An assessment of tissue harmonic versus fundamental imaging modes for echocardiographic measurements

The study aimed to evaluate whether a significant difference exists between tissue harmonic imaging (THI) and fundamental imaging (FI) in routine quantitative echocardiographic assessment. We also examined the effects of THI on endocardial definition (ED). Fifty-eight unselected patients (29 men, 29 women; mean age 53 years) referred for transthoracic echocardiography were studied with use of both FI and THI modes. Two independent observers made M-mode measurements of the following: left atrium, aortic root, and left ventricular internal dimensions and wall thickness; they also measured left ventricular outflow tract diameter and left atrial area from 2-dimensional images. Endocardial definition was assessed with use of an arbitrary scoring system (0 = endocardium not visualized, 1 = endocardium visualized but suboptimally, 2 = endocardium well defined) and the American Society of Echocardiography 16-segment model. No significant difference existed between cardiac measurements derived from FI and THI. However, a highly significant improvement in ED occurred with THI (ED index 1.83 versus 1.70, P <.0001). This study suggests that no systematic differences exist in standard echocardiographic measurements between THI and FI, even in the setting of improved ED.