Elsevier

JACC: Cardiovascular Imaging

Volume 3, Issue 11, November 2010, Pages 1127-1135
JACC: Cardiovascular Imaging

Original Research
Use of Contrast Enhancement and High-Resolution 3D Black-Blood MRI to Identify Inflammation in Atherosclerosis

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Objectives

We investigated the contributing factors for plaque enhancement and examined the relationships between regional contrast enhancement and the inflammatory activity of atherosclerotic plaques in an experimental rabbit model using contrast-enhanced high-resolution 3-dimensional (3D) black-blood magnetic resonance imaging (MRI) in comparison with histopathologic analysis.

Background

Inflammation plays a critical role in plaque initiation, progression, and disruption. As such, inflammation represents an emerging target for the treatment of atherosclerosis. MRI findings suggest that contrast agent–induced signal enhancement is associated with the degree of macrophage infiltration and neovessels that can be detected in plaque.

Methods

Ten atherosclerotic rabbits and 3 normal control rabbits underwent high-resolution 3D contrast-enhanced black-blood MRI. Magnetic resonance images and the corresponding histopathologic sections were divided into 4 quadrants. Plaque composition was analyzed for each quadrant according to histopathologic criteria (percent of lipid-rich, fibrous, macrophage area and microvessel density) and imaging criteria (enhancement ratio [ER], ER = signal intensitypost/signal intensitypre). Multiple linear regression analysis was performed to determine independent factors for plaque enhancement.

Results

A total of 62 noncalcified plaques (n = 248; 156 lipid-rich quadrants and 92 fibrous quadrants) were identified based on histopathologic analysis. Mean ER values were significantly higher in atherosclerotic vessel walls than in normal vessel walls (2.03 ± 0.25 vs. 1.58 ± 0.15; p = 0.017). The mean ER values were significantly higher in lipid-rich quadrants compared with the fibrous quadrants (2.14 ± 0.31 vs. 1.84 ± 0.21; p = 0.001). Mean ER values were significantly higher in macrophage-rich plaques compared with the macrophage-poor plaques (2.21 ± 0.28 vs. 1.81 ± 0.22; p = 0.001). Using multiple regression analysis, macrophage area and microvessel density were associated independently with ER values that reflected plaque enhancement (p < 0.001).

Conclusions

Contrast-enhanced high-resolution 3D black-blood MRI may be an efficient method to detect plaque inflammation.

Key Words

atherosclerosis
inflammation
magnetic resonance imaging
plaque

Abbreviations and Acronyms

2D
2-dimensional
3D
3-dimensional
DCE
dynamic contrast enhanced
ER
enhancement ratio
Gd-DTPA
gadolinium-diethylenetriaminepentaacetic acid
MRI
magnetic resonance imaging
SI
signal intensities

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This work was supported by a grant from the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare & Family Affairs, Republic of Korea (A090358). The authors have reported that they have no relationships to disclose.