Pitfalls of echocardiographic measurement in tissue harmonic imaging: In vitro and in vivo study

Background. Tissue harmonic imaging (THI) is a useful method for endocardial border detection by transthoracic echocardiography, especially in technically difficult patients, even though accuracy of this method in the echocardiographic measurement is unclear. The purpose of this study is to evaluate the accuracy of echocardiographic measurement by THI in vivo and in vitro. Methods: In vitro, we measured wall thickness, dimension, and volume of the excised hearts by THI. In 11 patients, we assessed the comparative accuracy of THI and fundamental imaging (FI) in determination of left ventricular (LV) wall thickness, dimension, volume, and ejection fraction. Results: In vitro, thickness measurements by THI overestimated true length, and both volume and dimension measurements by THI underestimated true values. In vivo, LV ejection fraction measurements obtained by THI exhibited excellent correlation and agreement with those obtained by FI. However, LV wall thickness determined by THI was significantly larger than that determined by FI, and the dimensions and volume of LV measured by THI were significantly smaller than those measured by FI. Conclusion: Although THI is an excellent imaging technique for determination of LV ejection fraction, echocardiographic measurement by THI underestimates LV dimensions and volume, and overestimates LV wall thickness.