Modeling Twinkling Artifact in Sonography

The purpose of this work was to re-examine the reasons for the appearance of power doppler artifact referred to as "twinkling" artifact, which is usually observed in hyperechoic regions and which introduces ambiguity in diagnosis. Two key parameters: physical dimensions of the analyzed object and its roughness or irregular shape were initially considered. Several tests were done on Renal and artificially generated stones in order to visualize twinkling artifact and to obtain meaningful results. It is shown that "Radiation force" which is generated by a change in the energy density of an incident acoustic field, causes an oscillation with a frequency equal to the PRF of the sonography device and therefore movement in the object being imaged which will cause the twinkling artifact. This artifact is modeled in the MATLAB programming language. The radiation force factor causing the vibration is applied to a stone which is assumed to be made of some random scatterers. The velocity of the scatterers movement which is causing the appearance of the twinkling artifact is calculated. Later the effects of different vibration parameters on the production of the twinkling artifact are shown. It is shown that the increase in vibration amplitude and frequency, both cause a velocity increase of the object being imaged. The size of the object being imaged has an indirect influence on the production of this artifact, while the roughness of the object intensifies the artifact.