# Photoacoustic Imaging for Management of Breast Cancer: A Literature Review and Future Perspectives
## 3 Results
### Endogenous Contrast Agents
[80] used antibody indocyanine green (ICG) conjugates in the spectroscopic PA imaging of transgenic murine breast cancer model to distinguish malignant breast tissue and normal breast tissue in mice. [PERSON] et al. [81] initially performed an in vivo PA imaging on a rat model with methylene blue as a contrast agent and identified SLNs from the acquired PA images. They continued this study with gold (Au) nanocages [82] as contrast agents to detect SLNs and observed improved performance over methylene blue, especially these contrast agents eliminated the requirement of invasive axillary staging procedures. In addition to SLN mapping in rats with gold nanorods as contrast agents, they performed spectroscopic PA imaging at three wavelengths 757 nm, 807 nm, and 820 nm [83] to eliminate the need for acquiring control image before the injection of gold nanorods. Further, they performed 3D PA imaging on mice and rats with the use of Evans blue dye [84] and with the acquired high-speed (\(\sim\)0.2 Hz frame rate) 3D PA images, they monitored the dynamic accumulation and clearance of the dye into SLNs. [PERSON] et al. [85] performed in vivo PA imaging on a rat model with single-walled carbon nanotubes (SWNT) as a contrast agent and identified SLNs from the acquired PA images. [PERSON] et al. [86] performed PA imaging to detect SLNs using gold nanobeacons (GNBs) as contrast agents in a rodent model. [PERSON] et al. [87] performed in vivo PA imaging on a rat with perfluorocarbon (PFC) nanoparticles loaded with NIR dye PPCy-C8 as a contrast agent and successfully detected lymph nodes. [PERSON] et al. [88] performed in vivo PA imaging on a rat with methylene blue as a contrast agent and visualized SLNs, and accomplished PA image-guided needle insertion into the rat SLN with the use of methylene blue. They continued this study with ICG as a contrast agent [89] and successfully visualized SLNs and lymphatic vessels. Further, they [90] employed a handheld PA probe on a rat with the help of ICG as a contrast agent and, in addition to SLN mapping, they successfully achieved PA image-guided needle-insertion into the axillary lymph nodes of the rat. [PERSON] et al. [91] performed in vivo PA imaging on rats with methylene blue as a contrast agent and with the acquired 3D PA images, they dynamically visualized the flow of methylene blue through lymph vessels to the SLNs. [PERSON] et al. [92] performed in vivo PA imaging on a rodent model using PA Tomography (PAT) system with copper neodecanoate nanoparticles as contrast agents and detected SLNs. [PERSON] et al. [93] performed the real-time US and PA imaging for SLN mapping in a mouse model with the help of silica-coated gold nanoparticles (Si-AuNPs). [PERSON] et al. [94] performed PA imaging on rats with the use of super-paramagnetic iron oxide nanoparticles (Endorem) as a contrast agent. Through PA scans, they visualized the accumulation of these nanoparticles in the lymph nodes, which enabled them to differentiate between normal lymph node and metastatic lymph node. [PERSON] et al. [95] performed in vivo PA imaging on a rat model with copper selenide nanocrystals (Cu\({}_{2\text{-}}\)Se NCs) as a contrast agent and achieved SLN mapping. [PERSON] et al. [96] performed in vivo PA imaging on a rat using their PA imaging system with the use of single-walled carbon nanotubes (SWNTs) conjugated with ICG as a PA contrast agent and clearly visualized SLNs. [PERSON] et al. [97]performed in vivo dual-color PA imaging with nano-formulated napthalocyanines (nanonaps) on rats and successfully visualized rat's lymph nodes buried inside 10 mm thick layer of chicken breast. [PERSON] et al. [98] performed in vitro and in vivo studies using their dual modality PA-US system with carbon nanoparticles added with liquid-gas phase-transition nanodroplets (CNPs) as contrast agents produced excellent contrasts for PA-US imaging. They claimed from the results of this study that these CNPs are highly capable as the theranostic agents in SLNs detection as well as in the therapy of metastatic lymph nodes.