Serum PTX3 Levels Correlate with Fibrous Cap Discontinuity and Focal Inflammation in Carotid Vulnerable Plaque: A High-Resolution Magnetic Resonance Vessel Wall Imaging Study

<b>Background</b>: Pentraxin 3 (PTX3) is a well-established inflammatory biomarker with significant implications in the pathogenesis and prognostic assessment of cardiovascular diseases. This study aimed to investigate the potential value of serum PTX3 as a circulating biomarker when combined with the high-resolution magnetic resonance vessel wall imaging (HR-VWI) for identifying carotid vulnerable plaque (CVP) and its specific vulnerable features. <b>Methods</b>: This prospective cross-sectional study enrolled 86 patients with carotid atherosclerosis who underwent HR-VWI. Patients were classified into CVP and non-carotid vulnerable plaque (NCVP) groups, and CVP was divided into unilateral carotid vulnerable plaque (UCVP) and bilateral carotid vulnerable plaque (BCVP). CVP was defined as meeting ≥ 1 major criteria: lipid-rich necrotic core (LRNC) maximum area percentage > 40% combined with thin fibrous cap (FC), intraplaque hemorrhage (IPH), FC discontinuity, and focal inflammation. Multivariate logistic regression analysis identified factors influencing CVP and the formation of specific vulnerable features. <b>Results</b>: Serum PTX3 levels progressively increased across the NCVP, UCVP, and BCVP groups (median 638.23, 858.52, 1113.62 pg/mL; <i>p</i> < 0.001). PTX3 independently predicted the presence of CVP (OR = 2.88; 95% CI: 1.16-8.91; <i>p</i> = 0.039) and specific vulnerable features, including FC discontinuity (OR = 2.47; 95% CI: 1.32-4.63; <i>p</i> = 0.005) and focal inflammation (OR = 2.25; 95% CI: 1.18-4.32; <i>p</i> = 0.014) with high diagnostic performance for these conditions. PTX3 levels exhibited a moderate positive correlation with the number of vulnerable features (r = 0.610, <i>p</i> < 0.01). <b>Conclusions</b>: Elevated serum PTX3 levels were significantly associated with HR-VWI-defined carotid plaque vulnerability and its severity, serving as a reliable circulating biomarker for identifying FC discontinuity and focal inflammation.