Associations between Morphological Characteristics of Intracranial Arteries and Atherosclerosis Risk Factors in Subjects with Less Than 50% Intracranial Arterial Stenosis

PURPOSE: To assess associations between morphological characteristics of intracranial arteries in time-of-flight MR angiography (TOF-MRA) and atherosclerotic risk factors. MATERIALS AND METHODS: From January 2014 to October 2015, a total of 129 patients (65 men and 64 women) without intracranial arterial stenosis > 50% were included in this study. All MRIs were performed using a 3T machine with 3D TOF-MRA sequences. We evaluated irregularity, tortuosity, and dilatation of intracranial arteries in maximal intensity projection (MIP) of TOF-MRA. Subjects' risk factors for atherosclerosis including history of hypertension and diabetes were collected by reviewing their medical records. Associations between morphological characteristics and each known atherosclerosis risk factor were examined using univariate regression analysis. Multivariate regression models were built to determine combined association between those risk factors and morphologic changes of intracranial arteries. RESULTS: In multivariate analysis, hypertension (coefficient [95% CI]: 0.162 [0.036, 0.289], P = 0.012) and absence of diabetes (coefficient [95% CI]: −0.159 [−0.296, −0.023], P = 0.022) were associated with large diameter of intracranial arteries. Males (coefficient [95% CI]: 0.11 [−0.006, 0.23], P = 0.062) and higher age (coefficient [95% CI]: 0.003 [−0.001, 0.008], P = 0.138) had marginal association with increased diameter. Tortuosity was associated with old age (OR: 1.04 [1.02, 1.07], P < 0.001). Irregular contour of intracranial arteries was significantly associated with old age (OR: 1.05 [1.02, 1.09], P = 0.004), presence of diabetes (OR: 2.88 [1.36, 6.15], P = 0.0058), and previous ischemic stroke (OR: 3.91 [1.41, 11.16], P = 0.0092). CONCLUSION: Morphological characteristics (irregularity, tortuosity, dilatation) of intracranial arteries seen in TOF-MRA might be associated with atherosclerotic risk factors in subjects with no or mild stenosis.

The Added Prognostic Value of Intracranial Artery Morphology to Predict Non-Cardioembolic Ischemic Stroke

PURPOSE@#To assess the added prognostic value of the morphologic characteristics of intracranial arteries in the risk modeling of a future non-cardioembolic stroke.@*MATERIALS AND METHODS@#This retrospective study included 86 patients without acute ischemic stroke who first underwent magnetic resonance imaging (MRI) including the time-of-flight magnetic resonance angiography (TOF-MRA) at 3T. Diffusion-weighted imaging (DWI) was performed for the follow-up imaging of these patients > 120 days after the initial MRI. The TOF-MRA result was used to analyze three morphological characteristics: dilatation, stenosis, and tortuosity. The presence of acute ischemic stroke was assessed using the follow-up DWI data. We built two prognostic models: model 1 includes the conventional stroke-risk factors, while model 2 includes the conventional risk factors and the morphologic characteristics of the intracranial arteries. We used the likelihood-ratio test to compare these two models. The models' performances were evaluated using Harrell's concordance index.@*RESULTS@#Fourteen patients suffered non-cardioembolic strokes. The performances of the two models differed significantly regarding the future-risk modeling of the non-cardioembolic stroke (p = 0.031). The Harrell's concordance index of model 2 (0.78 ± 0.05) exceeded that of model 1 (0.72 ± 0.07).@*CONCLUSION@#In addition to the conventional stroke-risk factors, the morphologic characteristics of the intracranial arteries were useful in the modeling of the future risk of the non-cardioembolic ischemic stroke.