Biomedical Engineering Reference
In-Depth Information
Fig. 10.1
Electromagnetic spectrum and associated imaging modalities
PET/DOT, MRI/DOS (diffuse optical spectroscopy), X-ray/DOT, US/DOS, and
other combinations using optical methods as a complementary imaging modality.
Each imaging technique relies on different physical tissue interaction principles
and in some cases on the use of different molecular probes (cf. Fig.
10.1
). As
a result, multimodal imaging methods may provide a unique combined set of
structural, functional, molecular, and/or metabolic information. The complexities of
integrating different methods are offset by the potential for increased performance
in both sensitivity and specificity (by reducing false-positive and false-negative
results) in screening, diagnosis, staging, treatment monitoring, or image-guided
intervention.
In this chapter, we will review the basic principles of diffuse optical imaging,
including instrumentation and reconstruction algorithm design. We will also discuss
the approaches for multimodal imaging strategies that integrate DOI with clinically
established modalities. The merit of the multimodal imaging approaches is demon-
strated in the context of optical mammography, but the techniques described herein
can be translated to other clinical scenarios such as brain functional imaging or
muscle functional imaging.
10.2
Tissue Optics for Diffuse Optical Imaging
Light propagation in biological samples is highly dependent on the probing
wavelength. Due to the strong light absorption properties of hemoglobin and water,
optical techniques that are based on ultraviolet or visible spectra are restricted to
interrogating shallow tissue. Thus, to probe tissue deeper than half a centimeter
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