Parameter estimation of atherosclerotic tissue optical properties from three-dimensional intravascular optical coherence tomography

Abstract

Abstract. We developed robust, three-dimensional methods, as opposed to traditional A-line analysis, for estimating the optical properties of calcified, fibrotic, and lipid atherosclerotic plaques from in vivo coronary artery intravascular optical coherence tomography clinical pullbacks. We estimated attenuation μ t and backscattered intensity I 0 from small volumes of interest annotated by experts in 35 pullbacks. Some results were as follows: noise reduction filtering was desirable, parallel line (PL) methods outperformed individual line methods, root mean square error was the best goodness-of-fit, and α-trimmed PL (α-T-PL) was the best overall method. Estimates of μ t were calcified (3.84 AE 0.95 mm −1 ), fibrotic (2.15 AE 1.08 mm −1 ), and lipid (9.99 AE 2.37 mm −1 ), similar to those in the literature, and tissue classification from optical properties alone was promising. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Processing to determine optical parameters of atherosclerotic disease from phantom and clinical intravascular optical coherence tomography three-dimensional pullbacks

“…In a preliminary study, we used 3-D spiral pullback acquisitions rather than stationary acquisitions, obtained during a single blood clearing operation to estimate optical properties of atherosclerotic plaques within 3-D volumes of interest (VOIs). 13,14 These reports are encouraging, and we extend investigation of optical property estimation in this paper.…”

“…We used a rectangular window in (r − θ), with the width along θ ≥ 2 times the width in r. We compared results to those from the traditional Lee filter used by us previously. 13 The traditional LEE assumes normally distributed multiplicative noise. 25 It replaces the center pixel of the kernel with the average of the pixel values within 2σ of the center pixel value.…”

“…13 The OCT signal is attenuated from the initial value I 0 in an exponential fashion with the total attenuation constant, μ t , and distance along the A-line, r.…”

“…We introduce multiple enhancements as compared to previous reports from others 4,12,[15][16][17] and our own report. 13,14 Improvements include, speckle noise reduction, baseline signal computation, and catheter eccentricity correction. Due to noise in a single A-line from a pullback, we estimate parameters from a collection of A-lines nearby in space, both within a polar (r − θ) image and across image frames in z.…”

Automatic classification of atherosclerotic plaques imaged with intravascular OCT

“…Recently, a method was proposed to estimate the attenuation coefficient as a function of depth for each A-line in order to to identify calcifications, necrotic core, and mixed plaque [15]. The estimation of optical parameters from volumes of interest has also been attempted in order to classify calcified, fibrotic and lipid plaques; however, this volumetric analysis can be computationally expensive [16]. A combined depth resolved spectral and attenuation model showed the potential of predicting lipid content in OCT images of atherosclerotic plaques [17].…”