| Research Background—muscle cramp is one of the common complications caused by cervical or thoracic injury in tetraplegia or paraplegia patients. The literature reported incidence between 65% and 78%. Severe spasm can cause contracture, joint pain, limited activity, influence function, increase the difficulty of nursing, reduce the patient’s quality of life, and the medical cost.The mechanical and pathological characteristics of soft tissues change relative to hardness. Therefore, soft tissue elasticity information plays an important reference value in the diagnosis of the disease; Palpation has become an important technical diagnosis. The hardness of diseased tissue can be as a judge index of benign and malignancy. But this diagnosis method is too subjective, and is limited to larger lesions and superficial organ. The development of ultrasound elastography technology in recent years makes the detection of lesions easier, replaced the use of touch perception of lesion. Ultrasound elasticity imaging first Proposed by J.Ophir et al., in 1991, has been the research hot spot and focus in medical imaging field. It changed soft tissue lesion detection judging from qualitative to quantitative diagnosis. It is very effective in the diagnosis of soft tissue lesions and existing relevant clinical its accuracy is verified by the experiments, the basic principle of elasticity imaging is:Using ultrasonic probe vertically press on the surface of organization, collection the radiofrequency signal of organization respectively before and after the compression, using cross-correlation analysis method which is widely applied in the time delay estimation of to analyze signals and to calculate the displacement field of the organization image, and strain distribution within the organization. As a new method of ultrasonic imaging, ultrasonic elasticity imaging through access to information about the flexibility of organization for imaging. Makes up for the X-ray, ultrasonography (US) and magnetic resonance imaging (MRI), computed tomography (CT) and other traditional medical imaging mode cannot directly provide organization flexibility. For advantages such as noninvasive, simple, cheap and easy to application, ultrasonic elasticity imaging is widely used in clinical, become a research hotspot of current medical elastic imaging. The present study is mainly used in the mammary gland, thyroid gland, liver, prostate and other parts of the diseased tissue.Ultrasonic shear wave elastography technology is based on this principle: organizational produce shear wave vibration after compressed, and shear wave propagation speed in soft tissue is slower more hard tissue. This imaging technology can quantitatively give shear modulus or shear wave velocity of different positions of the organizations. The shear wave velocity of different location can be draw in the form of color figure. Thus, we can quantitatively distinguish benign and malignant tumors.Also the mechanical characteristics and pathological of biological soft tissues change relative to their morphological properties. In recent 20 years, biomechanics researchers dedicated to the morphological parameters of muscles, such as the thickness of the muscle, pinnate Angle and so on. These parameters and the muscular structure characteristic parameters can be used to detect the change of the human body muscle function. So the timely detection of muscle function is of great significance. Scientific studies have shown that Pennation Angle (PA) in the passive or active contraction of muscle is a very important parameter. The definition of Pennation Angle (PA) is the angle between the e muscle fascicle and fascicle and deep aponeurosis, which reflected trigonometric function of axis torque and its component torque. Pennation angle Will shape Angle varies with the ankle dorsiflexion and plantar flexion. Facts have proved that the Achilles tendon moment has a direct relationship with the Pennation Angle. Pinnate Angle change can reflect the muscle function and status.In recent years, researchers try to analyses muscle ultrasonic image through all kinds of algorithms of image processing, in order to obtain these parameters automatically. Zhou and Zheng put forward algorithms calculating pinnate Angle of the muscle fibers based on Revoting Hough Transform method in the ultrasound images, and achieved good effect, further application of the algorithm in the dynamics processing of muscle movements for of pennate Angle. Zhao and Zhang implements automatic tracking and calculation of the pinnate Angle using the Radon Transform method.Research Methods—Considering this situation, we adopted two kinds of methods to detect human gastrocnemius. These two methods are Detection of gastrocnemius muscle hardness based on ultrasonic shear wave elastography and detection gastrocnemius pinnate Angle based on ultrasonic radiofrequency signals.1) Detection of gastrocnemius muscle hardness based on ultrasonic shear wave elastography.i. experimental animalThis research chooses SD rats as the research object. Implementation of 6 rats spinal cord crosscutting method made spasm after spinal cord injury model, for muscle spasms in model group, with only 1 as normal control group, ultrasonic testing the after building 1 month,2 months and 3 months respectivelyii. The preparation of the modelAll experimental rats with 3.6% chloral hydrate intraperitoneal injection of anesthetic dosage (LML/100 g weight), keep the body temperature of rats in 37℃. After anesthesia effect, to the next paragraph to thoracic surgery area for skin, stomach fixed on the operating table, T5-6 of superficial vein for surface positioning marks, centered on T10 spinous process, regular disinfection and spread towels, back in the middle of a longitudinal incision, reveal the T9-T11 spine and vertebral lamina. Removal of T9-T11 spine and lamina, cut free and superficial fascia and skin that covers them. Knife tablets against vertebral spine bone surface on both sides do muscle longitudinally, and eat bone artifacts in addition to the spine, show vertebral plate, avoid injury of spinal cord central arteriovenous, mosquito hemostatic forceps clamps vertebral plate until the epidural space. Be 0.10.3 ml of 1% lidocaine local anesthesia, previously mentioned gently, cut the catheter, microscopic scissors cut spinal cord, and gently sucking, away from the spinal cord. In order to better observe to make sure that the spinal cord completely severed, usually remove spinal cord V 1-2 mm. Local air foam gel fillingultrasonic testingThis research adopts the Supersonic Imagine (Supersonic Imagine, Aixen Provence, France) production of Aixplorer type shear wave elastography real-time ultrasound diagnostic instrument, L4-15 linear array probe,4-15 MHz frequency. After a successful build mound 1 month,2 months and 3 months three time points observation respectively in systolic and diastolic shear wave elastography detection under sedated state, side out of the hind legs in a quiet state.2) Detection gastrocnemius pinnate Angle based on ultrasonic radiofrequency signals.i. Ultrasound systemIn this paper, we adopts open comprehensive ultrasound system (Sonix RP, Ultrasonix, Canada), the system is equipped with a main frames (package letter PIV3.0 GHz dual CPU, hard disk 80 GB of system, and 1 GB of memory),display, a built-in 10 d/a conversion card (sampling frequency 40 MHz), and a center frequency of 10 MHz linear array ultrasonic probe (5-6 db bandwidth～14 MHz).This system adopts open PC platform-Microsoft(?) Visual Studio(?) environment, which can save the ultrasound image, ultrasonic video and ultrasound radiofrequency signal at the same time.ii. Ultrasonic testing and measurementFor normal male subjects, posture, knee into nearly 90 degrees, feet on the floor, with heels for fixed-point, ankle dorsiflexion 40 degrees, keep still. Take Medial Gastrocnemius muscle as the research object, the ultrasonic probe is placed along the longitudinal of the Medial Gastrocnemius muscle. When the display clearly showed plumes of gastrocnemius muscle bundle structure, gather ultrasound radiofrequency signals.By programming the software "muscle morphological analysis software", transferred to the acquisition of gastrocnemius ultrasound radiofrequency signal, the first reconstruction of ultrasound images, ultrasonic signal is sampled down along the longitudinal direction, interpolation along the transverse direction. In order to make the same with ultrasound device showed ultrasound image size (340 x 321).This article to hire an experienced clinical ultrasound doctors manual measure on the reconstructed ultrasonic image based on the radiofrequency signal. The result of Pennation Angle measurement as the "gold standard", and then use this cross-correlation method of automatic measurement Pennation Angle detection, as the result of the experiment, the last two sets of data for comparative analysis.iii. simulation experimentWrite a simulation program, using Field Ⅱ package, then design a test phantom 10 mm x 40 mm x 90 mm, in which 100000 scattering factor random distribution. Linear array ultrasonic probe is 128 crystals, with 3 MHZ center frequency, system sampling frequency is 100 MHZ, then calculated using Field Ⅱ 128 root reflex radiofrequency signals. Image dynamic range was compressed to 40 db. Using the presented cross-correlation method of automatic measurement pinnate Angle detection, measured values compared with the theoretical value of simulation design, and analysis of the effectiveness of the proposed method in this paper.Experimental Results—1) Detection of gastrocnemius muscle hardness based on ultrasonic shear wave elastography.Experiment tested the two rats’health and muscle cramps rats. Muscle structure of normal rats texture are clear, muscle atrophy rat muscle texture structure are of different degrees of disorder, At the same time due to spinal cord injury in rats, muscle atrophy, thinning of the muscle layer, especially the calf muscles. Experimental results of normal rats’ left hind leg calf in the contracting state of the shear modulus value is (37.64±7.70 kPa) is greater than the state of diastolic shear modulus value (14.42±3.76 kPa), left posterior calf muscle spasm group rats in the two months after the building inspection, the contraction state shear modulus value (90.78±15.54 kPa) is greater than the state of diastolic shear modulus value (42.42 the measured value and the mean value with the theoretical value is less than 1°.Using cross-correlation automatic measurement and manual measurement method respectively to obtain gastrocnemius pinnate angle 20.48°±0.47° and 21.20°±0.63°, coefficient of variation CV of the two methods are less than 3%, the root mean square error is less than 1°. Bland-Altman difference method analysis results showed that the consistency of the two methods is good.Research Conclusions—Preliminary results show that the supersonic Shear Wave Elastography can effectively detect muscle atrophy in rats. Results with previous Xiao detection such as biceps consistent.This experiment will be further used to type A botulinum toxin to restore muscle spasm of the role of the study.Shear Wave Elastography imaging technology has been increasingly used in muscle of quantitative evaluation, acquired muscle cross-sectional area, thickness, pinnate Angle and muscle fiber muscle structural parameters, such as long, to assess the change of the muscle function, and the muscles are of important guiding significance to the rehabilitation training. However, these muscles structural parameters measurement at present are mostly manual annotation measurement, the larger muscle ultrasound images and such measurements time-consuming, laborious automatic measurement method research has practical significance. Currently reported gastrocnemius pinnate Angle detection method is mostly based on ultrasonic grayscale image, through analyzing the ultrasound image processing, automatic gain muscle structure parameters, achieved good effect. As previously mentioned ultrasonic gray image is ultrasound radiofrequency signal through a variety of processing, its purpose is to make the image more clear, but, after all, lost a part of the information and ultrasound radiofrequency signal to retain the organization of the original information. If make full use of the information you can get more details. However, the cross-correlation automatic measurement method based on ultrasonic radiofrequency signal also has limitations, such as the bad continuity of muscle fiber, while relying on small pieces of muscle also can determine the direction of the beam, the Pennation Angle calculation, When calculating fascicle length, but produces large error. Because the muscle bundle length can be defined as a bundle of muscle from shallow tendon membrane to the length of the deep tendon membrane. Future research can be based on the results of this paper try to take advantage of a priori knowledge increase search, connect broken fiber search, in order to obtain more accurate muscle bundle length.In view of the present research status, this paper presents a radiofrequency signal based on ultrasonic cross-correlation automatically track beam direction and measure the Angle of pinnate algorithm, the algorithm are verified by the simulation data and the human body data repeatability and consistency of manual measuring method. This method under the condition of serious noise can still be accurate tracking of the gastrocnemius muscle bundle, automatic measurement of gastrocnemius pinnate Angle. On the basis of the study can further improve with automatic measuring parameters such as muscle fascicle length and thickness.In a word, new technology of ultrasound images can improve the accuracy of muscle testing, and can bring more convenience for people prevention than treatment of diseases. |
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