Tracing how knowledge diffuses through scientific networks reveals how research builds on prior findings, but doing so at scale remains challenging. We present an LLM-based approach, Citation-Aware Research Diffusion Summarization (CARDS), which describes how knowledge diffuses through the scientific landscape. We trace citations from research funded by the U.S. National Institutes of Health through the landscape quantified by CSET’s Map of Science cluster dataset to generate Research Diffusion Pathways, and compare LLM-generated summaries based on (1) cluster-level metadata and (2) citation-aware connections between research clusters. We find that CARDS outperforms cluster-based summaries under both human annotation and LLM-as-a-judge evaluation. Our work outlines a methodology for generating research diffusion paths, and for summarizing them with greater specificity.