Exhibit Hall | Forum 8
Purpose: Iterative beam-hardening corrections (iBHC) can increase the accuracy of CT numbers for iodine and calcium. However, the use of iBHC in multi-energy CT (MECT) has been largely unexplored. The purpose of this work was to investigate effects of iBHC on MECT material decomposition using several applications in Siemens Healthineers syngo.via software.
Methods: Iodine and calcium quantification was performed with a DualSpiral MECT technique on the Siemens SOMATOM Definition Edge CT scanner. Images were acquired of the Gammex MECT abdomen and head phantoms containing calcium and iodine inserts. Iodine and calcium enhancement/un-enhancement images (in HU) were created in the LiverVNC and BoneMarrow applications, respectively. Several image processing workflows were explored investigating the effects of iBHC and the interplay between iBHC and two parameters used in syngo.via: the size-specific dual-energy ratio (DER) and the syngo.via beam-hardening correction (sBHC).
Results: iBHC increased the accuracy of CT numbers within iodine and calcium inserts in the low- and high-energy images, which led to better agreement in DER values between the abdomen and head phantom. The use of iBHC deactivated the sBHC, thus a single DER value for all phantom sizes could be beneficial. However, the plot of CT numbers for all iodine and calcium concentrations in the low-energy image as a function of the high-energy image was less linear (average R2(iBHC)=0.9991, average R2(no-iBHC)=1.000). These deviations from linearity resulted in errors in the corresponding MECT enhancement and un-enhancement images of up to 40 HU.
Conclusion: While the use of iBHC can increase the accuracy of CT numbers for single-energy CT, the use of iBHC for MECT imaging is not straightforward. In the conditions of this study, the most accurate MECT material quantification was calculated on images without iBHC. It is important to understand the interplay between iBHC with MECT material decomposition parameters.
Funding Support, Disclosures, and Conflict of Interest: Dr. Lawless and Dr. Miller have received research funding through Siemens Healthineers.