Evaluation of Photon-Counting CT for Spectral Imaging in Cardiovascular Applications: Impact of Lumen Size, Dose, and Patient Habitus.

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, XL: 40×50 cm, representing the 99th percentile of US patient sizes), and iodine concentrations (2, 5, and 10 mg/mL). Scans were performed at radiation dose levels of 5, 10, 15, and 20 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 phantom sizes, with deviations consistently below 0.6 mg/mL. Whereas, for 4 mm lumens, stability is observed primarily in smaller to medium phantoms, highlighting the influence of patient size and radiation dose on quantification accuracy. Virtual Monoenergetic Imaging (VMI) at 70 keV showed stable performance for larger lumens (≥6 mm) with variations of 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. Importantly, the study demonstrates that PCCT delivers stable and highly accurate imaging across nearly the entire range of patient sizes in the U.S..

Advances in knowledge: This study demonstrates PCCT's potential to enhance spectral imaging in vascular applications, surpassing conventional or Dual Energy CT.