Dai JC, et al. - Researchers undertook a comparative evaluation of the measured kidney stone size and posterior acoustic shadow in clinical ultrasound (US) images. The results displayed that US overestimated the stone size compared to computed tomography (CT). When compared to direct stone measurement, retrospective measurement of the acoustic shadow from the same clinical US images served as a more accurate reflection of true stone size. Researchers determined that maximum stones without a posterior shadow were ≤ 5 mm.