Sophisticated Prediction of Carotid-Plaque Vulnerability by Nanocluster Sensitized High-resolution Vessel-Wall-Imaging Profile in Rabbit Atherosclerotic Model

OBJECTIVE To innovatively developed a macrophage-target nanoparticle based contrast-enhanced high-resolution magnetic resonance vessel wall imaging (HR-VWI) strategy to characterize the plaques’ vulnerable features on rabbits. BACKGROUND Lacking of sensitive and specific image-marker of HR-VWI leads this technique depending upon the plaque morphological characteristics. Nanoparticle-based contrast agents modified with targeting ligands allow amplifying MR signals of the interested components. The key to successful translation is the requirement that conducting studies in larger animals to provide reasonable diagnostic readouts. METHODS The HR-VWI enhanced with macrophage-targeted PP1-Au@GSH@Gd (GdMG) nanoclusters (NCs) and the conventional Gadovist were utilized for the plaque vulnerability evaluation by a systematic histogram analysis in atherosclerosis (AS) rabbit model. RESULTS Due to the compelling targeting capacity of GdMG NCs to foamy macrophages, the contrast-to-noise ratio (CNR) from pre-injection baseline dramatically raised from 6.50 to 36.91 ( p < 0.001), with an increment of 1.39-fold higher than that of the Gadovist approach. Spearman’ s correlation test confirmed that the coefficient of variation (CV) derived from the histogram analysis based on GdMG NCs HR-VWI was indeed positively linearly correlated with pathology vulnerability index (VIP) significantly ( p < 0.05) with adjusted R2 = 0.775. Finally, mathematic formulas with histogram-derived parameters as variables were fitted to quantitatively calculate the histogram vulnerability index (VIH) with the strength of the adjusted R2 = 0.952 ( p < 0.001), and Area under the curve (AUC) of 0.875 ( p < 0.001) to realize the in vivo and quantitative calculation of the plaque vulnerability. CONCLUSION Profiting from the splendid inflammation targeted capacity and excellent MRI performance of GdMG NCs, as well as the highly quantitative characteristics of histogram analysis, we disclosed that our established imaging protocol was able to identify the plaques’ vulnerability index that were comparable to pathological examinations in both retrospective and prospective experiments. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was funded by the Natural Science Foundation of China (82171916, 81871342), the Natural Scientific Foundation of Tianjin (21CYBJC01580), Tianjin Health Science and technology project (Specific projects of key disciplines) (TJWJ2022XK019), Tianjin Key Medical Discipline (Specialty) Construction Project (TJYXZDXK-041A). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All protocols in this work were conducted with approval from the Institutional Animal Care and Use Committee of Nankai University (No. 2021-SYDWLL-000425). The experimental procedures were strictly conducted on the National Institutes of Health guidelines to make every effort to minimize rabbits' suffering and discomfort. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data that support the findings of this study are available from the corresponding author,Shuang Xia, upon reasonable request. * AS : List Atherosclerosis GdMG NCs : Gd-modified macrophage-target gold nanoclusters HR-VWI : high-resolution vessel wall imaging PPI : a novel 16-mer peptide targeted scavenger receptor AI SR-A : scavenger receptors A TOF-MRA : time-of-flight magnetic resonance angiography CV : coefficient of variation