Quantitative assessment of motion effects in dual-source dual-energy CT and dual-source photon-counting detector CT.

Conventional dual-source CT scanners can be used to either provide better temporal resolution or dual-energy imaging, but not both at the same time. This presents a dilemma in cardiac CT as both high temporal resolution and multi-energy imaging are desirable. The current study evaluated a dual-source photon-counting-detector (DS-PCD) CT which can acquire multi-energy images at high temporal resolution. A cardiac motion phantom with a 3-mm diameter iodinated rod, mimicking the right coronary artery, was scanned 25 times using a DS-PCD CT (66 ms resolution) and a dual-source dual-energy (DS-DE, 125 ms resolution) CT. Low/high energy images and iodine maps were reconstructed at 40% and 75% cardiac phases. To quantify the impact of motion on image quality, dice similarity coefficient was computed between the low/high energy images while the circularity and effective diameter of the iodinated rod were computed on the iodine maps. The dice coefficients were higher for DS-PCD with a mean of 0.89 and 0.91 at the 40% and 70% phases, while DS-DE had a lower mean of 0.20 and 0.78, respectively. The circularity was excellent for DS-PCD with a mean of 0.97 and 0.98 at the 40% and 75% phases, while DS-DE had a mean of 0.71 and 0.98, respectively. The effective diameter was accurate for DS-PCD with a mean of 2.9 mm (true size of 3 mm) at both phases, while DS-DE had a mean of 4.0 mm and 3.2 mm at the 40% and 75% phases, respectively. These results indicate that DS-PCD CT enables simultaneous high temporal resolution and multi-energy cardiac imaging with minimal motion artifacts.