Review of Conflict Series, by Dozier Bell, at June Fitzpatrick Gallery in Port

Review of Conflict Series, by Dozier Bell, at June Fitzpatrick Gallery in Portland, through August 1

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

<div><p>Background and purpose</p><p>Techniques to stratify subgroups of patients with asymptomatic carotid artery disease are urgently needed to guide decisions on optimal treatment. Reliance on estimates of % luminal stenosis has not been effective, perhaps because that approach entirely disregards potentially important information on the pathological process in the <i>wall</i> of the artery.</p><p>Methods</p><p>Since plaque lipid is a key determinant of plaque behaviour we used a newly validated, high-sensitivity T2-mapping MR technique for a systematic survey of the quantity and distribution of plaque lipid in patients undergoing endarterectomy. Lipid percentage was quantified in 50 carotid endarterectomy patients. Lipid distribution was tested, using two imaging indices (contribution of the largest lipid deposit towards total lipid (LLD %) and a newly-developed LAI ‘lipid aggregation index’).</p><p>Results</p><p>The bifurcation contained maximal lipid volume. Lipid percentage was higher in symptomatic <i>vs</i>. asymptomatic patients with degree of stenosis (DS ≥ 50%) and in the total cohort (P = 0.013 and P = 0.005, respectively). Both LLD % and LAI was higher in symptomatic patients (P = 0.028 and P = 0.018, respectively), suggesting that for a given plaque lipid volume, coalesced deposits were more likely to be associated with symptomatic events. There was no correlation between plaque volume or lipid content and degree of luminal stenosis measured on ultrasound duplex (r = -0.09, P = 0.53 and r = -0.05, P = 0.75), respectively. However, there was a strong correlation in lipid between left and right carotid arteries (r = 0.5, P <0.0001, respectively).</p><p>Conclusions</p><p>Plaque lipid content and distribution is associated with symptomatic status of the carotid plaque. Importantly, plaque lipid content was not related to the degree of luminal stenosis assessed by ultrasound. Determination of plaque lipid content may prove useful for stratification of asymptomatic patients, including selection of optimal invasive treatments.</p></div

Difference in lipid percentage between symptomatic and asymptomatic patients.

<p>(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.</p

Assessment of lipid distribution using T2 mapping technique.

<p>(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.</p

Baseline characteristics of recruited patients.

<p>Baseline characteristics of recruited patients.</p

Spearman’s rank correlation between left and right carotid plaque and lipid volume.

<p>(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).</p