Phantom-based quantification of the spectral accuracy of lower extremity vascular imaging using a second-generation dual-layer spectral CT at 100 kVp and 120kVp

This study quantitatively evaluated the effects of tube voltage, CTDIvol, energy level, and iodine concentration on the performance of lower-extremity vascular imaging using a second-generation dual-layer spectral CT (DSCT). We further assessed the potential for reducing radiation dose and contrast agent use without compromising image quality. A spectral CT phantom with tissue-equivalent inserts and varying iodine concentrations (4, 8, 12, and 16 mgI/mL) was scanned at different tube voltages (100/120 kVp), CTDIvol levels (2.5, 5, 10 mGy), and virtual monoenergetic levels (40, 70, 100 keV), alongside conventional imaging. Vessel diameters of 2.5, 4, and 5 mm were evaluated. Objective image quality was assessed via CT attenuation, SD, SNR, and CNR. Two radiologists used a 5-point Likert scale to assess the subjective image quality. No significant differences were observed in subjective or objective scores between tube voltages or across CTDIvol levels (p > 0.05). Low-energy 40 keV images yielded comparable quality to 70 keV and conventional images. At 40 keV, ultra-low iodine concentrations (4 mgI/mL) achieved image quality similar to higher concentrations (12/16 mgI/mL) in conventional scans. The combination of 100 kVp, 2.5 mGy, and 40 keV provided superior image quality relative to conventional CT. Second-generation DSCT at 100 kVp provides high-accuracy lower-limb vascular imaging, even at low radiation doses and contrast concentrations, supporting its potential for clinical dose-reduction strategies.