title: In vivo lymph node mapping by Cadmium Tellurium quantum dots in rats.
abstract: BACKGROUND
  Intraoperative lymph node mapping (LNM) is highly significant for many surgeries in patients with cancer. Many types of tracers are currently used, but the ideal method has not yet been identified. We aimed to identify a stable lymphatic drainage pathway in an animal model and compared the effects of quantum dots (QD), a new fluorescent tracer, with those of methylene blue in intraoperative LNM.
  
  
  METHODS
  Indian ink (0.2 mL) was subcutaneously injected into the plantar metatarsal regions of six Sprague-Dawley rats. After 2 wk of incubation and subsequent dissection, the potentially stained LNs were examined pathologically to identify the lymphatic drainage pathway. After applying anesthesia, 0.1 mL methylene blue (2%) and QD (1 mg/mL) were injected into the plantar metatarsal regions of six rats for intraoperative LNM. The QD group was observed with a near-infrared imaging system, and the methylene blue group was directly observed. Drainages were recorded at 5, 10, 30, 60, and 120 min and at 1 d.
  
  
  RESULTS
  Two three-level drainage pathways, that is, a peripheral drainage (popliteal LNs, inguinal LNs, and axillary LNs) and a central drainage (popliteal lymph node [LN], iliac LN, and renal LN) pathways were identified. Both methylene blue and QD stained the sentinel lymph node (SLNs) quickly, but methylene blue was difficult to identify in the deep tissues and the LNs beyond the SLN. Furthermore, the blue-stained LNs remain dyed for only 2 h. In contrast, the QDs exhibited high target-to-background ratios in both the SLNs and the following LNs. Additionally, the fluorescence lasted from 5 min-1 d after injection.
  
  
  CONCLUSIONS
  An ideal lymphatic drainage model was found. QDs are excellent tracers for intraoperative LNM compared with methylene blue. Near infrared fluorescent imaging is a promising LNM method for clinical practice.
authors.affiliation: Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Chengshuai
authors.initials: C
authors.lastname: Si
authors.affiliation: Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Life Science, Fudan University, Shanghai, China; Molecular and Cell Biology Lab, Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
authors.forename: Xianbo
authors.initials: X
authors.lastname: Lv
authors.affiliation: State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, China; Department of Macromolecular Science, Fudan University, Shanghai, China.
authors.forename: Wuli
authors.initials: W
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, China; Department of Macromolecular Science, Fudan University, Shanghai, China.
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Ran
authors.affiliation: Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China; Department of General Surgery, Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: Sunpn@msn.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Sun
mesh_terms: D000818:Animals; D002104:Cadmium; D005456:Fluorescent Dyes; D006614:Hindlimb; D007432:Intraoperative Period; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000033:anatomy & histology* / Q000601:surgery*; D008297:Male; D008751:Methylene Blue; D046529:Microscopy, Electron, Transmission; D009369:Neoplasms / Q000601:surgery; D045663:Quantum Dots; D017207:Rats, Sprague-Dawley; D021701:Sentinel Lymph Node Biopsy; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013691:Tellurium
chemical_list: D005456:Fluorescent Dyes; D002104:Cadmium; D013691:Tellurium; D008751:Methylene Blue
keywords: Lymph node mapping; Near infrared fluorescent imaging; Quantum dots