title: In vivo quantification of optical contrast agent dynamics in rat tumors by use of diffuse optical spectroscopy with magnetic resonance imaging coregistration.
abstract: We present a study of the dynamics of optical contrast agents indocyanine green (ICG) and methylene blue (MB) in an adenocarcinoma rat tumor model. Measurements are conducted with a combined frequency-domain and steady-state optical technique that facilitates rapid measurement of tissue absorption in the 650-1000-nm spectral region. Tumors were also imaged by use of contrast-enhanced magnetic resonance imaging (MRI) and coregistered with the location of the optical probe. The absolute concentrations of contrast agent, oxyhemoglobin, deoxyhemoglobin, and water are measured simultaneously each second for approximately 10 min. The differing tissue uptake kinetics of ICG and MB in these late-stage tumors arise from differences in their effective molecular weights. ICG, because of its binding to plasma proteins, behaves as a macromolecular contrast agent with a low vascular permeability. A compartmental model describing ICG dynamics is used to quantify physiologic parameters related to capillary permeability. In contrast, MB behaves as a small-molecular-weight contrast agent that leaks rapidly from the vasculature into the extravascular, extracellular space, and is sensitive to blood flow and the arterial input function.
authors.affiliation: Laser Microbeam and Medical Program, Beckman Laser Institute, University of California Irvine, Irvine, California 92612, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Cuccia
authors.forename: Frederic
authors.initials: F
authors.lastname: Bevilacqua
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Durkin
authors.forename: Sean
authors.initials: S
authors.lastname: Merritt
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Tromberg
authors.forename: Gultekin
authors.initials: G
authors.lastname: Gulsen
authors.forename: Hon
authors.initials: H
authors.lastname: Yu
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Orhan
authors.initials: O
authors.lastname: Nalcioglu
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000818:Animals; D004396:Coloring Agents; D003287:Contrast Media; D007208:Indocyanine Green; D008279:Magnetic Resonance Imaging; D008751:Methylene Blue; D009368:Neoplasm Transplantation; D055095:Optics and Photonics; D051381:Rats; D011916:Rats, Inbred F344; D012878:Skin Neoplasms / Q000175:diagnosis*
chemical_list: D004396:Coloring Agents; D003287:Contrast Media; D007208:Indocyanine Green; D008751:Methylene Blue