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DOT/MRI Dual-Modality Cancer Imaging Using a Bifunctional Contrast Agent

Final Report Summary - UNLU_IRG2010 (DOT/MRI Dual-Modality Cancer Imaging Using a Bifunctional Contrast Agent)

There were two goals of the project. The first was the technology development. The technology development part consisted of two sub goals: a) the development of a novel multi-modality dynamic imaging system and b) the development of polymer based bi-functional and mono- functional optical agents. It is important to note that bi-functional contrast agents are ideal for multimodal imaging systems. Each imaging modality can independently track the dynamics of the same contrast agent. This enables various applications such as in vivo validation studies.

Both goals were achieved successfully. During the project, one large and one medium size polymer based bi-functional contrast agent were produced for a combined diffuse optical tomography/magnetic resonance imaging (DOT/MRI) system that was located in Tu and Yuen Center for Functional Onco-Imaging, University of California, Irvine. The system was able to measure the enhancement kinetics of the mono-functional optical contrast agents or bi-functional optical/MR contrast agents. Besides, the detection of the endogenous contrast difference between normal and cancerous tissue due to differences in hemoglobin content and scattering properties was possible.

The bi-functional contrast agents were tested in small animal tumor models. All animal procedures were approved by the Institutional Animal Care and Use Committee at University of California, Irvine. Fisher rats with 180 gram average weight were used in the studies. The rat was placed inside the DOT/MRI system. The polymer based bi-functional contrast agents produced by GE Global Research, NY were injected. Data acquisition was done simultaneously by DOT and MRI systems.

Results showed that the enhancement kinetics measured by DOT and MRI were similar. In particular, wash in pattern and the location of the peak enhancement in time detected by both modalities overlapped. However, in general, MRI kinetic curve showed a faster wash-out pattern whereas the optical one was slower.