Association of the procedure complexity index with diffusion-weighted imaging lesion burden and neurological complications following coil embolization of unruptured intracranial aneurysms: a retrospective study

Objective: Diffusion-weighted imaging (DWI) lesions after coil embolization of intracranial aneurysms reflect procedure-related microembolic injury.We developed a procedure complexity index (PCI) to quantify technical complexity during coil embolization and investigated its association with DWI lesion burden and periprocedural neurologic events.Methods: We retrospectively analyzed 292 patients who underwent endovascular coil embolization for unruptured intracranial aneurysms between January 2021 and December 2023.The PCI score (range, 0-14) integrates 6 procedural domains: microcatheter navigation difficulty, adjunctive device use, coil deployment complexity, procedure duration, fluoroscopy time, and thrombus-related events.The primary outcome was DWI lesion count, which was analyzed using multivariable negative binomial regression.The secondary outcome was periprocedural neurologic events, evaluated using multivariable logistic regression and receiver operating characteristic analysis.Results: The median PCI score was 6 (interquartile range, 4-8).Each 1-point increase in PCI was independently associated with an 18% increase in DWI lesion count (incidence rate ratio, 1.18; 95% confidence interval, 1.09-1.28;P < 0.001).The highest PCI quartile had greater DWI lesion burden and a higher rate of DWI positivity than the lowest quartile (62% vs. 22%).PCI was also an independent predictor of periprocedural neurologic events (odds ratio, 1.34 per 1-point increase; 95% confidence interval, 1.18-1.52;P < 0.001), beyond conventional clinical and aneurysm-related factors.Conclusion: The PCI is an objective measure of technical difficulty during coil embolization and independently predicts both DWI lesion burden and periprocedural neurologic events.PCI may serve as a practical intra-procedural risk-stratification tool, although prospective validation is required.