Lipid Core Burden Index Assessed by Near-Infrared Spectroscopy of Symptomatic Carotid Plaques: Association with Magnetic Resonance T1-Weighted Imaging

Abstract

<b><i>Introduction:</i></b> Vulnerable plaques are a strong predictor of cerebrovascular ischemic events, and high lipid core plaques (LCPs) are associated with an increased risk of embolic infarcts during carotid artery stenting (CAS). Recent developments in magnetic resonance (MR) plaque imaging have enabled noninvasive assessment of carotid plaque vulnerability, and the lipid component and intraplaque hemorrhage (IPH) are visible as high signal intensity areas on T1-weighted MR images. Recently, catheter-based near-infrared spectroscopy (NIRS) has been shown to accurately distinguish LCPs without IPH. This study aimed to determine whether the results of assessment of high LCPs by catheter-based NIRS correlate with the results of MR plaque imaging. <b><i>Methods:</i></b> We recruited 82 consecutive symptomatic carotid artery stenosis patients who were treated with CAS under NIRS and MR plaque assessment. Maximum lipid core burden index (max-LCBI) at minimal luminal areas (MLA), defined as max-LCBI<sub>MLA</sub>, and max-LCBI for any 4-mm segment in a target lesion, defined as max-LCBI<sub>AREA</sub>, were assessed by NIRS. Correlations were investigated between max-LCBI and MR T1-weighted plaque signal intensity ratio (T1W-SIR) and MR time-of-flight signal intensity ratio (TOF-SIR) in the same regions as assessed by NIRS. <b><i>Results:</i></b> Both T1W-SIR<sub>MLA</sub> and T1W-SIR<sub>AREA</sub> were significantly lower in the high LCP group (max-LCBI >504, <i>p</i> < 0.001 for both), while TOF-SIR<sub>MLA</sub> and TOF-SIR<sub>AREA</sub> were significantly higher in the high LCP group (<i>p</i> < 0.001 and <i>p</i> = 0.004, respectively). A significant linear correlation was present between max-LCBI<sub>MLA</sub> and both TIW-SIR<sub>MLA</sub> and TOF-SIR<sub>MLA</sub> (<i>r</i> = −0.610 and 0.452, respectively, <i>p</i> < 0.0001 for both). Furthermore, logistic regression analysis revealed that T1W-SIR<sub>MLA</sub> and TOF-SIR<sub>MLA</sub> were significantly associated with a high LCP assessed by NIRS (OR, 44.19 and 0.43; 95% CI: 6.55–298.19 and 0.19–0.96; <i>p</i> < 0.001 and = 0.039, respectively). <b><i>Conclusions:</i></b> A high LCP assessed by NIRS correlates with the signal intensity ratio of MR imaging in symptomatic patients with unstable carotid plaques.

Dual-layered stents reduce cerebral embolism compared with first-generation stents during carotid stenting of high lipid core plaque lesions

“…The present study focused on the degree of lipid component of carotid plaque detected by NIRS in patients undergoing CAS compared with the efficacy of avoiding cerebral embolisms between dual-layered and first-generation stents. Our results appear consistent with these previous findings 17 32. In high-LCP lesions, the ipsilateral embolism rate was significantly lower with dual-layered stents than with first-generation stents.…”

“…In the present study, no symptomatic plaque protrusion occurred in the dual-layered stent group, although asymptomatic plaque protrusion occurred in four cases, probably due to the inner shaft-pushing maneuver during deployment of the dual-layered stent in early-phase cases. A recent study suggested that high LCP as assessed by NIRS correlates with the SIR of MRI in patients with unstable plaques and a significant linear correlation was present between max-LCBI MLA and TIW-SIR MLA (r=−0.610, p<0.0001) 17. The present study focused on the degree of lipid component of carotid plaque detected by NIRS in patients undergoing CAS compared with the efficacy of avoiding cerebral embolisms between dual-layered and first-generation stents.…”

“…SIR at the minimal luminal areas was defined as plaque SIR MLA and maximal SIR at all stenotic lesions was defined as plaque SIR AREA . Diffusion-weighted images were acquired using multisection, single-shot, spin-echo planar imaging 18–24 hours after the CAS procedure using the Magnetom Verio 3 T system 17. Imaging parameters were: echo time, 100 ms; field of view, 23 cm; intersection gap, 1 mm; matrix, 96×128; and section thickness, 5 mm.…”