Tumor development and growth, as well as metastatic spread, are strongly influenced by various, mostly innate, immune cells, which are recruited to the tumor site and driven to establish a specific tumor-supportive microenvironment. The contents of this microenvironment, such as myeloid cells, are a major factor in the overall prognosis of malignant disease, addressed by a constantly growing armament of therapeutic interventions targeting tumor-supportive immune cells. Current clinical imaging has long ignored the growing need for diagnostic approaches addressing these microenvironmental contents—approaches enabling a sensitive and specific classification of tumor immune crosstalk and the resulting tumor-associated immune cell activity. In this focus article we review the present status of, and promising developments in, the in vivo molecular imaging of tumor immune components designed to allow for inferences to be made on the cross-talk between tumor cells and the immune system. Current imaging modalities based on the infiltrating cell types are briefly discussed.

肿瘤的发展和生长以及转移扩散受到各种（主要是先天）免疫细胞的强烈影响，这些免疫细胞被招募到肿瘤部位并驱动建立特定的肿瘤支持微环境。这种微环境的内容物，例如骨髓细胞，是恶性疾病总体预后的主要因素，通过不断增长的针对肿瘤支持性免疫细胞的治疗干预措施来解决这一问题。目前的临床成像长期以来忽视了对解决这些微环境内容的诊断方法日益增长的需求——能够对肿瘤免疫串扰以及由此产生的肿瘤相关免疫细胞活性进行敏感和特定分类的方法。在这篇焦点文章中，我们回顾了肿瘤免疫成分的体内分子成像的现状和有希望的发展，该成像旨在对肿瘤细胞和免疫系统之间的串扰进行推断。简要讨论了当前基于浸润细胞类型的成像方式。