What question did this study set out to answer?

To evaluate early postoperative T2-weighted MRI abnormalities and identify predictors of non-ischemic parenchymal changes after aneurysm clipping.

February 8, 2026

Early T2-weighted magnetic resonance imaging changes after microsurgical clipping of unruptured aneurysms: Biomarkers of corridor-related tissue impact

Key Points

To evaluate early postoperative T2-weighted MRI abnormalities and identify predictors of non-ischemic parenchymal changes after aneurysm clipping.
Retrospective analysis of 797 anterior circulation UIA clipping procedures by a single surgeon.
Early postoperative MRI obtained on days 4–5 and follow-up at 12 months.
Classification of T2WI hyperintensities as non-ischemic parenchymal changes.
Stratified analyses based on surgical approach and aneurysm location.
Multivariate regression analysis to identify independent predictors.
Non-ischemic T2WI changes seen in 20.1% of procedures.
Higher incidence in interhemispheric approaches (50.7%) compared to trans-sylvian approaches (13.8%).
Within IH approaches, anterior communicating artery aneurysms had a higher incidence (68.8%) than distal anterior cerebral artery aneurysms (11.6%).
Independent predictors included IH approach (OR = 3.34), deep location (OR = 2.28), and aneurysm size ≥7 mm (OR = 1.71).
97.2% of lesions resolved or decreased at 12-month follow-up.

Abstract

Background: Diffusion-weighted imaging (DWI) detects ischemic injury after microsurgical clipping of unruptured intracranial aneurysms (UIAs), yet non-ischemic parenchymal effects remain poorly characterized. This study evaluated early postoperative T2-weighted imaging (T2WI) abnormalities to characterize corridor-related tissue impact and identify anatomical determinants of non-ischemic parenchymal changes. Methods: This retrospective study analyzed 797 anterior circulation UIA clipping procedures performed by a single surgeon under uniform protocol. Early postoperative magnetic resonance imaging (day 4–5) and 12-month follow-up were obtained. T2WI hyperintensities without restricted diffusion were classified as non-ischemic parenchymal changes. Stratified analyses isolated the effects of aneurysm depth within trans-sylvian (TS) approaches and rectal gyrus separation within interhemispheric (IH) approaches. Multivariate regression identified independent predictors. Results: Non-ischemic T2WI changes occurred in 20.1% (160/797) of procedures. IH approaches showed significantly higher incidence (50.7%) than TS approaches (13.8%, P < 0.001). Within IH approaches, anterior communicating artery aneurysms demonstrated a higher incidence (68.8%) than distal anterior cerebral artery aneurysms (11.6%, P < 0.001). Independent predictors included IH approach (odds ratio OR = 3.34, P < 0.001), deep location (OR = 2.28, P < 0.001), and aneurysm size ≥7 mm (OR = 1.71, P = 0.015). At 12-month follow-up, 97.2% of lesions resolved or decreased. DWI-detected ischemia occurred in 7.0% of procedures. No permanent neurological deficits occurred. Conclusion: Early postoperative T2WI abnormalities represent a distinct imaging signature of corridor-related tissue impact, strongly associated with approach depth and anatomy. Their reversibility indicates transient mechanical stress rather than permanent injury. T2WI serves as an objective biomarker complementing DWI-based assessment and may inform surgical quality monitoring and patient counseling.

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