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Abstract

Echocardiographic modalities have challenged the myocardial tissue characterization, but this reliability has not reached to the clinical use. This study investigated whether combined tissue harmonic imaging (THI) and integrated backscatter analysis (IB) provide the reliable and quantitative information about myocardial fibrosis in idiopathic dilated cardiomyopathy (DCM) in comparison with myocardial biopsy findings. We studied 56 patients with DCM. All patients underwent left ventricular endomyocardial biopsy and IB with fundamental imaging (FI) and THI. In patients with good echocardiographic image quality, excellent correlations between the percentage of area occupied by myocardial fibrosis (% fibrosis) and the mean of integrated backscatter during a cardiac cycle (m-IB) measured with FI or THI were seen, and the correlation was closer with THI compared with FI. While in patients with poor image quality the correlation between m-IB and % fibrosis was only modest with FI, but the correlation was excellent with THI. Four cut-off values of m-IB with THI obtained from receiver operating characteristic curve discriminated between % fibrosis of more and less than 25, 30, 35, and 40% with high sensitivity and specificity. Multivariate analysis revealed that m-IB with THI was an independent predictor for discrimination of the severity of myocardial fibrosis. Combined IB and THI are a clinically applicable method and may be an alternative to myocardial biopsy in evaluating quantitatively myocardial fibrosis in DCM. Copyright 2007 S. Karger AG, Basel.

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Clinical use of ultrasound tissue harmonic imaging.

F Tranquart, N Grenier, V Eder … (1999)

The recent introduction of tissue harmonic imaging could resolve the problems related to ultrasound in technically difficult patients by providing a marked improvement in image quality. Tissue harmonics are generated during the transmit phase of the pulse-echo cycle, that is, while the transmitted pulse propagates through tissue. Tissue harmonic images are formed by utilizing the harmonic signals that are generated by tissue and by filtering out the fundamental echo signals that are generated by the transmitted acoustic energy. To achieve this, two processes could be used; one by using filters for fundamental and harmonic imaging and the second using two simultaneous pulses with a 180 degrees difference in phase. The introduction of harmonics allows increased penetration without a loss of detail, by obtaining a clearer image at depth with significantly less compromise to the image quality caused by the use of lower frequencies. This imaging mode could be used in different organs with a heightening of low-contrast lesions through artefact reduction, as well as by the induced greater intrinsic contrast sensitivity of the harmonic imaging mode.

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Use of harmonic imaging without echocardiographic contrast to improve two-dimensional image quality.

KirkT Spencer, James Bednarz, PatrickG Rafter … (1998)

The aim of this study was to determine whether harmonic imaging (HI) improves endocardial visualization during 2-dimensional echocardiography without echocardiographic contrast. HI differs from fundamental imaging (FI) by transmitting ultrasound at one frequency and receiving at twice the transmitted frequency. This technique has been used in conjunction with contrast echocardiography to enhance myocardial contrast visualization. HI and FI were sequentially performed in 20 patients. Images were digitally stored and subsequently reviewed by 2 observers for the quality of endocardial visualization. In addition, acoustic quantification was performed in both FI and HI modes and endocardial tracking qualitatively judged. HI was compared with FI during dobutamine stress echocardiography in 17 patients who were imaged at baseline and peak stress. Overall, the harmonic images had less clutter and better myocardial blood contrast. Individual segments were better visualized with HI in 30% to 73% of cases. The acoustic quantification endocardial tracking was rated better with HI in 67% of short-axis views and in 58% of apical 4-chamber views. During dobutamine stress testing the overall number of interpretable segments improved from 64% for FI to 84% with HI. Many segments traditionally difficult to image were improved with HI. HI without the use of contrast agents improved endocardial visualization during routine 2-dimensional echocardiography. This improved endocardial visualization led to better endocardial tracking with acoustic quantification and to more segments being clinically interpretable during dobutamine stress testing.

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A relationship between ultrasonic integrated backscatter and myocardial contractile function.

S Wickline, L Thomas, J Miller … (1985)

We have shown previously that the physiologic, mechanical cardiac cycle is associated with a parallel, cardiac cycle-dependent variation of integrated backscatter (IB). However, the mechanisms responsible are not known. The mathematical and physiological considerations explored in the present study suggest that the relationship between backscatter and myocardial contractile function reflects cyclic alterations in myofibrillar elastic parameters, with the juxtaposition of intracellular and extracellular elastic elements that have different intrinsic acoustic impedances providing an appropriately sized scattering interface at the cellular level. Cardiac cycle-dependent changes in the degree of local acoustic impedance mismatch therefore may elicit concomitant changes in backscatter. Because acoustic impedance is determined partly by elastic modulus, changes in local elastic moduli resulting from the non-Hookian behavior of myocardial elastic elements exposed to stretch may alter the extent of impedance mismatch. When cardiac cell mechanical behavior is represented by a three-component Maxwell-type model of muscle mechanics, the systolic decrease in IB that we have observed experimentally is predicted. Our prior observations of regional intramural differences in IB and the dependence of IB on global contractile function are accounted for as well. When the model is tested experimentally by assessing its ability to predict the regional and global behavior of backscatter in response to passive left ventricular distention, good concordance is observed.

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PubMed ID:: 16960443

DOI:: 10.1159/000095595

ScienceOpen disciplines: Chemistry

Keywords: Adult,Aged,Analysis of Variance,Biopsy, Needle,Cardiomyopathy, Dilated,pathology,ultrasonography,Case-Control Studies,Cohort Studies,Echocardiography, Three-Dimensional,methods,Endomyocardial Fibrosis,Female,Humans,Image Processing, Computer-Assisted,Immunohistochemistry,Male,Middle Aged,Observer Variation,Probability,ROC Curve,Reproducibility of Results,Sensitivity and Specificity,Severity of Illness Index

Non-invasive quantitation of myocardial fibrosis using combined tissue harmonic imaging and integrated backscatter analysis in dilated cardiomyopathy.

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Karger: Cardiovascular System

Most cited references 14

Clinical use of ultrasound tissue harmonic imaging.

Use of harmonic imaging without echocardiographic contrast to improve two-dimensional image quality.

A relationship between ultrasonic integrated backscatter and myocardial contractile function.

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