In vivo quantification of optical contrast agent dynamics in rat tumors by use of diffuse optical spectroscopy with magnetic resonance imaging coregistration.
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.
Cuccia
David J
DJ
Laser Microbeam and Medical Program, Beckman Laser Institute, University of California Irvine, Irvine, California 92612, USA.
Bevilacqua
Frederic
F
Durkin
Anthony J
AJ
Merritt
Sean
S
Tromberg
Bruce J
BJ
Gulsen
Gultekin
G
Yu
Hon
H
Wang
Jun
J
Nalcioglu
Orhan
O
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*
D004396:Coloring Agents; D003287:Contrast Media; D007208:Indocyanine Green; D008751:Methylene Blue