Ultrasonic Tissue Characterization in Cardiology

Abstract

The standard clinical applications of echocardiography involve display of the smooth surfaces of the heart, such as the endocardium, epicardium and valve leaflets. A relatively new area of endeavor in cardiac ultrasound is the attempt to evaluate myocardial tissue composition and/or structure based on the acoustic properties of the heart. The rationale for this area of study - termed ultrasound tissue characterization - is that ultrasound interacts (is absorbed or reflected) differently with abnormal myocardium than with normal myocardium. This rationale stems from the common clinical observation that certain abnormalities of the heart (calcification, amyloidosis, and others) affect the appearance of échocardiographie images. Several approaches to the evaluation of tissue composition with ultrasound include the display of acoustically abnormal tissue using gray scale or color encoding, the measurement of classical acoustic variables, and computer-based analysis of ultrasound signals and images. Promising results have been obtained through the use of ultrasound tissue characterization methods to identify acute ischemia, acute and chronic myocardial infarction, cardiomyopathies, myocardial contusion, and intracardiac masses. Although many technical problems remain to be solved, ultrasound tissue characterization may soon be added to the routine diagnostic armamentarium of the cardiologist.

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

“…Of the 70 regions of interest, histology identified 11 normal regions (-32.5±9.4 dB), 5 '-15 In particular, the internal backscatter of the arterial wall rises markedly from lipidic to fibrofatty to calcific plaques. Such differentiation can be reliably achieved even with the "peak amplitude value" of the reflected signal, which, unlike the internal backscatter, is much simpler to obtain but also markedly phase sensitive.9 In our study, we used an index related to the internal backscatter, which is derived through a frequency and spatial averaging method and can therefore be considered relatively phase insensitive, since fluctuations are expected to occur randomly and may fall within statistically specified limits.…”

Ultrasonic Tissue Characterization and Doppler Tissue Imaging in the Analysis of Left Ventricular Function in Essential Arterial Hypertension: A Preliminary Study

“…IBS is a relative measure of the total ultrasonic energy backscattered by a small volume of the interrogated tissue. 29 Using special hardware, the IBS processor operates on the digitally beamformed radiofrequency (RF) acoustic signals in incremental time windows along each acoustic line to generate the real-time IBS image at a frame rate of 25 Hz. The useful dynamic range of the IBS image data is 60 dB.…”

Long-Term Effect of Spironolactone on Cardiac Structure as Assessed by Analysis of Ultrasonic Radio-Frequency Signals in Patients With Ventricular Hypertrophy

“…5 Integrated ultrasonic backscatter is a simple and widely used parameter for myocardial tissue characterization, [6][7][8][9][10] and we reported a significant correlation between myocardial integrated backscatter and LV fibrosis. 11 However, serious problems regarding standardization limit its use.…”