Characterizing tissue calcifications using the color Doppler ultrasound twinkling artifact

Abstract

Rapid Doppler shifts highlight some kidney stones with a rapid change of color in ultrasound imaging in what is termed the “twinkling artifact.” While many hypotheses exist to describe the origin of twinkling, the currently accepted hypothesis is that surface microbubbles are stabilized in the crevices on the surface of the kidney stone. The objective here is to evaluate the distribution of bubbles stabilized on the kidney stone surface and to determine whether other calcified tissues display the twinkling artifact. A Verasonics® research ultrasound system with the Verasonics® L22-14 and Philips/ATL L7-4 and P4-2 transducers was used to quantify twinkling on kidney stones and in minerals deposited by osteogenic stem cells over a range of frequencies. Preliminary results on kidney stones suggest that surface roughness and chemical composition influence the magnitude of twinkling. Osteogenic stem cells were also found to twinkle when minerals were present; correlating twinkling magnitude with the quantity and distribution of mineral deposition is a topic of ongoing research. The appearance of twinkling on even small tissue calcifications indicates ultrasound is very sensitive to mineral deposition and suggests that bubbles may be byproduct of the calcification process.