ABSTRACT
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Conflict of Interest Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
The medical field has been revolutionized by technologies that visualize tissue for diagnostic pur-
poses. However, quantitative characterization of tissue structure and function remains a challenge
due to structural heterogeneity and functional diversity across spatial scales. Optical technologies
have proven to be an inexpensive and safe method to visualize tissue at a multitude of spatial scales.
The focus of this chapter is on meso-to macroscopic (∼0.1-5 cm) imaging of tissue. Over these
length scales, light is multiply scattered, thus rendering the resulting images blurry and more diffi-
cult to interpret. The loss of structural information is balanced, in part, by the exquisite sensitivity
of multiply scattered “diffuse” light to small changes in tissue functional properties. Thus, quantita-
tive characterization of tissue optical scattering and absorption can provide the key to understanding
tissue structure and function, respectively. There has been extensive work on a number of measure-
ment methods to characterize light transport in tissue. In this chapter, we will review some general
approaches used to characterize thick tissue and will focus in detail on frequency domain spatial
and temporal techniques for quantitative tissue analysis.
