Room: AAPM ePoster Library
Purpose: Dual Energy CT (DECT) provides differentiation of residual iodinated contrast from hemorrhagic transformations in stroke patients. However, iodine enhancement and blood suppression in iodine maps may be affected by reconstruction filters. This study evaluates the effects of five reconstruction filters on the enhancement of iodine and suppression of blood in iodine maps and virtual monochromatic images (VMIs).
Methods: A multi-energy CT phantom with stroke-mimicking materials was scanned five times in a single source sequential DECT scanner, resulting in a CTDIvol of 54 mGy. The vendor-recommended abdomen reconstruction filter was assessed in addition to two brain and two bone filters. VMIs were reconstructed to assess measured HU accuracy with respect to theoretical calculated HUs. Iodine maps were generated by raw (RDS) and image data software (IDS). Using Matlab, regions of interest were placed on the central axial slice of the phantom. CT Numbers were analyzed for all materials and iodine enhancement (HU) versus iodine concentration linear curves were plotted.
Results: In both RDS- and IDS-processed iodine maps, blood materials were enhanced by bone filters (51 ± 0.6 HU) and suppressed by the abdomen filter (5 ± 0.5 HU). Bone filter iodine enhancement linear curves had y-intersection shifts of 16 HU in comparison to abdomen and head filter linear curves. In comparison to IDS, RDS iodine maps on average had 9.5 ± 0.5 HU greater iodine enhancement for all filters. Abdomen filter VMIs had an R squared value of 1 for the iodine 5 mg/mL concentration HU accuracy.
Conclusion: Although DECT is capable of differentiating between acute bleeds and iodine in the brain, proper selection of reconstruction filter must be utilized. This study recommends utilizing RDS iodine maps in conjunction with smooth abdomen filters for optimal blood suppression and iodine enhancement.
Funding Support, Disclosures, and Conflict of Interest: Funding provided by Canon Medical Systems to the radiology's department's budget. Grant money funded partial PhD student's tuition costs at the University of Florida. No co-author directly received payment for this work. No conflicts of interest to disclose.