Ultrasonic techniques to assess the properties of hard and soft biological tissues

When an ultrasonic wave is propagated in a medium, propagation parameters, such as speed of sound, attenuation, and backscattering, of different materials corresponding to their own elastic properties would not necessary to be the same. This further allows the application of these parameters to characterize biological tissues, known as ultrasonic tissue characterization. In this study, we tend to use these parameters to assess changes of elastic properties in the bone tissues of different bone masses and the blood during the formation of clot. A 1 MHz ultrasound was applied to assess the tibia bone in the leg. Results showed that backscattered strengths were unable to differentiate properties of the bone from osteoportic and healthy volunteers. However, this dilemma was resolved using the pattern of the probability density function calculated from the envelope of backscattering signals quantified by the signal-to-noise ratio and m parameter from the Nakagami distribution. A 4.5 MHz ultrasound furthermore was applied to detect the clot formation in the porcine blood. Results demonstrated that all three ultrasonic parameters were able to detect change of properties in the blood during its coagulation process. Among results obtained from these parameters, the attenuation coefficient does the least variation and has a 0.94 correlation coefficient with those results of blood viscosity measured using the viscometer. These results demonstrated that ultrasonic techniques are sensitive and feasible to be applied to assess properties of biological tissues in diagnoses.