Photoacoustic spectroscopic imaging of infra-tumor heterogeneity and molecular identification

Keith M. Stantz, Bo Liu, Minsong Cao, Dan Reinecke, Kathy Miller, Robert Kruger

Research output: Chapter in Book/Report/Conference proceedingConference contribution

24 Scopus citations

Abstract

Purpose. To evaluate photoacoustic spectroscopy as a potential imaging modality capable of measuring intra-tumor heterogeneity and spectral features associated with hemoglobin and the molecular probe indocyanine green (ICG). Material and Methods. Immune deficient mice were injected with wildtype and VEGF enhanced MCF-7 breast cancer cells or SKOV3× ovarian cancer cells, which were allowed to grow to a size of 6-12 mm in diameter. Two mice were imaged alive and after euthanasia for (oxy/deoxy)-hemoglobin content. A 0.4 mL volume of 1 μg/mL concentration of ICG was injected into the tail veins of two mice prior to imaging using the photoacoustic computed tomography (PCT) spectrometer (Optosonics, Inc., Indianapolis, IN 46202) scanner. Mouse images were acquired for wavelengths spanning 700-920 nm, after which the major organs were excised, and similarly imaged. A histological study was performed by sectioning the organ and optically imaging the fluorescence distribution. Results. Calibration of PCT-spectroscopy with different samples of oxygenated blood reproduced a hemoglobin dissociation curve consistent with empirical formula with an average error of 5.6%. In vivo PCT determination of SaO 2 levels within the tumor vascular was measurably tracked, and spatially correlated to the periphery of the tumor. Statistical and systematic errors associated with hypoxia were estimated to be 10 and 13%, respectively. Measured ICG concentrations determined by contrast-differential PCT images in excised organs (tumor, liver) were approximately 0.8 μg/mL, consistent with fluorescent histological results. Also, the difference in the ratio of ICG concentration in the gall bladder-to-vasculature between the mice was consistent with excretion times between the two mice. Conclusion. PCT spectroscopic imaging has shown to be a noninvasive modality capable of imaging intra-tumor heterogeneity of (oxy/deoxy)-hemoglobin and ICG in vivo, with an estimated error in SaO 2 at 17% and in ICG at 0.8 μg/mL in excised tissue. Ongoing development of spectroscopic analysis techniques, probe development, and calibration techniques are being developed to improve sensitivity to both exogenous molecular probes and (oxy/deoxy)-hemoglobin fraction.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
DOIs
StatePublished - May 8 2006
Event7th Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics - Photons Plus Ultrasound: Imaging and Sensing 2006 - San Jose, CA, United States
Duration: Jan 22 2006Jan 26 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6086
ISSN (Print)0277-786X

Other

Other7th Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics - Photons Plus Ultrasound: Imaging and Sensing 2006
CountryUnited States
CitySan Jose, CA
Period1/22/061/26/06

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Keywords

  • Breast cancer
  • Idocyanine green
  • Ovarian cancer
  • Oxyhemoglobin
  • Photoacoustic spectroscopy

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Stantz, K. M., Liu, B., Cao, M., Reinecke, D., Miller, K., & Kruger, R. (2006). Photoacoustic spectroscopic imaging of infra-tumor heterogeneity and molecular identification. In Proceedings of SPIE - The International Society for Optical Engineering [608605] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 6086). https://doi.org/10.1117/12.645106