Photon-counting X-ray and Optical Tomography for Preclinical Cancer Research

用于临床前癌症研究的光子计数X射线和光学层析成像 摘要 临床前成像是癌症研究中的重要工具。由于癌症表现出非常复杂的时空 因此，迫切需要开发新的成像技术来表征癌症 组织及其微环境。为此，多模式成像最有潜力提供 在活的和完整的动物中同时提供解剖、功能和分子信息。我们的主要利益所在， 人表皮生长因子受体2(HER2)在乳腺组织中的表达具有预后和预测价值 癌症。目前，抑制受体二聚化的治疗性抗HER2单抗是FDA- 批准了。然而，对于HER2在乳腺癌中的作用，已经出现了一个越来越复杂的观点 从基因组测序中突出了肿瘤内和肿瘤内异质性在治疗中的重要性 抵抗。因此，显然需要一种非侵入性的临床前成像方式，它能够 监测HER2受体表达水平、靶向药物输送和肿瘤反应之间的相互作用。 该项目的总体目标是开发一种高维光学X射线和光学混合原型 能量分辨微型CT(GEM)引导下的体层(热)成像，对乳腺肿瘤进行可视化和量化 临床前模型中的异质性、HER2表达和二聚化以及治疗反应。在x上- 射线端，光子计数微型CT记录单个X射线光子及其能级，并使 特定于化学物质的分解。因此，老鼠的解剖结构可以表示为 水、脂、骨、钙、碘和Gd。在光学方面，光学分子层析图谱 功能生物标志物和分子探针的分布。对靶向治疗非常重要，在 活体宏观荧光寿命Förster共振能量转移(MFRI-FRET)成像 结果表明，定量mfli-fret信号与细胞内药物传递密切相关。 病理部位经体外免疫组织化学分析证实。协同作用，基础材料 用光子计数微CT进行分辨，可以与独特的光学性质有关，并用于校正 用于定量光学分子层析成像的非均相光学背景。此外，对比- 增强的Micro-CT可以识别感兴趣的区域，以规范光学分子断层扫描。具体的 目标是(1)建立一个用于综合和协同X射线和光学的混合HOTGEM系统的原型 成像，(2)开发联合方法，从多对比度数据集与 HOTGEM系统，以及(3)HER2和HER2水平不同的异种移植系统中乳腺癌的特征 HER2-使用HOTGEM系统激活突变。建成后，拟议的HOTGEM系统将 经验证可为材料分解提供50微米的x射线分辨率和100微米的光学分辨率 每种杂交体内扫描的联合配准中的目标定位在30分钟内，证明是一种 层析HER2成像的突破，并准备进行技术转让和商业翻译。

Photon-counting X-ray and Optical Tomography for Preclinical Cancer Research ABSTRACT Preclinical imaging is a critical tool in cancer research. Since cancer exhibits very complex spatiotemporal features, there is a strong need for the development of novel imaging technologies to characterize cancerous tissues and their microenvironments. For this purpose, multimodal imaging has the best potential to provide anatomical, functional and molecular information concurrently in live and intact animals. Of our primary interest, human epidermal growth factor receptor 2 (HER2) expression has prognostic and predictive values in breast cancer. Currently, therapeutic monoclonal anti-HER2 antibodies that inhibit receptor dimerization are FDA- approved. However, an increasingly more complex view of the role of HER2 in breast cancer has emerged from genome sequencing that highlights the importance of inter- and intra-tumor heterogeneity in therapy resistance. Thus, there is a clear need for a non-invasive preclinical imaging modality that is capable of monitoring the interplay between HER2 receptor expression level, targeted drug delivery, and tumor response. The overall goal of this project is to develop a hybrid x-ray and optical prototype for High-dimensional Optical Tomography (HOT) Guided-by Energy-resolved Micro-CT (GEM), visualize and quantitate breast tumor heterogeneity, HER2 expression and dimerization, and therapeutic response in preclinical models. On the x- ray side, photon-counting micro-CT records individual x-ray photons and their energy levels, and enables chemically-specific material decomposition. As a result, a mouse anatomy can be represented in terms of water, lipid, bone, Calcium, Iodine, and Gadolinium. On the optical side, optical molecular tomography maps the distribution of functional biomarkers and molecular probes. Of great importance to targeted therapy, with in vivo Macroscopy Fluorescence Lifetime Förster Resonance Energy Transfer (MFLI-FRET) imaging, our recent results demonstrate that quantitative MFLI-FRET signals correlate strongly with intracellular drug delivery at the pathological site as validated via ex vivo immunohistochemistry analysis. Synergistically, basis materials resolved with photon-counting micro-CT can be related to unique optical properties, and used to correct a heterogeneous optical background for quantitative optical molecular tomography. Furthermore, contrast- enhanced micro-CT can identify regions of interest to regularize optical molecular tomography. The specific aims are to (1) prototype a hybrid HOTGEM system for comprehensive and synergistic x-ray and optical imaging, (2) develop joint methods for image reconstruction from datasets in multi-contrasts collected with the HOTGEM system, and (3) characterize breast cancer in xenograft systems with varying levels of HER2 and HER2-activating mutations using the HOTGEM system. Upon completion, the proposed HOTGEM system will have been validated to offer 50µm x-ray resolution for material decomposition and 100µm optical resolution for target localization in co-registration within 30 minutes for each hybrid in vivo scan, demonstrated to be a breakthrough for tomographic HER2 imaging, and ready for technology transfer and commercial translation.