Technical feasibility of CT perfusion using a C-Arm CBCT system

It is highly desirable to obtain perfusion information with the C-arm CBCT system in the interventional room. However, due to hardware limitations, it is still elusive to achieve cone-beam CT perfusion measurements. In this study, we performed a systematic study to investigate what the main limiting factors are that need to be addressed for future C-arm cone beam CT perfusion imaging. To do so, we performed systematic numerical simulation studies using a diagnostic CT perfusion data set. Specifically, a forward projection was performed to simulate cone-beam CT perfusion experiment with C-arm CBCT geometry and temporal behavior. Different x-ray delays after contrast injection have been simulated with this method. The view angle undersampling artifacts, shading artifacts from dynamic objects, and the importance of arterial input function (AIF) for perfusion study were investigated in this study with different x-ray delay times. From the simulation results, it was found that the view angle undersampling artifacts do not have much impact on perfusion maps. The shading artifacts from dynamic object were shown to have a negligible effect on the NRMSE in perfusion maps. The accuracy of AIF is an important but not a dominating factor for perfusion studies. C-arm CBCT cannot accurately recover the slowly changing contrast in brain tissues due to the low temporal resolution. Therefore, to enable cone beam C-arm CT perfusion measurement, it is critical to improve the temporal behavior of CBCT by either employing new hardware upgrades or introducing new software methods.