Quantitative photoacoustic imaging: Correcting for heterogeneous light fluence distributions using diffuse optical tomography

Adam Q. Bauer, Ralph E. Nothdurft, Todd N. Erpelding, Lihong V. Wang, Joseph P. Culver

Research output: Contribution to journalArticlepeer-review

94 Scopus citations

Abstract

The specificity of molecular and functional photoacoustic (PA) images depends on the accuracy of the photoacoustic absorption spectroscopy. The PA signal is proportional to the product of the optical absorption coefficient and local light fluence; quantitative PA measurements of the optical absorption coefficient therefore require an accurate estimation of optical fluence. Light-modeling aided by diffuse optical tomography (DOT) can be used to map the required fluence and to reduce errors in traditional PA spectroscopic analysis. As a proof-of-concept, we designed a tissue-mimicking phantom to demonstrate how fluence-related artifacts in PA images can lead to misrepresentations of tissue properties. To correct for these inaccuracies, the internal fluence in the tissue phantom was estimated by using DOT to reconstruct spatial distributions of the absorption and reduced scattering coefficients of multiple targets within the phantom. The derived fluence map, which only consisted of low spatial frequency components, was used to correct PA images of the phantom. Once calibrated to a known absorber, this method reduced errors in estimated absorption coefficients from 33 to 6. These results experimentally demonstrate that combining DOT with PA imaging can significantly reduce fluence-related errors in PA images, while producing quantitatively accurate, high-resolution images of the optical absorption coefficient.

Original languageEnglish
Article number096016
JournalJournal of biomedical optics
Volume16
Issue number9
DOIs
StatePublished - Sep 2011

Keywords

  • diffuse optical tomography
  • light modeling
  • multimodal imaging
  • quantitative photoacoustic imaging

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