The role of tissue harmonic imaging in fetal echocardiography

To define the role of tissue harmonic imaging (THI) in fetal echocardiography.

Three trials were conducted in a tertiary referral center: Study A was a prospective randomized trial including 50 women referred for fetal echocardiography. Those allocated to Arm 1 underwent conventional fundamental frequency ultrasound (FFU) and those allocated to Arm 2 underwent THI. Study B was conducted in 21 patients who were obese or overweight with significant weight gain in pregnancy. In these patients, both THI and FFU echocardiography were performed and compared. In Study C, THI was employed as a second-line rescue technique in cases of inadequate or incomplete examination by FFU. A subjective scoring system was used by a reviewer who had not performed the examinations to assess the comprehensiveness of the examination and the image resolution. The reviewer was blinded to the image modality.

In Study A, no difference was found in the diagnostic accuracy between THI and FFU echocardiography but the resolution was significantly poorer in the THI arm. In studies B and C, THI performed significantly better than FFU (P < 0.001).

THI echocardiography seems to be the best technique to employ in obese women and in those in whom FFU fails to provide diagnostic information. However, due its poorer resolution in women of average weight, FFU echocardiography should remain the technique of choice.