoss() optimizer_autoencoder = optim.Adam(autoencoder.parameters(), lr=0.001) optimizer_gnn = optim.Adam(gnn.parameters(), lr=0.001) # 训练过程(伪代码) for epoch in range(num_epochs): # 使用自编码器计算重建误差 reconstructed_data = autoencoder(data) reconstruction_loss = criterion(reconstructed_data, data) # 构建残差图并传递给GNN residual_graph = compute_residual_graph(reconstruction_loss) gnn_output = gnn(residual_graph) # 更新模型参数 optimizer_autoencoder.zero_grad() optimizer_gnn.zero_grad() reconstruction_loss.backward() gnn_output.backward() optimizer_autoencoder.step() optimizer_gnn.step() ``` #### 阈值设定与异常分类 通过分析图神经网络的输出,可以为每个节点分配一个异常分数。根据预先设定的阈值,将分数高于阈值的节点标记为异常。阈值的选择通常基于历史数据的分布特性,或者通过交叉验证确定最佳值[^4]。 --- ###
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