Early recurrent ischemic lesions on diffusion-weighted imaging in symptomatic intracranial atherosclerosis

Background: Prior observations have shown that early recurrent ischemic lesions (ERILs) on diffusion-weighted imaging occur frequently within the first week after an index stroke. Objective: To investigate differential patterns of ERILs among stroke subtypes, particularly intracranial large-artery atherosclerosis (IC-LAA). Design: Retrospective study. Setting: Tertiary university hospital. Patients: We included 133 patients who experienced an acute ischemic stroke and who underwent initial diffusion-weighted imaging within 24 hours and subsequent diffusion- weighted imaging within 7 days after onset, and whose stroke subtype was IC-LAA, extracranial LAA (EC-LAA), or cardioembolism (CE). Main Outcome Measure: Early recurrent ischemic lesions were defined as new ischemic lesions on follow-up diffusion- weighted imaging, separate from the index stroke lesion. Results: Early recurrent ischemic lesions were observed in the following proportions: 50.9% (28/55) in the IC-LAA group, 47.4% (9/19) in the EC-LAA group, and 44.1% (26/59) in the CE group. Early recurrent ischemic lesions in the IC-LAA group had the following characteristics: (1) they occurred mostly (27[96.4%] of 28) in the pial area of the same vascular territory as the index stroke; (2) they were more frequently observed in a higher grade of stenosis than in milder stenosis (P <.001), whereas ERILs in the EC-LAA group were not related to the degree of stenosis; (3) they were not associated with subsequent recanalization, whereas ERILs in the CE group were mostly associated with subsequent recanalization (P <.001); and (4) they were more closely associated with clinical recurrence than in the EC-LAA or CE group (P=.02). Conclusion: Early recurrent ischemic lesions in the IC-LAA group are relatively frequent and have different patterns than in the EC-LAA or CE group.