P2B-2 Fundamental Study of Subharmonic Imaging Used Amplitude-Modulated Ultrasound Wave

It is known that the second harmonic and subharmonic components, the frequencies of which are twice and one half the fundamental frequency, are included in echoes from contrast agents. An imaging method, which employs a second harmonic is widely used in medical diagnosis. On the other hand, subharmonic are expected to provide a higher contrast between biological tissues and blood flow because echo signals are generated only from blood containing the contrast agents. However, the subharmonic component echo signal power from contrast agents is relatively low. This has resulted in little progress in the field of subharmonic imaging. In this study, we proposed a new imaging method using amplitude-modulated waves as transmitted waves combined with the pulse inversion method to enhance subharmonic echo signals. Furthermore, we reconstructed a B-mode ultrasound image of agar phantom imitated biological tissue and showed the effectiveness of our method. As a result, the proposed method was found to improve the subharmonic echo power compared with the conventional imaging method