Photon-Counting CT Angiography vs. Energy-Integrating CT Angiography for Intracranial Vascular Implant Imaging

Abstract Purpose Photon-counting detector (PCD) CT angiography (CTA) is an emerging technology that improves spatial resolution and reduces artifacts, potentially enhancing imaging of intracranial implants. No in vivo intra-individual comparisons with energy-integrating detector (EID) CTA in patients with intracranial vascular implants have been reported. The purpose was to fill that gap by directly comparing PCD-CTA and EID-CTA. Methods In this retrospective single-center observational study, all patients with intracranial vascular implants scanned with PCD-CT from April 2023 to March 2024 were included after ethics approval. Intra-individual comparisons were performed using dual-source EID-CT from the same manufacturer. Image quality was evaluated subjectively with a 5-point Likert scale (1 = lowest, 5 = highest) and objectively via signal-to-noise ratios (SNR). Wilcoxon signed-rank tests were used for statistical analysis. Results Among 693 PCD-CT scans, 52 patients (7.5%) had intracranial vascular implants; 10 underwent both PCD-CTA and EID-CTA (median age 56.5 years, IQR 53.8–61; 90% female). PCD-CTA with iterative metal artifact reduction (MAR) demonstrated fewer artifacts and higher diagnostic value than EID-CTA (median Likert scores 4.5 and 5 vs. 3 and 3; p = 0.004). Objective image quality was superior with PCD-CTA compared to EID-CTA with MAR (SNR 34.4 vs. 17.1; p = 0.005) but not significantly different without MAR (27.8 vs. 9.9; p = 0.203). Conclusions PCD-CTA with MAR offers superior image quality and artifact reduction in patients with intracranial vascular implants, highlighting its potential as a non-invasive alternative for follow-up imaging. Larger studies are warranted to validate these findings.