Wu Yiran, Wang Zhen, Ripplinger Crystal M, Sato Daisuke
Department of Pharmacology, University of California, Davis, Davis, CA, United States.
Front Physiol. 2022 Apr 6;13:805161. doi: 10.3389/fphys.2022.805161. eCollection 2022.
Deep neural networks (DNN) have shown their success through computer vision tasks such as object detection, classification, and segmentation of image data including clinical and biological data. However, supervised DNNs require a large volume of labeled data to train and great effort to tune hyperparameters. The goal of this study is to segment cardiac images in movie data into objects of interest and a noisy background. This task is one of the essential tasks before statistical analysis of the images. Otherwise, the statistical values such as means, medians, and standard deviations can be erroneous. In this study, we show that the combination of unsupervised and supervised machine learning can automatize this process and find objects of interest accurately. We used the fact that typical clinical/biological data contain only limited kinds of objects. We solve this problem at the pixel level. For example, if there is only one object in an image, there are two types of pixels: object pixels and background pixels. We can expect object pixels and background pixels are quite different and they can be grouped using unsupervised clustering methods. In this study, we used the -means clustering method. After finding object pixels and background pixels using unsupervised clustering methods, we used these pixels as training data for supervised learning. In this study, we used logistic regression and support vector machine. The combination of the unsupervised method and the supervised method can find objects of interest and segment images accurately without predefined thresholds or manually labeled data.
深度神经网络(DNN)已通过诸如目标检测、分类以及对包括临床和生物数据在内的图像数据进行分割等计算机视觉任务展现出其成效。然而,有监督的DNN需要大量带标签的数据来进行训练,并且在调整超参数方面需付出巨大努力。本研究的目标是将电影数据中的心脏图像分割为感兴趣的对象和噪声背景。此任务是图像统计分析之前的关键任务之一。否则,诸如均值、中位数和标准差等统计值可能会出现错误。在本研究中,我们表明无监督学习和有监督学习的结合能够使这个过程自动化,并准确地找到感兴趣的对象。我们利用了典型临床/生物数据仅包含有限种类对象这一事实。我们在像素级别解决这个问题。例如,如果一幅图像中只有一个对象,那么存在两种类型的像素:对象像素和背景像素。我们可以预期对象像素和背景像素有很大差异,并且可以使用无监督聚类方法将它们分组。在本研究中,我们使用了k均值聚类方法。在使用无监督聚类方法找到对象像素和背景像素之后,我们将这些像素用作有监督学习的训练数据。在本研究中,我们使用了逻辑回归和支持向量机。无监督方法和有监督方法的结合能够在无需预定义阈值或手动标注数据的情况下找到感兴趣的对象并准确分割图像。