Medical Physics

Biography

Biography: Julianna C. Simon

Abstract

The “twinkling artifact,” a rapid color change that highlights hard objects in color- Doppler ultrasound, has the potential to improve kidney stone detection; however, its inconsistent appearance has limited its clinical use. Recently published work supports that crevice micro-bubbles on the kidney stone surface cause twinkling [Lu et al. Ultrasound Med Biol. (2013)]; the work has been challenged because bubbles have not been observed. We used high-magnification, high-speed photography to confirm the presence of bubbles on the kidney stone surface in addition to using a programmable Verasonics ultrasound engine and a custombuilt pressure chamber to analyze the effects of ambient pressure on twinkling. The overpressure threshold to diminish twinkling was found to be dependent on a variety of factors, including the stability of twinkling on the stone, the gas content of the liquid and stone, and the number of cycles in the Doppler pulse. In stable twinkling locations, the artifact was found to disappear at pressures as low as 3 atm (absolute); in other locations, twinkling was only diminished when the pressure exceeded 8 atm. When stones were exposed to hypobaric conditions of 0.2 atm, the twinkling amplitude was found to increase. Upon high-speed photography during color-Doppler ultrasound, a bubble with a maximum diameter of 30 μm was found to oscillate. Results support the crevice bubble hypothesis to describe the origin of the twinkling artifact. [Work supported by the National Space Biomedical Research Institute through NASA NCC 9-58 and NIH grants DK043881 and DK092197].