Because cyclic rules are quite sensitive to a little noise, this paper uses the noise ratio as the criterion of identifying cyclic itemsets for dealing with the problem and utilizes the cycle pruning technique to reduc.

To increase signal-to-noise ratio(SNR) of medical ultrasound image,a frequency-modulated(FM) ultrasound transmitted imaging method is developed,where a weighted linear FM ultrasound is transmitted to enhance the emission energy without increasing the emission ultrasound pressure,and the image signal is formed by the demodulated ultrasound.