Figure 1b. US images from the cyst phantom. (a) Representative directly scanned US image obtained by scanning perpendicular to the top edge of the phantom (top of image). A region of increased through-transmission (t), or distal acoustic enhancement, is present internal to the simulated cyst. Refractile shadowing (r) is seen at the lateral edges of the area of increased through-transmission. The thick white line indicates the plane of the reconstructed image in b, and the thin white line denoted by the curved arrow indicates the plane of the reconstructed image in c. (b) Coronal US image of the simulated cyst reconstructed from the 3D data set in the plane indicated by the thick white line in a. (c) Coronal US image reconstructed in the plane indicated by the thin white line in a. The increased through-transmission (t) manifests as an oval area of increased echogenicity produced by the simulated cyst in a, and this oval area is surrounded by the hypoechoic refractile artifact (r). The two regions are completely artifactual and were not present in direct coronal scans obtained in the same plane, which showed only the homogeneous speckle pattern of the phantom substrate. Note that in c, the artifacts mimic the appearance of an echogenic lesion with a hypoechoic halo. This appearance in vivo would simulate an echogenic mass.