High-resolution magnetic resonance imaging of acute intracranial artery thrombus.

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.

Association of carotid artery geometries with middle cerebral artery atherosclerosis.

BACKGROUND AND AIMS: Evidence shows that artery geometries play a role in atherogenesis by influencing blood flow dynamics. However, whether upstream artery geometries influence downstream atherosclerosis remains unclear. We aimed to investigate whether carotid artery geometries were associated with middle cerebral artery (MCA) atherosclerosis. METHODS: We reviewed our institutional database of 3-dimensional head-neck combined high-resolution magnetic resonance imaging. The carotid artery geometries, carotid atherosclerosis, MCA configurations, and MCA atherosclerosis were examined. The associations between carotid artery geometry and MCA atherosclerosis were also analyzed. A final model integrating carotid artery geometries was established, and the incremental diagnostic value was evaluated and compared to a basic model that included only traditional risk factors. RESULTS: Among the 575 artery units of the ipsilateral carotid artery and MCA, the artery units with MCA plaques (n = 273) were associated with a larger bifurcation angle (odds ratio [OR], 1.138 per 10-degree increase; 95% confidential interval [CI], 1.023-1.264) and kinking-type extracranial internal carotid artery (ICA; OR, 2.193; 95%CI, 1.283-3.748) compared with those without MCA plaques (n = 302). These associations were independent of traditional risk factors, carotid atherosclerosis, and MCA configuration. A larger carotid bifurcation angle was also associated with tandem ICA and MCA atherosclerosis (OR, 1.211 per 10-degree increase; 95%CI, 1.110-1.321). The incremental diagnostic value of carotid artery geometry to traditional risk factors was revealed by comparing the area under the curves of the two diagnostic models (basic model, 0.673 vs. final model, 0.701; p = 0.016). CONCLUSIONS: Carotid artery geometries are independently associated with ipsilateral MCA atherosclerosis, providing new insights into the pathophysiology of intracranial atherosclerosis.