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BEST IN PHYSICS (IMAGING) - The Feasibility of Multiplexed Biomarker Detection Using X-Ray Stimulated Fluorescence Imaging

Y Kuang

Y Kuang*, G Pratx, B Meng, J Qian, M Bazalova, L Xing, Stanford University, Stanford, CA

TH-A-213CD-2 Thursday 8:00:00 AM - 9:55:00 AM Room: 213CD

Purpose: A feasible way of enhancing diagnosis reliability is to detect multiple biomarkers at the same time via simultaneously using multiple probes to achieve multiplexed molecular imaging. However, no routine approach to directly measure multiple biomarkers currently exists via X-ray CT, which is the most commonly used imaging modality in the clinic. In this study, we investigated the feasibility of multiplexed biomarker detection using X-ray stimulated fluorescence CT (XSF-CT).

Methods: This method utilizes high atomic number (Z) nanoprobes, i.e. Gold (Au), Gadolinium (Gd) and Barium (Ba), that emit XSF photons when excited by ionizing photons. Since the XSF spectrum is unique to each element, this provides a means of detecting the presence of multiple nanoparticles coated with antibodies or peptides that specifically bind to biomarkers found only in tumor. In this study, a polychromatic X-ray source was used to stimulate emission of XSF photons from the probes. XSF-CT used a first-generation CT geometry. The data were collected using a cadmium telluride detector to sort out a set of spectra. The spectra were then used to generate sinogram. The biodistribution and concentration of each element were reconstructed with the ML-EM algorithm.

Results: The acquired XSF spectra showed sharp peaks emitted from Au, Gd and Ba molecules with small FWHM values, which supports the potential of XSF-CT for multiplexed imaging. The distributions of Au, Gd and Ba molecules in the phantom were clearly identifiable on the reconstructed XSF images. In addition, our results also showed the linear relationships between the XSF intensity of each tested element and their concentrations, respectively.

Conclusions: XSF imaging would transform the CT landscape into a multiplexed biomarker detection feature for early detection of cancer and/or imaging the intervention processes in vivo. It could have major predictive value for the clinical outcome in the long term patient care.

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