Plaque development, vessel curvature, and wall shear stress in coronary arteries assessed by X-ray angiography and intravascular ultrasound

Abstract

The relationships among vascular geometry, hemodynamics, and plaque development in the coronary arteries are complex and not yet well understood. This paper reports a methodology for the quantitative analysis of in vivo coronary morphology and hemodynamics, with particular emphasis placed on the critical issues of image segmentation and the automated classification of disease severity. We were motivated by the observation that plaque more often developed at the inner curvature of a vessel, presumably due to the relatively lower wall shear stress at these locations. The presented studies are based on our validated methodology for the three-dimensional fusion of intravascular ultrasound (IVUS) and X-ray angiography, introducing a novel approach for IVUS segmentation that incorporates a robust, knowledge-based cost function and a fully optimal, threedimensional segmentation algorithm. Our first study shows that circumferential plaque distribution depends on local vessel curvature in the majority of vessels. The second study analyzes the correlation between plaque distribution and wall shear stress in a set of 48 in vivo vessel segments. The results were conclusive for both studies, with a stronger correlation of circumferential plaque thickness with local curvature than with wall shear stress. The inverse relationship between local wall shear stress and plaque thickness was significantly more pronounced (p < 0.025) in vessel cross sections exhibiting compensatory enlargement (positive remodeling) without luminal narrowing than when the full spectrum of disease severity was considered. The inverse relationship was no longer observed in vessels where less than 35% of vessel cross sections remained without luminal narrowing. The findings of this study confirm, in vivo, the hypothesis that relatively lower wall shear stress is associated with early plaque development.

Relation between plaque type, plaque thickness, blood shear stress, and plaque stress in coronary arteries assessed by X‐ray Angiography and Intravascular Ultrasound

“…The findings in Ref. 19 confirm, in vivo, the hypothesis that relatively lower wall shear stress is associated with early plaque development.…”

“…Wahle et al 19 proposed a complete and exhaustive analysis of the relation among vascular geometry, hemodynamic wall shear stress, and amount of plaque in the coronary arteries, which is based on a similar 3D reconstruction technique. In his study, the relation between wall shear stress, local curvature, and radial plaque thickness was described.…”

Cardiac Flow Analysis Applied to Phase Contrast Magnetic Resonance Imaging of the Heart

“…Apart from such localized measurements that can provide interactive visualization in cardiovascular flow, 74 phase contrast MRI has also been utilized in global flow measurements such as determination of flow volumes in arterial structures, and in particular, blood ejection volumes in the ascending aorta 39,40,55 as well as arterial wall shear stress. 50,51,68 It has been widely documented that phase contrast MRI is an established flow-imaging scheme for cardiovascular examination of human subjects and compares well with ultrasound technology. 40 Further development of phase contrast MRI to produce multi-slice cine images involves an electrocardiogram synchronized time-resolved framework to allow assessment of blood-flow characteristics with high spatial and temporal resolution of a cardiovascular region of interest.…”

IVUS Role in Studies Assessing Atherosclerosis Development

“…Normal ESS is pulsatile and unidirectional with magnitude that vary within a range of 15-70 dyne/cm 2 over the cardiac cycle 17 . Stone et al 19 published that plaque progression in minimally diseased coronary artery subsegments occurs almost exclusively in the areas of low ESS. At the same time, the vessels react on plaque progression by positive remodeling in the regions with a low ESS.…”

“…The reconstructions may also serve as input for hemodynamic and morphologic analyses and allow for interactive visualization 34 (Figure 1). Fig.…”