This improves signal to noise ratios, allowing better penetration with high frequencies and enables us to receive the doubled frequency of the returning echoes at a broad bandwidth. With coded harmonics, the beam can be transmitted at a center frequency of 6MHz and received at a center frequency of 12MHz, allowing adequate penetration to the chest wall for breast imaging. Low-frequency artifacts are excluded from the beam while axial resolution is maintained, and in some instances, even improved over fundamental imaging. Reverberation, side-lobe, clutter, and speckle artifacts are all reduced, improving contrast resolution and diagnostic certainty. Coded harmonics helps distinguish artifactual internal echoes within cysts from true internal echoes.
Coded harmonics reduces reverberation echoes from breast cysts.
We have found that most cysts appear more hypoechoic or anechoic when imaged with coded harmonics than they do with fundamental imaging. Indeterminate cystic versus solid lesions have become clearly cystic when scanned with coded harmonics. Conversely, harmonics may increase the echogenicity of complex cystic lesions, accentuating true internal echoes. Coded harmonics also improves imaging of implants, solid nodules and normal breast tissues. The near-field reverberation artifact that obscure implants is improved dramatically, allowing better identification of abnormal echogenic extravasated silicone gel insinuated between the fibrous capsule and the implant shell. .