High‐resolution magnetic resonance imaging of acute intracranial artery thrombus

Abstract Background and purpose The development of high‐resolution magnetic resonance imaging (HR‐MRI) has enabled submillimeter‐level evaluation of intracranial artery plaque and luminal thrombus. We sought to investigate the value of HR‐MRI in assessing the pathogenesis of acute intracranial artery thrombus. Methods We examined the presence of intracranial thrombus on three‐dimensional T1‐weighted HR‐MRI in acute ischemic stroke patients with intracranial artery occlusion on magnetic resonance angiography. We defined two thrombus‐related HR‐MRI features (peri‐thrombus plaque and distal residual flow beyond the thrombus) and analyzed their association with potential embolic sources. Results Luminal thrombus and a shrunken artery without luminal thrombus were detected in 162 (96.4%) and six (3.6%) of 168 patients with intracranial artery occlusion, respectively. Among 111 patients with culprit major artery thrombus, peri‐thrombus plaques were observed in 46.8% and distal residual flow beyond the thrombus in 64.0%. Patients with peri‐thrombus plaque had a higher prevalence of diabetes (44.2% vs. 25.4%; p = 0.037), a lower prevalence of potential sources of cardioembolism (0% vs. 16.9%; p = 0.002), and a nonsignificantly lower prevalence of potential embolic sources from extracranial arteries (9.6% vs. 20.3%; p = 0.186) than those without. Patients with distal residual flow beyond the thrombus had a lower prevalence of potential sources of cardioembolism (1.4% vs. 22.5%; p < 0.001) and smaller infarct volumes (5.0 [1.4–12.7] mL vs. 16.6 [2.4–94.6] mL; p = 0.012) than those without. Conclusions Our study showed that HR‐MRI helps clarify the pathogenesis of acute intracranial artery thrombus. The presence of peri‐thrombus plaque and distal residual flow beyond the thrombus favor the stroke mechanism of atherosclerosis rather than cardioembolism.