Increased Multispectral CT Iodine Concentrations in Patients With Transient Neurological Deterioration Following Endovascular Neurointerventional Procedures: an Argument in Favor of the Elusive Contrast-Induced Encephalopathy?

Abstract

Background and purpose: So-called contrast-induced encephalopathy (CIE) is a rare but worrying condition occurring after cerebral angiography or neuroendovascular interventions using iodine contrast media. This study aimed to compare cerebral iodine concentrations in patients suspected of having CIE after endovascular procedures to those in matched controls.

Methods: This is a retrospective monocentric study of 25 suspected CIE patients in a tertiary care teaching hospital diagnosed from June 2017 to February 2024. Cerebral multispectral computed tomography (CT) iodine mean concentrations were measured and compared with 1:1 matched controls using the CT constructor's workstation in the whole brain and in specific regions of interest (ROIs) corresponding to a vascular territory downstream of the procedure. Concentration values were compared with paired samples t‑test.

Results: During the study period, 1097 patients underwent aneurysm embolization and 137 arteriovenous malformation (AVM) embolization procedures. So-called CIE was suspected in 25 patients after aneurysm or AVM embolization (2%). Mean iodine concentrations in the procedure vascular territory ROIs were higher in suspected CIE cases (mean 543 ± 147 µg/cm³) compared to matched controls (mean 463 ± 141 µg/cm³; p = 0.01). Whole brain mean iodine concentrations were modestly higher in CIE patients compared to controls across all subgroups, without reaching statistical significance.

Conclusions: CIE may be associated with modest increase in CT iodine concentration in the procedure vascular territory after neurointerventional procedures. The underlying pathophysiology of this condition remains uncertain and merits further investigation.

Key messages: Contrast-induced encephalopathy (CIE) is known as a rare neurologic condition following iodine contrast media use in neuroendovascular interventions, with unclear pathophysiology.

What this study adds: This study provides evidence that suspected CIE is associated with higher cerebral iodine concentrations in affected vascular territories, a novel quantifiable change. Implications for research, practice, or policy: These findings suggest the potential for iodine concentration monitoring to refine CIE diagnosis and prevention strategies in clinical practice.

Keywords: Complication; Contrast-induced encephalopathy (CIE); Dual-energy computed tomography (DECT); Neuroendovascular procedures; Vascular territories.