In Vitro Assessment of Histology Verified Intracranial Atherosclerotic Disease by 1.5T Magnetic Resonance Imaging

Abstract

Intracranial atherosclerotic disease (ICAD), as a most common cause of ischemic stroke, has been drawing increased attentions of clinicians and researchers in the worldwide. 1 Advanced imaging techniques, especially High Resolution Magnetic Resonance Imaging (HRMRI), could visualize the pathology of intracranial arterial diseases.2 However, current knowledge about histology of intracranial atherosclerosis lags behind the development of updated imaging modalities due to lacking of vessel specimens. Our previous post-mortem study showed that both luminal stenosis and percentage of lipid area or intraplaque neovasculature may play a key role in leading to ischemic stroke. 3 Recent clinical trial studies on carotid arteries showed that, in addition to luminal stenosis, plaque eccentricity (symmetry) is among the plaque features associated with more frequent cerebrovascular events. 4 The aim of the current study was to investigate the eccentricity of histology-verified intracranial atherosclerotic lesions on 1.5T MRI vessel wall imaging and its potential clinical implications. Materials and Methods SpecimensWe recruited, consecutively, Chinese patients aged 45 years old or above, who died and underwent postmortem study at the Prince of Wales Hospital, Hong Kong (a regional general hospital) during a period of 19 months. The study was approved by the Clinical Research Ethics Committee of the Chinese University of Hong Kong. Among 58 elderly autopsy cases, 10 cases were excluded due to poor image quality (3 due to improper location of brain within the head coil, 3 due to inaccurate orientation of MRI scanning, 4 due to too large air rather than brain tissue which caused difficulties in acquiring proper imaging). Histology of middle cerebral arteries (MCAs) belonging to 10Background and Purpose-Clinical trial studies show that plaque eccentricity (symmetry) is among the plaque features that have been associated with more frequent cerebrovascular events. Plaque eccentricity of intracranial atherosclerotic disease is unclear because of lacking of cerebral artery specimens. Methods-1.5T magnetic resonance imaging was performed in the postmortem brains to scan the cross sections of middle cerebral artery. The whole brain was obtained fresh and intact during the process of autopsies. The MCAs were washed with water to clear the possible blot inside. Then the whole brain was fresh frozen at 4°C until imaged. The period between autopsy and imaging was less than 5 days. MRIThe MRI examinations of the brains were performed by a 1.5-T scanner (Sonata, Siemens Medical Systems, Erlangen, Germany) with a standard head coil (with 8 channels). To keep the arteries uncollapsed, diluted barium solution was injected into the lumen to distend the artery. Then the brains were positioned in the scanner to resemble a supine head first position in routine clinical scanning. The orientation of the MCA was localized by the TSE T2 sequence of the whole brain. An experienced radiologist would then choose an imaging plane perpendicular to each MCA...

Vessel wall differences between middle cerebral artery and basilar artery plaques on magnetic resonance imaging

“…For intracranial vascular disease, eccentric wall thickening has been used to distinguish intracranial atherosclerosis from other etiologies1819. A recent in vitro study showed that eccentric plaques were associated with a non-significant higher risk of cerebrovascular events compared with concentric plaques (30.77% vs. 17.39%; n = 72, P = 0.241)5. Our study showed that symptomatic plaques were associated with a significantly higher eccentricity index than asymptomatic plaques after adjusting for the plaque burden (P = 0.028).…”

“…The eccentricity index was defined as follows: (maximum wall thickness−minimum wall thickness)/maximum wall thickness (Fig. 1)5.…”

“…The use of VWMRI has greatly improved the understanding of the pathophysiology of atherosclerosis3. The plaque features on VWMRI may be important predictors of stroke and were shown to correlate with pathological findings45678.…”

Diagnostic and Therapeutic Approach of Carotid and Cerebrovascular Plaque on the Basis of Vessel Imaging

“…3,4,7,8 Recent study 8 17.39%, p=0.241). 42 Retrospective high resolution MR study including non-significant stenosis in the intracranial vessel demonstrated that eccentricity was more higher in the symptomatic plaque than in the asymptomatic plaque (p=0.028). 45 Another study including symptomatic significant MCA stenosis showed that plaques with non-significant luminal narrowing was associated with eccentricity (p<0.05).…”

Smaller outer diameter of atherosclerotic middle cerebral artery associated with RNF213 c.14576G>A Variant (rs112735431)

“…Progress in imaging technology such as high-resolution magnetic resonance imaging (MRI) has enabled the visualization of arterial morphological changes in ICAS,[1243] and as reported in the coronary and other systemic arteries,[347182031323839] cerebral atherosclerotic lesions are known to exhibit considerable heterogeneity in morphological structures. Several arterial remodeling patterns, such as the “positive/negative” remodeling pattern, which is defined by the presence of outward expansion of the outer diameter, and the “eccentric/concentric” remodeling pattern, which is defined by the eccentricity of the wall morphology, have been reported previously.…”