Quantitative ultrasonic tissue characterization with real-time integrated backscatter imaging in normal human subjects and in patients with dilated cardiomyopathy.

Abstract

We have shown previously that the physical properties of myocardium in dogs can be characterized with quantitative ultrasonic integrated backscatter and that interrogation of the tissue with ultrasound can delineate cardiac cycle-dependent changes in ultrasonic backscatter in normal tissue that disappear with ischemia and reappear with reperfusion if functional integrity is restorable. To determine whether this approach can be applied to man, we implemented an automatic gain compensation and continuous data acquisition system to characterize myocardium with quantitative ultrasonic backscatter and to detect cardiac cycle-dependent changes in real time. We developed a two-dimensional echocardiographic system with quantitative integrated backscatter imaging capabilities for use in human subjects that can automatically differentiate ultrasonic signals from blood as opposed to those obtained from tissue and adjust the slope of the gain compensation appropriately. Real-time images were formed from a continuous signal proportional to the logarithm of the integrated backscatter along each A-line. In our initial investigation, 15 normal volunteers (ages 17 to 40 years, heart rates 44 to 88 beats/min) and five patients with dilated cardiomyopathy (ages 22 to 52, heart rates 82 to 120 beats/min) were studied with conventional parasternal long-axis echocardiographic views. Diastolic-to-systolic variation of integrated backscatter in the interventricular septum and left ventricular posterior wall was seen in each of the normal subjects averaging 4.6 + 1.4 dB (SD) and 5.3 + 1.5 dB (n = 127 sites), respectively. In patients with dilated cardiomyopathy, the magnitude of this variation was either reduced or absent, averaging 0.9 + 0.8 dB in the interventricular septum and 1.8 + 1.2 dB in the left ventricular posterior wall (n = 31 sites; p < .01 for both). in eight of the 31 sites in myopathic hearts, no variation was detectable. The results obtained demonstrate that quantitative ultrasonic tissue characterization is feasible in man. Real-time integrated backscatter imaging delineates cardiac cycle-dependent changes in normal human myocardium and quantitatively differentiates between normal and myopathic myocardium. This system offers promise for the quantitative, diagnostic detection of diverse disease processes, including myocardial ischemia and responses of the tissue to reperfusion.

Long-Term Treatment with Valsartan Improved Cyclic Variation of the Myocardial Integral Backscatter Signal and Diastolic Dysfunction in Hypertensive Patients: The Echocardiographic Assessment

“…Ultrasonic IBS reflects the acoustic properties of the myocardium, particularly structural changes of the fibrous component, in both normal subjects and patients with various heart diseases (16)(17)(18)(19)(20)(21). Among the tissue characterization parameters, the IBS-CV and the peak diastolic IBS value are commonly used as non-invasive parameters of myocardial fibrosis in hypertensive patients.…”

Ultrasonic Backscatter and Serum Marker of Cardiac Fibrosis in Hypertensives

“…Thus, for each region a time-dependent curve was obtained from which MI and CV were calculated as described elsewhere. 19 For covariates in the statistical analysis, time-gain compensation and depth were also measured in each region.…”

“…Thus, this cutoff value of PIP can be used to separate hypertensives likely presenting with severe myocardial fibrosis from subjects with nonsevere fibrosis. 13 Quantitative characterization of myocardial texture by analysis of ultrasonic reflectivity has been experimentally 14 -17 and clinically 18,19 shown to correlate with the collagen content of the myocardial tissue. We thus have hypothesized that PIP serum concentrations above 127 g/L should be associated with alterations in myocardial ultrasonic reflectivity detected by backscatter analysis.…”

Myocardial integrated ultrasonic backscatter for early detection of cardiac involvement in patients with Wilson disease

“…Quantitative characterization of myocardial texture by IBS imaging has been experimentally (6-9) and clinically (10)(11)(12)(13) shown to be useful for detecting the pathologic changes affecting the myocardium, such as an aging heart (14), myocardial ischemia (15), hypertrophic and dilated cardiomyopathy (16,17), hypertensive heart disease (18), and acute cardiac rejection (19), resulting in alterations in its fundamental physical properties.…”