Research Of Quasi-static3D Ultrasound Elastography

Ultrasonic imaging technology has been widely used in clinical environment due to itsunique advantages. Compare with other medical imaging techniques such as computedtomography (CT) and magnetic resonance imaging (MRI), the advantage of ultrasonicimaging is its wide application, good instantaneity, convenient and flexible operation, noionizing radiation damage to patients, and low price. As is known to all that tissue elasticity isdeeply related to its pathological state due to the significant difference in lesion tissue andnormal tissue. Ultrasound elastography is an emerging medical imaging technique that aimsto measure the tissue elasticity information. It has been used for tumor diagnosis andtreatment such as breast and prostate diseases and monitoring RF ablation. Ultrasoundelastography has become a concerned focus and has been rapid development in medicalultrasonic imaging technologies since it proposed.This paper is focused on quasi static three-dimensional ultrasound elastography.Compared with2-D elastography,3-D ultrasound elastography is visual, and can offermulti-angle observation in clinical application.3-D ultrasound elastography enhances thequality and accuracy of elastography and has very important research significance.This paper digs into the basic principles of ultrasound elastography, and analyzes kindsof ultrasound elastography techniques and the core of quasi-static elastography, displacementestimation algorithm. A displacement estimation algorithm based on dynamic programming isselected as the displacement estimation algorithm of this paper because of its dynamic rangeis up to10%. Quasi static three-dimensional ultrasound elastography techniques can beroughly divided into two categories, the elastography technique based on3-D imaging probeand the traditional ultrasound probe. In consideration of the advantages of mechanicalpositioning and Freehand system based on positioning device, this paper fixes a traditionalultrasound linear array probe on a linear slide rail which fixed on a height adjustable shelf.The operator can freehand carry out ultrasound data collection. According to the dataacquisition program, a quasi static three-dimensional ultrasound elastography reconstructionalgorithm is proposed. The visualization and interactive function of the strain reconstructionresults is implemented by using the Visualization Toolkit.This paper realizes the quasi static three-dimensional ultrasound elastography system onSonixRP, a high-performance medical ultrasound imaging research and development platform.The system calibration of space and time calibration experiments is carried out. Therelationship between radio frequency signals plane and position sensor is established, and the time delay between positional information and ultrasound radio frequency signal frame isobtained. Then the experiments on the ultrasound breast elastography phantom, ultrasonicelasticity QA phantoms and human body are implemented. Experimental results show that thequasi static three-dimensional ultrasound elastography system can accurately measures thedistribution of three-dimensional strain information.