Assessment of image quality and feasibility of Photon-Counting detector CT for the Non-Contemporaneous follow-up of intracranial aneurysms treated with flow diverter stents.

BACKGROUND: Noninvasive imaging is essential for long-term surveillance of flow diverter-treated intracranial aneurysms. We evaluate the image quality and feasibility of photon-counting detector CT (PCD-CT) in a real-world, non-contemporaneous follow-up setting, comparing it with intraoperative baseline DSA and flat-panel detector CT (VasoCT). METHODS: This retrospective cohort study included 30 patients (32 aneurysms) followed with PCD-CT (median: 6.5 months) after flow diverter treatment. Three neurointerventionalists, blinded to clinical data, assessed stent lumen visibility and diagnostic confidence using a 5-point Likert scale. Quantitative metrics included signal-to-noise ratio, contrast-to-noise ratio, relative metal artifact width, and radiation doses. A mixed linear model identified predictors of image quality. RESULTS: PCD-CT stent lumen visibility (4.6 ± 0.7) was significantly higher than baseline DSA (3.0 ± 0.5, P < 0.001) and VasoCT (3.1 ± 1.2, P < 0.001). Diagnostic confidence scores were significantly higher for DSA (5.0 ± 0.0) and PCD-CT (4.8 ± 0.6) than for VasoCT (3.4 ± 1.0, both P < 0.001), while PCD-CT was slightly but significantly lower than DSA (P = 0.031). Inter-observer agreement was excellent (ICC ≥ 0.945). PCD-CT effective dose (0.79 ± 0.07 mSv) was higher than localized DSA (0.13 ± 0.02 mSv) and VasoCT (0.55 ± 0.08 mSv) due to whole-brain coverage. Mixed model identified PCD-CT as the strongest positive predictor for lumen visibility (β = 1.65, P < 0.001), and this advantage remained robust across different aneurysm morphologies and the predominant stent designs evaluated in this cohort. CONCLUSION: PCD-CT provides superior stent lumen visualization compared to baseline imaging, while maintaining a sub-millisievert radiation dose. It represents a promising non-invasive surveillance tool, though prospective validation of its diagnostic accuracy for in-stent stenosis is required.