Sonographic twinkle artefact in renal calculus detection: Impact of scanning factors in a phantom model

A common clinical use of the twinkle artefact is to detect and confirm renal calcification on ultrasound. There is however variable demonstration of this artefact using newer generation ultrasound machines. The purpose of this study was to assess the impact of altering multiple scanning factors on ultrasound machines from four major manufacturers on the demonstration of the twinkle artefact. Two custom-made phantoms and five-point Likert-like Scale were utilised.

These phantoms contained a range of urinary calculi varying in size, composition, surface contour and depth. The calculi were serially imaged with each ultrasound machine, using manufacturers presets and varying just one imaging factor or parameter at a time. The documented twinkle artefact in the images were subsequently analysed, together with the imaging preset and factor changes that had been made.

Those factors that had the greatest effect in order of impact were colour write priority, colour gain, transducer type, depth of calculus, acoustic power and size of calculus. Variability was also demonstrated between manufacturers.

By isolating the effect of scanning factor changes, their importance and contribution to appearances in the ultrasound image can be assessed. Image interpretation in the clinical setting requires an understanding of the underlying physics, particularly in the evaluation of artefacts associated with renal calculi.