NEW CONCEPT IN ECHOCARDIOGRAPHY - HARMONIC IMAGING OF TISSUE WITHOUT USE OF CONTRAST AGENT

Background Endocardial border detection is important for echocardiogra phic assessment of left-ventricular function. Second harmonic imaging of contrast agents enhances this border detection. We discovered that harmonic imaging improves tissue visualisation even before contrast in jection. We therefore sought objectively to demonstrate the degree of enhancement of endocardial and myocardial visualisation. Methods An AT L HDI-3000 scanner with software for contrast harmonic imaging was use d to record short-axis images of the left ventricle in 27 patients wit h possible myocardial disease and 22 controls, in the fundamental mode and with harmonic imaging. A computer program measured the relative g rey-scale values within six segments of the endocardium and myocardium . An Acuson Sequoia Scanner equipped with software for tissue harmonic imaging was used to investigate the reproducibility of ejection-fract ion calculations in 22 patients with ischaemic heart disease. Findings Harmonic imaging produced brighter endocardium within each segment. R elative to the mean grey value of the total imaging sector, the values for harmonic and fundamental imaging were 171.5 vs 85.6% (p<0.0001) i n end diastole and 194.1 vs 106.7% (p<0.0001) in end systole. Results for the myocardial segments were also significantly better for harmoni c imaging. Structure enhancement of similar magnitude was seen among p atients and healthy controls. Use of harmonic imaging reduced the prop ortion of unacceptable images by 14-46% in different views and improve d the reproducibility of biplane ejection-fraction measurements. Inter pretation In comparison with fundamental imaging, the relative endocar dial and myocardial brightness is enhanced by harmonic imaging.