Ex vivo high-resolution hybrid micro-CT imaging using photon counting and energy integrating detectors
Spectral micro-CT shows great potential to provide accurate material composition by utilizing the energy dependence of x-ray attenuation in different materials. This is especially well-suited for pre-clinical imaging using nanoparticle-based contrast agents in situations where quantitative material decomposition helps probe processes which are otherwise limited by poor soft tissue contrast. Our group has developed multiple generations of pre-clinical prototype PCCT systems and applied them in cancer and cardiac studies using nanoparticle contrast agents. This work aims to describe and assess the performance of a hybrid system for ex vivo high-resolution micro-CT using photon counting and energy integrating detectors. Both phantom and ex vivo mouse micro-CT data were reconstructed using our iterative, multi-channel algorithm based on the split Bregman method and regularization with rank-sparse kernel regression. A post-reconstruction spectral decomposition method was used. The system is capable of high resolution (15.6 lp/mm, 10% MTF) tomographic imaging. Despite the anti-coincidence corrections, the spectral performance of the PCD is, however, not perfect. Preliminary results show that adding energy integrating data to the PCD scan reduces the prevalence of certain PCD-specific artifacts and offers the potential for various hybrid approaches to PCD corrections. We also show that our spectral hybrid micro-CT separates calcified plaques from the iodine accumulation in our atherosclerosis mouse model. This is not possible in the EID-based CT imaging. Such hybrid spectral micro-CT will benefit both nanotechnology and imaging developments by providing an ex vivo high resolution imaging method that can validate experiments in theranostics.
