Comparison of tissue harmonic imaging with conventional US in abdominal disease

Harmonic waves are generated from nonlinear distortion of an acoustic signa l as an ultrasound wave insonates tissues in the body. These beams are inte ger multiples of a fundamental transmitted frequency. Potential advantages of harmonic imaging include improved axial resolution due to higher frequen cies and better lateral resolution due to narrower beams. Decreased noise f rom side lobes improves signal-to-noise ratios and reduces artifacts. Delet erious effects of the body wall are also reduced. The authors prospectively studied ultrasonographic (US) findings in 100 adult patients with 202 abdo minal lesions by comparing harmonic US images with conventional US images. The results were subjected to statistical analysis. Harmonic imaging was su perior to conventional US in regard to lesion visibility and diagnostic con fidence. Harmonic imaging was particularly useful for depicting cystic lesi ons and those containing echogenic tissues such as fat, calcium, or air. In patients with a body mass index of 30 or more, harmonic imaging was clearl y better for lesion visibility and confidence of diagnosis. The authors rec ommend routine use of harmonic imaging for abdominal US studies in all adul t patients.