Intracranial Atherosclerotic Burden on 7T MRI Is Associated with Markers of Extracranial Atherosclerosis: The SMART-MR Study

Abstract

BACKGROUND AND PURPOSE: Intracranial atherosclerosis, a major risk factor for ischemic stroke, is thought to have different atherogenic mechanisms than extracranial atherosclerosis. Studies investigating their relationship in vivo are sparse and report inconsistent results. We studied the relationship between intracranial atherosclerosis and extracranial atherosclerosis in a cohort of patients with a history of vascular disease. MATERIALS AND METHODS: Within the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART) study, cross-sectional analyses were performed in 130 patients (mean age, 68 6 9 years) with a history of vascular disease and with assessable 7T intracranial vessel wall MR imaging data. Intracranial atherosclerosis burden was defined as the number of intracranial vessel wall lesions in the circle of Willis and its major branches. Age-and sex-adjusted unstandardized regression coefficients (b-value) were calculated with intracranial atherosclerosis burden as the dependent variable and extracranial atherosclerosis markers as independent variables. RESULTS: Ninety-six percent of patients had $1 vessel wall lesion, with a mean intracranial atherosclerosis burden of 8.5 6 5.7 lesions. Significant associations were observed between higher intracranial atherosclerosis burden and carotid intima-media thickness (b 4 0.53 lesions per þ0.1 mm; 95% CI, 0.1-1.0 lesions), 50%-100% carotid stenosis versus no stenosis (b 4 6.6 lesions; 95% CI, 2.3-10.9 lesions), ankle-brachial index # 0.9 versus .0.9 (b 4 4.9 lesions; 95% CI, 1.7-8.0 lesions), and estimated glomerular filtration rate (b 4-0.77 lesions per þ10 mL/min; 95% CI, À1.50 to À0.03 lesions). No significant differences in intracranial atherosclerosis burden were found among different categories of vascular disease. CONCLUSIONS: Intracranial atherosclerosis was associated with various extracranial markers of atherosclerosis, not supporting a different etiology. ABBREVIATIONS: ABI 4 ankle-brachial index; cIMT 4 carotid intima-media thickness; ECAS 4 extracranial atherosclerosis; eGFR 4 estimated glomerular filtration rate; ICAS 4 intracranial atherosclerosis

Intracranial vessel wall lesions on 7T MRI and MRI features of cerebral small vessel disease: The SMART-MR study

“…dissection, vasculitis), especially in our population and study setting, is very low. Additionally, their correlation with vascular risk factors 16 and extracranial atherosclerosis, 17 further supports its use as a marker of ICAS. Third, our study sample has a high burden of manifest arterial disease and high frequency of vascular risk factors, which may have limited power to adjust for these factors.…”

“…Vessel wall MRI can be used to image the actual vessel wall, making it possible to detect arterial vessel wall thickening independently from stenosis, leading to a significant improvement in plaque detection, 12,13 with 7 T MRI adding further improvement. 14,15 Of note, intracranial vessel wall lesions have been associated with vascular risk factors 16 and markers of extracranial atherosclerosis, 17 supporting its use as a neuroimaging marker of ICAS burden.…”

Reply:

“…W e thank Dr Alexander and colleagues for their interest in our work and appreciate the opportunity to respond to their concerns. 1 A concern is raised regarding the interpretation of our results, which led us to conclude that our findings do not support "a different etiology" between extracranial atherosclerosis (ECAS) and intracranial atherosclerosis (ICAS). We agree with the data used to substantiate their concern, including data on histopathology and etiology, but do not share their opinion that our findings are contradictory.…”

MRI with ultrahigh field strength and high-performance gradients: challenges and opportunities for clinical neuroimaging at 7 T and beyond

“…Intracranial atherosclerosis is a major risk factor of ischemic stroke [ 101 ]. Beyond depicting the lumen of smaller caliber intracranial arteries, research has leveraged the advantages of ultrahigh field imaging to evaluate directly the intracranial vessel wall [ 102 – 104 ]. MRI at 7 T was superior to 3-T MRI in vessel wall characterization and visualization of the fibrous cap and lipid core within atherosclerotic plaques in patients with intracranial atherosclerotic disease [ 105 ], suggesting the potential role of 7-T MR in risk stratification in intracranial atherosclerosis.…”

“…Another study correlating in vitro intravascular sonography and 7-T MRI findings with histology concluded that 7-T MRI is a reliable method for detecting atherosclerotic burden within the intracranial arteries [ 106 ]. A recent study in 130 patients with a history of vascular diseases examined the association between intracranial atherosclerosis burden measured with intracranial vessel wall sequences at 7 T and several markers of extracranial atherosclerosis and found that ankle brachial index, the presence of extracranial carotid stenosis, carotid intima-media thickness, and decreasing glomerular filtration rate were all associated with a higher intracranial atherosclerotic burden, suggesting that similar atherogenic mechanisms underlie both processes [ 104 ]. Lindenholz et al [ 102 ] investigated the association between intracranial vessel wall lesion burden and vascular risk factors in patients with ischemic stroke or transient ischemic attack of the anterior circulation.…”