title: Noninvasive photoacoustic identification of sentinel lymph nodes containing methylene blue in vivo in a rat model.
abstract: Sentinel lymph node biopsy (SLNB) has become the standard method of axillary staging for patients with breast cancer and clinically negative axillae. Even though SLNB using both methylene blue and radioactive tracers has a high identification rate, it still relies on an invasive surgical procedure with associated morbidity. Axillary ultrasound has emerged as a diagnostic tool to evaluate the axilla, but it can only assess morphology and cannot specifically identify sentinel lymph nodes (SLNs). In this pilot study, we propose a noninvasive photoacoustic SLN identification system using methylene blue injection in a rat model. We successfully image a SLN with high optical contrast (146+/-41, standard deviation) and good ultrasonic resolution (approximately 500 microm) in vivo. We also show potential feasibility for clinical applications by imaging 20- and 31-mm-deep SLNs in 3-D and 2-D, respectively. Our results suggest that this technology would be a useful clinical tool, allowing clinicians to identify SLNs noninvasively in vivo.
authors.affiliation: Washington University in Saint Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, Campus Box 1097, One Brookings Drive, Saint Louis, Missouri 63130-4899, USA.
authors.forename: Kwang Hyun
authors.initials: KH
authors.lastname: Song
authors.forename: Erich W
authors.initials: EW
authors.lastname: Stein
authors.forename: Julie A
authors.initials: JA
authors.lastname: Margenthaler
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D004195:Disease Models, Animal; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008751:Methylene Blue; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*
chemical_list: D008751:Methylene Blue