The effect of respiratory gas composition on kidney stone detection with the color Doppler ultrasound twinkling artifact

Abstract

The color Doppler ultrasound twinkling artifact, which is thought to arise from microbubbles on and within the stone, has the potential to improve kidney stone detection in space; however, bubbles are known to be sensitive to the elevated levels of carbon dioxide (CO2) found on space vehicles. Here, we investigate the effect of respiratory gas composition on twinkling in swine implanted with kidney stones. Thirteen swine were initially exposed to either 100% oxygen (O2) or room air and then to air with elevated CO2 at 0.8%, 0.54%, or 0.27%. Stones were imaged with a Verasonics ultrasound system and ATL P4-2 transducer. The 9 swine initially breathing 100% O2 showed a significant reduction in twinkling when exposed to air with elevated CO2, with the degree of decrease in twinkling occurring in the order: 0.8%>0.54%>0.27% CO2. An additional 4 swine were oscillated between air with 0.04% CO2 (normal air) and 0.5% CO2. A reduction in twinkling was observed over the course of the experiment. The effect of respiratory gas composition should be further investigated before using twinkling to diagnose a kidney stone in space. [Work supported by NSBRI through NASA NCC 9-58 and NIH DK043881.]