Impact of Vessel Size, Dose Levels, and Body Habitus on Iodine Quantification in Cardiovascular Photon-Counting Computed Tomography.

Objectives: This study evaluates the performance of a clinical dual-source photon-counting computed tomography (PCCT) system in quantifying iodine within calcified vessels, using 3D-printed phantoms with vascular-like structures lined with calcium.

Methods: Parameters assessed include lumen diameters (4, 6, 8, 10, and 12 mm), phantom sizes (S: 20 × 20 cm, M: 25 × 25 cm, L: 30 × 40 cm), and iodine concentrations (2, 5, and 10 mg/mL). Scans were performed with a cardiac high-pitch acquisition protocol at radiation dose levels of 5 and 10 mGy to systematically evaluate iodine quantification accuracy and spectral imaging performance.

Results: The results indicate that for lumen diameters ≥6 mm, iodine quantification remains stable across all dose levels and smaller phantom sizes, where error remained consistently below 0.9 mg/mL. Furthermore, iodine quantification revealed a significant dependence on phantom size while selected radiation dose levels were insignificant. Virtual Monoenergetic Imaging (VMI) at 70 keV showed stable performance for larger lumens (≥6 mm) with variations of 20.3 ± 13.2 HU across all conditions, while smaller lumens remained stable in medium to small phantoms.

Conclusions: These findings highlight the influence of lumen diameter, patient size, and radiation dose in optimizing PCCT protocols for spectral imaging. Results indicate that PCCT maintains stable and precise imaging performance across diverse patient anatomies, with robust differentiation of iodine and calcium in adjacent regions.

Advances in knowledge: This study demonstrates PCCT's potential to enhance spectral imaging in vascular applications, characterizing iodine quantification at relevant lesion sizes for vascular imaging.