Follow-Up Results of Partially Thrombosed Intracranial Aneurysms with Cross-Sectional Imaging: The Case for...

Current angiographic grading systems assess parent vessel reconstruction and aneurysmal contrast filling. They, however, overlook extraluminal space, which is crucial for assessing long-term stability of treatment and correlating radiologic findings with neurologic outcomes in partially thrombosed intracranial aneurysms (PTIAs). To address this gap, we categorized patients using cross-sectional imaging (CSI) according to posttreatment size changes, independent of angiographic results.

We retrospectively reviewed patients with PTIAs treated exclusively with flow diverters (FDs) and followed for at least 12 months with MRI/CT. Patients were divided into 3 groups: group I, progressive reduction of the thrombosed mass; group II, stable size; and group III, interval growth. For comparison, all cases were also assessed using the O'Kelly-Marotta (OKM) classification.

Thirty-four PTIAs were analyzed, with a mean follow-up of 50.9 months. Posterior circulation location was independently associated with worse outcomes in the CSI-based grouping (OR = 10.84; P = .015). Neurologic outcomes improved in 17 patients (48.6%), worsened in 2 (5.7%), and remained stable in 15 (42.9%). Functional improvement (mRS) was significantly associated with the CSI-based grouping (OR = 0.15; P = .04), but not with OKM (OR = 9.74; P = .215). At last imaging, 32 patients were OKM D and 2 were OKM C; transition C→D was independently associated with better CSI-based group outcomes (OR = 0.013; P = .021). Perianeurysmal edema decreased in all patients.

The CSI-based 3-group categorization provides a more clinically meaningful assessment of PTIAs treated with FDs than conventional angiographic classifications, because it uniquely captures size changes of the thrombosed mass and correlates with functional outcomes.