Multimodal Diffuse Optical Imaging - Biomedical Optical Imaging Technologies: Design and Applications - page 366

PET is a clinically established modality that relies on exogenous contrast
agents to measure noninvasively physiological processes in vivo with 18 F-
fluorodeoxyglucose ( 18 F-FDG) being the main tracer used clinically. This
tracer accumulates in metabolically active tissue over time providing functional
information of the state of the tissue. Clinical PET imaging session are generally
performed with whole body system, but recently dedicated PET breast imagers have
been developed [ 84 , 85 ]. Such dedicated systems allow for efficient coregistration
and thus comparison of specific regions between the two stand-alone modalities.
Current work performed at the University of Pennsylvania demonstrated spatial
congruence between PET and optical contrast from patient with tumors [ 86 ](cf.
Fig. 10.6 ). Hardware fusion of these dedicated imagers with optical imaging system
is poised to occur in the near future.

10.6 Conclusion

Diffuse optical imaging, particularly diffuse optical tomography, is an emerging
clinical modality capable of providing unique functional information, at a relatively
low cost, and with nonionizing radiation. However, DOT suffers from low spatial
resolution and associated contrast dilution. To overcome this limitation, DOT has
been combined with established anatomical clinical modalities such as MRI, CT,
or US. Multimodal diffuse optical imaging has enabled a synergistic combination
of functional and anatomical information: the quality of DOT reconstructions have
been significantly improved by incorporating the structural information derived by
the combined anatomical modality. Current multimodal DOT implementations are
being designed to optimize and facilitate their use in the clinical environment and to
provide functional information of added diagnostic value to the radiologist.

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