Coded excitation methods in biomedical ultrasound

Peak acoustic power limits the signal to noise ratio of real-time ultrasound images. Since the average power of conventional scan formats is well below heating limits, the signal to noise ratio can be significantly increased using coded excitation. A coded system transmits a broadband, temporally elongated excitation pulse. The received signal must be decoded to produce an imaging pulse with improved signal to noise ratio resulting from the higher average power in the elongated excitation. A specific coding scheme appropriate for synthetic aperture imaging is presented. A 14.5 dB signal to noise ratio improvement is demonstrated on a forward-looking imaging system appropriate for intravascular applications.