Research On Ultrasonic Transient Measurement Method Based On Code Detection

Tissue elasticity and viscosity are closely related to pathological changes. Therefore, quantitative measurement of tissue viscoelasticity has important medical applications. Ultrasound-based elastography, which has the advantages of real-time, noninvasive, low-cost, et. al, have been one of the most popular study fields. However, the penetrate depth is limited in this technique, especially for obese patients. This study applied transient elastography system integrated with code detection to investigate the effects of code detection for elasticity measurement and the non-alcoholic fatty liver disease(NAFLD) staging.We developed a strict synchronization vibration-controlled transient elastography(VCTE) system, which can realize traditional detection and code detection. Elasticity QA Phantom(MODEL 049, CIRS) and in vitro pork livers were used to test the system's performance. The Elasticity QA Phantom results showed that the system has a high degree of repeatability, vibration diversity and reliable measurement results, 7-bit and 13-bit Barker code detection can increase SNR(Signal-to-Noise ratio, SNR) 8dB. Results from in vitro pork livers showed that traditional detection and 7-bit?13-bit Barker code detection obtained similar shear wave velocities.Finally, the system was used for rat nonalcoholic fatty liver disease(NAFLD) staging experiments. According to the classification results of the pathology slice, the rat livers were staged from S0 to S4 and the degree of the fatty liver is incremented one by one. Statistical analysis with shear wave velocity showed that in addition to the vibration width with 2.9ms, 7-bit Barker code detection can distinguish S0-S1 and S2-S4, other methods had no obvious staging.Moreover, rat livers results showed that traditional detection and 7-bit?13-bit Barker code detection obtained shear wave velocities has no significance difference, and 7-bit and 13-bit Barker code can improve SNR 12~15 dB, the detection depth can increase 22%~33%. Therefore, code detection can improve the VCTE's performance.