Analysis of transmural trend of myocardial integrated ultrasound backscatter for differentiation of hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension

New technology in echocardiography II: imaging techniques

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Ultrasonic myocardial tissue characterization in patients with dilated cardiomyopathy: value in noninvasive assessment of myocardial fibrosis

Dilated cardiomyopathy (DCM) is usually diagnosed from the left ventricular functional viewpoint by the detection of dilated ventricular cavity and depressed myocardial contractility. Although histologic analysis of the myocardium no doubt provides clinically important information, it is possible only with microscopic examination of biopsy specimen of the myocardium. The objective of this particular study is to clarify the comparative values of the measures of ultrasonic tissue characterization, that is, calibrated myocardial integrated backscatter (IB) and the magnitude of cyclic variation in IB, with conventional echocardiographic parameters in assessing histologic condition of the myocardium. The magnitude of cyclic variation in IB and myocardial IB at end-diastole calibrate with the power of Doppler signals from the blood were measured in addition to conventional echocardiographic parameters in 14 patients with DCM. Calibrated myocardial IB was higher in patients with more fibrosis in the biopsy specimen of the heart tissue, whereas the magnitude of variation in IB or conventional echocardiographic parameters did not significantly correlate with a histologic estimate of myocardial fibrosis. Calibrated myocardial IB provides information about the myocardial fibrosis that cannot be assessable with conventional echocardiographic parameters. Calibrated myocardial IB and the magnitude of cyclic variation of IB are likely to reflect somewhat different acoustic properties of the myocardium.

Analysis of transmural trend of myocardial integrated ultrasonic backscatter in patients with old myocardial infarction

Changes in myocardial integrated backscatter (IB) reflect myocardial viability in patients with myocardial infarction. IB may be obtained separately in the subendocardial and subepicardial layers to establish a transmural trend. The purpose of this study is to examine the possibilities that the measurement of the transmural trend in myocardial IB may provide a new estimate of transmurality of infarction in patients with old myocardial infarction. A calibrated myocardial IB and its transmural trend were measured both in the septum and posterior wall in 21 normal subjects, 24 patients with anteroseptal old myocardial infarction (13 patients with Q-wave myocardial infarction and 11 patients with non-Q-wave myocardial infarction). The transmural trend in myocardial IB was assessed by measuring the acoustic parameter separately in the right and left ventricular halves of the septum, and in the endocardial and epicardial halves of the posterior wall. The magnitude of cyclic variation of IB (a difference between minimum and maximum peaks) was lower, and calibrated myocardial IB (the maximum value of myocardial IB at end diastole calibrated with the power of Doppler signals from the blood along the same ultrasound beam) was higher in patients with anteroseptal old myocardial infarction in the septum, compared with normal subjects. Among patients with myocardial infarction, the difference in these IB parameters between the right and left ventricular halves of the septum was found only in patients with non-Q-wave myocardial infarction. The transmural trend of myocardial IB was likely to reflect the transmurality of myocardial infarction. Therefore, our data give another insight into the assessment of transmural inhomogeneity of myocardial fibrosis or viability in patients with myocardial infarction.

Influence of preload, afterload, and contractility on myocardial ultrasonic tissue characterization with integrated backscatter

Influence of hemodynamic changes in preload, afterload and contractility on myocardial integrated backscatter (IB) was studied in 26 adult mongrel dogs by measuring myocardial IB calibrated with the backscatter from the blood during volume infusion (preload alteration), during aortic constriction (afterload alteration), and during dobutamine or propranolol infusion (contractility alteration). Changes in preload, afterload or contractility did not significantly affect the calibrated myocardial IB either in the septum or in the posterior wall. Changes in preload and afterload did not affect the magnitude of cyclic variation in IB. However, dobutamine produced a significant increase in the magnitude of cyclic variation in IB and propranolol significantly decreased the magnitude of cyclic variation in IB. These data indicated that the calibrated myocardial IB is independent of preload, afterload and contractility, and that the magnitude of cyclic variation in IB is influenced by contractility. We may estimate static (related to histological changes such as fibrosis, edema, necrosis, and so on) and dynamic (related to myocardial contraction such as sarcomere length, muscle fiber orientation, and so on) properties of the myocardium more precisely using myocardial IB calibrated with the backscatter from the blood in addition to the magnitude of cyclic variation in IB.

The variation of integrated backscatter in human hearts in differing ultrasonic transthoracic views

It has been shown previously that in normal subjects the interventricular septum imaged in the long-axis view (LAX) and the left ventricular posterior wall imaged in both the LAX and the short-axis view (SAX) exhibit cyclic variation of integrated backscatter (IB) throughout the cardiac cycle, with maximum values occurring at end diastole (ED) and minimum at end systole (ES). The ability to demonstrate this cyclic variation within these myocardial regions in only two ultrasonic views has limited the potential clinical utility of an IB imaging system. To determine whether clinically useful information on the variation of IB is available from different myocardial regions in different ultrasonic views, we measured ED to ES variation of IB from the parasternal and apical views in normal subjects with a radiofrequency acquisition technique. Two independent clinical observers analyzed ED to ES variation of IB from 14 normal volunteers (mean age 32 +/- 6 years; range 21 to 45 years) in reconstructed two-dimensional ultrasonic images obtained from the parasternal LAX and SAX and apical two-chamber (2C) and four-chamber (4C) views. ED to ES variation of IB was measured from manually traced regions of interest (ROI) within the myocardium. These ROIs were chosen interactively and were located within the midposterior wall and the midanteroseptum in LAX views; within the midposterior wall, midanteroseptum, midseptum, and midlateral wall in SAX views; within the midseptum and the midlateral wall in 4C views; and within the midinferior wall and the midanterior wall 2C views. In all analyzed ROIs within the parasternal and apical views, ED to ES variation of IB was found. We have shown that the maximum magnitude of IB was at ES within the midseptum and in 10 out of 14 volunteers in the midanteroseptum measured from SAX views, the midanterior wall from 2C views, and the midlateral wall from 4C views. The rest of the ROIs analyzed exhibited the maximum value of IB cyclic variation at ED. We have confirmed that the ED to ES variation of IB is present not only when measured from the two standard parasternal views but also from the two apical views in all analyzed myocardial walls, and the minimum of this cyclic variation was not always coincident with ES nor the maximum with ED.