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

Abstract

The aim of this study in vitro of human fresh specimens was to quantitatively evaluate the contribution of the aqueous phase-intima interface (the first 400 msec of the reflected signal) in normal and atherosclerotic arterial walls. Seventy-five samples were studied, 15 normal, 15 fatty, 15 fibrofatty, 15 fibrous, and 15 calcific. A broadband transducer (4 to 14 MHz) was used. The aqueous phase-intima reflection (expressed in dB, mean + SD) was lowest in the fatty plaques (-35.3 + 2.5), differing in a highly significant way from that in all other groups: normal (-13.2 ± 8.8), fibrofatty ( -20.4 8.3), fibrous ( -13.0 ± 9.7), calcific ( -5.9 -+ 3.4). The echo coming from the intimamedia transition was of relatively low amplitude in normal and in fatty samples; typically, strong reflections from the intima-media transitions were present in the other pathologic subsets. In conclusion, the time domain echo pattern of the arterial wall may provide a useful clue to the structure of the plaque. Circulation 77, No. 3, 654-659, 1988. 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. 13 The aim of this study was to quantitatively evaluate the contribution of the "first interface" intimal echo in various normal and pathologic subsets of arterial wall. Materials and methodsExperimental procedure. Fresh specimens of arterial wall were taken from human aortas at autopsy and those with one of four distinct kinds of lesions (fatty, fibrofatty, fibrotic, and

Noninvasive Measurement of Medium-Sized Artery Intima-Media Thickness in Humans: In vitro Validation

“…This 'double peak' signal is very similar to the 'double-line pattern' observed on the typical B-mode image of a longitudinally scanned normal artery wall [22][23][24] and has been related to the distinct acoustic interfaces between intima, media and adventitia. Although the origin of these ultrasonographic layers re mains controversial, it has been suggested that the first high-amplitude signal reflects the lumen-intima interface, the hypoechogenic zone part of the media, and the second high-amplitude signal the media-adventitia interface [7].…”

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.…”

Integrated Backscatter Intravascular Ultrasound

“…In studies of the myocardium, calibrated myocardial IB values were significantly correlated with the relative volume of interstitial fibrosis (Picano, 1990 et al;Naito et al, 1996). In preliminary studies in vitro, IB values reflected the structural and biochemical composition of atherosclerotic lesion and could differentiate fibrofatty, fatty and calcification of arterial walls (Barziliai et al, 1987;Urbani et al, 1993;Picano et al, 1988). It was also reported that anisotropy of the direction and backscatter power is related to plaque type (De Kroon et al, 1991).…”