Neuroimaging technologies have been applied to the diagnosis of schizophrenia. In order to improve the performance of the single-modal neuroimaging-based computer-aided diagnosis (CAD) for schizophrenia, an ensemble learning algorithm based on learning using privileged information (LUPI) was proposed in this work. Specifically, the extreme learning machine based auto-encoder (ELM-AE) was first adopted to learn new feature representation for the single-modal neuroimaging data. Random project algorithm was then performed on the learned high-dimensional features to generate several new feature subspaces. After that, multiple feature pairs were built among these subspaces to work as source domain and target domain, respectively, which were used to train multiple support vector machine plus (SVM+) classifier. Finally, a strong classifier is learned by combining these SVM+ classifiers for classification. The proposed algorithm was evaluated on a public schizophrenia neuroimaging dataset, including the data of structural magnetic resonance imaging (sMRI) and functional MRI (fMRI). The results showed that the proposed algorithm achieved the best diagnosis performance. In particular, the classification accuracy, sensitivity and specificity of the proposed algorithm were 72.12% ± 8.20%, 73.50% ± 15.44% and 70.93% ± 12.93%, respectively, on the sMRI data, and it also achieved the classification accuracy of 72.33% ± 8.95%, sensitivity of 68.50% ± 16.58% and specificity of 75.73% ± 16.10% on the fMRI data. The proposed algorithm overcomes the problem that the traditional LUPI methods need the additional privileged information modality as source domain. It can be directly applied to the single-modal data for classification, and also can improve the classification performance. Therefore, it suggests that the proposed algorithm will have wider applications.
神经影像技术目前已经应用于精神分裂症的诊断。为了提升基于单模态神经影像的精神分裂症计算机辅助诊断（CAD）的性能，本文提出一种基于特权信息学习（LUPI）分类器的集成学习算法。该算法首先对单模态数据采用极限学习机-自编码器（ELM-AE）进行特征二次学习，然后通过随机映射算法将高维特征随机分成多个子空间，并进行两两组合形成源领域和目标领域数据对，用于训练多个支持向量机+（SVM+）弱分类器，最终通过集成学习获得一个强分类器，实现有效的模式分类。本算法在公开的精神分裂症神经影像数据库中进行了实验，包括结构磁共振成像和功能磁共振成像数据。结果表明该算法取得了最优的诊断结果，其在基于结构磁共振成像诊断的分类精度、敏感性和特异性分别可以达到 72.12% ± 8.20%、73.50% ± 15.44% 和 70.93% ± 12.93%，而基于功能磁共振成像诊断的分类精度、敏感性和特异性分别为 72.33% ± 8.95%、68.50% ± 16.58%、75.73% ± 16.10%。本文算法的主要创新点在于克服了传统的 LUPI 分类器需要额外的特权信息模态的不足，可以直接应用于单模态数据分类问题，而且还提升了分类性能，因此具有较为广泛的应用前景。.
Keywords: deep learning; ensemble learning using privileged information; extreme learning machine based auto-encoder; schizophrenia; single-modal neuroimaging.