Efficiency and Optimization of Iodinated Contrast Agents in Cerebral Aneurysm CT Angiography: A Systematic Review

Background/Objectives: The demand for reducing iodinated contrast agent (ICA) dose in cerebral CT angiography (CTA) for aneurysm detection has increased due to concerns over patient safety and image quality. The aim of this study is to systematically review the diagnostic accuracy, image quality, and dose efficiency of optimized ICA protocols in CTA for intracranial aneurysm detection. We also aimed to distinguish between direct diagnostic studies reporting aneurysm sensitivity/specificity and indirect technical studies, emphasizing patient-specific tailoring using cardiac output and lean body weight. Methods: Following PRISMA 2020 guidelines, PubMed, Scopus, and Web of Science were searched up to 2 June 2026. Two reviewers independently screened studies, extracted data, and assessed risk of bias using QUADAS-2 and the NIH tool. Due to clinical and technical heterogeneity, a narrative synthesis was performed. Results: Eleven studies comprising 716 patients were included. Low tube voltage (70-80 kVp) combined with reduced iodine load (8-30 mL, 3.2-9 gI) maintained diagnostic accuracy for aneurysms >3 mm compared to standard protocols. Iterative reconstruction and deep learning improved contrast-to-noise ratio by 23-45% at reduced dose. Technical studies showed feasibility of ultra-low-volume protocols but lacked aneurysm-specific DSA validation. Conclusions: Reduced-contrast and low-kVp CTA protocols may preserve diagnostic performance for intracranial aneurysm detection while lowering iodine exposure. However, current evidence is limited by small sample sizes and heterogeneous protocols. Prospective, aneurysm-specific validation is required before clinical implementation.