Passive cavitation detection analysis of color Doppler twinkling from polymethyl methacrylate

The color Doppler twinkling artifact has been attributed to existing microbubbles or cavitation has been reported for objects with rough surfaces like kidney stones, sandpaper, and polymethyl methacrylate (PMMA) bone cement. Passive cavitation detection (PCD) is a method for determining the presence of bubble oscillation from subharmonic, ultraharmonic, and inharmonic components in the Fourier domain. We evaluated multiple PMMA samples with varying twinkling amounts as well as a non-twinkling metal rod. Ultrasound scans were conducted using a Verasonics L11-4v probe on a V1 system from 3–9 MHz Doppler transmit frequency. A Sonic Concepts Y-107 PCD probe connected to a JSR DPR300 pulser/receiver collected data during Doppler ultrasound transmission. The Fourier spectra showed increased magnitude trends in the midband frequency range between the fundamental, f, and second harmonic, 2f, on the twinkling samples compared to non-twinkling metal rod. The midband increase was highest at frequencies that showed the most twinkling. This work indicates that the presence of color Doppler twinkling signal on PMMA gives rise to additional peaks in the Fourier domain, particularly in the midband range. Additionally, as there were no distinct subharmonic peaks, the increased midband magnitudes could be due to cavitation on the rough surfaces of the PMMA.