Ultrasound Imaging and the Ring Vortex Phantom: Initial Experience
By Alana Matthews, University of Sheffield
Aim
The ring vortex complex flow phantom is a prototype device designed to challenge and assess quantitative flow imaging technologies. Its use of the ring vortex as its reference flow offers predictable, reproducible and stable vortical dynamics along with flow complexity and well-characterised velocities at the sub-mm scale. This study explored the performance of established clinical ultrasound techniques (B-mode and PW Doppler) in the context of the flow phantom.
Method
Using a GE LOGIQ E9 scanner and 9L-D probe, ring vortex flows seeded with 10μm-diameter polyamide particles were imaged in B-mode. Five different ring speeds were investigated, ranging from 5cm/s-26cm/s. Ten rings were generated at each speed. Cine loops were analysed to determine the translational speeds of the rings and compared to experimental recordings, with further comparison to Laser-PIV benchmark datasets. Intra-ring velocities were measured using PW Doppler with a 1mm gate, positioned down the ring’s length in increments of 2mm. Five measurements were taken for each gate position, with maximum velocities averaged. These values were compared to benchmark Laser-PIV datasets.
Results
Analysis of B-mode images produced values which lay consistently within 10% of both real-time recordings and previously collected Laser-PIV measurements. Measurements of PW Doppler maximum velocities also correlated well to benchmark values across the length of the ring vortex, with higher velocities observed at the vortex cores.
Discussion and Conclusion
This phantom has previously established itself as a dependable flow reference, operating to within tolerances of 10%. The B-mode analysis confirmed anticipated correlation with the test object. PW Doppler traces mirrored benchmark measurements, with the expected biphasic signature observed at the vortex cores. The clear visualisation of the vortices invites further measurements, where future work will include crossmanufacturer and cross-transducer studies, and expansion to more state-of-the-art technologies.