DWI-ADC mismatch predicts infarct growth rate and endovascular thrombectomy outcomes in anterior circulation stroke.

Background: Current automatic software uses a fixed apparent diffusion coefficient (ADC) threshold (≤620×10⁻⁶ mm²/s) to quantify stroke volume before endovascular thrombectomy (EVT). Clinically, infarcts are visually detected by diffusion-weighted imaging (DWI) hyperintensity coupled with ADC hypointensity, which encompasses a broad range of ADC values, often exceeding the threshold. We investigated the clinical significance of large discrepancies between DWI hyperintense volumes and ADC ≤620×10⁻⁶ mm²/s volumes (DWI-ADC mismatch) on pre-EVT MRI.

Methods: This retrospective single-center study included consecutive patients with first-ever acute ischemic stroke who underwent EVT for symptomatic anterior circulation large vessel occlusion within 24 hours (January 2018-January 2020) and had high-quality pre- and post-EVT MRI. DWI-ADC mismatch was defined as a ratio of DWI hyperintense volume to ADC ≤620×10⁻⁶ mm²/s volume of ≥2. Demographics, clinical characteristics, procedural details, and outcomes were compared between mismatch and no-mismatch groups.

Results: Of 73 patients included, 20 (27.4%) had DWI-ADC mismatch. The mismatch group showed slower infarct growth (3.8 vs 7.5 mL/hour, P=0.04), significantly more parent artery stenosis (65% vs 20.8%, P<0.001), and a greater need for angioplasty/stenting (45% vs 17%, P=0.013). Imaging analysis showed a higher DWI reversal percentage (37.7% vs 21.2%, P=0.02) and a trend towards a lower ADC lowering percentage (25.3% vs 32.2%, P=0.05). Other characteristics were comparable.

Conclusions: Pre-EVT DWI-ADC mismatch identifies patients with slower infarct progression, distinct procedural requirements, and a higher likelihood of tissue reversal. Recognizing this pattern may improve EVT planning and optimize outcomes.