Background and Purpose—The aim of the present study was to investigate atherosclerotic plaque characteristics in patients with artery-to-artery (A-to-A) embolic infarction by whole-brain high-resolution magnetic resonance imaging.Methods—Seventy-four patients (mean age, 54.7±12.1 years; 59 men) with recent stroke in the territory of middle cerebral artery because of intracranial atherosclerotic disease were prospectively enrolled. Whole-brain high-resolution magnetic resonance imaging was performed in all the patients both precontrast and postcontrast administration by using a 3-dimensional T1-weighted vessel wall magnetic resonance imaging technique known as inversion-recovery prepared sampling perfection with application-optimized contrast using different flip angle evolutions. Patients were divided into A-to-A embolic infarction and non–A-to-A embolic infarction groups based on diffusion-weighted imaging findings. The characteristics of the intracranial atherosclerotic plaques were compared between groups.Results—A total of 74 intracranial atherosclerotic plaques were analyzed (36 in A-to-A embolism group and 38 in non–A-to-A embolism group). Hyperintense plaques (HIPs) were more frequently observed in A-to-A embolism group (75.0% versus 21.1%; P<0.001). Eighteen of the 27 HIPs (66.7%) demonstrated hyperintense spots or areas located adjacent to the lumen versus 9 HIPs (33.3%) located within the plaque in A-to-A embolism group. Furthermore, a higher prevalence of plaque surface irregularity was also observed in A-to-A embolism group (41.7% versus 18.4%; P=0.029). Logistic regression analysis showed that HIP was the most powerful independent predictor of A-to-A embolic infarction (P<0.001), with the odds ratio of 11.2 (95% confidence interval, 3.5–36.2).Conclusions—A-to-A embolic infarction has distinct vulnerable plaque characteristics compared with non–A-to-A embolic infarction. HIP and plaque surface irregularity may predict A-to-A embolic infarction.