Quantification of carotid plaque lipid content with magnetic resonance T2 mapping in patients undergoing carotid endarterectomy

Figures

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  Fig 1. Difference in lipid percentage between symptomatic and asymptomatic patients. (A) Using slice with maximal lipid content, symptomatic patients are more likely to have lipid in patients with degree of stenosis of more than 50%. (B) Similarly but using averaged 10 slices, symptomatic patients have larger lipid percentage than asymptomatic ones in the total 100 carotid arteries.

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  Fig 2. Assessment of lipid distribution using T2 mapping technique. (A) Cross sectional T1-weighted image of bilateral carotid arteries stenoses in the same patient. Segmented T2 map of the symptomatic right vessel of two weeks old history of transient ischaemic event (left sided facial weakness)- showing LAI of 40.48 suggestive of coalesced lipid compared to the left asymptomatic side with LAI of 2.41 (panel A). (B) Median LDD % is statistically higher in symptomatic patients compared to asymptomatic ones. (C) Similarly, median lipid aggregation index is statistically higher in symptomatic patients compared to asymptomatic ones. Notably two outlier vessels were identified with extremely high LDD % and LAI at the time of MRI where the corresponding plaque was yet still silent.

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  Fig 3. Plaque and lipid volume relationship with degree of luminal stenosis. (A) Scatter plot graph displaying the absence of correlation between degree of luminal stenosis measured on ultrasound duplex and carotid vessel wall volume. (B) Similarly scatter plot graph displaying the absence of correlation between degree of luminal stenosis measured on ultrasound duplex and carotid lipid volume.

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  Fig 4. Correlation between carotid plaque and lipid volume (log transformed). Scatter plot graph illustrating a strong correlation between plaque lipid content and plaque volume in total of one hundred carotid arteries analysed using T2 map. Dotted lines indicate 95% confidence intervals. Note that increasing plaque size is associated with an increasing variation of lipid content; i.e. points fall further outside the 95% CI.

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  Fig 5. Spearman’s rank correlation between left and right carotid plaque and lipid volume. (A) Scatter plot graph demonstrating statistically significant correlation between plaque burden (total plaque volume) between left and right carotid arteries. (B) Scatter plot graph showing statistically significant correlation between lipid volumes of the right and left carotid arteries quantified on T2 map (panel B).