An initial quantitative comparative study of the axial and lateral spatial resolutions of different ultrasound transducers

Abstract

Background: The axial and lateral spatial resolution of ultrasound transducers is the ability of the scanner to distinguish between two structures that are very close to each other. Ultrasound transducers are devices that generate sound waves and record reflected echoes produced from tissue-interfaces. The spatial resolution of ultrasound transducers can be assessed either quantitatively (using the 'FullWidth-Half-Maximum' (FWHM)) or subjectively ('visually'). This study provides an in-depth comparative evaluation of the spatial resolution of different ultrasound transducers. Objectives: (1) Compare the axial and lateral spatial resolutions of various ultrasound transducers (2) Investigate the effect of spatial resolution with depth for different transducers (3) Investigate the effect of spatial resolution with different frequencies for different type of transducers Research Design: The spatial resolution results are from acceptance tests performed between February 2019 and March 2023 for 14 ultrasound scanners equipped with 51 transducers: 22-linear, 23-curvilinear, and 6-sector. An ultrasound phantom was also used (CIRS model 040GSE). In addition, ImageJ was used to calculate the spatial resolution of the different ultrasound transducers at different depths within the phantom quantitatively. Results: Linear transducers showed the best axial and lateral spatial resolution, especially at higher frequencies. Lateral resolution deteriorated with increasing depth for all transducers, while axial resolution remained approximately constant with depth. Axial resolution was found to be performing better than lateral resolution. Conclusion: A high-frequency transducer achieve optimal spatial resolution. Lateral resolution changes significantly at different depths and as frequency is reduced. Current standards need to be revised. Recommendations: Revise and improve current spatial resolution standards. Moreover, repeating this study by using a larger number of transducers and scanners with various frequencies as well as comparing the spatial resolution for different transducers from different manufacturers.