Wang Wei-qi

A double beam doppler ultrasound method for quantitative blood flow velocity measurement

A method for measuring the absolute blood flow velocity waveform is reported. Two independent beams of ultrasound illuminate a vessel simultaneously, producing complementary Doppler signals. The two Doppler frequency shift signals are processed by subtraction and addition at the receiver. The optimum probe position where blood flow velocity is detected can be found as the position where the subtractor output reaches zero. At this position the blood flow velocity is the output from the adder. By this means the influence of the angle between the probe and blood flow is eliminated so that a quantitative measurement is obtained. Both in vitro and clinical results are reported.

Simulation of propagation characteristics of ultrasonic guided waves in fractured long bone

Using ultrasonic guided waves (GW) to assess fractures in long bones has gained considerable attention. This paper focuses on using an improved hybrid boundary element method (HBEM) to analyze and calculate reflection coefficients (RC) and transmission coefficients (TC) of low-order GWs for cracks with different depth-to-width ratios (d/w) in fractured long bones. The results showed that the primary received modes, which include the transmitted and reflected modes, are the same as the incident modes. For some values of d/w, the TC of different GW always had local maxima at adjacent frequencies. For some other cracks with different d/w, most of the TC curves had local maxima of which frequencies and values are not overlapped. These results obtained could be useful for optimizing the excitation of GWs on quantitative assessment of fractured long bones.

The automatic detection of hiding narcotics in human bodies based on fractal dimension and SVM classification

In consideration of the harm to society, hiding narcotics in human bodies should be investigate strictly. While the automatic detection method is absent nowadays, and the inspection rate by human eyes is low. So we introduce a new method based on directional fractal dimension texture feature extraction and support vector machine(SVM) to classify the inspection x-ray images. Using this method, the detection could be totally automatic. It has been compared by cross validation in RBF and linear kernel. In our method, the classification accuracy is 95% and negative predictive value is 100% when 40 images had been tested.

Feasibility analysis of low-intensity pulsedultrasound treatment for osteoporosis

Osteoporosis is a musculoskeletal disease which is mainly characterized by bone loss and deterioration of bone microstructure, to which the middle-aged and elderly people are susceptible. It is often accompanied with bone pain, humpback, fractures and other symptoms, seriously affecting the quality of life of patients. As the population ages, osteoporosis incidence is increasing year by year, and currently these are approximately 200 million patients suffered from osteoporosis in the whole world. Furthermore, osteoporotic fracture has also caused great economic burden to families and society. On the other hand, in the weightless space environment, osteoporosis induced by unloading bones has become one of the important problems of astronauts’ health, leading to impair their space exploration ability enhancement. Hence it is of great significance to its early diagnosis and timely treatment. Ultrasound as a therapeutic method has the advantage of low cost, non-invasive, non-ionizing radiation, fast and can be carried, and the findings in recent years show that ultrasonic backscatter signals can effectively reflect the micro-structure information of cancellous bone, therefore the evaluation of cancellous bone and diagnosis of osteoporosis with ultrasonic backscatter signal has become a focus. And clinical evaluation of bone has made significant progress in adults and newborns. Currently, the main treatment of osteoporosis is drug therapy (common used drugs are bisphosphonates, calcium, vitamin D, calcitonin, estrogen). Drug therapy typically has systemic effects along with side effects, however. Physical therapy such as ultrasound, magnetic therapy and hyperthermia is able to avoid the adverse effect of drug therapy. Low-intensity pulsed ultrasound (LIPUS) has been proved to be an effective mechanical signal to bone tissue and it is used to the treatment of orthopedic diseases, which can play its mechanical effect and avoid the damage of thermal effect to the tissue cells. Study in recent years has demonstrated that LIPUS with certain parameters plays a positive role in the progress of fracture healing, it can promote cell proliferation and differentiation, accelerate calcium mineralization and regulate gene expression and cell growth factors associated with bone tissue cells release, so as to accelerate the progress of bone formation and effectively shorten the healing time. Osteoporosis is a kind of bone disease with main feature of bone mass loss and it is reasonable to consider that the treatment of osteoporosis has the similar physiological mechanism as fracture healing, thus it may be an important potential means of osteoporosis treatment. By referring to numerous documentations related to “LIPUS”, “fracture”, “osteoporosis”, this article begins from the bone structure and function, biological mechanisms of LIPUS treatment for orthopedic diseases and experimental methods of LIPUS treatment for osteoporosis to analyze and demonstrate the effective basis for LIPUS treatment of osteoporosis and review the current study situation of LIPUS treatment for osteoporosis, so as to provide theoretical evidences and new ideas for treatment of osteoporosis.

Quantitative evaluation of long bone fractures by ultrasonic guided waves

Using ultrasonic guided waves to assess fractured long bone has become one of the hottest topics in recent years. To quantitatively evaluate long bone fractures, this paper uses two-dimension finite-difference time-domain (FDTD) simulations to quantitatively analyze the transmission of guided wave in long bone with partially and completely diaphyseal osteotomy. It is illustrated that under the narrowband low-frequency excitation, two fundamental guided modes S0 and A0 can be excited successfully. Different from S0 mode, A0 mode is very sensitive to the fracture geometry. An amplitude ratio parameter between S0 and A0 (S0/A0) is proposed to quantify the bone fracture degree. The simulation indicates that S0/A0 significantly increases with the fracture deepening and widening. Thus, the guided mode conversion can be used to evaluate depth and width of the diaphyseal fracture, which may also be helpful to monitor the fracture healing of long cortical bone.

A noninvasive diagnostic method for aortic regurgitation by detecting carotid blood flow with bidirectional Doppler ultrasound

This paper reports a safe, noninvasive and accurate method for estimating aortic regurgitation. It is possible to detect some quantitative features of the disease from the velocity information obtained from the common carotid artery with the bi-directional velocimeter (model F1) developed by the authors. The diastolic murmur over the aortic region is a quantitative feature of the disease. With the theory of quantification I, both qualitative and quantitative variables were processed. A prediction formula was obtained to assess the degree of aortic regurgitation. The results of such predictions in 15 normal subjects and 25 patients are given. All the patients underwent retrograde aortography or operation to provide comparison with the ultrasonic measurements.