Ultrasonic myocardial characterisation: Application of an original method of acoustic quantification to analysis of healthy and hypertrophic interventricular septal myocardium.

Echocardiography does not provide objective tissue characterisation of soni fied tissues. A recent advance has been the introduction of the radiofreque ncy signal. At present, its exploitation remains a research tool. The requi red material for quantification is still insufficiently robust and discrimi native. The indices derived from histograms of grey scales are calculated b y the majority of workers for regions of interest manually positioned in th e image. This statistical method allows analysis of the average grey level but not of the architecture of the tissue examined. Tissue characterisation is, therefore, only a potential feature of echocardiography. The authors' approach consists in developing software applied to digital si gnal provided by the echograph and not directly by the transducer, as in th e research based on the use of radiofrequency signals. This software allows characterisation of the texture by two statistical methods applied to sign al processing : the histograms of the grey scales, the matrix of co-occurre nce (assessing the make-up of the different grey scales in the region of in terest). This tool of tissue characterisation is presented here in the stud ies of the interventricular septum in the parasternal long axis view. Two p opulations, one with healthy myocardium and the other with myo cardial hype rtrophy, have been studied. These two populations are differentiated in a s ignificant manner by their respective values of parameters of myocardial te xture characterisation in early diastole. Despite a number of methodological problems, this study confirms the hopes that it will be possible in the near future to obtain a quantitative " hist ological " definition of tissues by echocardiography.