Application Of Ultrasonic Shear Wave Elastography In Quantitative Evaluation Of Skeletal Muscle Stiffness

The Ice Bucket Challenge’s upsurge on the Internet has led to a growing concern about Amyotrophic Lateral Sclerosis(ALS)patients.ALS is a progressive neurodegenerative disease.It affects the spinal cord and the brain associated with the movement of nerve cells,resulting in motor neuron death,leading to muscle degeneration and atrophy.ALS incidence of about two hundred thousandths to five hundred thousandths,is a rare disease;and once diagnosed,the patient’s life expectancy will be between 3 to 5 years.At present,musculoskeletal ultrasonography has been used for the early diagnosis of ALS,which is mainly assessed by changes in echo intensity and thickness of muscle tissue,but these indicators are susceptible to system setting and scanning approaches,and musculoskeletal ultrasound is difficult to directly assess the mechanical properties of the muscles.Ultrasound shear wave elastography can be used to quantitatively evaluate the mechanical properties of muscles in different status,so that it can provide supplemental information for the diagnosis of ALS.The basic principle of the ultrasound shear wave elastography is that,an ultrasound transducer emits hundreds of microseconds of long pulses into the tissue,resulting in acoustic radiation force,then the acoustic radiation force stimulates the tissue to produce a shear wave propagating inside the tissue with displacement in the order of micrometers.Such displacement can be tracked and then the shear wave velocity can be calculated.The main purpose of this study is to develop the different shear wave elastic imaging algorithms and evaluate if they are applicable for the early diagnosis of ALS.The main contents of this study include:(1)Using the simulation data to investigate the high frame rate plane wave imaging and acoustic radiation shear wave elastic imaging techniques.(2)Developing a variety of shear wave elastic imaging algorithms based on Verasonics Vantage 256 Ultrasonic Open Platform and Philips L7-4 Linear Probes,including unfocused push,focused push,unfocused comb-push and focused comb-push methods,respectively.The shear wave caused by these four diffferent methods are tracked with high frame rate plane wave imaging technique.Experimental phantom data are quantitatively analized,so that to determine an appropriate one for clinical study.(3)Carring out clinical pre-experiments to further validate and optimize the relevant algorithms.With collaboration with Shenzhen Second People’s Hospital,healthy volunteers(n: 7,age: 26.28±6.55,BMI: 20.72±1.62)and amyotrophic lateral sclerosis patients(n: 3,age: 54.33±17.61,BMI: 19.56±4.29)are recruited for clinical experiments.The results show that: the shear wave speed could not distinguish between amyotrophic lateral sclerosis patients and healthy volunteers.