有监督的多模态数据融合方法及其在脑疾病影像学标记检测中的应用

CASIA OpenIR > 毕业生 > 博士学位论文

	有监督的多模态数据融合方法及其在脑疾病影像学标记检测中的应用
	戚世乐
	2017-11
学位类型	工学博士
中文摘要	多模态脑影像能够从不同的角度反映大脑的功能或者结构信息。尽管从扫描对象采集多种模态的影像数据已经比较普遍，实际操作中却常常被分开单独分析，或者是对各个磁共振影像(MRI)数据的分析结果进行简单比较或相关，模态间的互信息(cross information)无法得到充分利用。最近的研究表明，结合多种模态的影像数据不仅能够从多个角度理解人脑，并且具有一定的互补性，能够发现与脑疾病有关的多种模态之间的共变性, 这是单模态分析无法实现的。目前已经有较多功能的(fMRI)或者结构的(sMRI, dMRI)影像学研究尝试以无监督的数据驱动方式挖掘神经影像学标记物，以加深对于脑疾病患者的认知障碍和相关神经病理机制的理解。除此以外，充分利用多模态影像数据、临床和行为学数据，挖掘与感兴趣指标密切相关的脑影像共变模式，并以此来实现认知能力与治疗疗效的个体化预测，则是当前研究的热点和难点。本论文致力于开发一种有监督的、多变量脑影像学融合方法，能够充分利用临床感兴趣的指标如认知、症状、行为、基因变量等作为先验参考信息引导多模态 MRI 影像的联合分析，从而精准地挖掘出与特定临床指标显著关联的多模态 MRI 共变模式，并以此开展进一步的影像学标记对认知、行为等的预测。本文的主要创新性工作包括： (1)提出一种有监督的多模态融合方法 MCCAR+jICA (multi-site canonical correlation analysis with reference + joint independent component analysis)，该方法能够基于参考信息挖掘与之显著相关的多模态共变模式。在模拟实验中，我们从多个层面对比了 MCCAR+jICA 及它的多种变形方法，结果表明 MCCAR+jICA 能够更准确的提取出与先验参考信息相关的影像成分，并且达到更高的估计精度。在真实数据实验中，我们以工作记忆评分作为参考信息来探索精神分裂症中与工作记忆损伤显著相关的 3 模态共变模式。结果表明分数低频振荡振幅(fALFF)中的中央执行网络、灰质体积 GM 中的突显网络、分数各项异性 FA 中的胼胝体白质纤维束等作为三模态共变的(fMRI-sMRI-dMRI)脑网络模式不仅与工作记忆评分密切相关，而且在健康对照和病人之间存在显著差异，更重要的是该三模态共变模式能够在独立数据集中高度复现，验证了 MCCAR+jICA 方法的有效性和广泛的应用前景。 (2)研究与认知功能损伤密切相关的磁共振影像学标记，实现个体化多子域认知水平的预测。认知功能损伤被认为是包括精神分裂症在内的多种脑疾病广泛存在的功能障碍，基于提出的有监督融合方法 MCCAR+jICA、多种认知评分(总分和注意力、工作记忆、语言学习三项认知子域评分)，和两个独立的三模态 MRI 数据集, 本工作对精神分裂症与认知损伤相关的多模态共变脑网络进行了深入挖掘和多重验证。结果表明： a)与精神分裂症的认知损伤相关的影像标记网络 (neuromarker network)包括突显网络、执行控制网络和后默认网络，该核心三网络具有模态特异性和共変性, 并且在独立数据集可复现； b) 通过比较 4 个认知子域对应的影像学标记网络，发现结构影像特征(GM/FA)的空间分布在子域间高度一致，而功能影像特征(fALFF)则在不同子域存在较大的分布差异，即对不同认知功能(任务)间的细微差异反映更敏感； c) 更重要的是，检测得到的核心多模态特征能够较好的预测个体化认知总分(r=0.463)，并且能够泛化到多种认知功能 (子域)的预测。 (3)首次以 microRNA 为参考信息，探索抑郁症中与 miR-132 异常表达相关的多模态脑影像(fMRI-sMRI-dMRI)共变模式，这是一种影像基因关联研究的新方式。通过将血液中 miR-132 的表达量(抑郁症>正常人)作为参考信息来引导 3 种 MRI 特征的融合，我们发现: a) 抑郁症中高表达的 miR-132 与前额叶—边缘系统降低的 fALFF 和 GM 相关； b)高表达 miR-132 相关的脑区与抑郁症的注意力和执行功能损伤密切相关。上述关联关系在未用药 MDD 全体和从未用药的子集(drug-naïve MDDs)中均一致存在。这些发现加深了我们对 MDD 中 miR-132 异常表达与前额叶—边缘系统以及认知损伤的理解，而它们之间内在的因果关系有待于进一步验证。
英文摘要	Noninvasive neuroimaging has provided remarkable new insights into human brain structure and function in both health and disease. There is increasing evidence that instead of using a single imaging modality to study its relationship with physiological or cognitive features, people are paying more attention to multimodal fusion, an approach that is able to capitalize on the strength of multiple imaging techniques, since it can uncover the hidden relationships that might be missed from separate unimodal imaging studies. Compelling evidence has confirmed that neuropsychiatric disorders reflect fundamental differences in brain structure and function. By jointly analyzing rich types of data and taking advantage of the crossinformation, multimodal fusion can help better reveal the potential functional-structural covariations. For example, how brain structure shapes brain function, and to what degree brain function is related to the underlying brain anatomy, can be examined. Increasingly, studies are focusing on identifying the intrinsic functional or structural brain patterns that may ultimately drive a specific domain of human cognition or behavior, whereas most existing fusion models are purely data-driven. Hence in this work, we are motivated to develop a supervised multimodal fusion method that is able to discover the co-varying imaging patterns particularly related to a referred measurement more precisely and robustly. The main achievements of our study are as follows: (1) We proposed a fusion with reference model called “multi-site canonical correlation analysis with reference + joint independent component analysis” (MCCAR+jICA), which can precisely identify co-varying multimodal imaging patterns closely related to the reference, such as cognitive scores. In a three-way fusion simulation, the proposed method was compared with its alternatives on multiple facets; MCCAR+jICA outperforms others with higher estimation precision and high accuracy on identifying a target component with the right correspondence. In human imaging data, working memory performance was utilized as a reference to investigate the co- varying working memory associated brain patterns among three modalities and how they are impaired in schizophrenia. Two independent cohorts were used. Similar brain maps were identified between the two cohorts along with substantial overlaps in the central executive network in fMRI, salience network in sMRI, and major white matter tracts in dMRI. These regions have been linked with working memory deficits in schizophrenia in multiple reports and MCCAR+jICA further verified them in a repeatable, joint manner, demonstrating the ability of the proposed method to identify potential neuromarkers for mental disorders. (2) Cognitive dysfunction has been recognized as a primary and enduring core deficit in many psychotic disorders, including schizophrenia. Imaging neuromarkers that interrelate cognitive impairments and can ultimately predict individual cognitive performance are a major focus in the new era of psychiatric study. To this end, we utilize our supervised fusion approach to identify multimodal brain networks that are closely associated with cognitive impairment. We combine three types of magnetic resonance imaging features guided by cognitive scores in a discovery dataset and replicated in an independent dataset. Domain scores of attention, working memory and verbal learning were used as references to identify common and domain-specific multimodal neuromarkers in health individuals and schizophrenia patients. Results show structure features are more consistent cross different cognitive domains, while functional features are more sensitive to cognitive domain differences. Three multimodal networks: the salience network, the central executive network and the posterior default mode network may play a crucial role as anatomical substrates of neurocognition. These networks achieved high accuracy for predicting the cognitive scores (r=0.463) which can be generalized to predict multiple cognitive performance. This work defines modalityspecific brain networks that may be broadly applicable as neuromarkers of cognitive impairment. (3) This work will be the first attempt to investigate how microRNA132 dysregulation may impact covariation of multimodal brain imaging data in 81 unmedicated major depressive patients and 123 demographically-matched healthy controls, as well as in a medication-naïve subset of major depressive patients. MicroRNA132 values in blood (patients>controls) was used as a prior reference to guide fusion of three MRI features, i.e., fractional amplitude of low frequency fluctuations, gray matter volume, and fractional anisotropy. The multimodal components correlated with microRNA132 also show significant group difference in loadings. Results indicate: 1) Higher microRNA132 levels in major depressive disorder are associated with both lower fractional amplitude of low frequency fluctuations and lower gray matter volume in fronto-limbic network; 2) The identified brain regions linked with increased microRNA132 levels were also associated with poorer cognitive performance in attention and executive function. All of the above associations are consistent on either unmedicated or medication-naïve patients. These findings support that the frontal-limbic system previously implicated in major depression in both functional, anatomical and structural brain-imaging studies, were associated with miR- 132 dysregulation, while the intrinsic causality between miR-132 and brain alterations awaits further investigation and verification.
关键词	有监督的多模态融合精神分裂症抑郁症认知损伤 Microrna132
文献类型	学位论文
条目标识符	http://ir.ia.ac.cn/handle/173211/20404
专题	毕业生_博士学位论文
作者单位	中国科学院自动化研究所
第一作者单位	中国科学院自动化研究所
推荐引用方式 GB/T 7714	戚世乐. 有监督的多模态数据融合方法及其在脑疾病影像学标记检测中的应用[D]. 北京. 中国科学院研究生院,2017.

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