Influence of catheter position on estimated strain in intravascular elastography

Abstract

In elastography, an erroneous strain estimate is obtained when the radial strain and the probing ultrasound beam are not properly aligned: the "strain projection artifact". In practice, an angle between the strain and the ultrasound beam will be present in most of the cases due to inhomogeneities or nonuniform compression. In this study, a theoretical function describing the strain projection artifact is derived as a function of the angle between the radial strain and the ultrasound beam. Two main factors for an angle between strain and ultrasound beam in intravascular elastographic experiments are eccentricity and tilt of the transducer. The theoretical functions describing these errors are corroborated with strain estimates from an experiment with a circular, homogeneous gel-based vessel phantom. Comparison between the theoretical functions and the experimental results reveals that the strain projection artifact is well described by the theoretical findings. As a result, the experimental data can be corrected for this artifact. The corrected elastograms reveal that correct strain estimates are obtained when the eccentricity of the intravascular catheter is less than 63%. An "off-the-wall" device may be required to advance intravascular elastography to in vivo implementation.

Estimation of the Transverse Strain Tensor in the Arterial Wall Using IVUS Image Registration

“…To deal with this problem, one strategy is to minimize the tissue and catheter motion by limiting the luminal pressure difference for the strain measurement; de Korte et al (2002a) used a pressure difference of ϳ5 mm Hg with resulting strains of Ͻ2%. Another strategy is to compensate for the catheter motion before the strain estimation (de Korte et al 1999;Janssen et al 2000;Leung et al 2006;Saijo et al 2004;Shi et al 2005). Despite these efforts, the issue is not well resolved.…”

A general solution for catheter position effects for strain estimation in intravascular elastography

“…de Korte et al (2000) have performed both in vitro and in vivo validation studies on excised human coronary and femoral arteries, and Yucatan minipig models with atherosclerosis (de Korte et al 2002). Initial catheter position correction studies in IVUS elastography was also performed by de Korte et al (1999), where they derive an expression that corrects for catheter eccentricity and tilt occurring independently within the lumen.…”

“…In IVUS elastography, misalignment of the US beam and the radial stress introduce errors into strain estimates referred to as "strain projection artifacts" (SPA) (de Korte et al 1999). Several methods have been used to correct these artifacts, such as the geometric center algorithm (Shapo et al 1996).…”

Atherosclerotic plaque characterization using plaque area variation in IVUS images during compression: a computational investigation

“…The maximum of 1 atm was chosen, because level of pressure provides a good tradeoff between high deformation ratio and risk of plaque rupture during acquisition procedures. Moreover, by using the balloon, problems with catheter eccentricity and inclination are overcome, ensuring the reliability of the deformed values (Choi et al, 2002;De Korte et al, 1999;Shapo et al, 1996). The fixed nodes, at the external border, after the adventitia tissue, were selected to be the boundary condition.…”

“…Therefore, extra information about tissue composition and vulnerability is provided, as a result Volume 30, Número 2, p. 159-172, 2014 the best therapeutic procedure can be carried out (Céspedes et al, 1993;Ophir et al, 1991). Basically, the Elastography procedure is divided into three main blocks: First, the images are acquired with a variation of intraluminal pressure -usually arterial pressure and inflated balloon are used as source of pressure (De Korte et al, 1999;Shapo et al, 1996). Second, the displacements of microstructures are computed, followed by the strain map computation.…”