Research On High-frequency Ultrasound Based Intravascular Dual Mode Imaging Method

Cardiovascular disease has become the highest mortality rate in the world.Every year,more than 20 million people die of cardiovascular diseases.Intravascular ultrasound imaging is an endoscopic imaging tool that can intuitively reflect the inside of blood vessels.With regard to tissue and lesions,this technology combines ultrasound imaging technology with catheter intervention technology to provide not only vascular lumen tissue and plaque morphology information,but also detailed characteristics of tissue structure,provide accurate imaging guidance for the diagnosis and treatment of clinical vascular diseases.This article describes the research work of high-frequency ultrasound imaging platform and a new type of ultrasound dual-mode transducer catheter.Based on the platform,a series of endovascular imaging experiments are performed in combination with a new type of transducer catheter.The tissue images and blood flow velocity distribution maps in the same plane and in the same cross section in the blood vessel was obtained.Finally,the real-time blood flow values were calculated based on the blood flow velocity and the inner diameter of the blood vessel.The ultrasonic imaging platform developed in this project can support 5-80 MHz dual-channel high-frequency ultrasound imaging.The system uses field-programmable logic gate array(FPGA)to complete the sequential logic control and signal processing,through the development of different digital signal processing logic algorithms,the multi-mode imaging function of the system platform is realized.The new ultrasonic transducer catheter developed has two ultrasound probes,one on the side of the catheter tip and one on the front of the catheter tip.The forward-looking probe is used for Doppler imaging to collect the blood flow velocity signal in the blood vessel.The working center frequency is 23 MHz.;Side-view probes are used for Brightness-mode(B-mode)imaging to acquire intravascular tissue signals.The working center frequency is 40 MHz.The imaging system and catheters are applied to blood vessel phantom andblood phantom for data acquisition.The pulsation pump simulates the pulsation cycle of the human heart pumping function.Then different acquisition methods are designed to obtain different blood flow data and tissues within the endovascular plane.At the same time,ultra-high resolution small animal color Doppler ultrasound real-time imaging system Vevo?2100 for extravascular data acquisition.The results of the image data after reconstruction from the two systems were compared to verify the newly developed systems and catheters.The parameters and their accuracy meet the requirements of intravascular ultrasound imaging and are suitable for ultrasound imaging of different imaging modes.With the development of materials science,electronic technology and production technology,the performance of ultrasound imaging systems and endoscopic transducer catheters will be greatly improved,and the imaging quality of intravascular ultrasound imaging technology will be greatly improved,and its application area will be more extensive.