First-generation Photon-counting Computed Tomography Angiography Versus Third-generation Dual-energy Computed Tomography Angiography for Peripheral Artery Disease Imaging.

Objective: To investigate the objective performance and subjective image quality of lower extremity CT angiography (CTA) in peripheral artery disease (PAD) through comparison of the first-generation photon-counting CT (PCCT) technology and the third-generation dual source energy-integrating detector CT (DECT) technology.

Materials And Methods: Patients who underwent a CTA either on a PCCT or on a DECT were included in this retrospective analysis. All included patients received a digital subtraction angiography (DSA) as reference standard for stenosis grading. Virtual monoenergetic image data sets were reconstructed at 40, 45, 50, 55, and 60 keV. The noise, the signal-to-noise ratio (SNR), and the contrast-to-noise ratio (CNR) of vascular structures, as well as the subjective image quality using a standardized 5-point Likert Scale, were determined. Finally, the sensitivity, specificity, and accuracy of the stenotic disease detection for either technology (DECT and PCCT) were analyzed.

Results: PCCT angiography was performed in 50 PAD patients (31 males, mean age 76.16 ± 10.26), and DECT angiography was pursued in 50 PAD patients as well (29 males, mean age 74.0 ± 14.26). PCCT reached significantly higher CNR compared with DECT in all assessed arterial territories [eg, 27.84 (IQR: 22.57 to 34.66) vs 17.25 (IQR: 12.12 to 23.71), at the iliac arterial vasculature at 40 keV, P < 0.001]. Image quality and contrast were rated significantly higher for PCCT compared with DECT [eg, mean vessel contrast 5 (IQR: 4 to 5) vs 4 (IQR: 4 to 4)], at the calf arterial vasculature at 40 keV, P <0.001. Overall sensitivity, specificity, and accuracy for PCCT were 96%, 97%, and 97%, respectively, in comparison to 93%, 96%, and 94%, respectively, for DECT image data sets at 55 keV.

Conclusion: PCCT offers superior objective performance and better subjective image quality compared with DECT. Hence, PCCT angiography is improving cross-sectional PAD imaging.