Abstract Body:
Introduction: An apparent diffusion coefficient (ADC) threshold of ≤ 620 × 10-6 mm2/s identifies irreversible infarcts and guides endovascular thrombectomy (EVT) decisions. However, in hyperacute ischemic infarcts, diffusion-weighted imaging (DWI) hyperintense lesions can show varying ADC values. This study investigates DWI-ADC mismatch, defined as the significant difference between DWI hyperintense lesion volume and ADC ≤ 620 × 10-6 mm2/s volume.
Methods: This retrospective, single-center study included patients with acute large vessel occlusion in the anterior circulation who: (1) underwent MRI within 24 hours of stroke onset, (2) received EVT, and (3) had follow-up MRI within 5 days of EVT from January 2018 to January 2020. Neuroradiologists segmented DWI hyperintense infarcts with ADC hypointensity on pre- and post-EVT MRI, using Fluid-attenuated inversion recovery (FLAIR) sequences to avoid T2 shine-through effects. The DWI/ADC volume ratio was calculated by dividing DWI volume by ADC ≤ 620 × 10-6 mm2/s volume. DWI-ADC mismatch was defined as a DWI/ADC ratio ≥ 2, with no mismatch indicated by a ratio < 2. Final infarct segmentation included hemorrhagic transformation. DWI lesion reversal (DWIR) was defined as the volume of normal-appearing voxels on follow-up DWI but previously hyperintense. DWIR% = (DWIR/baseline DWI volume) × 100 was calculated. We compared demographics, radiological findings, clinical outcomes, and follow-up results between mismatch and no mismatch groups.
Results: Among 73 patients, 20 (27.4%) had DWI-ADC mismatch. Baseline demographics and National Institutes of Health Stroke Scale (NIHSS) were similar between groups. The DWI/ADC ratio was higher in the mismatch group (2.9 vs. 1.5, P < 0.0001). Follow-up lesion volumes and functional outcomes were similar; however, the mismatch group showed a slower infarct growth rate (3.8 ml/h vs. 7.5 ml/h, P = 0.04), a higher likelihood of parent artery stenosis (65% vs. 20.8%, P < 0.001), and increased need for angioplasty or stenting (50% vs. 17%, P < 0.001). The mismatch group also had a higher DWIR% (37.7% vs. 21.2%, P = 0.02).
Conclusions: DWI-ADC mismatch is associated with slower infarct growth, greater likelihood of parent artery stenosis, increased need for angioplasty or stenting, and more DWI lesion reversal in anterior circulation large vessel occlusion patients undergoing EVT. These findings suggest DWI-ADC mismatch could be important in EVT decision-making and outcome prediction.