Mapping DWI signal reversal and long-term tissue outcomes following endovascular therapy in acute ischemic stroke

OBJECTIVES: Diffusion-weighted imaging lesion reversal (DWI-R) is commonly observed on MRI after treatment for acute ischemic stroke. However, its extent across different brain regions post-endovascular therapy (EVT) and its long-term tissue-specific consequences are inadequately described in the literature. This study evaluated DWI-R across brain regions and tissue types and assessed long-term changes after 1 month.

MATERIALS AND METHODS: This cohort study included acute ischemic stroke patients with MRI acquired before and 12 to 36 h after EVT. DWI lesions were segmented and co-registered to MNI space to generate probabilistic maps of DWI-R distribution. The probability of DWI-R was analyzed in relation to the involvement of white matter, cortical regions, and deep gray matter. Changes indicative of tissue damage were evaluated in a subgroup with follow-up imaging > 1 month post-EVT.

RESULTS: Of 565 consecutive EVT patients in the period January 2017-March 2022, 303 were included. DWI-R was observed in all major vascular territories. White matter showed 1.95 times higher probability of DWI-R compared to deep gray matter (p < 0.001), with no significant difference compared to cortical regions. Among 62 DWI-R cases with follow-up imaging, 29 (47%) showed no signal changes in areas of the initial lesion, with no significant difference between white and gray matter.

CONCLUSIONS: Caution is advised when excluding patients from EVT based on restrictive diffusion, as both white and gray matter frequently responded to treatment in this study.

KEY POINTS: Question Understanding diffusion-weighted imaging reversal following endovascular therapy is crucial for stroke diagnostics, yet its regional distribution and long-term tissue-specific consequences remain poorly characterized. Findings Diffusion-weighted imaging reversal occurred throughout the brain, often persisted, and did not significantly differ between white matter and cortical regions. Clinical relevance Restrictive diffusion on MRI should be used with caution to exclude acute ischemic stroke patients from endovascular therapy, as such changes often respond to treatment both in white and gray matter.