Unidentified bright objects in the kidney parenchyma.Tiny echogenic foci (arrow) are occasionally seen in the parenchyma on ultrasonography. They are called unidentified bright objects (UBOs). These echogenic foci frequently accompany the reverberation artifact, but posterior shadowing is absent. The possible causes of UBOs in the kidney are tiny stones, tiny cysts, small calyceal diverticulum areas with wall calcification or milk of calcium, calcified arteries, and tiny angiomyolipomas. However, UBOs observed on ultrasonography may not be clearly observed on computed tomography.