Correlations between carotid plaque progression and mechanical stresses change sign over time: a patient follow up study using MRI and 3D FSI models

Dalin Tang,Chun Yuan,Zheyang Wu,Chun Yang,Thomas Hatsukami,Gador Canton

doi:10.1186/1475-925x-12-105

Abstract

BackgroundIncreasing evidence suggests that mechanisms governing advanced plaque progression may be different from those for early progression and require further investigation. Serial MRI data and 3D fluid–structure interaction (FSI) models were employed to identify possible correlations between mechanical stresses and advanced plaque progression measured by vessel wall thickness increase (WTI). Long-term patient follow up was used to gather data and investigate if the correlations identified above were reproducible.MethodsIn vivo MRI data were acquired from 16 patients in a follow-up study with 2 to 4 scans for each patient (scan interval: average 18 months and standard deviation 6.8 months). A total of 38 scan pairs (baseline and follow-up) were formed for analysis using the carotid bifurcation as the registration point. 3D FSI models were constructed to obtain plaque wall stress (PWS) and flow shear stress (FSS) to quantify their correlations with plaque progression. The Linear Mixed-Effects models were used to study possible correlations between WTI and baseline PWS and FSS with nodal dependence taken into consideration.ResultsOf the 38 scan pairs, 22 pairs showed positive correlation between baseline PWS and WTI, 1 pair showed negative correlation, and 15 pairs showed no correlation. Thirteen patients changed their correlation sign (81.25%). Between baseline FSS and WTI, 16 pairs showed negative correlation, 1 pair showed positive correlation. Twelve patients changed correlation sign (75%).ConclusionOur results showed that advanced plaque progression had an overall positive correlation with plaque wall stress and a negative correlation with flow shear stress at baseline. However, long-term follow up showed that correlations between plaque progress and mechanical stresses (FSS and PWS) identified for one time period were not re-producible for most cases (>80%). Further investigations are needed to identify the reasons causing the correlation sign changes.

Highlights

Atherosclerosis development consists of three stages: early initiation, long-term slow progression, and some of them final rupture
In the PREDICTION study, Stone et al reported that plaque area was a good predictor of change in plaque area (p
In a multi-patient (n=20) intravascular ultrasound (IVUS)-based follow-up study of patients with coronary atherosclerosis, by dividing slices into low (25 dyn/cm2) flow shear stress (FSS) groups and comparing the low and high FSS groups with the intermediate-FSS group, Samady et al found that low-FSS segments demonstrated greater reduction in vessel (P

Summary

Introduction

Atherosclerosis development consists of three stages: early initiation, long-term (several decades) slow progression, and some of them final rupture. The LFSS hypothesis cannot explain why intermediate and advanced plaques continue to grow under elevated high shear stress conditions [8]. Using in vivo MRI of human carotid data, Tang et al (2008) reported that 18 out of 21 patients showed negative correlations between human carotid atherosclerotic plaque progression and plaque wall stress on follow-up scan [8]. In a multi-patient (n=20) intravascular ultrasound (IVUS)-based follow-up study of patients with coronary atherosclerosis, by dividing slices into low (25 dyn/cm2) flow shear stress (FSS) groups and comparing the low and high FSS groups with the intermediate-FSS group, Samady et al found that low-FSS segments demonstrated greater reduction in vessel (P

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Conclusion