Fibrosis, lipids, and calcium in human atherosclerotic plaque. In vitro differentiation from normal aortic walls by ultrasonic attenuation.

Abstract

This study was designed to determine whether attenuation of ultrasound by the aortic wall is potentially useful in characterizing the atherosclerotic lesion. Measurements were made on fresh specimens taken from a human aorta at autopsy. Four hundred different sites, 4 mm in diameter each, corresponding to the dimension of the ultrasonic beam at the focal zone, were ultrasonically analyzed and histologically studied. Attenuation of ultrasound in each site was assessed by Fourier analysis of the echo produced by a specular reflector placed behind the specimen. Two parameters were measured over the range 7-11 MHz: the integrated attenuation index (per cm), and slope (per cm per MHz) of the best fit straight line relating attenuation and frequency. Histological examination--performed for each of the 400 sites where attenuation had been measured--identified four subsets (100 samples each): normal aortic walls, fibrous plaques, fibrofatty plaques, and calcified plaques. Results obtained from ultrasonic and histological analyses showed that the integrated attenuation index was lowest in normal walls (24 +/- 2.1, mean +/- SE) and progressively increased in fibrous (32 +/- 3.1), fibrofatty (82 +/- 6.5), and calcific (185 +/- 8.7) subsets (all intergroup differences were significant, except for the normal vs. fibrous comparison). The slope value was significantly lower in the fibrous than in the normal subsets: (10(-3)) 31.9 +/- 4.5 vs. (10(-3)) 99.5 +/- 9.1, respectively. Values of fibrofatty and calcific plaques overlapped: (10(-3)) 383 +/- 21 vs. (10(-3)) 320 +/- 23, respectively. Both were significantly different from normal and fibrous groups.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo radiofrequency-based ultrasonic tissue characterization of the atherosclerotic plaque.

“…[9][10][11][12][13][14][15] We performed ultrasonographic examinations of the carotid arteries and assessed the acoustic properties of atherosclerotic plaques by means of a suitably modified echographic apparatus allowing direct access to the radiofrequency signal in 15 patients who subsequently underwent endarterectomy. The ultrasonic findings were correlated with the histological analysis, independently performed on the arterial samples.…”

Time domain echo pattern evaluations from normal and atherosclerotic arterial walls: a study in vitro.

“…ULTRASONIC tissue characterization of atherosclerosis has been attempted in several studies in vitro. [1][2][3][4][5][6][7][8][9][10][11][12] The purpose of these studies has been twofold: (1) to test new variables of potential diagnostic use, and (2) to provide basic information for a better definition of limits and applicability of clinical echocardiography.Findings in vitro show that, in predominantly fatty samples of aortic wall, the values of the internal backscatter tend to overlap with those found in normal walls.9 In this previous study, the value of the specular echoes of aqueous phase-tissue interface -which is supposed to be strongly angle dependent -was purportedly "gated out." However, the detection of specular reflections is fundamental for the border identification with conventional echocardiographic instruments.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] The purpose of these studies has been twofold: (1) to test new variables of potential diagnostic use, and (2) to provide basic information for a better definition of limits and applicability of clinical echocardiography.…”

Imaging Cardiovascular Calcification

“…It also allows monitoring of the natural history of plaque formation and identification of the compositional features. Usually, atherosclerotic plaque may appear in 3 distinct textural patterns by parameters of acoustic attenuation129: hypoechoic (lipid‐rich or hemorrhagic plaque), moderately hyperechoic (fibrotic or fibrofatty plaque), and markedly hyperechoic with shadowing (calcific plaque). Hyperechoic calcified plaque is easily identified by its strongly reflective ultrasound properties with an attenuation 700% greater than that in normal wall and 300% greater than that in atherosclerotic noncalcific plaques.…”