Fig. 8.

PAT imaging aided by exogenous contrast agents. PA images acquired before (a) and $\sim 52\min$ after (b) methylene blue injection, showing a dramatic PA signal increase in a sentinel lymph node (SLN). PA images acquired (c) before and (d) 6 h after gold nanoparticle injection, showing a significant PA signal increase in a melanoma tumor. Reproduced with permission from Refs. ¹¹⁵ (a) and (b) and ¹⁰⁸ (c) and (d).