Suppression of reverberation artifact by subtraction imaging

Reverberations in ultrasound pulse‐echo signals are the result of parallel specular reflectors that are perpendicular to the incident sound beam. The multiple reflections within the space between the reflectors cause a decaying pulse train of echoes to be superimposed on the returned echoes due to other structures. In a medical ultrasound B‐scan, these reverberant signals obscure detail in the underlying tissue. One method to suppress these reverberation artifacts may be to subtract the images obtained at two different frequencies. This approach was tested in a water bath on a phantom of two parallel thin plastic plates in front of a foam sponge. A 5‐ and a 7.5‐MHz transducer with similar beam profiles in the region of interest were used to create the B‐mode images. The results showed that subtraction imaging resulted in a significant decrease in the reverberation artifact. Application of this method to the phantom without the sponge indicate a 7‐ to 13‐dB decrease in the reverberant signal level.