Quantitative Ultrasonic Tissue Characterization Can Identify High-Risk Atherosclerotic Alteration in Human Carotid Arteries

Abstract

Background-Recently, ultrasonic tissue characterization of the composition of plaques has been performed in a quantitative fashion on the basis of integrated backscatter (IBS) analysis, but most of those studies have used high-frequency ultrasound to obtain microscopic images. Methods and Results-We performed B-mode measurement and IBS signal analysis with acoustic densitometry with a 7.5-MHz linear-array transducer in freshly excised human aortas (nϭ58) (normal, atheromatous, and fibrous tissue) obtained at autopsy. Atheromatous and fibrous tissue had a similar intima-media thickness (IMT), but the IBS value in atheromatous specimens was lower than that in fibrous specimens. We further applied this method to human carotid ultrasonography. The subjects were young (80 regions), middle aged with 1 or no coronary risk factors (low risk) (120 regions), middle aged with Ն2 coronary risk factors (high risk) (240 regions), or elderly (80 regions) or were patients with myocardial infarction (MI) with multivessel disease (90 regions). The IMT was similar in middle-aged, elderly, and MI subjects. In contrast, the IBS value was significantly higher in elderly subjects and lower in high-risk middle-aged and MI subjects compared with that in low-risk middle-aged subjects. The percent of regions diagnosed as atheromatous (IBS less than mean minus 2-SD value of IBS in young subjects) was 11% in low-risk middle-aged subjects, 29% in high-risk middle-aged subjects, and 63% in the MI group. Conclusions-In conjunction with conventional B-mode imaging, IBS analysis with carotid ultrasonography appeared to provide prognostic information to identify a high-risk group with systemic atherosclerosis, which could lead to coronary heart disease in individuals with early-stage disease. (Circulation. 2000;102:766-770.)

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“…Advanced mathematical algorithms including radiofrequency analysis (RFA) and elastography allow a more detailed analysis 96,97 . IVUS-derived RFA (virtual histology, VH-IVUS) displays the reconstructed data as a color coded tissue map of plaque composition based on validation to histology [98][99][100] . VH-IVUS classifies plaque components into four basic tissue types: fibrous (dark-green), fibro-fatty (light-green), necrotic core (red), and dense calcium (white) 101 .…”

Normalization of catecholamine production following resection of phaeochromocytoma positively influences carotid vascular remodelling

“…The system automatically calculated the average value of the IBS, which was also displayed in dB. By adopting the adventitia as the reference object, we then corrected the IBS value (C-IBS) by subtracting the IBS value obtained from a reference ROI placed within the adventitia (23,27).…”

“…Thus, acoustic densitometry is now believed to be a clinically applicable ultrasonic backscatter imaging technology that provides an integrated online capability to measure, display and quantify the presence of fibrous tissue in intima-media complex of human arteries. This relatively simple, repeatable and quantitative analysis is able to evaluate the vascular structure in a non-invasive manner (23).…”

Transesophageal Echocardiographic Evaluation of Atherosclerosis

“…Thus, with acoustic densitometry, IBS offers a clinically promising method for assessing myocardial contractile performance independent of wall motion 37)38) or quantitative evaluation of the vessel wall plaque composition: fibrosis, calcification, or lipid deposition. 39)40) The latter approach can provide for a new evaluation of thoracic aortic atherosclerosis. Wickline et al 36) have shown that IBS can be applied to aortic atherosclerosis in vivo.…”

“…However, IBS has not been established as a standard reference. The authors have used the IBS signal from the vessel lumen as a reference object, while other investigators have used left ventricular cavity, 41) myocardium, 42) pericardium, 43) and adventitia 39) as references. The established standard reference tissue for quantitative ultrasonic tissue characterization with IBS analysis is indispensable when this index is used as a 'noninvasive ultrasonic biopsy' in the clinical setting.…”