Abstract 18972: Iron Quantification in Carotid Artery Atherosclerosis Predicts Downstream Injury by Magnetic Resonance Imaging

• Published in: Circulation (New York, N.Y.) N.Y.), 2014-11, Vol.130 (suppl_2)
• Main Authors: Sharkey-Toppen, Travis P, Tran, Tam, Smart, Suzanne, McCarthy, Beth, Nguyen, Xuan, Raman, Subha V
• Format: Article
• Language: English
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/circ.130.suppl_2.18972

Abstract only Introduction: Luminal stenosis is the primary imaging parameter used to guide management of patients with carotid artery atherosclerosis (CAA). However, neuroimaging identifies subclinical events in patients with CAA not meeting anatomic guidelines for intervention. Strategies to characterize atherosclerotic plaque beyond %stenosis may help reduce the downstream ischemic burden of atherosclerotic disease. Hypothesis: Using noncontrast MRI T2* tissue mapping that we have previously validated for plaque iron characterization, we tested the hypothesis that carotid plaque T2* better predicts ischemic injury by brain MRI than symptom history. Methods: We enrolled 26 individuals with carotid artery stenosis ≥50%. Each subject underwent MRI that included carotid plaque T2* mapping (TR=75ms, 5 TEs, 20° flip angle, 0.44x0.44x2mm resolution), brain diffusion weighted imaging (TR=4436ms, TE=93ms, 0.9x0.9x3mm resolution) and brain fluid attenuated inverse recovery imaging (TR=13970ms, TE=2500ms, 150° flip angle, and 0.9x0.9x3mm resolution). Plaque T2* quantification and brain MRI were independently assessed by experienced observers blinded to patient history and other results. Brain MRIs with Wahlund score ≥2 were classified as positive for ischemic damage. Results: Patients with brain imaging positive for ischemic damage had shorter intraplaque T2* compared to patients with negative brain MRI (17.2±2.9 vs. 20.3±3.2ms, p=.012, Figure). Conversely, presence/absence of brain injury did not correlate with symptoms (p=.352). Conclusions: Noncontrast atherosclerosis imaging using an MRI biomarker of intraplaque iron in patients with carotid artery disease can discriminate between patients with vs. those without ischemic brain injury. Prospective studies that couple plaque characterization with anatomic and clinical factors may better identify at-risk patients with carotid artery disease before significant ischemic brain injury has accrued.