title: New concept in echocardiography: harmonic imaging of tissue without use of contrast agent.
abstract: BACKGROUND
  Endocardial border detection is important for echocardiographic 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 injection. We therefore sought objectively to demonstrate the degree of enhancement of endocardial and myocardial visualisation.
  
  
  METHODS
  An ATL HDI-3000 scanner with software for contrast harmonic imaging was used to record short-axis images of the left ventricle in 27 patients with possible myocardial disease and 22 controls, in the fundamental mode and with harmonic imaging. A computer program measured the relative grey-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-fraction calculations in 22 patients with ischaemic heart disease.
  
  
  RESULTS
  Harmonic imaging produced brighter endocardium within each segment. Relative 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) in end diastole and 194.1 vs 106.7% (p<0.0001) in end systole. Results for the myocardial segments were also significantly better for harmonic imaging. Structure enhancement of similar magnitude was seen among patients and healthy controls. Use of harmonic imaging reduced the proportion of unacceptable images by 14-46% in different views and improved the reproducibility of biplane ejection-fraction measurements.
  
  
  CONCLUSIONS
  In comparison with fundamental imaging, the relative endocardial and myocardial brightness is enhanced by harmonic imaging.
authors.affiliation: Department of Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden. caidahl@clinphys.gu.se
authors.forename: K
authors.initials: K
authors.lastname: Caidahl
authors.forename: E
authors.initials: E
authors.lastname: Kazzam
authors.forename: J
authors.initials: J
authors.lastname: Lidberg
authors.forename: G
authors.initials: G
authors.lastname: Neumann Andersen
authors.forename: J
authors.initials: J
authors.lastname: Nordanstig
authors.forename: S
authors.initials: S
authors.lastname: Rantapää Dahlqvist
authors.forename: A
authors.initials: A
authors.lastname: Waldenström
authors.forename: R
authors.initials: R
authors.lastname: Wikh
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003287:Contrast Media; D004452:Echocardiography / Q000379:methods*; D004699:Endocardium / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging; D012595:Scleroderma, Systemic / Q000000981:diagnostic imaging; D016277:Ventricular Function, Left
chemical_list: D003287:Contrast Media