Our goal is to provide accurate, object-independent estimates of contrast-agent concentration using energy- resolved CT. Energy-resolved CT has the potential to reduce the contrast dose and radiation dose of CT angiography exams. Combining energy-resolved CT with targeted K-edge contrast agents facilitates quantitative molecular CT, with the potential for improved spatial resolution (sub-mm), temporal resolution (sub-second) and quantitative accuracy (~5%) compared to nuclear medicine methods. Unlike conventional dual-kVp methods, energy-resolved CT distinguishes contrast materials by their distinct K-edge, enabling direct quantification. However, the accuracy and scan time of energy-resolved CT is currently limited by technological issues. This project develops innovative reconstruction and correction methods to overcome the limitations of energy-resolved CT, while increasing accuracy and reducing dose. This effort will enable faster translation of this beneficia technology into the clinic. We hypothesize that the proposed methods will quantify contrast-agent concentration to within 5% error with a one-second scan time. Specifically, the project will: (1) develop a practical spectral-response correction method, (2) develop region-of-interest material decomposition algorithms to reduce dose and pulse-pileup effects, and (3) develop a method for simultaneous estimation of contrast agent and scatter. The methods will be tested through phantom and animal experiments on our prototype energy-resolved CT system. Successful completion of the project will reduce radiation and contrast dose of CT angiography and provide important information about physiological function and disease states when combined with targeted tracers.

Public Health Relevance

This project will the challenges currently limiting the application of energy-resolved CT technology, with the goal of providing accurate contrast-agent information at fast scan times and low dose so that this new technology can be translated into the clinic.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Exploratory/Developmental Grants (R21)
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Biomedical Imaging Technology Study Section (BMIT)
Program Officer
Lopez, Hector
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Marquette University
Biomedical Engineering
Schools of Engineering
United States
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Schmidt, Taly Gilat; Barber, Rina Foygel; Sidky, Emil Y (2017) A Spectral CT Method to Directly Estimate Basis Material Maps From Experimental Photon-Counting Data. IEEE Trans Med Imaging 36:1808-1819
Foygel Barber, Rina; Sidky, Emil Y; Gilat Schmidt, Taly et al. (2016) An algorithm for constrained one-step inversion of spectral CT data. Phys Med Biol 61:3784-818
Schmidt, Taly Gilat; Zimmerman, Kevin C; Sidky, Emil Y (2015) The effects of extending the spectral information acquired by a photon-counting detector for spectral CT. Phys Med Biol 60:1583-600
Zimmerman, Kevin C; Schmidt, Taly Gilat (2015) Experimental comparison of empirical material decomposition methods for spectral CT. Phys Med Biol 60:3175-91