High-risk plaque features can be detected in non-stenotic carotid plaques of patients with ischaemic stroke classified as cryptogenic using combined 18F-FDG PET/MR imaging
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The aim of this study was to investigate in 18 patients with ischaemic stroke classified as cryptogenic and presenting non-stenotic carotid atherosclerotic plaques the morphological and biological aspects of these plaques with magnetic resonance imaging (MRI) and 18F-fluoro-deoxyglucose positron emission tomography (18F-FDG PET) imaging.
Carotid arteries were imaged 150 min after injection of 18F-FDG with a combined PET/MRI system. American Heart Association (AHA) lesion type and plaque composition were determined on consecutive MRI axial sections (n = 460) in both carotid arteries. 18F-FDG uptake in carotid arteries was quantified using tissue to background ratio (TBR) on corresponding PET sections.
The prevalence of complicated atherosclerotic plaques (AHA lesion type VI) detected with high-resolution MRI was significantly higher in the carotid artery ipsilateral to the ischaemic stroke as compared to the contralateral side (39 vs 0 %; p = 0.001). For all other AHA lesion types, no significant differences were found between ipsilateral and contralateral sides. In addition, atherosclerotic plaques classified as high-risk lesions with MRI (AHA lesion type VI) were associated with higher 18F-FDG uptake in comparison with other AHA lesions (TBR = 3.43 ± 1.13 vs 2.41 ± 0.84, respectively; p < 0.001). Furthermore, patients presenting at least one complicated lesion (AHA lesion type VI) with MRI showed significantly higher 18F-FDG uptake in both carotid arteries (ipsilateral and contralateral to the stroke) in comparison with carotid arteries of patients showing no complicated lesion with MRI (mean TBR = 3.18 ± 1.26 and 2.80 ± 0.94 vs 2.19 ± 0.57, respectively; p < 0.05) in favour of a diffuse inflammatory process along both carotid arteries associated with complicated plaques.
Morphological and biological features of high-risk plaques can be detected with 18F-FDG PET/MRI in non-stenotic atherosclerotic plaques ipsilateral to the stroke, suggesting a causal role for these plaques in stroke. Combined 18F-FDG PET/MRI systems might help in the evaluation of patients with ischaemic stroke classified as cryptogenic.
KeywordsAtherosclerosis Vulnerable plaque Carotid arteries Stroke MRI PET 18F-FDG
We thank Sylvia Schachoff, Anna Winter, and Claudia Meisinger for their valuable help in acquiring PET/MR images in the patients of this study and Isabelle Dregelly for setting up MRI sequences.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. The local Ethics Committee approved the study and all participants provided written informed consent.
Clinical Trial Registration: Unique Identifier NCT01284933; URL: https://clinicaltrials.gov
This work was supported by the Advanced Research Grant “Multimodal Molecular Imaging” (MUMI; Grant number: 294582; European Research Council Executive Agency) and by the Deutsche Forschungsgemeinschaft (DFG; Grossgeräteinitiative).
Conflicts of interest
Markus Schwaiger has a research cooperation contract with Siemens Healthcare AG. The other authors have no potential conflicts of interest relevant to this article.
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