title: In vivo photothermal optical coherence tomography of gold nanorod contrast agents.
abstract: Photothermal optical coherence tomography (PT-OCT) is a potentially powerful tool for molecular imaging. Here, we characterize PT-OCT imaging of gold nanorod (GNR) contrast agents in phantoms, and we apply these techniques for in vivo GNR imaging. The PT-OCT signal was compared to the bio-heat equation in phantoms, and in vivo PT-OCT images were acquired from subcutaneous 400 pM GNR Matrigel injections into mice. Experiments revealed that PT-OCT signals varied as predicted by the bio-heat equation, with significant PT-OCT signal increases at 7.5 pM GNR compared to a scattering control (p < 0.01) while imaging in common path configuration. In vivo PT-OCT images demonstrated an appreciable increase in signal in the presence of GNRs compared to controls. Additionally, in vivo PT-OCT GNR signals were spatially distinct from blood vessels imaged with Doppler OCT. We anticipate that the demonstrated in vivo PT-OCT sensitivity to GNR contrast agents is sufficient to image molecular expression in vivo. Therefore, this work demonstrates the translation of PT-OCT to in vivo imaging and represents the next step towards its use as an in vivo molecular imaging tool.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, 5824 Stevenson Center, Nashville, TN 37235,  USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Tucker-Schwartz
authors.forename: T A
authors.initials: TA
authors.lastname: Meyer
authors.forename: C A
authors.initials: CA
authors.lastname: Patil
authors.forename: C L
authors.initials: CL
authors.lastname: Duvall
authors.forename: M C
authors.initials: MC
authors.lastname: Skala