Comparison of multilayer and single-layer coronary plaque models on stress/strain calculations based on optical coherence tomography images

Abstract

Mechanical stress and strain conditions are closely related to atherosclerotic plaque progression and rupture and have been under intensive investigations in recent years. It is well known that arteries have a three-layer structure: intima, media and adventitia. However, in vivo image-based multilayer plaque models are not available in the current literature due to lack of multilayer image segmentation data. A multilayer segmentation and repairing technique was introduced to segment coronary plaque optical coherence tomography (OCT) image to obtain its three-layer vessel structure. A total of 200 OCT slices from 20 patients (13 male; 7 female) were used to construct multilayer and single-layer 3D thin-slice models to calculate plaque stress and strain and compare model differences. Our results indicated that the average maximum plaque stress values of 20 patients from multilayer and single-layer models were 385.13 ± 110.09 kPa and 270.91 ± 95.86 kPa, respectively. The relative difference was 42.2%, with single-layer stress serving as the base value. The average mean plaque stress values from multilayer and single-layer models were 129.59 ± 32.77 kPa and 93.27 ± 18.20 kPa, respectively, with a relative difference of 38.9%. The maximum and mean plaque strain values obtained from the multilayer models were 11.6% and 19.0% higher than those from the single-layer models. Similarly, the maximum and mean cap strains showed increases of 9.6% and 12.9% over those from the single-layer models. These findings suggest that use of multilayer models could improve plaque stress and strain calculation accuracy and may have large impact on plaque progression and vulnerability investigation and potential clinical applications. Further large-scale studies are needed to validate our findings.

Impact of residual stress on coronary plaque stress/strain calculations using optical coherence tomography image-based multi-layer models

“…Accurate models are the base for reliable and precise stress/strain calculations. We recently introduced an OCT multi-layer segmentation method and OCT-based multi-layer plaque models ( 10 ). In this paper, we are adding residual stress to multi-layer models for further improvement.…”

“…c 1 , c 2 , D 1 , D 2 , K 1 and K 2 are material parameters. Parameter values for the vessel layers and p l aque components used in our models are ( 10 , 18 ): Intima: c 1 = −169.23 kPa, c 2 = 177.40 kPa, D 1 = 2.4 kPa, D 2 = 13, K 1 = 32 kPa, K 2 = 36; Media: c 1 = −67.25 kPa, c 2 = 35.01 kPa, D 1 = 17 kPa, D 2 = 2, K 1 = 7 kPa, K 2 = 4, φ = 24.9°; Adventitia; c 1 = −94.44 kPa, c 2 = 102.42 kPa, D 1 = 0.8 kPa, D 2 = 10, K 1 = 10 kPa, K 2 = 40, φ = 75.3°; lipid core: c 1 = 0.5 kPa, c 2 = 0 kPa, D 1 = 0.5 kPa, D 2 = 1.5; calcification: c 1 = 920 kPa, c 2 = 0 kPa, D 1 = 360 kPa, and D 2 = 2.0. For single-layer models, intima parameter values were used for the entire vessel wall.…”

“… Stress–stretch curves of three layers and plaque components derived from the mooney-rivlin models and used in finite element modelling. σ c , circumferential stress; σ z , axial stress ( 10 ). …”

“…While it is well known that arteries have three-layer structure and residual stress ( 7 , 8 ), single-layer models without residual stress were used in most current publications due to lack of available multi-layer image and residual stress data. With unprecedented optical coherence tomography (OCT) resolution (5–15 μm), we introduced a multi-layer OCT image segmentation method and multi-layer plaque models recently to demonstrate the impact of multi-layer structure on plaque stress/strain conditions ( 9 , 10 ). In this paper, OCT-based multi-layer coronary plaque models with and without residual stress inclusion were constructed and compared with single-layer models to investigate the influence of model residual stress inclusion on plaque stress/strain calculations.…”