| Summary: | <h4>Objectives</h4> <p>This study aimed to: (1) provide tissue validation of quantitative T2 maps to measure plaque lipid content; and (2) to investigate whether this technique could discern differences in plaque characteristics between symptom-related and non symptom-related carotid plaques.</p> <h4>Background</h4> <p>Non-invasive plaque lipid quantification is appealing both for stratification in treatment selection and as a possible predictor of future plaque rupture. However, current magnetic resonance imaging (MRI) methods are insensitive, require a coalesced mass of lipid ‘core’ and rely on multicontrast acquisition with contrast media and extensive post-processing.</p> <h4>Methods</h4> <p>Patients scheduled for carotid endarterectomy were recruited for 3T carotid MRI before surgery. Lipid Area was derived from segmented T2 maps and compared directly to plaque lipid defined by histology.</p> <h4>Results</h4> <p>Lipid Area (%) on T2 mapping and histology showed excellent correlation, both by individual slices (R = 0.85, P < 0.001) and plaque average (R = 0.83, P < 0.001). Lipid Area (%) on T¬2 maps was significantly higher in symptomatic compared to asymptomatic plaques (31.5 ± 3.7% vs. 15.8 ± 3.1%, P = 0.005) despite similar degrees of carotid stenosis. Receiver operating characteristic curve analysis showed that T2 mapping has a fair to good ability to discriminate between symptomatic and asymptomatic plaques.</p> <h4>Conclusions</h4> <p>MRI T2 mapping accurately quantifies plaque lipid content non-invasively. Greater plaque lipid content was found in symptomatic plaques. This new technique may find a role in determining optimum treatment e.g. providing an indication for intensive lipid lowering or by informing decisions of stents vs. surgery.</p>
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